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Versions: 00 01 02 03 04 05 06 07 08 09 10 RFC 4535

Internet Engineering Task Force
INTERNET-DRAFT                                      H Harney (SPARTA)
                                                      U Meth (SPARTA)
                                                 A Colegrove (SPARTA)
                                                 G Gross (IdentAware)
draft-ietf-msec-gsakmp-sec-10.txt   SPARTA, Inc., IdentAware Security
Expires:  November 16, 2005                                  May 2005

     GSAKMP: Group Secure Association Group Management Protocol


Status of this memo

  By submitting this Internet-Draft, each author represents that any
  applicable patent or other IPR claims of which he or she is aware
  have been or will be disclosed, and any of which he or she becomes
  aware will be disclosed, in accordance with Section 6 of BCP 79.

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Abstract

    This document specifies the Group Secure Association
    Key Management Protocol (GSAKMP). The GSAKMP provides a
    security framework for creating and managing cryptographic
    groups on a network.  It provides mechanisms to disseminate
    group policy and authenticate users, rules to perform
    access control decisions during group establishment and
    recovery, capabilities to recover from the compromise of


INTERNET-DRAFT                     GSAKMP                    May 2005
    group members, delegation of group security functions, and
    capabilities to destroy the group.  It also generates group
    keys.






















  Copyright Notice Copyright (c) The Internet Society (2005).  All
                          Rights Reserved.

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Contents
1 Overview                                                          9
  1.1 GSAKMP Overview  . . . . . . . . . . . . . . . . . . . . . .  9
  1.2 Document Organization . . . . . . . . . . . . . . . . . . .  10
2 Terminology                                                      11
3 Security Considerations                                          13
  3.1 Security Assumptions  . . . . . . . . . . . . . . . . . . .  13
  3.2 Related Protocols . . . . . . . . . . . . . . . . . . . . .  15
    3.2.1 ISAKMP  . . . . . . . . . . . . . . . . . . . . . . . .  15
    3.2.2 FIPS Pub 196  . . . . . . . . . . . . . . . . . . . . .  15
    3.2.3 LKH . . . . . . . . . . . . . . . . . . . . . . . . . .  15
    3.2.4 Diffie-Hellman  . . . . . . . . . . . . . . . . . . . .  15
  3.3 Denial of Service (DoS) Attack  . . . . . . . . . . . . . .  16
  3.4 Rekey Availability  . . . . . . . . . . . . . . . . . . . .  16
  3.5 Proof of Trust Hierarchy  . . . . . . . . . . . . . . . . .  16
4 Architecture                                                     17
  4.1 Trust Model . . . . . . . . . . . . . . . . . . . . . . . .  17
    4.1.1 Components  . . . . . . . . . . . . . . . . . . . . . .  17
    4.1.2 GO  . . . . . . . . . . . . . . . . . . . . . . . . . .  18
    4.1.3 GC/KS . . . . . . . . . . . . . . . . . . . . . . . . .  18
    4.1.4 Subordinate GC/KS . . . . . . . . . . . . . . . . . . .  18
    4.1.5 GM  . . . . . . . . . . . . . . . . . . . . . . . . . .  19
    4.1.6 Assumptions . . . . . . . . . . . . . . . . . . . . . .  20
  4.2 Rule-Based Security Policy  . . . . . . . . . . . . . . . .  20
    4.2.1 Access Control  . . . . . . . . . . . . . . . . . . . .  21
    4.2.2 Authorizations for security relevant actions  . . . . .  22
  4.3 Distributed Operation . . . . . . . . . . . . . . . . . . .  22
  4.4 Concept of Operation  . . . . . . . . . . . . . . . . . . .  24
    4.4.1 Assumptions . . . . . . . . . . . . . . . . . . . . . .  24
    4.4.2 Creation of a Policy Token  . . . . . . . . . . . . . .  24
    4.4.3 Creation of a Group . . . . . . . . . . . . . . . . . .  25
    4.4.4 Discovery of GC/KS  . . . . . . . . . . . . . . . . . .  26
    4.4.5 GC/KS registration policy enforcement . . . . . . . . .  26
    4.4.6 GM registration policy enforcement  . . . . . . . . . .  26
    4.4.7 Autonomous Distributed GSAKMP Operations  . . . . . . .  26
5 Group Life Cycle                                                 29
  5.1 Group Definition  . . . . . . . . . . . . . . . . . . . . .  29
  5.2 Group Establishment . . . . . . . . . . . . . . . . . . . .  29
    5.2.1 Standard Group Establishment  . . . . . . . . . . . . .  30
        5.2.1.1 Request to Join . . . . . . . . . . . . . . . . .  32
        5.2.1.2 Key Download  . . . . . . . . . . . . . . . . . .  33
        5.2.1.3 Request to Join Error . . . . . . . . . . . . . .  35
        5.2.1.4 Key Download - Ack/Failure  . . . . . . . . . . .  36
        5.2.1.5 Lack of Ack . . . . . . . . . . . . . . . . . . .  37
    5.2.2 Cookies - Group Establishment with Denial of Service
       Protection . . . . . . . . . . . . . . . . . . . . . . . .  38
    5.2.3 Group Establishment for Receive-Only Members  . . . . .  40
  5.3 Group Maintenance . . . . . . . . . . . . . . . . . . . . .  41

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    5.3.1 Group Management  . . . . . . . . . . . . . . . . . . .  41
        5.3.1.1 Rekey Events  . . . . . . . . . . . . . . . . . .  41
        5.3.1.2 Policy Updates  . . . . . . . . . . . . . . . . .  42
        5.3.1.3 Group Destruction . . . . . . . . . . . . . . . .  42
    5.3.2Leaving a Group  . . . . . . . . . . . . . . . . . . . .  42
        5.3.2.1 Eviction  . . . . . . . . . . . . . . . . . . . .  43
        5.3.2.2 Voluntary Departure without Notice  . . . . . . .  43
        5.3.2.3 De-Registration . . . . . . . . . . . . . . . . .  43
           5.3.2.3.1 Request to Depart  . . . . . . . . . . . . .  43
           5.3.2.3.2 Departure_Response . . . . . . . . . . . . .  44
           5.3.2.3.3 Departure_ACK  . . . . . . . . . . . . . . .  46
6 Security Suite                                                   47
  6.1 Assumptions . . . . . . . . . . . . . . . . . . . . . . . .  47
  6.2 Definition Suite 1  . . . . . . . . . . . . . . . . . . . .  47
7 GSAKMP Payload Structure                                         48
  7.1 GSAKMP Header . . . . . . . . . . . . . . . . . . . . . . .  49
    7.1.1 GSAKMP Header Structure . . . . . . . . . . . . . . . .  49
        7.1.1.1 GroupID Structure . . . . . . . . . . . . . . . .  52
           7.1.1.1.1 UTF-8  . . . . . . . . . . . . . . . . . . .  52
           7.1.1.1.2 Octet String . . . . . . . . . . . . . . . .  52
           7.1.1.1.3 IPv4 Group Identifier  . . . . . . . . . . .  53
           7.1.1.1.4 IPv6 Group Identifier  . . . . . . . . . . .  53
    7.1.2 GSAKMP Header Processing  . . . . . . . . . . . . . . .  54
  7.2 Generic Payload Header  . . . . . . . . . . . . . . . . . .  56
    7.2.1 Generic Payload Header Structure  . . . . . . . . . . .  56
    7.2.2 Generic Payload Header Processing . . . . . . . . . . .  57
  7.3 Policy Token Payload  . . . . . . . . . . . . . . . . . . .  57
    7.3.1 Policy Token Payload Structure  . . . . . . . . . . . .  57
    7.3.2 Policy Token Payload Processing . . . . . . . . . . . .  58
  7.4 Key Download Payload  . . . . . . . . . . . . . . . . . . .  59
    7.4.1 Key Download Payload Structure  . . . . . . . . . . . .  59
        7.4.1.1 Key Datum Structure . . . . . . . . . . . . . . .  61
        7.4.1.2 Rekey Array Structure . . . . . . . . . . . . . .  63
    7.4.2 Key Download Payload Processing . . . . . . . . . . . .  64
  7.5 Rekey Event Payload . . . . . . . . . . . . . . . . . . . .  65
    7.5.1 Rekey Event Payload Structure . . . . . . . . . . . . .  65
        7.5.1.1 Rekey Event Header Structure  . . . . . . . . . .  67
        7.5.1.2 Rekey Event Data Structure  . . . . . . . . . . .  68
           7.5.1.2.1 Key Package Structure  . . . . . . . . . . .  69
    7.5.2 Rekey Event Payload Processing  . . . . . . . . . . . .  69
  7.6 Identification Payload  . . . . . . . . . . . . . . . . . .  72
    7.6.1 Identification Payload Structure  . . . . . . . . . . .  72
        7.6.1.1 ID_U_NAME Structure . . . . . . . . . . . . . . .  75
    7.6.2 Identification Payload Processing . . . . . . . . . . .  75
        7.6.2.1 ID_U_NAME Processing  . . . . . . . . . . . . . .  76
  7.7 Certificate Payload . . . . . . . . . . . . . . . . . . . .  77
    7.7.1 Certificate Payload Structure . . . . . . . . . . . . .  77
    7.7.2 Certificate Payload Processing  . . . . . . . . . . . .  78
  7.8 Signature Payload . . . . . . . . . . . . . . . . . . . . .  79
    7.8.1 Signature Payload Structure . . . . . . . . . . . . . .  79

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    7.8.2 Signature Payload Processing  . . . . . . . . . . . . .  81
  7.9 Notification Payload  . . . . . . . . . . . . . . . . . . .  82
    7.9.1 Notification Payload Structure  . . . . . . . . . . . .  82
        7.9.1.1 Notification Data - Acknowledgment (ACK) Payld Typ 85
        7.9.1.2 Notification Data - Cookie_Required and Cookie
            Payload Type. . . . . . . . . . . . . . . . . . . . .  85
        7.9.1.3 Notification Data - Mechanism Choices Payload Type 86
        7.9.1.4 Notification Data - IPv4 and IPv6 Value Payld Types87
    7.9.2 Notification Payload Processing . . . . . . . . . . . .  87
  7.10 Vendor ID Payload  . . . . . . . . . . . . . . . . . . . .  88
    7.10.1 Vendor ID Payload Structure  . . . . . . . . . . . . .  88
    7.10.2 Vendor ID Payload Processing . . . . . . . . . . . . .  89
  7.11 Key Creation Payload . . . . . . . . . . . . . . . . . . .  90
    7.11.1 Key Creation Payload Structure . . . . . . . . . . . .  90
    7.11.2 Key Creation Payload Processing  . . . . . . . . . . .  91
  7.12 Nonce Payload  . . . . . . . . . . . . . . . . . . . . . .  92
    7.12.1 Nonce Payload Structure  . . . . . . . . . . . . . . .  92
    7.12.2 Nonce Payload Processing . . . . . . . . . . . . . . .  93
8 GSAKMP State Diagram                                             94
9 IANA Considerations                                              97
  9.1 IANA Port Number Assignment . . . . . . . . . . . . . . . .  97
  9.2 Initial IANA Registry Contents  . . . . . . . . . . . . . .  97
10 Acknowledgments                                                 98
11 References                                                      98
  11.1 Normative References . . . . . . . . . . . . . . . . . . .  98
  11.2 Informative References . . . . . . . . . . . . . . . . . .  99
A APPENDIX A -- LKH Information                                   101
  A.1 LKH Overview . . . . . . . . . . . . . . . . . . . . . . .  101
  A.2 LKH and GSAKMP . . . . . . . . . . . . . . . . . . . . . .  102
  A.3 LKH Examples . . . . . . . . . . . . . . . . . . . . . . .  103
    A.3.1 LKH Key Download Example . . . . . . . . . . . . . . .  103
    A.3.2 LKH Rekey Event Example  . . . . . . . . . . . . . . .  104
B APPENDIX B -- Change History (To Be Removed from RFC)           105
  B.1 Changes from GSAKMP-00 to GSAKMP-01 February 2003  . . . .  105
  B.2 Changes from GSAKMP-01 to GSAKMP-02 June 2003  . . . . . .  106
  B.3 Changes from GSAKMP-02 to GSAKMP-03 August 2003  . . . . .  106
  B.4 Changes from GSAKMP-03 to GSAKMP-04 October 2003 . . . . .  106
  B.5 Changes from GSAKMP-04 to GSAKMP-05 February 2004  . . . .  111
    B.5.1Major Modification/Reorganization of Specification  . .  111
        B.5.1.1Key Terms and Payloads Modified . . . . . . . . .  111
    B.5.2Modification By Section . . . . . . . . . . . . . . . .  112
  B.6 Changes from GSAKMP-05 to GSAKMP-06 May 2004 . . . . . . .  115
  B.7 Changes from GSAKMP-06 to GSAKMP-07 December 2004  . . . .  120
  B.8 Changes from GSAKMP-07 to GSAKMP-08 March 2005 . . . . . .  121
  B.9 Changes from GSAKMP-08 to GSAKMP-09 April 2005 . . . . . .  121
  B.10Changes from GSAKMP-09 to GSAKMP-10 May 2005 . . . . . . .  122
Authors' Addresses                                                122

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Full Copyright Statement                                          123
IPR Considerations                                                123

























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List of Figures
  1   GSAKMP Ladder Diagram . . . . . . . . . . . . . . . . . . .  31
  2   GSAKMP Ladder Diagram with Cookies  . . . . . . . . . . . .  39
  3   GSAKMP Header Format  . . . . . . . . . . . . . . . . . . .  49
  4   GroupID UTF-8 Format  . . . . . . . . . . . . . . . . . . .  52
  5   GroupID Octet String Format . . . . . . . . . . . . . . . .  53
  6   GroupID IPv4 Format . . . . . . . . . . . . . . . . . . . .  53
  7   GroupID IPv6 Format . . . . . . . . . . . . . . . . . . . .  54
  8   Generic Payload Header  . . . . . . . . . . . . . . . . . .  56
  9   Policy Token Payload Format . . . . . . . . . . . . . . . .  57
  10  Key Download Payload Format . . . . . . . . . . . . . . . .  59
  11  Key Download Data Item Format . . . . . . . . . . . . . . .  60
  12  Key Datum Format  . . . . . . . . . . . . . . . . . . . . .  62
  13  Rekey Array Structure Format  . . . . . . . . . . . . . . .  64
  14  Rekey Event Payload Format  . . . . . . . . . . . . . . . .  66
  15  Rekey Event Header Format . . . . . . . . . . . . . . . . .  67
  16  Rekey Event Data Format . . . . . . . . . . . . . . . . . .  68
  17  Key Package Format  . . . . . . . . . . . . . . . . . . . .  69
  18  Identification Payload Format . . . . . . . . . . . . . . .  72
  19  Unencoded Name (ID-U-NAME) Format . . . . . . . . . . . . .  75
  20  Certificate Payload Format  . . . . . . . . . . . . . . . .  77
  21  Signature Payload Format  . . . . . . . . . . . . . . . . .  79
  22  Notification Payload Format . . . . . . . . . . . . . . . .  82
  23  Notification Data - Acknowledge Payload Type Format . . . .  85
  24  Notification Data - Mechanism Choices Payload Type Format .  86
  25  Vendor ID Payload Format  . . . . . . . . . . . . . . . . .  88
  26  Key Creation Payload Format . . . . . . . . . . . . . . . .  90
  27  Nonce Payload Format  . . . . . . . . . . . . . . . . . . .  92
  28  GSAKMP State Diagram  . . . . . . . . . . . . . . . . . . .  94
  29  A. 1:  LKH Tree  . . . . . . . . . . . . . . . . . . . . .  101
  30  A. 2:  GSAKMP LKH Tree . . . . . . . . . . . . . . . . . .  102










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List of Tables
  1   Request to Join (RTJ) Message Definition  . . . . . . . . .  32
  2   Key Download (KeyDL) Message Definition . . . . . . . . . .  33
  3   Request to Join Error (RTJ-Err) Message Definition  . . . .  35
  4   Key Download - Ack/Failure (KeyDL-A/F) Message Definition .  36
  5   Lack of Ack (LOA) Message Definition  . . . . . . . . . . .  37
  6   Cookie Download Message Definition  . . . . . . . . . . . .  39
  7   Rekey Event Message Definition  . . . . . . . . . . . . . .  42
  8   Request_to_Depart (RTD) Message Definition  . . . . . . . .  44
  9   Departure_Response (DR) Message Definition  . . . . . . . .  45
  10  Departure_ACK (DA) Message Definition . . . . . . . . . . .  46
  11  Group Identification Types  . . . . . . . . . . . . . . . .  49
  12  Payload Types . . . . . . . . . . . . . . . . . . . . . . .  50
  13  Exchange Types  . . . . . . . . . . . . . . . . . . . . . .  51
  14  Policy Token Types  . . . . . . . . . . . . . . . . . . . .  58
  15  Key Download Data Item Types  . . . . . . . . . . . . . . .  61
  16  Cryptographic Key Types . . . . . . . . . . . . . . . . . .  63
  17  Rekey Event Types . . . . . . . . . . . . . . . . . . . . .  66
  18  Identification Classification . . . . . . . . . . . . . . .  73
  19  Identification Types  . . . . . . . . . . . . . . . . . . .  74
  20  Certificate Payload Types . . . . . . . . . . . . . . . . .  78
  21  Signature Types . . . . . . . . . . . . . . . . . . . . . .  80
  22  Notification Types  . . . . . . . . . . . . . . . . . . . .  84
  23  Acknowledgment Types  . . . . . . . . . . . . . . . . . . .  85
  24  Mechanism Types . . . . . . . . . . . . . . . . . . . . . .  86
  25  Nonce Hash Types  . . . . . . . . . . . . . . . . . . . . .  87
  26  Types Of Key Creation Information . . . . . . . . . . . . .  91
  27  Nonce Types . . . . . . . . . . . . . . . . . . . . . . . .  93
  28  GSAKMP States . . . . . . . . . . . . . . . . . . . . . . .  95
  29  State Transition Events . . . . . . . . . . . . . . . . . .  96











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1 Overview


  This protocol provides policy distribution, policy enforcement,
  key distribution, and key management for cryptographic groups.
  Cryptographic groups all share a common (set of) key(s) for data
  processing.  These keys all support a system level security policy
  so that the cryptographic group can be trusted to perform security
  relevant services.

  The ability of a group of entities to perform security services
  requires that a Group Secure Association (GSA) be established.  A
  GSA ensures that there is a common "group level" definition of
  security policy and enforcement of that policy.  The distribution of
  cryptographic keys is a mechanism utilizing the group level policy
  enforcements.



1.1 GSAKMP Overview


  Protecting group information requires the definition of a security
  policy and the enforcement of that policy by all participating
  parties.  Controlling dissemination of cryptographic key is the
  primary mechanism to enforce the access control policy.  It is the
  primary purpose of GSAKMP to generate and disseminate a group key in
  a secure fashion.

  GSAKMP separates group security management functions and
  responsibilities into three major roles:  1) Group Owner, 2) Group
  Controller Key Server, and 3) Group Member.  The Group Owner is
  responsible for creating the security policy rules for a group
  and expressing these in the Policy Token.  The Group Controller
  Key Server (GC/KS) is responsible for creating and maintaining
  the keys and enforcing the group policy by granting access to
  potential Group Members (GM) in accordance with the Policy Token.
  To enforce a group's policy the potential Group Members need to have
  knowledge of the access control policy for the group, an unambiguous
  identification of any party downloading keys to them, and verifiable
  chains of authority for key download.  In other words, the Group
  Members need to know who potentially will be in the group and to
  verify that the key disseminator is authorized to act in that
  capacity.

  In order to establish a Group Secure Association (GSA) to support
  these activities, the identity of each party in the process MUST be
  unambiguously asserted and authenticated.  It MUST also be verified
  that each party is authorized, as defined by the Policy Token, to
  function in his role in the protocol (e.g., GM or GC/KS).

  The security features of the establishment protocol for the GSA

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  include



   -  Group policy identification

   -  Group policy dissemination

   -  GM to GC/KS SA establishment to protect data

   -  Access control checking


  GSAKMP provides mechanisms for cryptographic group creation and
  management.  Other protocols may be used in conjunction with GSAKMP
  to allow various applications to create functional groups according
  to their application-specific requirements.  For example, in a
  small-scale video conference the organizer might use a session
  invitation protocol like SIP [RFC 3261] to transmit information
  about the time of the conference, the address of the session, and
  the formats to be used.  For a large-scale video transmission, the
  organizer might use a multicast announcement protocol like SAP [RFC
  2974].

  This document describes a useful default set of security algorithms
  and configurations, Security Suite 1.  This suite allows an entire
  set of algorithms and settings to be described to prospective group
  members in a concise manner.  Other security suites MAY be defined as
  needed and MAY be disseminated during the out-of-band announcement of
  a group.

  Distributed architectures support large scale cryptographic groups.
  Secure distributed architectures require authorized delegation of GSA
  actions to network resources.  The fully specified Policy Token is
  the mechanism to facilitate this authorization.  Transmission of this
  Policy Token to all joining GMs allows GSAKMP to securely support
  distributed architectures and multiple data sources.

  Many-to-many group communications require multiple data sources.
  Multiple data sources are supported because the inclusion of a policy
  token and policy payloads allow group members to review the group
  access control and authorization parameters.  This member review
  process gives each member (each potential source of data), the
  ability to determine if the group provides adequate protection for
  member data.


1.2 Document Organization


  The remainder of this document is organized as follows:  Section 2
  presents the terminology and concepts used to present the

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  requirements of this protocol.  Section 3 outlines the security
  considerations with respect to GSAKMP. Section 4 defines the
  architecture of GSAKMP. Section 5 describes the group management
  life-cycle.  Section 6 describes the Security Suite Definition.
  Section 7 presents the message types and formats used during each
  phase of the life-cycle.  Section 8 defines the state diagram for the
  protocol.



2 Terminology


  The following terminology is used throughout the GSAKMP paper.


  Requirements Terminology:   Keywords "MUST", "MUST NOT", "REQUIRED",
      "SHOULD", "SHOULD NOT" and "MAY" that appear in this document are
      to be interpreted as described in [RFC 2119].

  Certificate:   A data structure used to verifiably bind an identity
      to a cryptographic key (e.g., X.509v3).

  Compromise Recovery:   The act of recovering a secure operating
      state after detecting that a group member cannot be trusted.
      This can be accomplished by rekey.

  Cryptographic Group:   A set of entities sharing or desiring to
      share a GSA.

  Group Controller Key Server (GC/KS):  A group member with authority
      to perform critical protocol actions including creating and
      distributing keys and building and maintaining the rekey
      structures.  As the group evolves, it MAY become desirable to
      have multiple controllers perform these functions.

  Group Member (GM):  A Group Member is any entity with access to
      the group keys.  Regardless of how a member becomes a part of
      the group or how the group is structured, GMs will perform the
      following actions:


       -  Authenticate and validate the identities and the
          authorizations of entities performing security relevant
          actions

       -  Accept group keys from the GC/KS

       -  Request group keys from the GC/KS

       -  Enforce the cooperative group policies as stated in the


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          group policy token

       -  Perform peer review of key management actions

       -  Manage local key



  Group Owner (GO):  A Group Owner is the entity authorized for
      generating and modifying an authenticatable policy token for the
      group, and notifying the GC/KS to start the group.

  Group Policy:   The Group Policy completely describes the protection
      mechanisms and security relevant behaviors of the group.  This
      policy MUST be commonly understood and enforced by the group for
      coherent secure operations.

  Group Secure Association (GSA):  A GSA is a logical association of
      users or hosts that share cryptographic key(s).  This group may
      be established to support associations between applications or
      communication protocols.

  Group Traffic Protection Key (GTPK):  The key or keys created for
      protecting the group data.

  Key Datum:   A single key and its associated attributes for its
      usage.

  Key Encryption Key (KEK):  Key used in an encryption mechanism for
      wrapping another key.

  Key Handle:   The identifier of a particular instance or version of
      a key.

  Key ID:  The identifier for a key that MUST stay static throughout
      the life-cycle of this key.

  Key Package:   Type/Length/Data format containing a Key Datum.

  Logical Key Hierarchy (LKH) Array:   The group of keys created to
      facilitate the LKH compromise recovery methodology.

  Policy Token (PT):  The policy token is a data structure used to
      disseminate group policy and the mechanisms to enforce it.  The
      policy token is issued and signed by an authorized Group Owner.
      Each member of the group MUST verify the token, meet the group
      join policy, and enforce the policy of the group, (e.g., encrypt
      application data with a specific algorithm).  The group policy
      token will contain a variety of information including:


       -  GSAKMP protocol version

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       -  Key creation method

       -  Key dissemination policy

       -  Access control policy

       -  Group authorization policy

       -  Compromise recovery policy

       -  Data protection mechanisms



  Rekey:   The act of changing keys within a group as defined by
      policy.

  Rekey Array:   The construct that contains all the rekey information
      for a particular member.

  Rekey Key:   The KEK used to encrypt keys for a subset of the group.

  Subordinate Group Controller Key Server (S-GC/KS):  Any group member
      having the appropriate processing and trust characteristics as
      defined in the group policy that has the potential to act as a
      S-GC/KS. This will allow the group processing and communication
      requirements to be distributed equitably throughout the network
      (e.g., distribute group key).  The optional use of GSAKMP with
      Subordinate Group Controller Key Servers will be documented in a
      separate paper.

  Wrapping KeyID:  - The Key ID of the key used to wrap a Key Package.

  Wrapping Key Handle:   The key handle of the Key used to wrap the
      Key Package.


3 Security Considerations


  In addition to the specification of GSAKMP itself, the security of an
  implemented GSAKMP system is affected by supporting factors.  These
  are discussed here.


3.1 Security Assumptions


  The following assumptions are made as the basis for the security
  discussion



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  1.  GSAKMP assumes its supporting platform can provide the process
      and data separation services at the appropriate assurance level
      to support its groups.

  2.  The key generation function of the cryptographic engine will only
      generate strong keys.

  3.  The security of this protocol is critically dependent on the
      randomness of the randomly chosen parameters.  These should be
      generated by a strong random or properly seeded pseudo-random
      source [RFC 1750].

  4.  The security of a group can be affected by the accuracy of the
      system clock.  Therefore, GSAKMP assumes that the system clock
      is close to correct time.  If a GSAKMP host relies on a network
      time service to set its local clock, then that protocol must
      be secure against attackers.  The maximum allowable clock skew
      across the group membership:  policy configurable, with a default
      of 5 minutes.

  5.  As described in the message processing section, the use of the
      Nonce value used for freshness along with a signature is the
      mechanism used to foil replay attacks.  In any use of Nonces
      a core requirement is unpredictability of the nonce, from an
      attackers viewpoint.  The utility of the Nonce relies on the
      inability of an attacker to either reuse old Nonces or predict
      the Nonce value.

  6.  GSAKMP does not provide identity protection.

  7.  The group's multicast routing infrastructure is not secured
      by GSAKMP, and therefore it may be possible to create a
      multicast flooding denial of service attack using the multicast
      application's data stream.  Either an insider (i.e.  a rogue GM)
      or a non-member could direct the multicast routers to spray data
      at a victim system.

  8.  The compromise of a S-GC/KS forces the re-registration of all GMs
      under its control.  The GM recognizes this situation by finding
      the S-GC/KSs certificate on a CRL as supplied by a service such
      as LDAP.

  9.  The compromise of the GO forces termination of the group.  The
      GM recognizes this situation by finding the GOs certificate on a
      Certificate Revocation List (CRL) as supplied by a service such
      as LDAP.







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3.2 Related Protocols


  GSAKMP derives from two (2) existing protocols:  ISAKMP [MSST98] and
  FIPS Pub 196 [FIPS 196].  In accordance with Security Suite 1, GSAKMP
  implementations MUST support the use of Diffie-Hellman key exchange
  [DH77] for two party key creation and MAY use Logical Key Hierarchy
  (LKH) [RFC 2627] for rekey capability.


3.2.1 ISAKMP


  ISAKMP provides a flexible structure of chained payloads in support
  of authenticated key exchange and security association management
  for pairwise communications.  GSAKMP builds upon these features
  to provide policy enforcement features in support of diverse group
  communications.


3.2.2 FIPS Pub 196


  FIPS Pub 196 provides a mutual authentication protocol.


3.2.3 LKH


  When group policy dictates that a recovery of the group security
  is necessary after the discovery of the compromise of a GM, then
  GSAKMP relies upon a rekey capability, i.e., LKH, to enable group
  recovery after a compromise [RFC 2627].  This is optional since in
  many instances it may be better to destroy the compromised group and
  rebuild a secure group.


3.2.4 Diffie-Hellman


  A Group may rely upon two party key creation mechanisms, i.e.,
  Diffie-Hellman, to protect sensitive data during download.

  The information in this section is borrowed heavily from [IKEv2] as
  this protocol has already worked through similar issues and GSAKMP
  is using the same security considerations for its purposes.  This
  section will contain paraphrased sections of [IKEv2] modified for
  GSAKMP as appropriate.

  The strength of a key derived from a Diffie-Hellman exchange using
  specific p and g values depends on the inherent strength of the


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  values, the size of the exponent used, and the entropy provided by
  the random number generator used.  A strong random number generator
  combined with the recommendations from [RFC 3526] on Diffie-Hellman
  exponent size is recommended as sufficient.  An implementation should
  make note of this conservative estimate when establishing policy and
  negotiating security parameters.

  Note that these limitations are on the Diffie-Hellman values
  themselves.  There is nothing in GSAKMP which prohibits using
  stronger values nor is there anything which will dilute the strength
  obtained from stronger values.  In fact, the extensible framework of
  GSAKMP encourages the definition of more Security Suites.

  It is assumed that the Diffie-Hellman exponents in this exchange
  are erased from memory after use.  In particular, these exponents
  MUST NOT be derived from long-lived secrets such as the seed to a
  pseudo-random generator that is not erased after use.



3.3 Denial of Service (DoS) Attack


  This GSAKMP specification addresses the mitigation for a distributed
  IP spoofing attack (a subset of possible DoS attacks) in section
  5.2.2, Cookies.


3.4 Rekey Availability


  In addition to GSAKMP having the capability to do rekey operations,
  GSAKMP MUST also have the capability to make this rekey information
  highly available to GMs.  The necessity of GMs receiving rekey
  messages, requires the use of methods to increase the likelihood
  of receipt of Rekey Messages.  These methods MAY include multiple
  transmissions of the rekey message, posting of the rekey message on
  a bulletin board, etc.  Compliant GSAKMP implementations supporting
  the optional rekey capability MUST support retransmission of rekey
  messages.


3.5 Proof of Trust Hierarchy


  As defined by [HCM], security group policy MUST be defined in a
  verifiable manner.  GSAKMP anchors its trust in the creator of the
  group, the GO.

  The Policy Token explicitly defines all the parameters that create a
  secure verifiable infrastructure.  The GSAKMP Policy Token is issued


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  and signed by the GO. The GC/KS will verify it and grant access to
  GMs only if they meet the rules of the Policy Token.  The new GMs
  will accept access only if 1) the token verifies, 2) the GC/KS is an
  authorized disseminator, and 3) the group mechanisms are acceptable
  for protecting the GMs data.



4 Architecture


  This architecture presents a trust model for GSAKMP and a concept of
  operations for establishing a trusted distributed infrastructure for
  group key and policy distribution.

  GSAKMP conforms to the IETF MSEC architectural concepts as specified
  in the MSEC Architecture document [RFC 3740].  GSAKMP uses the MSEC
  components to create a trust model for operations that implement the
  security principles of mutual suspicion and trusted policy creation
  authorities.


4.1 Trust Model


4.1.1 Components


  The trust model contains four key components:


   -  Group Owners (GO),

   -  Group Controllers / Key Servers (GC/KS),

   -  Subordinate GC/KS (S-GC/KS), and

   -  Group Members (GM).


  The goal of the GSAKMP trust model is to derive trust from a common
  trusted policy creation authority for a group.  All security
  relevant decisions and actions implemented by GSAKMP are based on
  information that ultimately is traceable to and verified by the
  trusted policy creation authority.  There are two trusted policy
  creation authorities for GSAKMP, the GO (policy creation authority)
  and the PKI root that allows us to verify the GO.






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4.1.2 GO


  The GO is the policy creation authority for the group.  The GO has a
  well defined identity that is relevant to the group.  That identity
  can be of a person or of a group trusted component.  All potential
  entities in the group have to recognize the GO as the individual with
  authority to specify policy for the group.

  The policy reflects the protection requirements of the data in a
  group.  Ultimately, the data and the application environment drives
  the security policy for the group.

  The GO has to determine the security rules and mechanisms that are
  appropriate for the data being protected by the group keys.  All this
  information is captured in a policy token (PT). The GO creates the PT
  and signs it.


4.1.3 GC/KS


  The GC/KS is authorized to perform several functions:  key creation,
  key distribution, rekey, and group membership management.

  As key creation authority, the GC/KS will create the set of keys for
  the group.  These keys include the Group Traffic Protection Keys
  (GTPK) and first tier rekey keys.  There may be second tier rekey
  trees if a distributed rekey management structure is required for the
  group.

  As the key distribution (registration) authority, it has to notify
  the group of its location for registration services.  The GC/KS will
  have to enforce key access control as part of the key distribution
  and registration processes.

  As the group rekey authority, it performs rekey in order to change
  the group's GTPK. Change of the GTPK limits the exposure of data
  encrypted with any single GTPK.

  Finally, as group membership management authority, the GC/KS can
  manage the group membership (registration, eviction, de-registration,
  etc.).  This may be done in part by using key tree approaches such as
  Logical Key Hierarchies (LKH), as an optional approach.


4.1.4 Subordinate GC/KS


  A subordinate GC/KS is used to distribute the GC/KS functionality
  across multiple entities.  The S-GC/KS will have all the authorities


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  of the GC/KS except one:  it will not create the GTPK. It is assumed
  here that the group will transmit data with a single GTPK at any one
  time.  This GTPK comes from the GC/KS.

  Note that relative to the GC/KS, the S-GC/KS is responsible for
  an additional security check:  the S-GC/KS must register as a
  member with the GC/KS, and during that process it has to verify the
  authority of the GC/KS.


4.1.5 GM


  The GM has two jobs - make sure all security relevant actions are
  authorized and properly use the group keys.  During the registration
  process, the GM will verify that the PT is signed by a recognized GO.
  In addition, it will verify that the GC/KS or S-GC/KS engaged in the
  registration process is authorized, as specified in the PT. If rekey
  and new PTs are distributed to the group, the GM will verify that
  they are proper and all actions are authorized.

  The GM is granted access to group data through receipt of the group
  keys This carries along with it a responsibility to protect the key
  from unauthorized disclosure.

  GSAKMP does not offer any enforcement mechanisms to control which
  GM are multicast speakers at a given moment.  This policy and its
  enforcement depend on the multicast application and its protocols.
  However, GSAKMP does allow a group to have one of three Group
  Security Association multicast speaker configurations:



   -  There is a single GM authorized to be the group's speaker.  There
      is one multicast application SA allocated by the GO in support
      of that speaker.  The PT initializes this multicast application
      SA and identifies the GM that has been authorized to be speaker.
      All GM share a single TPK with that GM speaker.  Sequence number
      checking for anti-replay protection is feasible and enabled
      by default.  This is the default group configuration.  GSAKMP
      implementations MUST support this configuration.

   -  The GO authorizes all of the GM to be a group speaker.  The
      GO allocates one multicast application SA in support of these
      speakers.  The PT initializes this multicast application SA and
      indicates that any GM can be a speaker.  All of the GM share
      a single TPK and other SA state information.  Consequently,
      some SA security features such as sequence number checking
      for anti-replay protection can not be supported by this
      configuration.  GSAKMP implementations MUST support this group
      configuration.


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   -  The GO authorizes a subset of the GM to be a group speaker
      (which may be the subset comprised of all GM). The GO allocates
      a distinct multicast application SA for each of these speakers.
      The PT identifies the authorized speakers, and initializes
      each of their multicast application Security Associations.
      The speakers still share a common TPK across their SA, but
      each speaker has a separate SA state information instance
      at every peer GM. Consequently, this configuration supports
      SA security features such as sequence number checking for
      anti-replay protection or source authentication mechanisms that
      require per speaker state at the receiver.  The drawback of
      this configuration is that it does not scale to a large numbers
      of speakers.  GSAKMP implementations MAY support this group
      configuration.



4.1.6 Assumptions


  The assumptions for this trust model are:


   -  the GCKS is assumed to be never compromised,

   -  the GO is assumed to be never compromised,

   -  the PKI, subject to certificate validation, is assumed to be
      trustworthy,

   -  The GO is capable of creating a security policy to meet the
      demands of the group,

   -  the compromises of a group member will be detectable and reported
      to the GO in a trusted manner,

   -  the subsequent recovery from a compromise will deny inappropriate
      access to protected data to the compromised member,

   -  no security relevant actions depend on a precise network time,

   -  that there is confidentiality, integrity, multicast source
      authentication and anti-replay protection mechanisms for all
      GSAKMP control messages.


4.2 Rule-Based Security Policy


  The trust model for GSAKMP revolves around the definition and
  enforcement of the security policy.  In fact, the use of the key is


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  only relevant, in a security sense, if it represents the successful
  enforcement of the group security policy.

  Group operations lend themselves to rule-based security policy.  The
  need for distribution of data to many endpoints often leads to the
  defining of those authorized endpoints based on rules.  For example,
  all IETF attendees at a given conference could be defined as a single
  group.

  If the security policy rules are to be relevant, they must be coupled
  with validation mechanisms.  The core principle here is that the
  level of trust one can afford a security policy is exactly equal to
  the level of trust one has in the validation mechanism used to prove
  that policy.  For example, if all IETF attendees are allowed in then
  they could register their identity from their certificate upon check
  in to the meetings.  That certificate is issued by a trusted policy
  creation authority (PKI root) that is authorized to identify someone
  as being an IETF attendee.  The GO could make admittance rules to
  the IETF group based on the identity certificates issued from trusted
  PKIs.

  In GSAKMP, every security policy rule is coupled with an explicit
  validation mechanism.  For interoperability considerations, GSAKMP
  requires its supporting PKI implementations MUST be compliant to RFC
  3280.

  If a GM public key certificate is revoked, then the entity that
  issues that revocation SHOULD signal the GO, so that the GO can
  expel that GM. The method that signals this event to the GO is not
  standardized by this specification.

  A direct mapping of rule to validation mechanism allows the use of
  multiple rules and PKIs to create groups.  This allows a GO to define
  a group security policy that spans multiple PKI domains, each with
  their own Certificate Authority public key certificate.


4.2.1 Access Control


  The access control policy for the group keys is equivalent to the
  access control policy for the multicast application data the keys are
  protecting.

  In a group, each data source is responsible for ensuring that the
  access to the source's data is appropriate.  This implies that every
  data source should have knowledge of the access control policy for
  the group keys.

  In the general case, GSAKMP offers a suite of security services to
  its applications, and does not prescribe how they use those services.


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  GSAKMP supports the creation of GSAs with multiple data sources.  It
  also supports architectures where the GC/KS is not itself a data
  source.  In the multiple data source architectures GSAKMP requires
  that the access control policy is precisely defined and distributed
  to each data source.  The reference for this data structure is the
  GSAKMP Policy Token [ref CH02].


4.2.2 Authorizations for security relevant actions


  A critical aspect of the GSAKMP trust model is the authorization
  of security relevant actions.  Security relevant actions include -
  download of group key, rekey, and PT creation and updates.  These
  actions could be used to disrupt the secure group and all entities
  in the group must verify that they were instigated by authorized
  entities within the group.



4.3 Distributed Operation


  Scalability is a core feature of GSAKMP. GSAKMP's approach to
  scalable operations is the establishment of S-GC/KSs.  This allows
  the GSAKMP systems to distribute the workload of setting up and
  managing very large groups.

  Another aspect of distributed S-GC/KS operations is the enabling of
  local management authorities.  In very large groups, subordinate
  enclaves may be best suited to provide local management of the
  enclaves' group membership, due to a direct knowledge of the group
  members.

  One of the critical issues involved with distributed operation is the
  discovery of the security infrastructure location and security suite.
  Many group applications that have dynamic interactions must "find"
  each other to operate.  The discovery of the security infrastructure
  is just another piece of information that has to be known by the
  group in order to operate securely.

  There are several methods for infrastructure discovery:


   -  Announcements

   -  Anycast

   -  Rendezvous points / Registration


  One method for distributing the security infrastructure location

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  is to use announcements.  The SAP is commonly used to announce
  the existence of a new multicast application or service.  If an
  application uses SAP[Ref RFC 2974] to announce the existence of a
  service on a multicast channel, that service could be extended to
  include the security infrastructure location for a particular group.

  Announcements can also be used by GSAKMP in one of two modes -
  Expanding Ring Searches (ERS) of security infrastructure and
  expanding ring searches for infrastructure discovery.  In either
  case, the GSAKMP would use a multicast broadcast that would slowly
  increase in its range by incremental multicast hops.  The multicast
  source controls the packet's multicast range by explicitly setting
  its Time To Live count.

  An expanding ring announcement operates by the GC/KS announcing
  its existence for a particular group.  The number of hops this
  announcement would travel would be a locally configured number.  The
  GMs would listen on a well know multicast address for GC/KSs that
  provide service for groups of interest.  If multiple GC/KSs are found
  that provide service, then the GM would pick the closest one (in
  terms of multicast hops).  The GM would then send a GSAKMP Request
  to Join message (RTJ) to the announced GC/KS. If the announcement
  is found to be spurious then that is reported to the appropriate
  management authorities.  The ERA concept is slightly different from
  SAP in that it could occur over the data channel multicast address,
  instead of a special multicast address dedicated for the SAP service.

  An expanding ring search operates in the reverse order than the ERA.
  In this case, the GM is the announcing entity.  The (S-)GC/KSs listen
  for the requests for service, specifically the RTJ. The (S-)GC/KS
  responds to the RTJ. .  If the GM receives more than one response,
  it would either ignore the responses or send NACKs based on local
  configuration.

  Anycast is a service that is very similar to ERS. It also can be used
  to provide connection to the security infrastructure.  In this case,
  the GM would send the RTJ to a well-known service request address.
  This anycast service would route the RTJ to an appropriate GC/KS.
  The anycast service would have security infrastructure and network
  connectivity knowledge to facilitate this connection.

  Registration points can be used to distribute many group relevant
  data, including security infrastructure.  Many group applications
  rely on well known registration points to advertise the availability
  of groups.  There is no reason that GSAKMP could not use the same
  approach for advertising the existence and location of the security
  infrastructure.  This is a simple process if the application being
  supported already supports registration.  The GSAKMP infrastructure
  can always provide a registration site if the existence of this
  security infrastructure discovery hub is needed.  The registration
  of S-GC/KSs at this site could be an efficient way to allow GM


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  registration.

  GSAKMP infrastructure discovery can use whatever mechanism suits a
  particular multicast application's requirements, including mechanisms
  that have not been discussed by this architecture.  However, GSAKMP
  infrastructure discovery is not standardized by this version of the
  GSAKMP specification.



4.4 Concept of Operation


  This concept of operation shows how the different roles in GSAKMP
  interact to set up a secure group.  This particular concept of
  operation focuses on a secure group that utilizes the distributed key
  dissemination services of the S-GC/KS.


4.4.1 Assumptions


  The most basic assumption here is one or more trustworthy PKI for the
  group.  That trusted PKI will be used to create and verify security
  policy rules.

  There is a GO that all GMs recognize as having group policy creation
  authority.  All GM must be securely pre-configured to know the GO
  public key.

  All GMs have access to the GO PKI information, both the trusted
  anchor public keys and the certificate path validation rules.

  There is sufficient connectivity between the GSAKMP entities.


   -  The registration SA requires that GM can connect to the GC/KS or
      S-GC/KS using either TCP or UDP.

   -  The rekey SA requires that the data layer multicast communication
      service be available.  This can be multicast IP, overlay networks
      using TCP, or NAT tunnels.

   -  GSAKMP can support many different data layer secure applications
      each with unique connectivity requirements.


4.4.2 Creation of a Policy Token


  The GO creates and signs the Policy Token for a group.  The policy
  token contains the rules for access control and authorizations for a

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  particular group.

  The PT consists of the following information:



   -  Identification - this allows an unambiguous identification of the
      PT and the group,

   -  Access Control Rules - these rules specify who can have access to
      the group keys,

   -  Authorization Rules - these rules specify who can be a S-GC/KS,

   -  Mechanisms - these rules specify the security mechanisms that
      will be used by the group, this is necessary to ensure there
      is no weak link in the group security profile, for example, for
      IPsec, this could include SPD/SAD configuration data,

   -  Source authentication of the PT to the GO - the PT is a CMS
      signed object and this allows all GMs to verify the PT.


4.4.3 Creation of a Group


  The PT is sent to a potential GC/KS. This can occur in several ways,
  and the method of transmittal is outside the scope of GSAKMP. The
  potential GC/KS will verify the GO signature on the PT to ensure that
  it comes from a trusted GO. Next, the GC/KS will verify that it is
  authorized to become the GC/KS, based on the authorization rules in
  the PT. Assuming that the GC/KS trusts the PT, is authorized to be a
  GC/KS, and is locally configured to become a GC/KS for a given group
  and the GO, then the GC/KS will create the keys necessary to start
  the group.  The GC/KS will take whatever action is necessary (if any)
  to advertise its ability to distribute key for the group.  The GC/KS
  will then listen for RTJs.

  The PT has a sequence number.  Every time a PT is distributed to
  the group the group members verify that the sequence number on the
  PT is increasing.  The PT lifetime is not limited to a particular
  time interval, other than by the lifetimes imposed by some of its
  attributes (e.g.  signature key lifetime).  The current PT sequence
  number is downloaded to the GM in the "Key Download" message.  Also,
  to avoid replay attacks, this sequence number is never reset to a
  lower value (i.e.  rollover to zero) as long as the group identifier
  remains valid and in use.  The GO MUST preserve this sequence number
  across re-boots.





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4.4.4 Discovery of GC/KS


  Potential GMs will receive notice of the new group via some
  mechanism:  announcement, Anycast, registration look-up.  The GM will
  send an RTJ to the GC/KS.


4.4.5 GC/KS registration policy enforcement


  The GC/KS may or may not require cookies, depending on Denial of
  Service environment and the local configuration.

  Once the RTJ has been received, the GC/KS will verify that the
  GM is allowed to have access to the group keys.  The GC/KS will
  then verify the signature on the RTJ to ensure it was sent by the
  claimed identity.  If the checks succeed, the GC/KS will ready a Key
  Download message for the GM. If not the GC/KS can notify the GM of a
  non-security relevant problem.


4.4.6 GM registration policy enforcement


  Upon receipt of the Key Download message, the GM will verify the
  signature on the message.  Then the GM will retrieve the PT from the
  Key Download message and verify that the GO created and signed the
  PT. Once the PT is verified as valid, the GM will verify that the
  GC/KS is authorized to distribute key for this group.  Then the GM
  will verify that the mechanisms used in the group are available and
  acceptable for protection of the GMs data (assuming the GM is a data
  source).  The GM will then accept membership in this group.

  The GM will then check to see if it is allowed to be a S-GC/KS for
  this group.  If the GM is allowed to be a S-GC/KS AND the local
  GM configuration allows the GM to act as a S-GC/KS for this group,
  then the GM changes its operating state to S-GC/KS. The GO needs to
  assign the authority to become a S-GC/KS in a manner that supports
  the overall group integrity and operations.


4.4.7 Autonomous Distributed GSAKMP Operations


  In autonomous mode, each S-GC/KS operates a largely self-contained
  sub-group for which the Primary-GC/KS delegates the sub-group's
  membership management responsibility to the S-GC/KS. In general,
  the S-GC/KS locally handles each Group Member's registration and
  de- registration without any interaction with the Primary-GC/KS.
  Periodically, the Primary-GC/KS multicasts a Re-Key Event message


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  addressed only to its one or more S-GC/KS.

  After a S-GC/KS successfully processes a Rekey Event message from the
  Primary-GC/KS, the S-GC/KS transmits to its sub-group its own Rekey
  Event message containing a copy of the group's new GTPK and policy
  token.  The S-GC/KS encrypts its Rekey Event message's sub-group key
  management information using Logical Key Hierarchy or a comparable
  re-key protocol.  The S-GC/KS uses the re-key protocol to realize
  forward and backward secrecy, such that only the authorized sub-group
  members can decrypt and acquire access to the new GTPK and policy
  token.  The frequency at which the Primary-GC/KS transmits a Re-Key
  Event message is a policy token parameter.

  For the special case of a S-GC/KS detecting an expelled or
  compromised group member, there is a mechanism defined to trigger
  an immediate group re-key rather than waiting for the group's re-key
  period to elapse.  See below for details.

  Each S-GC/KS will be registered by the GC/KS as a management node
  with responsibility for GTPK distribution, access control policy
  enforcement, LKH tree creation and distribution of LKH key arrays.
  The S-GC/KS will be registered into the primary LKH tree as an
  endpoint.  Each S-GC/KS will hold an entire LKH key array for the
  GC's LKH key tree.

  For the purpose of clarity the process of creating a distributed
  GSAKMP group will be explained in chronological order.

  First, the Group Owner will create a policy token that authorizes a
  subset of the group's membership to assume the role of S-GC/KS.

  The GO needs to ensure that the S-GC/KS rules in the policy token
  will be stringent enough to ensure trust in the S-GC/KSs.  This
  policy token is handed off to the primary GC.

  The GC will create the GTPK and initial LKH key tree.  The GC will
  then wait for a potential S-GC/KS to send a Request to Join (RTJ)
  message.

  A potential S-GC/KS will eventually send an RTJ. The GC will enforce
  the access control policy as defined in the policy token.  The
  S-GC/KS will accept the role of S-GC/KS and create its own LKH key
  tree for its sub-group membership.

  The S-GC/KS will then offer registration services for the group.
  There are local management decisions that are optional to control
  the scope of group members that can be served by a S-GC/KS. These
  are truly local management issues that allow the administrators of an
  S-GC/KS to restrict service to potential GMs.  These local controls
  do not effect the overall group security policy, as defined in the
  Policy Token.


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  A potential Group Member will send an RTJ to the S-GC/KS. The S-
  GC/KS will enforce the entire access control policy as defined in
  the PT. The GM will receive an LKH key array that corresponds to the
  LKH tree of the S-GC/KS. The key tree generated by the S-GC/KS is
  independent of the key tree generated by the GC/KS., they share no
  common keys.

  The GM then has the keys it needs to receive group traffic and be
  subject to rekey from the S-GC/KS. For the sake of this discussion
  let's assume the GM is to be expelled from the group membership.

  The S-GC/KS will receive notification that the GM is to be expelled.
  This mechanism is outside the scope of this protocol.

  Upon notification that a GM that holds a key array within its
  LKH tree is to be expelled the S-GC/KS does two things.  First
  the S-GC/KS initiates a de-registration exchange with the GC/KS
  identifying the member to be expelled.  (The S-GC/KS proxies a Group
  Member's de- registration informing the GC/KS that the Group Member
  has been expelled from the group.)  Second, the S-GC/KS will wait for
  a rekey action by the GC/KS. The immediacy of the rekey action by the
  GC/KS is a management decision at the GC/KS. Security is served best
  by quick expulsion of untrusted members.

  Upon receipt of the de-registration notification from the S-GC/KS the
  GC/KS will register the member to be expelled.  The GC/KS will then
  follow group procedure for initiating a rekey action (outside the
  scope of this protocol).  The GC/KS will communicate to the GO the
  expelled members information (outside the scope of this protocol).
  With this information, the GO will create a new PT for the group with
  the expelled GM identity added to the excluded list in the groups
  access control rules.  The GO provides this new PT to the GC/KS for
  distribution with the Rekey Event Message.

  The GC/KS will send out a rekey operation with a new PT. The S- GC/KS
  will receive the rekey and process it.  At the same time, all other
  S-GC/KSs will receive the rekey and note the excluded GM identity.
  All S-GC/KSs will review local identities to ensure that the excluded
  GM is not a local member.  If it is, then the S-GC/KS will create
  a rekey message.  The S-GC/KSs must always create a rekey message,
  whether the expelled Group Member is a member of their subtrees or
  not.

  The S-GC/KS will then create a local rekey message.  The S-GC/KS
  will send the wrapped Group TPK to all members of its local LKH tree,
  except the excluded member(s).







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5 Group Life Cycle


  The management of a cryptographic group follows a life-cycle:
  group definition, group establishment, and security relevant group
  maintenance.  Group definition involves defining the parameters
  necessary to support a secure group, including its policy token.
  Group establishment is the process of granting access to new members.
  Security relevant group maintenance messages include rekey, policy
  changes member deletions, and group destruction.  Each of these
  life-cycle phases is discussed in the following sections.

  The use and processing of the optional Vendor ID payload for all
  messages can be found in Section 7.10.



5.1 Group Definition


  A cryptographic group is established to support secure communications
  among a group of individuals.  The activities necessary to create a
  Policy Token in support of a cryptographic group include


   -  Determine Access Policy - identify the entities that are
      authorized to receive the group key.

   -  Determine Authorization Policy - identify which entities are
      authorized to perform security relevant actions, including key
      dissemination, policy creation, and initiation of security
      management actions.

   -  Determine Mechanisms - define the algorithms and protocols used
      by GSAKMP to secure the group.

   -  Create Group Policy Token - format the policies and mechanisms
      into a Policy Token and apply the GO signature.


5.2 Group Establishment


  GSAKMP Group Establishment consists of three mandatory-to-implement
  messages, the Request to Join, the Key Download, and the Key Download
  Ack/Failure.  The exchange may also include two OPTIONAL error
  messages, the Request to Join Error and the Lack_of_Ack messages.
  Operation using the mandatory messages only is referred to as "Terse
  Mode", while inclusion of the error messaging is referred to as
  "Verbose Mode".  GSAKMP implementations MUST support Terse Mode
  and MAY support Verbose Mode.  Group Establishment is discussed in


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  Section 5.2.1.

  A group is set in Terse or Verbose mode by a policy token parameter.
  All (S-)GC/KSs in a Verbose mode group MUST support Verbose mode.
  GSAKMP allows Verbose mode groups to have GMs that do not support
  Verbose mode.  Candidate GMs that do not support Verbose mode and
  receive a RTJ-Error or Lack-of-Ack message must handle these messages
  gracefully.  Additionally, a GM will not know a prior that it is
  interacting with the (S)-GC/KS in Verbose or Terse mode until the
  Policy Token is received.

  For Denial of Service protection, a Cookie Exchange MAY precede the
  Group Establishment exchange.  The Cookie Exchange is described in
  Section 5.2.2.

  Regardless of mode, any error message sent between component members
  indicates the first error encountered while processing the message.


5.2.1 Standard Group Establishment


  After the out-of-band receipt of a Policy Token, a potential Group
  Controller Key Server (GC/KS) verifies the token and its eligibility
  to perform GC/KS functionality.  It is then permitted to create any
  needed group keys and begin to establish the group.

  The GSAKMP Ladder Diagram, Figure 1, is presented to illustrate the
  process of establishing a cryptographic group.  The left side of the
  diagram represents the actions of the GC/KS. The right side of the
  diagram represents the actions of the GMs.  The components of each
  message shown in the diagram are presented in sections 5.2.1.1 -
  5.2.1.5.

  The Request to Join message is sent from a potential GM to the
  GC/KS to request admission to the cryptographic group.  The message
  contains key creation material, freshness data, an optional selection
  of mechanisms, and the signature of the GM.

  The Key Download message is sent from the GC/KS to the GM in response
  to an accepted Request to Join.  This GC/KS-signed message contains
  the identifier of the GM, freshness data, key creation material,
  encrypted keys, and the encrypted Policy Token.  The Policy Token
  is used to facilitate well-ordered group creation and MUST include
  the group's identification, group permissions, group join policy,
  group controller key server identity, group management information,
  and digital signature of the GO. This will allow the GM to determine
  whether group policy is compatible with local policy.

  The Request to Join Error message is sent from the GC/KS to the
  GM in response to an unaccepted Request to Join.  This message


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    CONTROLLER   Mandatory/     MESSAGE                  MEMBER
                 Optional
              !<-M----------Request to Join-------------!
    <Process> !                                         !
    <RTJ>     !                                         !
              !--M----------Key Download--------------->!
              !                                         !<Process KeyDL>
              !--O-------Request to Join Error--------->! or
              !                                         ! <Proc RTJ-Err>
              !<-M----Key Download - Ack/Failure--------!
   <Process  >!                                         !
   <KeyDL-A/F>!                                         !
              !--O------Lack of Acknowledgment--------->!
              !                                         ! <Proc LOA>
              !<=======SHARED KEYED GROUP SESSION======>!




                    Figure 1:  GSAKMP Ladder Diagram


  is not signed by the GC/KS for two reasons:  1) The GM, at this
  point, has no knowledge of who is authorized to act as a GC/KS
  and so the signature would thus be meaningless to the GM, and 2)
  Signing responses to denied join requests would provide a denial
  of service potential.  The message contains an indication of the
  error condition.  The possible values for this error condition
  are:  Invalid-Payload-Type, Invalid-Version, Invalid-Group-ID,
  Invalid-Sequence-ID, Payload-Malformed, Invalid-ID-Information,
  Invalid-Certificate, Cert-Type-Unsupported, Invalid-Cert-Authority,
  Authentication-Failed, Certificate-Unavailable,
  Unauthorized-Request, Prohibited-by-Group-Policy, and
  Prohibited-by-Locally-Configured-Policy.

  The Key Download Ack/Failure message indicates Key Download receipt
  status at the GM. It is a GM-signed message containing freshness data
  and status.

  The Lack_of_Ack message is sent from the GC/KS to the GM in response
  to an invalid or absent Key Download Ack/Failure message.  The signed
  message contains freshness and status data and is used to warn the
  GM of impending eviction from the group if a valid Key Download
  Ack/Failure is not sent.  Eviction means that the member will be
  excluded from the group after the next Rekey Event.  The policy of
  when a particular group needs to rekey itself is stated in the Policy
  Token.  Eviction is discussed further in Section 5.3.2.1.

  For the following message structure sections, details about payload
  format and processing can be found in Section 7.  Each message is
  identified by its exchange type in the header of the message.  Nonces


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  MUST be present in the messages unless synchronization time is
  available to the system.


5.2.1.1 Request to Join


  The exchange type for Request to Join is eight (8).

  The components of a Request to Join Message are shown in Table 1.


           Table 1:  Request to Join (RTJ) Message Definition

   Message Name  : Request to Join (RTJ)
   Dissection    : {HDR-GrpID, Key Creation, Nonce_I, [VendorID],
                 : [Notif_Mechanism_Choices], [Notif_Cookie],
                 : [Notif_IPValue]} SigM, [Cert]
   Payload Types : GSAKMP Header, Key Creation, [Nonce], [Vendor
                   ID], Signature, [Certificate], [Notifications]

     SigM        : Signature of Group Member
     Cert        : Necessary Certificates, zero or more
     {}SigX      : Indicates fields used in Signature
     []          : Indicate an optional data item

  As shown by Figure 1, a potential GM MUST generate and send an RTJ
  message to request permission to join the group.  At a minimum,
  the GM MUST be able to manually configure the destination for the
  RTJ. As defined in the dissection of the RTJ message, this message
  MUST contain a Key Creation payload for KEK determination.  A Nonce
  payload MUST be included for freshness and the Nonce_I value MUST be
  saved for potential later use.  Only if the Policy Token for this
  group defines the use of nonces versus synchronization time, will
  the GC/KS use this supplied nonce.  An OPTIONAL Notification payload
  of type Mechanism Choices MAY be included to identify the mechanisms
  the GM wants to use.  Absence of this payload will cause the GC/KS to
  select appropriate default Policy Token specified mechanisms for the
  Key Download.

  In response, the GC/KS accepts or denies the request based on local
  configuration.  <Process RTJ> indicates the GC/KS actions that will
  determine if the RTJ will be acted upon.  The following checks SHOULD
  be performed in the order presented.

  In this procedure, the GC/KS MUST verify that the message header is
  properly formed and confirm that this message is for this group by
  checking the value of the GroupID. If the header checks pass, then
  the identity of the sender is extracted from the Signature payload.
  This identity MUST be used to perform access control checks, find
  the GMs credentials (e.g.  certificate) for message verification,
  and MUST also be used in the Key Download message.  Then the GC/KS

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  will verify the signature on the message to ensure its authenticity.
  The GC/KS MUST use verified and trusted authentication material
  from a known root.  If the message signature verifies, the GC/KS
  then confirms that all required payloads are present and properly
  formatted based upon the mechanisms announced and/or requested.  If
  all checks pass, the GC/KS will create and send the Key Download
  message as described in section  5.2.1.2.

  If the GM receives no response to the RTJ within the GM's locally
  configured timeout value, the GM SHOULD resend the RTJ message up to
  three (3) times.

  NOTE: At any one time, a GC/KS MUST process no more that one (1)
  valid RTJ message from a given GM per group until its pending
  registration protocol exchange concludes.

  If any error occurs during RTJ message processing, and the GC/KS is
  running in Terse mode, the registration session MUST be terminated
  and all saved state information MUST be cleared.

  The OPTIONAL Notification payload of type Cookie is discussed in
  section  5.2.2.

  The OPTIONAL Notification payload of type IPValue may be used for the
  GM to convey a specific IP value to the GC/KS.


5.2.1.2 Key Download


  The exchange type for Key Download is nine (9).

  The components of a Key Download Message are shown in Table 2:


            Table 2:  Key Download (KeyDL) Message Definition

   Message Name  : Key Download (KeyDL)
   Dissection    : {HDR-GrpID, Member ID, [Nonce_R, Nonce_C], Key
                   Creation, (Policy Token)*, (Key Download)*,
                   [VendorID]} SigC, [Cert]
   Payload Types : GSAKMP Header, Identification, [Nonce], Key
                   Creation, Policy Token, Key Download, [Vendor
                   ID], Signature, [Certificate]

     SigC        : Signature of Group Controller Key Server
     Cert        : Necessary Certificates, zero or more
     {}SigX      : Indicates fields used in Signature
     []          : Indicate an optional data item
     (data)*     : Indicates encrypted information

  In response to a properly formed and verified RTJ message, the GC/KS

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  creates and sends the KeyDL message.  As defined in the dissection of
  the message, this message MUST contain payloads to hold the following
  information:  GM identification, Key Creation material, encrypted
  Policy Token, encrypted key information, and signature information.
  If synchronized time is not available, the Nonce payloads MUST be
  included in the message for freshness.

  If present, the nonce values transmitted MUST be the GC/KSs generated
  Nonce_R value and the combined Nonce_C value which was generated by
  using the GC/KSs Nonce_R value and the Nonce_I value received from the
  GM in the RTJ.

  If two party key determination is used, the key creation material
  supplied by the GM and/or the GC/KS will be used to generate the key.
  Generation of this key is dependant on the key exchange, as defined
  in Section 7.11, Key Creation Payload.  The Policy Token and key
  material are encrypted in the generated key.

  The GM MUST be able to process the Key Download message.  <Process
  KeyDL> indicates the GM actions that will determine how the Key
  Download message will be acted upon.  The following checks SHOULD be
  performed in the order presented.

  In this procedure, the GM will verify that the message header is
  properly formed and confirm that this message is for this group by
  checking the value of the GroupID. If the header checks pass, the GM
  MUST confirm that this message was intended for itself by comparing
  the Member ID in the Identification payload to its identity.

  After identification confirmation, the freshness values are checked.
  If using Nonces, the GM MUST use its saved Nonce_I value, extract the
  received GC/KS Nonce_R value, compute the combined Nonce_C value, and
  compare it to the received Nonce_C value.  If not using Nonces, the
  GM MUST check the timestamp in the Signature payload to determine if
  the message is new.

  After freshness is confirmed, the signature MUST be verified to
  ensure its authenticity, The GM MUST use verified and trusted
  authentication material from a known root.  If the message signature
  verifies, the key creation material is extracted from the Key
  Creation payload to generate the KEK. This KEK is then used to
  decrypt the Policy Token data.  The signature on the policy token
  MUST be verified.  Access control checks MUST be performed on both
  the GO and the GC/KS to determine both their authorities within this
  group.  After all these checks pass, the KEK can then be used to
  decrypt and process the key material from the Key Download payload.
  If all is successful, the GM will create and send the Key Download -
  Ack/Failure message as described in section 5.2.1.4.

  The Policy Token and Key Download payloads are sent encrypted in
  the KEK generated by the Key Creation payload information using the


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  mechanisms defined in the group announcement.  This guarantees that
  the sensitive policy and key data for the group and potential rekey
  data for this individual cannot be read by anyone but the intended
  recipient.

  If any error occurs during KeyDL message processing, regardless of
  whether the GM is in Terse or Verbose mode, the registration session
  MUST be terminated, the GM MUST send a Key Download - Ack/Failure
  message, nd all saved state information MUST be cleared.  If in
  Terse mode, the Notification Payload will be of type NACK to indicate
  termination.  If in Verbose mode, the Notification Payload will
  contain the type of error encountered.


5.2.1.3 Request to Join Error


  The exchange type for Request to Join Error is eleven (11).

  The components of the Request to Join Error Message are shown in
  Table 3:


      Table 3:  Request to Join Error (RTJ-Err) Message Definition

   Message Name  : Request to Join Error (RTJ-Err)
   Dissection    : {HDR-GrpID, [Nonce_I], Notification, [VendorID]}
   Payload Types : GSAKMP Header, [Nonce] Notification, [Vendor ID]


  In response to an unacceptable RTJ, the GC/KS MAY send a Request to
  Join Error (RTJ-Err) message containing an appropriate Notification
  payload.  Note that the RTJ-Err message is not a signed message for
  the following reasons:  the lack of awareness on the GM's perspective
  of who is a valid GC/KS as well as the need to protect the GC/KS from
  signing messages and using valuable resources.  Following the sending
  of an RTJ-Err, the GC/KS MUST terminated the session and all saved
  state information MUST be cleared.

  Upon receipt of an RTJ-Err message, the GM will validate the
  following:  the GroupID in the header belongs to a group to which
  the GM has sent an RTJ, and, if present, the Nonce_I matches a Nonce_I
  sent in an RTJ to that group.  If the above checks are successful,
  the GM MAY terminate the state associated with that GroupID and
  Nonce.  The GM SHOULD be capable of receiving a valid KeyDownload
  message for that GroupID and Nonce after receiving an RTJ-Err for a
  locally-configured amount of time.






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5.2.1.4 Key Download - Ack/Failure


  The exchange type for Key Download - Ack/Failure is four (4).

  The components of the Key Download - Ack/Failure Message are shown in
  Table 4:


   Table 4:  Key Download - Ack/Failure (KeyDL-A/F) Message Definition

   Message Name  : Key Download - Ack/Failure (KeyDL-A/F)
   Dissection    : {HDR-GrpID, [Nonce_C], Notif_Ack, [VendorID]}SigM
   Payload Types : GSAKMP Header, [Nonce], Notification, [Vendor
                   ID], Signature
     SigM        : Signature of Group Member
     {}SigX      : Indicates fields used in Signature


  In response to a properly processed KeyDL message, the GM creates and
  sends the KeyDL-A/F message.  As defined in the dissection of the
  message, this message MUST contain payloads to hold the following
  information:  Notification payload of type Acknowledgment (ACK) and
  signature information.  If synchronized time is not available, the
  Nonce payload MUST be present for freshness, and the nonce value
  transmitted MUST be the GMs generated Nonce_C value.  If the GM does
  not receive a KeyDL message within a locally configured amount of
  time, the GM MAY send a new RTJ. If the GM receives a valid LOA (see
  section 5.2.1.5) message from the GC/KS before receipt of a KeyDL
  message, the GM SHOULD send a KeyDL-A/F message of type NACK followed
  by a new RTJ.

  The GC/KS MUST be able to process the KeyDL-A/F message.  <Process
  KeyDL-A/F> indicates the GC/KS actions that will determine how the
  KeyDL-A/F message will be acted upon.  The following checks SHOULD be
  performed in the order presented.

  In this procedure, the GC/KS will verify that the message header
  is properly formed and confirm that this message is for this group
  by checking the value of the GroupID. If the header checks pass,
  the GC/KS MUST check the message for freshness.  If using Nonces,
  the GC/KS MUST use its saved Nonce_C value, and compare it to the
  received Nonce_C value.  If not using Nonces, the GC/KS MUST check
  the timestamp in the Signature payload to determine if the message
  is new.  After freshness is confirmed, the signature MUST be verified
  to ensure its authenticity, The GC/KS MUST use verified and trusted
  authentication material from a known root.  If the message signature
  verifies, the GC/KS processes the Notification payload.  If the
  notification type is of type ACK, then the registration has completed
  successfully and both parties SHOULD remove state information
  associated with this GM's registration.


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  If the GC/KS does not receive a KeyDL-A/F message of proper form, is
  unable to correctly process the KeyDL-A/F message, the Notification
  payload type is any value except ACK, or if no KeyDL-A/F message is
  received within the locally configured timeout, the GC/KS MUST evict
  this GM from the group in the next policy-defined Rekey Event.  The
  GC/KS MAY send the OPTIONAL Lack_of_Ack message if running in Verbose
  Mode as defined in section 5.2.1.5.


5.2.1.5 Lack of Ack


  The exchange type for Lack of Ack is twelve (12).

  The components of a Lack of Ack Message are shown in Table 5:


             Table 5:  Lack of Ack (LOA) Message Definition

   Message Name  : Lack of Ack (LOA)
   Dissection    : {HDR-GrpID, Member ID, [Nonce_R, Nonce_C],
                   Notification, [VendorID]} SigC, [Cert]
   Payload Types : GSAKMP Header, Identification, [Nonce],
                   Notification, [Vendor ID], Signature,
                   [Certificate]

     SigC        : Signature of Group Controller Key Server
     Cert        : Necessary Certificates, zero or more
     {}SigX      : Indicates fields used in Signature
     []          : Indicate an optional data item

  If the GC/KSs local timeout value expires prior to receiving a
  KeyDL-A/F from the GM, the GC/KS MAY create and send a LOA message
  to the GM. As defined in the dissection of the message, this
  message MUST contain payloads to hold the following information:  GM
  identification, Notification of error, and signature information.

  If synchronized time is not available, the Nonce payloads MUST be
  present for freshness, and the nonce values transmitted MUST be the
  GC/KSs generated Nonce_R value and the combined Nonce_C value which
  was generated by using the GC/KSs Nonce_R value and the Nonce_I value
  received from the GM in the RTJ. These values were already generated
  during the Key Download message phase.

  The GM MAY be able to process the LOA message based upon local
  configuration.  <Process LOA> indicates the GM actions that will
  determine how the LOA message will be acted upon.  The following
  checks SHOULD be performed in the order presented.

  In this procedure, the GM MUST verify that the message header is
  properly formed and confirm that this message is for this group by
  checking the value of the GroupID. If the header checks pass, the GM

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  MUST confirm that this message was intended for itself by comparing
  the Member ID in the Identification payload to its identity.  After
  identification confirmation, the freshness values are checked.  If
  using Nonces, the GM MUST use its save Nonce_I value, extract the
  received GC/KS Nonce_R value, compute the combined Nonce_C value, and
  compare it to the received Nonce_C value.  If not using Nonces, the
  GM MUST check the timestamp in the Signature payload to determine if
  the message is new.  After freshness is confirmed, access control
  checks MUST be performed on the GC/KS to determine its authority
  within this group.  Then signature MUST be verified to ensure its
  authenticity, The GM MUST use verified and trusted authentication
  material from a known root.

  If the checks succeed, the GM SHOULD resend a KeyDL-A/F for that
  session.


5.2.2 Cookies - Group Establishment with Denial of Service Protection


  This section defines an OPTIONAL capability that MAY be implemented
  into GSAKMP when using IP based groups.  The information in this
  section is borrowed heavily from [IKEv2] as this protocol has already
  worked through this issue and GSAKMP is copying this concept.  This
  section will contain paraphrased sections of [IKEv2] modified for
  GSAKMP to define the purpose of Cookies.

  An optional Cookie mode is being defined for the GSAKMP to help
  against DoS attacks.

  The term "cookies" originates with Karn and Simpson [RFC 2522] in
  Photuris, an early proposal for key management with IPSec.  The
  ISAKMP fixed message header includes two eight octet fields titled
  "cookies".  Instead of placing this cookie data in the header, in
  GSAKMP this data is moved into a Notification payload.

  An expected attack against GSAKMP is state and CPU exhaustion,
  where the target GC/KS is flooded with Request to Join requests
  from forged IP addresses.  This attack can be made less effective
  if a GC/KS implementation uses minimal CPU and commits no state
  to the communication until it knows the initiator potential GM can
  receive packets at the address from which it claims to be sending
  them.  To accomplish this, the GC/KS when operating in Cookie mode,
  SHOULD reject initial Request to Join messages unless they contain
  a Notification payload of type "cookie".  It SHOULD instead send
  a Cookie Download message as a response to the RTJ and include a
  cookie in a notify payload of type Cookie_Required.  Potential GMs
  who receive such responses MUST retry the Request to Join message
  with the responder GC/KS supplied cookie in its notification payload
  of type Cookie, as defined by the optional Notification payload of
  the Request to Join Msg as defined in section 5.2.1.1.  This initial


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  exchange will then be as shown in Figure 2 with the components of the
  new message Cookie Download shown in Table 6.  The exchange type for
  Cookie Download is ten (10).

    CONTROLLER                  MESSAGE                  MEMBER
    in Cookie Mode
              !<--Request to Join without Cookie Info---!
  <Gen Cookie>!                                         !
  <Response  >!                                         !
              !----------Cookie Download--------------->!
              !                                         ! <Process CD>
              !<----Request to Join with Cookie Info----!
    <Process> !                                         !
    <RTJ    > !                                         !
              !-------------Key Download--------------->!
              !                                         ! <Proc KeyDL>
              !<-----Key Download -  Ack/Failure--------!
   <Process  >!                                         !
   <KeyDL-A/F>!                                         !
              !<=======SHARED KEYED GROUP SESSION======>!



              Figure 2:  GSAKMP Ladder Diagram with Cookies


              Table 6:  Cookie Download Message Definition

   Message Name  : Cookie Download
   Dissection    : {HDR-GrpID, Notif_COOKIE_REQUIRED, [VendorID]}
   Payload Types : GSAKMP Header, Notification, [Vendor ID]

  The first two messages do not affect any GM or GC/KS state except for
  communicating the cookie.

  A GSAKMP implementation SHOULD implement its GC/KS cookie generation
  in such a way as to not require any saved state to recognize its
  valid cookie when the second Request to Join message arrives.  The
  exact algorithms and syntax they use to generate cookies does not
  affect interoperability and hence is not specified here.

  The following is an example of how an endpoint could use cookies to
  implement limited DoS protection.

  A good way to do this is to set the cookie to be:

    Cookie = <SecretVersionNumber> | Hash(Ni | IPi | <secret>)

  where <secret> is a randomly generated secret known only to the
  responder GC/KS and periodically changed, Ni is the Nonce value taken
  from the initiator potential GM, IPi is the asserted IP address of


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  the candidate GM. The IP address is either the IP header's source IP
  address, or else if it is present then the IP address contained in
  the optional Notification "IPvalue" payload.  <SecretVersionNumber>
  should be changed whenever <secret> is regenerated.  The cookie can
  be recomputed when the "Request to Join with Cookie Info" arrives
  and compared to the cookie in the received message.  If it matches,
  the responder GC/KS knows that all values have been computed since
  the last change to <secret> and that IPi MUST be the same as the
  source address it saw the first time.  Incorporating Ni into the hash
  assures that an attacker who sees only the Cookie_Download message
  cannot successfully forge a "Request to Join with Cookie Info"
  message.  This Ni value MUST be the same Ni value from the original
  "Request to Join" message for the calculation to be successful.

  If a new value for <secret> is chosen while there are connections
  in the process of being initialized, a "Request to Join with
  Cookie Info" might be returned with other than the current
  <SecretVersionNumber>.  The responder GC/KS in that case MAY reject
  the message by sending another response with a new cookie or it MAY
  keep the old value of <secret> around for a short time and accept
  cookies computed from either one.  The responder GC/KS SHOULD NOT
  accept cookies indefinitely after <secret> is changed, since that
  would defeat part of the denial of service protection.  The responder
  GC/KS SHOULD change the value of <secret> frequently, especially if
  under attack.

  An alternative example for Cookie value generation in a NAT
  environment is to substitute the IPi value with the IPValue received
  in the Notification payload in the RTJ message.  This scenario
  is indicated by the presence of the Notification payload of type
  IPValue.  With this substitution, a similar calculation as described
  above can be used.


5.2.3 Group Establishment for Receive-Only Members


  This section describes an OPTIONAL capability that may be implemented
  in a structured system where the authorized (S-)GC/KS is known in
  advance through out-of-band means and where synchronized time is
  available.

  Unlike Standard Group Establishment, in the Receive-Only system, the
  GMs and (S-)GC/KSs operate in terse mode and exchange one message
  only:  the Key Download.  Potential new GMs do not send an RTJ.
  (S)-GC/KSs do not expect Key Download - ACK/Failure messages and do
  not remove GMs for lack or receipt of the message.

  Operation is as follows:  upon notification via an authorized
  out-of-band event, the (S)-GC/KS forms and sends a Key Download
  message to the new member with the Nonce payloads ABSENT. The GM


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  verifies



   -  the ID payload identifies that GM

   -  the timestamp in the message is fresh

   -  the message is signed by an authorized (S)-GC/KS

   -  the signature on the message verifies


  When using a Diffie-Hellman Key Creation Type for receive-only
  members, a static-ephemeral model is assumed:  the Key Creation
  payload in the Key Download message contains the (S-)GC/KS's public
  component.  The member's public component is assumed to be obtained
  through secure out-of-band means.


5.3 Group Maintenance


  The Group Maintenance phase includes member joins and leaves, group
  rekey activities, policy updates, and group destruction.  These
  activities are presented in the following sections.


5.3.1 Group Management


5.3.1.1 Rekey Events


  A Rekey Event is any action, including compromise report or key
  expiration, that requires the creation of a new group key and/or
  Rekey information.

  Once an event has been identified (as defined in the group security
  policy token), the GC/KS MUST create and provide a signed message
  containing the GTPK and Rekey information to the group.

  Each GM who receives this message MUST verify the signature on the
  message to ensure its authenticity.  If the message signature does
  not verify, the message MUST be discarded.  Upon verification the
  GM will find the appropriate Rekey download packet and decrypt the
  information with a stored Rekey key(s).  If a new Policy Token is
  distributed with the message, it MUST be encrypted in the old GTPK.

  The exchange type for Rekey Event is five (5).

  The components of a Rekey Event message are shown in Table  7:

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                Table 7:  Rekey Event Message Definition

   Message Name  : Rekey Event
   Dissection    : {HDR-GrpID, ([Policy Token])*, Rekey Array,
                   [VendorID]}SigC, [Cert]
   Payload Types : GSAKMP Header, [Policy Token], Rekey Event,
                   [Vendor ID], Signature, [Certificate],

     SigC        : Signature of Group Controller Key Server
     Cert        : Necessary Certificates, zero or more
     {}SigX      : Indicates fields used in Signature
     (data)*     : Indicates encrypted information
     []          : Indicate an optional data item

5.3.1.2 Policy Updates


  New policy tokens are sent via the Rekey Event message.  These policy
  updates may be coupled with an existing rekey event or may be sent in
  a message with the Rekey Event Type of the Rekey Event Payload set to
  None(0) (see section 7.5.1.

  A policy token MUST NOT be processed if the processing of the Rekey
  Event message carrying it fails.  Policy token processing is type
  dependent and is beyond the scope of this document.


5.3.1.3 Group Destruction


  Group destruction is also accomplished via the Rekey Event message.
  In a Rekey Event message for group destruction, the Sequence ID is
  set to 0xFFFFFFFF. Upon receipt of this authenticated Rekey Event
  message, group components MUST terminate processing of information
  associated with the indicated group.


5.3.2 Leaving a Group


  There are several conditions under which a member will leave a group:
  eviction, voluntary departure without notice, and voluntary departure
  with notice -- or De-Registration.  Each of these is discussed in
  this section.








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5.3.2.1 Eviction


  At some point in the group's lifetime, it may be desirable to evict
  one or more members from a group.  From a key management viewpoint,
  this involves revoking access to the group's protected data by
  "disabling" the departing members' keys.  This is accomplished with
  a Rekey Event, which is discussed in more detail in section 5.3.1.1.
  If future access to the group is also to be denied, the members MUST
  be added to a denied access control list, and the policy token's
  authorization rules MUST be appropriately updated so that they
  will exclude the expelled GM(s).  After receipt of a new PT, GMs
  SHOULD evaluate the trustworthiness of any recent application data
  originating from the expelled GM(s).


5.3.2.2 Voluntary Departure without Notice


  If a member wishes to leave a group for which membership imposes no
  cost or responsibility to that member, then the member MAY merely
  delete local copies of group keys and cease group activities.


5.3.2.3 De-Registration


  If the membership in the group does impose cost or responsibility to
  the departing member, then the member SHOULD de-register from the
  group when that member wishes to leave.  De-Registration consists
  of a three-message exchange between the GM and the member's GC/KS:
  the Request_to_Depart, Departure_Response, and the Departure_Ack.
  Compliant GSAKMP implementations for GMs SHOULD support the
  De-Registration messages.  Compliant GSAKMP implementations for
  GC/KSs MUST support the De-Registration messages.


5.3.2.3.1 Request to Depart - The Exchange Type for a
  Request_to_Depart Message is thirteen (13).  The components of a
  Request_to_Depart Message are shown in Table 8.

  Any GM desiring to initiate the De-Registration process MUST generate
  and send an RTD message to notify the GC/KS of its intent.  As
  defined in the dissection of the RTD message, this message MUST
  contain payloads to hold the following information:  the GC/KS
  identification and Notification of the desire to leave the group.
  When synchronization time is not available to the system as defined
  by the Policy Token, a Nonce payload MUST be included for freshness,
  and the Nonce_I value MUST be saved for later use.  This message MUST
  then by signed by the GM.



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           Table 8:  Request_to_Depart (RTD) Message Definition

   Message Name  : Request_to_Depart (RTD)
   Dissection    : {HDR-GrpID, GC/KS_ID, [Nonce_I], Notif_Leave_Group,
                   [VendorID]} SigM, [Cert]
   Payload Types : GSAKMP Header, Identification, [Nonce],
                   Notification, [Vendor ID], Signature,
                   [Certificate]

     SigM        : Signature of Group Member
     Cert        : Necessary Certificates, zero or more
     {}SigX      : Indicates fields used in Signature
     []          : Indicate an optional data item

  Upon receipt of the RTD message, the GC/KS MUST verify that the
  message header is properly formed and confirm that this message is
  for this group by checking the value of the GroupID. If the header
  checks pass, then the identifier value in Identification payload
  is compared to its own, the GC/KSs identity, to confirm that the GM
  intended to converse with this GC/KS, the GC/KS who registered this
  member into the group.  Then the identity of the sender is extracted
  from the Signature payload.  This identity MUST be used to confirm
  that this GM is a member of the group serviced by this GC/KS. Then
  the GC/KS will confirm from the Notification payload that the GM
  is requesting to leave the group.  Then the GC/KS will verify the
  signature on the message to ensure its authenticity.  The GC/KS
  MUST use verified and trusted authentication material from a known
  root.  If all checks pass and the message is successfully processed,
  then the GC/KS MUST form a Departure_Response message as defined in
  section 5.3.2.3.2.

  If the processing of the message fails the de-registration session
  MUST be terminated and all state associated with this session is
  removed.  If the GC/KS is operating in Terse Mode, then no error
  message is sent to the GM. If the GC/KS is operating in Verbose Mode,
  then the GC/KS sends a Departure_Response Message with a Notification
  Payload of type Request_to_Depart_Error.


5.3.2.3.2 Departure_Response - The Exchange Type for a
  Departure_Response Message is fourteen (14).  The components of a
  Departure_Response Message are shown in Table 9.

  In response to a properly formed and verified RTD message, the GC/KS
  MUST create and send the DR message.  As defined in the dissection of
  the message, this message MUST contain payloads to hold the following
  information:  GM identification, Notification for acceptance of
  departure, and signature information.  If synchronization time is
  not available, the Nonce payloads MUST be included in the message for
  freshness.


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          Table 9:  Departure_Response (DR) Message Definition

   Message Name  : Departure_Response (DR)
   Dissection    : {HDR-GrpID, Member_ID, [Nonce_R, Nonce_C],
                   Notification, [VendorID]} SigC, [Cert]
   Payload Types : GSAKMP Header, Identification, [Nonce],
                   Notification, [Vendor ID], Signature,
                   [Certificate]

     SigC        : Signature of Group Member
     Cert        : Necessary Certificates, zero or more
     {}SigX      : Indicates fields used in Signature
     []          : Indicate an optional data item

  If present, the nonce values transmitted MUST be the GC/KSs generated
  Nonce_R value and the combined Nonce_C value which was generated by
  using the GC/KSs Nonce_R value and the Nonce_I value received from
  the GM in the RTD. This Nonce_C value MUST be saved relative to this
  departing GMs ID.

  The GM MUST be able to process the Departure_Response message.  The
  following checks SHOULD be performed in the order presented.

  The GM MUST verify that the message header is properly formed
  and confirm that this message is for this group by checking the
  value of the GroupID. If the header checks pass, the GM MUST
  confirm that this message was intended for itself by comparing the
  Member ID in the Identification payload to its identity.  After
  identification confirmation, the freshness values are checked.
  If using Nonces, the GM MUST use its saved Nonce_I value, extract
  the received GC/KS Nonce_R value, compute the combined Nonce_C
  value, and compare it to the received Nonce_C value.  If not using
  Nonces, the GM MUST check the timestamp in the signature payload
  to determine if the message is new.  After freshness is confirmed,
  confirmation of the identity of the signer of the DR message is
  the GMs authorized GC/KS is performed.  Then the signature MUST be
  verified to ensure its authenticity, The GM MUST use verified and
  trusted authentication material from a known root.  If the message
  signature verifies, then the GM MUST verify that the Notification is
  of Type Departure_Accepted or Request_to_Depart_Error.

  If the processing is successful, and the Notification payload
  is of type Departure_Accepted, the member MUST form the
  Departure_ACK message as defined in section 5.3.2.3.3.  If the
  processing is successful, and the Notification payload is of
  type Request_to_Depart_Error, the member MUST remove all state
  associated with the de-registration session.  If the member still
  desires to De-Register from the group, the member MUST restart the
  De-Registration process.



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  If the processing of the message fails the de-registration session
  MUST be terminated and all state associated with this session is
  removed.  If the GM is operating in Terse Mode, then a Departure_Ack
  Message with Notification Payload of type NACK is sent to the
  GC/KS. If the GM is operating in Verbose Mode, then the GM sends a
  Departure_Ack Message with a Notification Payload of the appropriate
  failure type.


5.3.2.3.3 Departure_ACK - The Exchange Type for a Departure_ACK
  Message is fifteen (15).  The components of the Departure_ACK Message
  are shown in Table 10:


            Table 10:  Departure_ACK (DA) Message Definition

   Message Name  : Departure_ACK (DA)
   Dissection    : {HDR-GrpID, [Nonce_C], Notif_Ack, [VendorID]}SigM
   Payload Types : GSAKMP Header, [Nonce], Notification, [Vendor
                   ID], Signature
     SigM        : Signature of Group Member
     {}SigX      : Indicates fields used in Signature


  In response to a properly processed Departure_Response message, the
  GM MUST create and send the Departure_ACK message.  As defined in
  the dissection of the message, this message MUST contain payloads
  to hold the following information:  Notification payload of type
  Acknowledgment (ACK) and signature information.  If synchronization
  time is not available, the Nonce payload MUST be present for
  freshness, and the nonce value transmitted MUST be the GMs generated
  Nonce_C value.

  Upon receipt of the Departure_ACK, the GC/KS MUST perform the
  following checks.  These checks SHOULD be performed in the order
  presented.

  In this procedure, the GC/KS MUST verify that the message header
  is properly formed and confirm that this message is for this group
  by checking the value of the GroupID. If the header checks pass,
  the GC/KS MUST check the message for freshness.  If using Nonces,
  the GC/KS MUST use its saved Nonce_C value, and compare it to the
  received Nonce_C value.  If not using Nonces, the GC/KS MUST check
  the timestamp in the signature payload to determine if the message
  is new.  After freshness is confirmed, the signature MUST be verified
  to ensure its authenticity, The GC/KS MUST use verified and trusted
  authentication material from a known root.  If the message signature
  verifies, the GC/KS processes the Notification payload.  If the
  notification type is of type ACK, this is considered a successful
  processing of this message.

  If the processing of the message is successful, the GC/KS MUST remove

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  the member from the group.  This MAY involve initiating a Rekey Event
  for the group.

  If the processing of the message fails or if no Departure_Ack is
  received, the GC/KS MAY issue a LOA message.



6 Security Suite


  The Security Definition Suite 1 MUST be supported.  Other security
  suite definitions MAY be defined in other Internet specifications.


6.1 Assumptions


  All potential GMs will have enough information available to them
  to use the correct Security Suite to join the group.  This can be
  accomplished by a well known default suite 'Security Suite 1' or by
  announcing/posting another suite.


6.2 Definition Suite 1


  GSAKMP implementations MUST support the following suite of algorithms
  and configurations.  The following definition of Suite 1 borrows
  heavily from IKE's Oakley group 2 definition and Oakley itself.

  The GSAKMP Suite 1 definition defines all the algorithm and
  cryptographic definitions required to process group establishment
  messages.  It is important to note that GSAKMP does not negotiate
  these cryptographic mechanisms.  This definition is set by the Group
  Owner via the Policy Token (passed during the GSAKMP exchange for
  member verification purposes).

  The GSAKMP Suite 1 definition is


  Key download and Policy Token encryption algorithm definition:
  Algorithm:  AES
  Mode:       CBC
  Key Length: 128 bits

  Policy Token digital signature algorithm is:
    DSS-ASN1-DER
    Hash algorithm is:
    SHA-1



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  Nonce Hash algorithm is:
    SHA-1

  The Key Creation definition is:
  Algorithm type is Diffie Hellman
  MODP group definition
  g:   2
  p:   "FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1"
       "29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD"
       "EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245"
       "E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED"
       "EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381"
       "FFFFFFFF FFFFFFFF"

  NOTE: The p and g values comes from IKE [RFC 2409], section 6.2
        Second Oakley Group, and p is 1024 bits long.


  The digital signature algorithm is:
  DSS-SHA1-ASN1-DER
  The digital signature ID type is:
  ID-DN-STRING



7 GSAKMP Payload Structure


  A GSAKMP Message is composed of a GSAKMP Header (Section  7.1)
  followed by at least one GSAKMP Payload.  All GSAKMP Payloads are
  composed of the Generic Payload Header (Section  7.2) followed by
  the specific payload data.  The message is chained by a preceeding
  payload defining its succeeding payload.  Payloads are not required
  to be in the exact order shown in the message dissection in
  Sections 5 provided that all required payloads are present.  Unless
  it is explicitly stated in a dissection that multiple payloads of
  a single type may be present, no more than one payload of each type
  allowed by the message may appear.  The final payload in a message
  will point to no succeeding payload.

  All fields of type integer in the Header and Payload structure that
  are larger than one octet, MUST be converted into Network Byte Order
  prior to data transmission.

  Padding of fields MUST NOT be done as this leads to processing
  errors.

  When a message contains a Vendor ID payload, the processing of the
  payloads of that message are modified as defined in Section 7.10.




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7.1 GSAKMP Header


7.1.1 GSAKMP Header Structure


  The GSAKMP Header fields are shown in Figure 3 and defined as:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! GroupID Type  ! GroupID Length!      Group ID Value           ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~               ! Next Payload  !   Version     ! Exchange Type !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Sequence ID                                                   !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Length                                                        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                     Figure 3:  GSAKMP Header Format


  Group Identification Type (1 octet)  - Table 11 presents the group
      identification types.  This field is treated as an unsigned
      value.

                  Table 11:  Group Identification Types


  Grp ID Type          Value       Description

  ______________________________________________________________________

  Reserved               0
  UTF-8                  1         Format defined in Section 7.1.1.1.1.
  Octet String           2         This type MUST be implemented.
                                   Format defined in Section 7.1.1.1.2.
  IPv4                   3         Format defined in Section 7.1.1.1.3.
  IPv6                   4         Format defined in Section 7.1.1.1.4.
  Reserved to IANA    5 - 192
  Private Use        193 - 255

  Group Identification Length (1 octet)  - Length of the Group ID
      field in octets.  This value MUST NOT be zero (0).  This field is
      treated as an unsigned value.

  Group Identification Value (variable length)  - Indicates the

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      name/title of the group.  All GroupID types should provide
      unique naming across groups.  GroupID types SHOULD provide this
      capability by including a random element generated by the creator
      (owner) of the group of at least eight (8) octets, providing
      extremely low probability of collision in group names.  The
      GroupID value is static throughout the life of the group.

  Next Payload (1 octet)  - Indicates the type of the next payload
      in the message.  The format for each payload is defined in the
      following sections.  Table 12 presents the payload types.  This
      field is treated as an unsigned value.


                        Table 12:  Payload Types


                   Next_Payload_Type        Value
                  ___________________________________

                   None                       0
                   Policy Token               1
                   Key Download Packet        2
                   Rekey event                3
                   Identification             4
                   Reserved                   5
                   Certificate                6
                   Reserved                   7
                   Signature                  8
                   Notification               9
                   Vendor ID                  10
                   Key Creation               11
                   Nonce                      12
                   Reserved to IANA        13 - 192
                   Private Use           193 -- 255

  Version (1 octet)  - Indicates the version of the GSAKMP protocol in
      use.  The current value is one (1).  This field is treated as an
      unsigned value.

  Exchange Type (1 octet)  - Indicates the type of exchange (also
      known as the message type).  Table 13 presents the exchange type
      values.  This field is treated as an unsigned value.

  Sequence ID (4 octets)  - The Sequence ID is used for replay
      protection of group management messages.  If the message is not
      a group management message, this value MUST be set to zero (0).
      The first value used by a (S-)GC/KS MUST be one (1).  For each
      distinct group management message that this (S-)GC/KS transmits,
      this value MUST be incremented by one (1).  Receivers of this
      group management message MUST confirm that the value received is
      greater that the value of the sequence ID received with the last


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                        Table 13:  Exchange Types


                 Exchange_Type                 Value
                ________________________________________

                 Reserved                      0 - 3
                 Key Download Ack/Failure        4
                 Rekey Event                     5
                 Reserved                      6 - 7
                 Request to Join                 8
                 Key Download                    9
                 Cookie Download                10
                 Request to Join Error          11
                 Lack of Ack                    12
                 Request to Depart              13
                 Departure Response             14
                 Departure Ack                  15
                 Reserved to IANA            16 - 192
                 Private Use                193 -- 255


      group management message from this (S-)GC/KS. Group Components
      (e.g., GMs, S-GC/KSs) MUST terminate processing upon receipt of
      an authenticated group management message containing a Sequence
      ID of 0xFFFFFFFF. This field is treated as an unsigned integer in
      network byte order.

  Length (4 octets)  - Length of total message (header + payloads) in
      octets.  This field is treated as an unsigned integer in network
      byte order.





















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7.1.1.1 GroupID Structure


  This section defines the formats for the defined GroupID types.


7.1.1.1.1 UTF-8 - The format for type UTF-8 [RFC 3629] is shown in
  Figure 4.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Random Value                                                  ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! UTF-8 String                                                  ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                     Figure 4:  GroupID UTF-8 Format


  Random Value (16 octets)  - For the UTF-8 GroupID type, the Random
      Value is represented as a string of exactly 16 hexadecimal digits
      converted from its octet values in network-byte order.  The
      leading zero hexadecimal digits and the trailing zero hexadecimal
      digits are always included in the string, rather than being
      truncated.

  UTF-8 String (variable length)  - This field contains the human
      readable portion of the GroupID in UTF-8 format.  Its length
      is calculated as the (GroupID Length - 16) for the Random Value
      field.  The minimum length for this field is one (1) octet.



7.1.1.1.2 Octet String


  The format for type Octet String is shown in Figure 5.


  Random Value (8 octets)  - The 8 octet unsigned random value in
      network byte order format.

  Octet String (variable length)  - This field contains the Octet

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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Random Value                                                  ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Octet String                                                  ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                 Figure 5:  GroupID Octet String Format


      String portion of the GroupID. Its length is calculated as the
      (GroupID Length - 8) for the Random Value field.  The minimum
      length for this field is one (1) octet.


7.1.1.1.3 IPv4 Group Identifier


  The format for type IPv4 Group Identifier is shown in Figure 6.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Random Value                                                  ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! IPv4 Value                                                    !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                     Figure 6:  GroupID IPv4 Format


  Random Value (8 octets)  - The 8 octet unsigned random value in
      network byte order format.

  IPv4 Value (4 octets)  - The IPv4 value in network byte order
      format.  This value MAY contain the multicast address of the
      group.


7.1.1.1.4 IPv6 Group Identifier


  The format for type IPv6 Group Identifier is shown in Figure 7.

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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Random Value                                                  ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! IPv6 Value                                                    ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                     Figure 7:  GroupID IPv6 Format


  Random Value (8 octets)  - The 8 octet unsigned random value in
      network byte order format.

  IPv6 Value (16 octets)  - The IPv6 value in network byte order
      format.  This value MAY contain the multicast address of the
      group.


7.1.2 GSAKMP Header Processing


  When processing the GSAKMP Header, the following fields MUST be
  checked for correct values:


  1.  Group ID Type - The Group ID Type value MUST be checked to be a
      valid group identification payload type as defined by Table 11.
      If the value is not valid, then an error is logged and if in
      Verbose mode an appropriate message containing notification value
      Payload-Malformed will be sent.

  2.  GroupID - The GroupID of the received message MUST be checked
      against the valid GroupIDs of the Group Component.  If no
      match is found, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Invalid-Group-ID will be sent.

  3.  Next Payload - The Next Payload value MUST be checked to be
      a valid payload type as defined by Table 12.  If the value
      is not valid, then an error is logged and if in Verbose


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      mode an appropriate message containing notification value
      Invalid-Payload-Type will be sent.

  4.  Version - The GSAKMP version number MUST be checked that its
      value is one (1).  For other values, see below for processing.
      The GSAKMP version number MUST be checked that it is consistent
      with the group's policy as specified in its Policy Token.  If
      the version is not supported or authorized, then an error is
      logged and if in Verbose mode an appropriate message containing
      notification value Invalid-Version will be sent.

  5.  Exchange Type - The Exchange Type MUST be checked to be a valid
      exchange type as defined by Table 13 and MUST be of the type
      expected to be received by the GSAKMP state machine.  If the
      exchange type is not valid, then an error is logged and if in
      Verbose mode an appropriate message containing notification value
      Invalid-Exchange-Type will be sent.

  6.  Sequence ID - The Sequence ID value MUST be checked for
      correctness.  For negotiation messages this value MUST be zero
      (0).  For group management messages, this value MUST be greater
      than the last sequence ID received from this (S-)GC/KS. Receipt
      of incorrect Sequence ID on group management messages MUST NOT
      cause a reply message to be generated.  Receipt of incorrect
      Sequence ID on non-group management messages, then an error is
      logged and if in Verbose mode an appropriate message containing
      notification value Invalid-Sequence-ID to be sent.



  The length fields in the GSAKMP Header (Group ID Length and Length)
  are used to help process the message.  If any field is found to
  be incorrect, then an error is logged and if in Verbose mode an
  appropriate message containing notification value Payload-Malformed
  will be sent.

  In order to allow a GSAKMP version one (1) (v1) implementation to
  interoperate with future versions of the protocol, some ideas will
  be discussed here to this affect.

  A (S)-GC/KS that is operating in a multi-versioned group as defined
  by the Policy Token can take many approaches on how to interact with
  the GMs in this group for a Rekey Message.

  One possible solution is for the (S)-GC/KS to send out multiple
  Rekey Messages, one per version level that it supports.  Then each
  GM would only process the message that has the version at which it is
  operating.

  An alternative approach which all GM v1 implementations MUST support
  is the embedding of a v1 message inside a version two (2) (v2)
  message.  If a GM running at v1 receives a GSAKMP message that has

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  a version value greater than one (1), the GM will attempt to process
  the information immediately after the Group Header as a Group Header
  for v1 of the protocol.  If this is in fact a v1 Group Header,
  then the remainder of this v1 message will be processed in place.
  After processing this v1 embedded message, the data following the
  v1 message should be the payload as identified by the Next Payload
  field in the original header of the message and will be ignored by
  the v1 member.  However, if the payload following the initial header
  is not a v1 Group Header, then the GM will gracefully handle the
  unrecognized message.



7.2 Generic Payload Header


7.2.1 Generic Payload Header Structure


  Each GSAKMP payload defined in the following sections begins with
  a generic header, shown in Figure 8, which provides a payload
  ``chaining`` capability and clearly defines the boundaries of a
  payload.  The Generic Payload Header fields are defined as follows:
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                    Figure 8:  Generic Payload Header



  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.







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7.2.2 Generic Payload Header Processing


  When processing the Generic Payload Header, the following fields MUST
  be checked for correct values:



  1.  Next Payload - The Next Payload value MUST be checked to be
      a valid payload type as defined by Table 12.  If the payload
      type is not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Invalid-Payload-Type will be sent.

  2.  RESERVED - This field MUST contain the value zero (0).  If the
      value of this field is not zero (0), then an error is logged and
      if in Verbose mode an appropriate message containing notification
      value Payload-Malformed will be sent.


  The length field in the Generic Payload Header is used to process the
  remainder of the payload.  If this field is found to be incorrect,
  then an error is logged and if in Verbose mode an appropriate message
  containing notification value Payload-Malformed will be sent.


7.3 Policy Token Payload


7.3.1 Policy Token Payload Structure


  The Policy Token Payload contains authenticatable group specific
  information that describes the group security relevant behaviors,
  access control parameters, and security mechanisms.  Figure 9 shows
  the format of the payload.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Policy Token Type             ! Policy Token Data             ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                 Figure 9:  Policy Token Payload Format

  The Policy Token Payload fields are defined as follows:



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  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Policy Token Type (2 octets)  - Specifies the type of Policy Token
      being used.  Table 14 identifies the types of policy tokens.
      This field is treated as an unsigned integer in network byte
      order format.


                      Table 14:  Policy Token Types

   Policy_Token_Type      Value         Definition/Defined In
  ____________________________________________________________________

  Reserved                  0
  GSAKMP_ASN.1_PT_V1        1          All implementations of GSAKMP
                                       MUST support this PT format.
                                       Format specified in [CH02].
  Reserved to IANA      2 - 49152
  Private Use         49153 - 65535

  Policy Token Data (variable length)  - Contains Policy Token
      information.  The values for this field are token specific and
      the format is specified by the PT Type field.


  If this payload is encrypted, only the Policy Token Data field is
  encrypted.

  The payload type for the Policy Token Payload is one (1).


7.3.2 Policy Token Payload Processing


  When processing the Policy Token Payload, the following fields MUST
  be checked for correct values:



  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Number of Items               ! Key Download Data Items       ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                 Figure 10:  Key Download Payload Format


  2.  Policy Token Type - The Policy Token Type value MUST be checked
      to be a valid policy token type as defined by Table 14.  If the
      value is not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Payload-Malformed will be sent.

  3.  Policy Token Data - This Policy Token Data MUST be processed
      according to the Policy Token Type specified.  The type will
      define the format of the data.


7.4 Key Download Payload


  Refer to the terminology section for the different terms relating to
  keys used within this section.


7.4.1 Key Download Payload Structure


  The Key Download Payload contains group keys (e.g., group keys,
  initial rekey keys, etc.).  These key download payloads can have
  several security attributes applied to them based upon the security
  policy of the group.  Figure 10 shows the format of the payload.

  The security policy of the group dictates that the key download
  payload MUST be encrypted with a key encryption key (KEK). The
  encryption mechanism used is specified in the Policy Token.  The
  group members MUST create the KEK using the key creation method
  identified in the Key Creation Payload.

  The Key Download Payload fields are defined as follows:


  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides


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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! KDD Item Type !  Key Download Data Item Length!               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~ Data for Key Download Data Item (Key Datum/Rekey Array)       ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                Figure 11:  Key Download Data Item Format


      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Number of Items (2 octets)  -- Contains the total number of traffic
      protection keys and Rekey Arrays being passed in this data block.
      This field is treated as an unsigned integer in network byte
      order format.

  Key Download Data Items (variable length)  - Contains Key
      Download information.  The Key Download Data is a sequence of
      Type/Length/Data of the Number of Items.  The format for each
      item is defined in figure 11.

      For each Key Download Data Item, the data format is as follows:


      Key Download Data (KDD) Item Type (1 octet)  -- Identifier for
          the type of data contained in this Key Download Data Item.
          See Table 15 for the possible values of this field.  This
          field is treated as an unsigned value.

      Key Download Data Item Length (2 octets)  -- Length in octets
          of the Data for the Key Download Data Item following this
          field.  This field is treated as an unsigned integer in
          network byte order format.

      Data for Key Download Data Item (variable length)  -- Contains
          Keys and related information.  The format of this field is
          specific depending on the value of the Key Download Data
          Item Type field.  For KDD Item Type of GTPK, this field will
          contain a Key Datum as defined in Section 7.4.1.1 .  For KDD
          Item Type Rekey - LKH, this field will contain a Rekey Array


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                 Table 15:  Key Download Data Item Types

    Key Download Data     Value      Definition
    Item Type
   __________________________________________________________________

    GTPK                    0        This type MUST be implemented.
                                     This type identifies that the
                                     data contains group traffic
                                     protection key information.
    Rekey - LKH             1        Optional
    Reserved to IANA     2 - 192
    Private Use         193 - 255


          as defined in Section 7.4.1.2 .


  The encryption of this payload only covers the data subsequent to the
  Generic Payload header (Number of Items and Key Download Data Items
  fields).

  The payload type for the Key Download Packet is two (2).


7.4.1.1 Key Datum Structure


  A Key Datum contains all the information for a key.  Figure 12 shows
  the format for this structure.


  Key Type (2 octets)  -- This is the cryptographic algorithm for
      which this key data is to be used.  This value is specified in
      the Policy Token.  See Table 16 for the possible values of this
      field.  This field is treated as an unsigned value.

  Key ID (4 octets)  -- This is the permanent ID of all versions of
      the key.  This value MAY be defined by the Policy Token.  This
      field is treated as an octet string.

  Key Handle (4 octets)  -- This is the value to uniquely identify a
      version (particular instance) of a key.  This field is treated as
      an octet string.

  Key Creation Date (15 octets)  -- This is the time value of when
      this key data was originally generated.  This field contains the
      timestamp in UTF-8 format YYYYMMDDHHMMSSZ, where YYYY is the year
      (0000 - 9999), MM is the numerical value of the month (01 - 12),
      DD is the day of the month (01 - 31), HH is the hour of the day


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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Key Type                      ! Key ID                        ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                               ! Key Handle                    ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                               ! Key Creation Date             ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !               ! Key Expiration Date                           ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                               !               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~ Key Data                                                      ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                      Figure 12:  Key Datum Format













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                   Table 16:  Cryptographic Key Types

   Cryptographic_Key_Types     Value         Description/Defined In
  _____________________________________________________________________

  Reserved                     0 - 2
  3DES_CBC64_192                 3           See [RFC 2451].
  Reserved                     4 - 11
  AES_CBC_128                    12          This type MUST be
                                             supported.  See [IKEv2].
  AES_CTR                        13          See [IKEv2].
  Reserved to IANA           14 - 49152
  Private Use              49153 - 65535


      (00 - 23), MM is the minute within the hour (00 - 59), SS is the
      seconds within the minute (00 - 59), and followed by the letter Z
      to indicate that this is Zulu time.  This format is loosely based
      on [RFC 3161].

  Key Expiration Date (15 octets)  -- This is the time value of when
      this key is no longer valid for use.  This field contains the
      timestamp in UTF-8 format YYYYMMDDHHMMSSZ, where YYYY is the year
      (0000 - 9999), MM is the numerical value of the month (01 - 12),
      DD is the day of the month (01 - 31), HH is the hour of the day
      (00 - 23), MM is the minute within the hour (00 - 59), SS is the
      seconds within the minute (00 - 59), and followed by the letter Z
      to indicate that this is Zulu time.  This format is loosely based
      on [RFC 3161].

  Key Data (variable length)  -- This is the actual key data, which is
      dependent on the Key Type algorithm for its format.


  NOTE: The combination of the Key ID and the Key Handle MUST be unique
  within the group.  This combination will be used to uniquely identify
  a key.


7.4.1.2 Rekey Array Structure


  A Rekey Array contains the information for the set of KEKs that is
  associated with a Group Member.  Figure  13 shows the format for this
  structure.


  Rekey Version (1 octet)  -- Contains the version of the Rekey
      protocol in which the data is formatted.  For Key Download Data
      Item Type of Rekey - LKH, refer to Section A.2 for a description


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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Rekey Version#! Member ID                                     ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~               ! Number of KEK Keys            !               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~ Key Datum(s)                                                  ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                Figure 13:  Rekey Array Structure Format


      of this value.  This field is treated as an unsigned value.

  Member ID (4 octets)  -- This is the Member ID of the Rekey sequence
      contained in this Rekey Array.  This field is treated as an octet
      string.  For Key Download Data Item Type of Rekey - LKH, refer to
      Section A.2 for a description of this value.

  Number of KEK Keys (2 octets)  -- This value is the number of
      distinct KEK keys in this sequence.  This value is treated as an
      unsigned integer in network byte order format.

  Key Datum(s) (variable length)  -- The sequence of KEKs in Key
      Datum format.  The format for each Key Datum in this sequence is
      defined in section 7.4.1.1.


       Key ID - For Key ID within the Rekey - LKH space, refer to
          Section A.2 for a description of this value.


7.4.2 Key Download Payload Processing


  Prior to processing its data, the payload contents MUST be decrypted.

  When processing the Key Download Payload, the following fields MUST
  be checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

  2.  KDD Item Type - All KDD Item Type fields MUST be checked to be
      a valid Key Download Data Item type as defined by Table 15.
      If the value is not valid, then an error is logged and if in


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      Verbose mode an appropriate message containing notification value
      Payload-Malformed will be sent.

  3.  Key Type - All Key Type fields MUST be checked to be a
      valid encryption type as defined by table 16.  If the value
      is not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Invalid-Key-Information will be sent.

  4.  Key Expiration Date - All Key Expiration Date fields MUST be
      checked confirm that their values represent a future and not a
      past time value.  If the value is not valid, then an error is
      logged and if in Verbose mode an appropriate message containing
      notification value Invalid-Key-Information will be sent.



  The length and counter fields in the payload are used to help process
  the payload.  If any field is found to be incorrect, then an error
  is logged and if in Verbose mode an appropriate message containing
  notification value Payload-Malformed will be sent.


7.5 Rekey Event Payload


  Refer to the terminology section for the different terms relating to
  keys used within this section.


7.5.1 Rekey Event Payload Structure


  The Rekey Event Payload MAY contain multiple keys encrypted in
  Wrapping KEKs.  Figure 14 shows the format of the payload.  If the
  data to be contained within a Rekey Event Payload is too large for
  the payload, the sequence can be split across multiple Rekey Event
  Payloads at a Rekey Event Data boundary.

  The Rekey Event Payload fields are defined as follows:


  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is

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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! RekeyEvnt Type!  Rekey Event Header                           ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~ Rekey Event Data(s)                                           ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                 Figure 14:  Rekey Event Payload Format


      treated as an unsigned integer in network byte order format.

  Rekey Event Type (1 octet)  - Specifies the type of Rekey Event
      being used.  Table 17 presents the types of Rekey events.  This
      field is treated as an unsigned value.


                      Table 17:  Rekey Event Types

  Rekey_Event_Type     Value       Definition/Defined In
  ______________________________________________________________________

  None                   0         This type MUST be implemented.
                                   In this case, the size of the Rekey
                                   Event Data field will be zero bytes
                                   long.  The purpose of a Rekey Event
                                   Payload with type None is when it is
                                   necessary to send out a new token
                                   with no rekey information.  GSAKMP
                                   Rekey Msg requires a Rekey Event
                                   Payload, and in this instance it
                                   would have rekey data of type None.
  GSAKMP_LKH             1         The rekey data will be of
                                   type LKH formatted according to
                                   GSAKMP. The format for this field
                                   is defined in Section 7.5.1.2.
  Reserved to IANA    2 - 192
  Private Use        193 - 255

  Rekey Event Header (variable length)  - This is the header
      information for the Rekey Event.  The format for this is defined
      in Section 7.5.1.1, Rekey Event Header Structure.

  Rekey Event Data(s) (variable length)  - This is the rekey
      information for the Rekey Event.  The format for this is defined
      in Section 7.5.1.2, Rekey Event Data(s) Structure.


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  The Rekey Event payload type is three (3).


7.5.1.1 Rekey Event Header Structure


  The format for the Rekey Event Header is shown in Figure 15.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !                    Group ID Value                             ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                    Group ID Value                             !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Time/Date Stamp                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                               ! RekeyEnt Type ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Algorithm Ver ! # of Rekey Event Data(s)      !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                  Figure 15:  Rekey Event Header Format


  Group Identification Value (variable length)  - Indicates the
      name/title of the group to be rekeyed.  This is the same format,
      length and value as the Group Identification Value in Section
      7.1 GSAKMP Message Header.

  Time/Date Stamp (15 octets)  -- This is the time value when the
      Rekey Event Data was generated.  This field contains the
      timestamp in UTF-8 format YYYYMMDDHHMMSSZ, where YYYY is the year
      (0000 - 9999), MM is the numerical value of the month (01 - 12),
      DD is the day of the month (01 - 31), HH is the hour of the day
      (00 - 23), MM is the minute within the hour (00 - 59), SS is the
      seconds within the minute (00 - 59), and followed by the letter Z
      to indicate that this is Zulu time.  This format is loosely based
      on [RFC 3161].

  Rekey Event Type (1 octet)  - This is the Rekey algorithm being
      used for this group.  The values for this field can be found in
      Table 17.  This field is treated as an unsigned value.

  Algorithm Version (1 octet)  - Indicates the version of the Rekey
      Type being used.  For Rekey Event Type of GSAKMP_LKH, refer to


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      Section A.2 for a description of this value.  This field is
      treated as an unsigned value.

  # of Rekey Event Data(s) (2 octets)  - The number of Rekey Event
      Data(s) contained in the Rekey Data.  This value is treated as an
      unsigned integer in network byte order.



7.5.1.2 Rekey Event Data Structure


  As defined in the Rekey Event Header, # of Rekey Data(s) field,
  multiple pieces of information are sent in a Rekey Event Data.  Each
  end user, will be interested in only one Rekey Event Data among all
  of the information sent.  Each Rekey Event Data, will contain all
  the Key Packages that a user requires.  For each Rekey Event Data,
  the data following the Wrapping fields is encrypted with the key
  identified in the Wrapping Header.  Figure 16 shows the format of
  each Rekey Event Data.
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Packet Length                 ! Wrapping KeyID                ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                               ! Wrapping Key Handle           ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                               ! # of Key Packages             !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Key Packages(s)                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                   Figure 16:  Rekey Event Data Format



  Packet Length (2 octets)  - Length in octets of the Rekey Event
      Data, which consists of the # of Key Packages and the Key
      Packages(s).  This value is treated as an unsigned integer in
      network byte order.

  Wrapping KeyID (4 octets)  - This is the Key ID of the KEK that is
      being used for encryption/decryption of the new (rekeyed) keys.
      For Rekey Event Type of Rekey - LKH, refer to Section A.2 for a
      description of this value.

  Wrapping Key Handle (4 octets)  - This is a Key Handle of the KEK
      that is being used for encryption/decryption of the new (rekeyed)
      keys.  Refer to Section 7.4.1.1 for the values of this field.

  # of Key Packages (2 octets)  - The number of key packages contained

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      in this Rekey Event Data.  This value is treated as an unsigned
      integer in network byte order.

  Key Package(s) (variable length)  - The type/length/value
      format of a Key Datum.  The format for this is defined in
      Section 7.5.1.2.1.



7.5.1.2.1 Key Package Structure


  Each Key Package contains all the information about the key.
  Figure 17 shows the format for a Key Package.
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! KeyPkg Type   ! Key Package Length            ! Key Datum     ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                     Figure 17:  Key Package Format


  Key Package Type (1 octet)  - The type of key in this key package.
      Legal values for this field are defined in Table 15, Key Download
      Data Types.  This field is treated as an unsigned value.

  Key Package Length (2 octets)  - The length of the Key Datum.  This
      field is treated as an unsigned integer in network byte order
      format.

  Key Datum (variable length)  - The actual data of the key.  The
      format for this field is defined in Section 7.4.1.1, Key Datum.



7.5.2 Rekey Event Payload Processing


  When processing the Rekey Event Payload, the following fields MUST be
  checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

  2.  Rekey Event Type field within "Rekey Event" payload header - The
      Rekey Event Type MUST be checked to be a valid rekey event type
      as defined by Table 17.  If the Rekey Event Type is not valid,
      then regardless of mode (e.g., Terse or Verbose) an error is

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      logged.  No response error message is generated for receipt of a
      Group Management Message.

  3.  Group ID Value - The Group ID value of the Rekey Event Header
      received message MUST be checked against the GroupID of the Group
      Component.  If no match is found, the payload is discarded, then
      regardless of mode (e.g., Terse or Verbose) an error is logged.
      No response error message is generated for receipt of a Group
      Management Message.

  4.  Date/Time Stamp - The Date/Time Stamp value of the Rekey Event
      Header MAY be checked to determine if the Rekey Event generation
      time is recent relative to network delay and processing times.
      If the TimeStamp is judged not to be recent, an error is logged.
      No response error message is generated for receipt of a Group
      Management Message.

  5.  Rekey Event Type field within the "Rekey Event Header" - The
      Rekey Event Type of the Rekey Event Header received message
      MUST be checked to be a valid rekey event type as defined by
      Table 17 and the same value of the Rekey Event Type earlier in
      this payload.  If the Rekey Event Type is not valid or not equal
      to the previous value of the Rekey Event Type, then regardless of
      mode (e.g., Terse or Verbose) an error is logged.  No response
      error message is generated for receipt of a Group Management
      Message.

  6.  Algorithm Version - The Rekey Algorithm Version number MUST be
      checked that it is supported.  If the version is not supported,
      then regardless of mode (e.g., Terse or Verbose) an error is
      logged.  No response error message is generated for receipt of a
      Group Management Message.



  The length and counter fields are used to help process the message.
  If any field is found to be incorrect, then termination processing
  MUST be initiated.

  A GM MUST process all the Rekey Event Datas as based on the Rekey
  method used there is a potential that multiple Rekey Event Datas are
  for this GM. The Rekey Event Datas are processed in order until all
  Rekey Event Datas are consumed.


  1.  Wrapping KeyID - The Wrapping KeyID MUST be checked against the
      list of stored KEKs that this GM holds.  If a match is found,
      then continue processing this Rekey Event Data.  Otherwise, skip
      to the next Rekey Event Data.

  2.  Wrapping Handle - If a matching Wrapping KeyID was found, then
      the Wrapping Handle MUST be checked against the handle of the KEK

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      for which the KeyID was a match.  If the handles match, then the
      GM will process the Key Packages associated with this Rekey Event
      Data.  Otherwise, skip to the next Rekey Event Data.



  If a GM has found a matching Wrapping KeyID and Wrapping Handle, the
  GM decrypts the remaining data in this Rekey Event Data according to
  policy using the KEK defined by the Wrapping KeyID and Handle.  After
  decrypting the data, the GM extracts the # of Key Packages field
  to help process the subsequent Key Packages.  The Key Packages are
  processed as follows:


  1.  Key Package Type - The Key Package Type MUST be checked to be
      a valid key package type as defined by Table 15.  If the Key
      Package Type is not valid, then regardless of mode (e.g., Terse
      or Verbose) an error is logged.  No response error message is
      generated for receipt of a Group Management Message.

  2.  Key Package Length - The Key Package Length is used to process
      the subsequent Key Datum information.

  3.  Key Type - The Key Type MUST be checked to be a valid key type as
      defined by Table 16.  If the Key Package Type is not valid, then
      regardless of mode (e.g., Terse or Verbose) an error is logged.
      No response error message is generated for receipt of a Group
      Management Message.

  4.  Key ID - The Key ID MUST be checked against the set of Key IDs
      that this user maintains for this Key Type.  If no match is
      found, then regardless of mode (e.g., Terse or Verbose) an error
      is logged.  No response error message is generated for receipt of
      a Group Management Message.

  5.  Key Handle - The Key Handle is extracted as is and is used to be
      the new Key Handle for the Key currently associated with the Key
      Package's Key ID.

  6.  Key Creation Date - The Key Creation Date MUST be checked that
      it is subsequent to the Key Creation Date for the currently
      held key.  If this date is prior to the currently held key, then
      regardless of mode (e.g., Terse or Verbose) an error is logged.
      No response error message is generated for receipt of a Group
      Management Message.

  7.  Key Expiration Date - The Key Expiration Date MUST be checked
      that it is subsequent to the Key Creation Date just received and
      that the time rules conform with policy.  If the expiration date
      is not subsequent to the creation date or does not conform with
      policy, then regardless of mode (e.g., Terse or Verbose) an error
      is logged.  No response error message is generated for receipt of

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      a Group Management Message.

  8.  Key Data - The Key Data is extracted based on the length
      information in the key package.



  If there were no errors when processing the Key Package, the key
  represented by the KeyID will have all of its data updated based upon
  the received information.


7.6 Identification Payload


7.6.1 Identification Payload Structure


  The Identification Payload contains entity-specific data used to
  exchange identification information.  This information is used to
  verify the identities of members.  Figure 18 shows the format of the
  Identification Payload.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! ID Classif    !  ID Type      !      Identification Data      ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                Figure 18:  Identification Payload Format

  The Identification Payload fields are defined as follows:


  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Identification (ID) Classification (1 octet)  - Classifies the
      ownership of the Identification Data.  Table 18 identifies

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      possible values for this field.  This field is treated as an
      unsigned value.


                Table 18:  Identification Classification

                     ID_Classification     Value
                    _______________________________

                     Sender                  0
                     Receiver                1
                     Third Party             2
                     Reserved to IANA     3 - 192
                     Private Use         193 - 255

  Identification (ID) Type (1 octet)  - Specifies the type of
      Identification being used.  Table 19 identifies possible values
      for this type.  This field is treated as an unsigned value.  All
      defined types are OPTIONAL unless otherwise stated.

  Identification Data (variable length)  - Contains identity
      information.  The values for this field are group-specific and
      the format is specified by the ID Type field.  The format for
      this field is stated in conjunction with the type in Table 19.


  The payload type for the Identification Payload is four (4).


























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                     Table 19:  Identification Types

  ID_Type              Value       PKIX Cert           Description
                                   Field               Defined In
  ______________________________________________________________________

  Reserved               0
  ID_IPV4_ADDR           1         SubjAltName         See [IKEv2]
                                   iPAddress           sec 3.5.
  ID_FQDN                2         SubjAltName         See [IKEv2]
                                   dNSName             sec 3.5.
  ID_RFC822_ADDR         3         SubjAltName         See [IKEv2]
                                   rfc822Name          sec 3.5.
  Reserved               4
  ID_IPV6_ADDR           5         SubjAltName         See [IKEv2]
                                   iPAddress           sec 3.5.
  Reserved             6 - 8
  ID_DER_ASN1_DN         9         Entire Subject,     See [IKEv2]
                                   bitwise Compare     sec 3.5.
  Reserved               10
  ID_KEY_ID              11        N/A                 See [IKEv2]
  Reserved            12 - 29                          sec 3.5.
  Unencoded Name         30        Subject             The format for
   (ID_U_NAME)                                         this type is
                                                       defined in
                                                       Section 7.6.1.1.
  ID_DN_STRING           31        Subject             See [OpenLDAP].
                                                       This type MUST be
                                                       implemented.
  Reserved to IANA    32 - 192
  Private Use        193 - 255











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7.6.1.1 ID_U_NAME Structure


  The format for type Unencoded Name (ID_U_NAME) is shown in Figure 19.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Serial Number                                                 ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Length                                                        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! DN Data                                                       ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



              Figure 19:  Unencoded Name (ID-U-NAME) Format


  Serial Number (20 octets)  -- The certificate serial number.  This
      field is treated as an unsigned integer in network byte order
      format.

  Length (4 octets)  -- Length in octets of the DN Data field.  This
      field is treated as an unsigned integer in network byte order
      format.

  DN Data (variable length)  -- The actual UTF-8 DN value (Subject
      field) using the slash (/) character for field delimiters.
      (e.g., "/C=US/ST=MD/L=Somewhere/O=ACME, Inc./OU=DIV1/CN=user1/
      Email=user1@acme.com" without the surrounding quotes)



7.6.2 Identification Payload Processing


  When processing the Identification Payload, the following fields MUST
  be checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header

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      Processing.

  2.  Identification Classification - The Identification Classification
      value MUST be checked to be a valid identification classification
      type as defined by Table 18.  If the value is not valid, then
      an error is logged and if in Verbose mode an appropriate message
      containing notification value Payload-Malformed will be sent.

  3.  Identification Type - The Identification Type value MUST be
      checked to be a valid identification type as defined by Table 19.
      If the value is not valid, then an error is logged and if in
      Verbose mode an appropriate message containing notification value
      Payload-Malformed will be sent.

  4.  Identification Data - This Identification Data MUST be processed
      according to the identification type specified.  The type will
      define the format of the data.  If the identification data
      is being used to find a match and no match is found, then an
      error is logged and if in Verbose mode an appropriate message
      containing notification value Invalid-ID-Information will be
      sent.



7.6.2.1 ID_U_NAME Processing


  When processing the Identification Data of type ID_U_NAME, the
  following fields MUST be checked for correct values:


  1.  Serial Number - The serial number MUST be a greater than or equal
      to one (1) to be a valid serial number from a conforming CA [RFC
      3280].  If the value is not valid, then an error is logged and
      if in Verbose mode an appropriate message containing notification
      value Payload-Malformed will be sent.

  2.  DN Data - The DN data is processed as a UTF-8 string.

  3.  The CA MUST be a valid trusted policy creation authority as
      defined by the Policy Token.


  These 2 pieces of information, Serial Number and DN Data, in
  conjunction will then be used for party identification.  These values
  are also used to help identify the certificate when necessary.







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7.7 Certificate Payload


7.7.1 Certificate Payload Structure


  The Certificate Payload provides a means to transport certificates
  or other certificate-related information via GSAKMP and can appear
  in any GSAKMP message.  Certificate payloads SHOULD be included
  in an exchange whenever an appropriate directory service (e.g.
  Secure DNS [DNSSEC]) is not available to distribute certificates.
  Multiple certificate payloads MAY be sent to enable verification of
  certificate chains.  Conversely, zero (0) certificate payloads may
  be sent and the receiving GSAKMP MUST rely on some other mechanism to
  retrieve certificates for verification purposes.  Figure 20 shows the
  format of the Certificate Payload.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Cert Type                     !    Certificate Data           ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                 Figure 20:  Certificate Payload Format

  The Certificate Payload fields are defined as follows:


  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Certificate Type (2 octets)  - This field indicates the type of
      certificate or certificate-related information contained in
      the Certificate Data field.  Table 20 presents the types of
      certificate payloads.  This field is treated as an unsigned
      integer in network byte order format.

  Certificate Data (variable length)  - Actual encoding of certificate


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                  Table 20:  Certificate Payload Types

  Certificate_Type                   Value         Description/
                                                   Defined In
  ______________________________________________________________________

  None                                 0
  Reserved                           1 - 3
  X.509v3 Certificate                  4           This type MUST be
    -- Signature                                   implemented.
    -- DER Encoding                                Contains a DER
                                                   encoded X.509
                                                   certificate.
  Reserved                           5 - 6
  Certificate Revocation List          7           Contains a BER
    (CRL)                                          encoded X.509 CRL.
  Reserved                           8 - 9
  X.509 Certificate                   10           See [IKEv2] sec 3.6.
    -- Attribute
  Raw RSA Key                         11           See [IKEv2] sec 3.6.
  Hash and URL of X.509               12           See [IKEv2] sec 3.6.
   Certificate
  Hash and URL of X.509               13           See [IKEv2] sec 3.6.
   bundle
  Reserved to IANA                14 -- 49152
  Private Use                   49153 -- 65535


      data.  The type of certificate is indicated by the Certificate
      Type/Encoding field.


  The payload type for the Certificate Payload is six (6).


7.7.2 Certificate Payload Processing


  When processing the Certificate Payload, the following fields MUST be
  checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

  2.  Certificate Type - The Certificate Type value MUST be checked
      to be a valid certificate type as defined by Table 20.  If the
      value is not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value


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      Cert-Type-Unsupported will be sent.

  3.  Certificate Data - This Certificate Data MUST be processed
      according to the certificate type specified.  The type will
      define the format of the data.  Receipt of a certificate of the
      trusted policy creation authority in a Certificate payload causes
      the payload to be discarded.  This received certificate MUST NOT
      be used to verify the message.  The certificate of the trusted
      policy creation authority MUST be retrieved by other means.



7.8 Signature Payload


7.8.1 Signature Payload Structure


  The Signature Payload contains data generated by the digital
  signature function.  The digital signature, as defined by the
  dissection of each message, covers the message from the GSAKMP
  Message Header through the Signature Payload up to but not including
  the Signature Data Length.  Figure 21 shows the format of the
  Signature Payload.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Signature Type                ! Sig ID Type   !               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~ Signature Timestamp                                           ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                               ! Signer ID Length              !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !                    Signer ID Data                             ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !     Signature Length          !     Signature Data            ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                  Figure 21:  Signature Payload Format

  The Signature Payload fields are defined as follows:

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  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Signature Type (2 octets)  -- Indicates the type of signature.
      Table 21 presents the allowable signature types.  This field is
      treated as an unsigned integer in network byte order format.


                       Table 21:  Signature Types

  Signature Type                         Value         Description/
                                                       Defined In
  ______________________________________________________________________

  DSS/SHA1 with ASN.1/DER encoding         0           This type MUST be
  (DSS-SHA1-ASN1-DER)                                  supported.
  RSA1024-MD5                              1           See [RFC 3447].
  ECDSA-P384-SHA3                          2           See [FIPS 186-2].
  Reserved to IANA                     3 - 41952
  Private Use                        41953 - 65536

  Signature ID Type (1 octet)  -- Indicates the format for the
      Signature ID Data.  These values are the same as those defined
      for the Identification Payload Identification types which can be
      found in Table 19.  This field is treated as an unsigned value.

  Signature Timestamp (15 octets)  -- This is the time value when the
      digital signature was applied.  This field contains the timestamp
      in UTF-8 format YYYYMMDDHHMMSSZ, where YYYY is the year (0000 -
      9999), MM is the numerical value of the month (01 - 12), DD is
      the day of the month (01 - 31), HH is the hour of the day (00
      - 23), MM is the minute within the hour (00 - 59), SS is the
      seconds within the minute (00 - 59), and followed by the letter Z
      to indicate that this is Zulu time.  This format is loosely based
      on [RFC 3161].

  Signer ID Length (2 octets)  - Length in octets of the Signer' ID.
      This field is treated as an unsigned integer in network byte
      order format.

  Signer ID Data (variable length)  -- Data identifying the Signer's
      ID (e.g., DN). The format for this field is based on the


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      Signature ID Type field and is shown where that type is defined.
      The contents of this field MUST be checked against the Policy
      Token to determine the authority and access of the Signer within
      the context of the group.

  Signature Length (2 octets)  -- Length in octets of the Signature
      Data.  This field is treated as an unsigned integer in network
      byte order format.

  Signature Data (variable length)  - Data that results from applying
      the digital signature function to the GSAKMP message and/or
      payload.



  The payload type for the Signature Payload is eight (8).


7.8.2 Signature Payload Processing


  When processing the Signature Payload, the following fields MUST be
  checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

  2.  Signature Type - The Signature Type value MUST be checked to
      be a valid signature type as defined by Table 21.  If the
      value is not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Payload-Malformed will be sent.

  3.  Signature ID Type - The Signature ID Type value MUST be checked
      to be a valid signature ID type as defined by Table 19.  If the
      value is not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Payload-Malformed will be sent.

  4.  Signature Timestamp - This field MAY be checked to determine
      if the transaction signing time is fresh relative to expected
      network delays.  Such a check is appropriate for systems in which
      archived sequences of events is desired.

      NOTE: The maximum acceptable age of a signature timestamp
      relative to the local system clock is a locally configured
      parameter that can be tuned by its GSAKMP management interface.

  5.  Signature ID Data - This field will be used to identify the
      sending party.  This information MUST then be used to confirm

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      that the correct party sent this information.  This field is also
      used to retrieve the appropriate public key of the certificate to
      verify the message.

  6.  Signature Data - This value MUST be compared to the recomputed
      signature to verify the message.  Information on how to verify
      certificates used to ascertain the validity of the signature
      can be found in [RFC 3280].  Only after the certificate
      identified by the Signature ID Data is verified can the signature
      be computed to compare to the signature data for signature
      verification.  A potential error that can occur during signature
      verification is Authentication-Failed.  Potential errors
      that can occur while processing certificates for signature
      verification are:  Invalid-Certificate, Invalid-Cert-Authority,
      Cert-Type-Unsupported, and Certificate-Unavailable.



  The length fields in the Signature Payload are used to process the
  remainder of the payload.  If any field is found to be incorrect,
  then termination processing MUST be initiated.


7.9 Notification Payload


7.9.1 Notification Payload Structure


  The Notification Payload can contain both GSAKMP and group specific
  data and is used to transmit informational data, such as error
  conditions, to a GSAKMP peer.  It is possible to send multiple
  independent Notification payloads in a single GSAKMP message.
  Figure 22 shows the format of the Notification Payload.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !        Payload Length         !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Notification Type             !  Notification Data            ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                 Figure 22:  Notification Payload Format

  The Notification Payload fields are defined as follows:


  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last

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      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Notification Type (2 octets)  - Specifies the type of notification
      message.  Table 22 presents the Notify Payload Types.  This field
      is treated as an unsigned integer in network byte order format.

  Notification Data (variable length)  - Informational or error data
      transmitted in addition to the Notify Payload Type.  Values for
      this field are Domain of Interpretation (DOI)-specific.



  The payload type for the Notification Payload is nine (9).
































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                      Table 22:  Notification Types

        Notification Type                             Value
       __________________________________________________________

        None                                            0
        Invalid-Payload-Type                            1
        Reserved                                      2 - 3
        Invalid-Version                                 4
        Invalid-Group-ID                                5
        Invalid-Sequence-ID                             6
        Payload-Malformed                               7
        Invalid-Key-Information                         8
        Invalid-ID-Information                          9
        Reserved                                     10 - 11
        Cert-Type-Unsupported                           12
        Invalid-Cert-Authority                          13
        Authentication-Failed                           14
        Reserved                                     15 - 16
        Certificate-Unavailable                         17
        Reserved                                        18
        Unauthorized-Request                            19
        Reserved                                     20 - 22
        Acknowledgment                                  23
        Reserved                                     24 - 25
        Nack                                            26
        Cookie-Required                                 27
        Cookie                                          28
        Mechanism Choices                               29
        Leave Group                                     30
        Departure Accepted                              31
        Request to Depart Error                         32
        Invalid Exchange Type                           33
        IPv4 Value                                      34
        IPv6 Value                                      35
        Prohibited by Group Policy                      36
        Prohibited by Locally Configured Policy         37
        Reserved to IANA                            38 - 49152
        Private Use                               49153 -- 65535







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7.9.1.1 Notification Data - Acknowledgment (ACK) Payload Type


  The data portion of the Notification payload of type ACK serves
  either for confirmation of correct receipt of the Key Download
  message, or, when needed, can provide other receipt information when
  included in a signed message.  Figure 23 shows the format of the
  Notification Data - Acknowledge Payload Type.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Ack Type      !       Acknowledgment Data                     ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



     Figure 23:  Notification Data - Acknowledge Payload Type Format

  The Notification Data - Acknowledgment Payload Type data fields are
  defined as follows:


  Ack Type (1 octet)  - Specifies the type of acknowledgment.
      Table 23 presents the Notify Acknowledgment Payload Types.  This
      field is treated as an unsigned value.


                     Table 23:  Acknowledgment Types

          ACK_Type             Value       Definition
         _____________________________________________________

          Simple                 0         Data portion null.
          Reserved to IANA    1 - 192
          Private Use        193 - 255


7.9.1.2 Notification Data - Cookie_Required and Cookie Payload Type


  The data portion of the Notification payload of types Cookie_Required
  and Cookie contain the Cookie value.  The value for this field will
  have been computed by the responder GC/KS and sent to the GM. The
  GM will take the value received and copy it into the Notification
  payload Notification Data field of type Cookie that is transmitted in
  the "Request to Join with Cookie Info" back to the GC/KS. The cookie
  value MUST NOT be modified.

  The format for this is already described in the discussion on cookies
  in section 5.2.2.


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7.9.1.3 Notification Data - Mechanism Choices Payload Type


  The data portion of the Notification payload of types Mechanism
  Choices contains the mechanisms the GM is requesting to use for the
  negotiation with the GC/KS. This information will be supplied by the
  GM in a RTJ message.  Figure 24 shows the format of the Notification
  Data - Mechanism Choices Payload Type.  Multiple type|length|data
  choices are strung together in one notification payload to allow a
  user to transmit all relevant information within one Notification
  Payload.  The length of the payload will control the parsing of the
  Notification Data Mechanism Choices field.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ! Mech Type     ! Mechanism Choice Data         !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..



  Figure 24:  Notification Data - Mechanism Choices Payload Type Format

  The Notification Data - Mechanism Choices Payload Type data fields
  are defined as follows:


  Mechanism Type (1 octet)  - Specifies the type of mechanism.
      Table 24 presents the Notify Mechanism Choices Mechanism Types.
      This field is treated as an unsigned value.


                       Table 24:  Mechanism Types

   Mechanism_Type             Value       Mechanism Choice
                                          Data Value Table Reference
  ___________________________________________________________________

   Key Creation Algorithm       0         Table 26
   Encryption Algorithm         1         Table 16
   Nonce Hash Algorithm         2         Table 25
   Reserved to IANA          3 - 192
   Private Use              193 - 255

  Mechanism Choice Data (2 octets) - The data value for the mechanism
      type being selected.  The values are specific to each Mechanism
      Type defined.  All tables necessary to define the values that
      are not defined elsewhere (in this specification or others) are
      defined here.  This field is treated as an unsigned integer in
      network byte order format.



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                       Table 25:  Nonce Hash Types

   Nonce_Hash_Type        Value         Description
  ___________________________________________________________________

   Reserved                 0
   SHA-1                    1           This type MUST be supported.
   Reserved to IANA     2 - 49152
   Private Use        49153 - 65535


7.9.1.4 Notification Data - IPv4 and IPv6 Value Payload Types


  The data portion of the Notification payload of type IPv4 and IPv6
  value contains the appropriate IP value in network byte order.  This
  value will be set by the creator of the message for consumption by
  the receiver of the message.


7.9.2 Notification Payload Processing


  When processing the Notification Payload, the following fields MUST
  be checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

  2.  Notification Type - The Notification type value MUST be checked
      to be a notification type as defined by Table 22.  If the
      value is not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Payload-Malformed will be sent.

  3.  Notification Data - This Notification Data MUST be processed
      according to the notification type specified.  The type will
      define the format of the data.  When processing this data,
      any type field MUST be checked against the appropriate table
      for correct values.  If the contents of the Notification Data
      are not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Payload-Malformed will be sent.







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7.10 Vendor ID Payload


7.10.1 Vendor ID Payload Structure


  The Vendor ID Payload contains a vendor defined constant.  The
  constant is used by vendors to identify and recognize remote
  instances of their implementations.  This mechanism allows a
  vendor to experiment with new features while maintaining backwards
  compatibility.  Figure 25 shows the format of the payload.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !                         Vendor ID (VID)                       ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                  Figure 25:  Vendor ID Payload Format

  A Vendor ID payload MAY announce that the sender is capable to
  accepting certain extensions to the protocol, or it MAY simply
  identify the implementation as an aid in debugging.  A Vendor ID
  payload MUST NOT change the interpretation of any information defined
  in this specification.  Multiple Vendor ID payloads MAY be sent.  An
  implementation is NOT REQUIRED to send any Vendor ID payload at all.

  A Vendor ID payload may be sent as part of any message.  Reception
  of a familiar Vendor ID payload allows an implementation to make
  use of Private Use numbers described throughout this specification
  -- private payloads, private exchanges, private notifications, etc.
  This implies that all the processing rules defined for all the
  payloads are now modified to recognize all values defined by this
  Vendor ID for all fields of all payloads.  Unfamiliar Vendor IDs MUST
  be ignored.

  Writers of Internet-Drafts who wish to extend this protocol MUST
  define a Vendor ID payload to announce the ability to implement the
  extension in the Internet-Draft.  It is expected that Internet-Drafts
  which gain acceptance and are standardized will be given assigned
  values out of the Reserved to IANA range and the requirement to use
  a Vendor ID payload will go away.

  The VendorID Payload fields are defined as follows:


  Next Payload (1 octet)  - Identifier for the payload type of the


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      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Vendor ID (variable length)  - The Vendor ID value.  The
      minimum length for this field is four (4) octets.  It is the
      responsibility of the person choosing the Vendor ID to assure its
      uniqueness in spite of the absence of any central registry for
      IDs.  Good practice is to include a company name, a person name
      or similar type data.  A message digest of a long unique string
      is preferable to the long unique string itself.



  The payload type for the Vendor ID Payload is ten (10).


7.10.2 Vendor ID Payload Processing


  When processing the Vendor ID Payload, the following fields MUST be
  checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

  2.  Vendor ID - The Vendor ID Data MUST be processed to determine if
      the Vendor ID value is recognized by the implementation.  If the
      Vendor ID value is not recognized, then regardless of mode (e.g.,
      Terse or Verbose) this information is logged.  Processing of the
      message MUST continue regardless of recognition of this value.


  It is recommended that implementations that want to use Vendor ID
  specific information attempt to process the Vendor ID payloads of an
  incoming message prior to the remainder of the message processing.
  This will allow the implementation to recognize that when processing
  other payloads that it can use the larger set of values for payload
  fields (Private Use values, etc.)  as defined by the recognized
  Vendor IDs.




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7.11 Key Creation Payload


7.11.1 Key Creation Payload Structure


  The Key Creation Payload contains information used to create key
  encryption keys.  The security attributes for this payload are
  provided in the Policy Token.  Figure 26 shows the format of the
  payload.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Key Creation Type             ! Key Creation Data             ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                 Figure 26:  Key Creation Payload Format

  The Key Creation Payload fields are defined as follows:


  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Key Creation Type (2 octets)  - Specifies the type of Key Creation
      being used.  Table 26 identifies the types of key creation
      information.  This field is treated as an unsigned integer in
      network byte order format.

  Key Creation Data (variable length)  - Contains Key Creation
      information.  The values for this field are group specific and
      the format is specified by the key creation type field.



  The payload type for the Key Creation Packet is eleven (11).



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              Table 26:  Types Of Key Creation Information

  Key Creation Type           Value         Definition/Defined In
  ______________________________________________________________________

  Reserved                    0 - 1
  Diffie-Hellman                2           This type MUST be supported.
    1024-bit MODP Group                     Defined in [IKEv2] B.2.
    Truncated                               If the output of the process
                                            is longer than needed for
                                            the defined mechanism, use
                                            the first X low order bits,
                                            and truncate the remainder.
  Reserved                   3 - 13
  Diffie-Hellman               14           Defined in [RFC 3526].
    2048-bit MODP Group                     If the output of the process
    Truncated                               is longer than needed for
                                            the defined mechanism, use
                                            the first X low order bits,
                                            and truncate the remainder.
  Reserved to IANA         15 - 49152
  Private Use             49153 - 65535


7.11.2 Key Creation Payload Processing


  The specifics of the Key Creation Payload are defined in
  section 7.11.

  When processing the Key Creation Payload, the following fields MUST
  be checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

  2.  Key Creation Type - The Key Creation Type value MUST be checked
      to be a valid key creation type as defined by Table 26.  If the
      value is not valid, then an error is logged and if in Verbose
      mode an appropriate message containing notification value
      Payload-Malformed will be sent.

  3.  Key Creation Data - This Key Creation Data MUST be processed
      according to the key creation type specified to generate the KEK
      to protect the information to be sent in the appropriate message.
      The type will define the format of the data.




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  Implementations that want to derive other keys from the initial Key
  Creation keying material, for example, DH Secret keying material,
  MUST define a Key Creation Type other than one of those shown in
  Table 26.  The new Key Creation Type must specify that derivation's
  algorithm, for which the KEK MAY be one of the keys derived.



7.12 Nonce Payload


7.12.1 Nonce Payload Structure


  The Nonce Payload contains random data used to guarantee freshness
  during an exchange and protect against replay attacks.  Figure 27
  shows the format of the Nonce Payload.
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Next Payload  !   RESERVED    !         Payload Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ! Nonce Type    !            Nonce Data                         ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                    Figure 27:  Nonce Payload Format

  The Nonce Payload fields are defined as follows:



  Next Payload (1 octet)  - Identifier for the payload type of the
      next payload in the message.  If the current payload is the last
      in the message, then this field will be 0.  This field provides
      the ``chaining`` capability.  Table 12 identifies the payload
      types.  This field is treated as an unsigned value.

  RESERVED (1 octet)  - Unused, set to 0.

  Payload Length (2 octets)  - Length in octets of the current
      payload, including the generic payload header.  This field is
      treated as an unsigned integer in network byte order format.

  Nonce Type (1 octet)  - Specifies the type of Nonce being used.
      Table 27 identifies the types of nonces.  This field is treated
      as an unsigned value.

  Nonce Data (variable length)  - Contains the nonce information.
      The values for this field are group-specific and the format
      is specified by the Nonce Type field.  If no group-specific

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                         Table 27:  Nonce Types

  Nonce_Type              Value       Definition
  ______________________________________________________________________

  None                      0
  Initiator (Nonce_I)       1
  Responder (Nonce_R)       2
  Combined (Nonce_C)        3         Hash (Append
                                      (Initiator_Value,Responder_Value))
                                      The hash type comes from the
                                      Policy (e.g., Security Suite
                                      Definition of Policy Token).
  Reserved to IANA       4 - 192
  Private Use           192 - 255


      information is provided, the minimum length for this field is 4
      bytes.


  The payload type for the Nonce Payload is twelve (12).


7.12.2 Nonce Payload Processing


  When processing the Nonce Payload, the following fields MUST be
  checked for correct values:


  1.  Next Payload, RESERVED, Payload Length - These fields are
      processed as defined in Section 7.2.2, Generic Payload Header
      Processing.

  2.  Nonce Type - The Nonce Type value MUST be checked to be a valid
      nonce type as defined by Table 27.  If the value is not valid,
      then an error is logged and if in Verbose mode an appropriate
      message containing notification value Payload-Malformed will be
      sent.

  3.  Nonce Data - This is the nonce data and it must be checked
      according to its content.  The size of this field is defined
      in Nonce Payload section 7.12.  Refer to the Message Processing
      Group Establishment section (Section 5.2) for interpretation of
      this field.






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8 GSAKMP State Diagram


  Figure 28 presents the states encountered in the use of this
  protocol.  Table 28 defines the states.  Table 29 defines the
  transitions.

         !-----------------> (                  )
         !   !-------------> (       Idle       ) <------------------!
         !   !               (                  )                    !
         !   !                !                !                     !
         !   !                !                !                     !
         !   !               (1a)             (1)                    !
         !   !                !                !                     !
         !   !                !                !                     !
         !   !                V                V                     !
         !   !---(5a)--- (Wait for  )       (Wait for  ) ----(5)-----!
         !               (Group     )       (GC/KS Event) <---
         !               (Membership)        ^  !   \        \
         !                    !              !  !    \        \
         !                    !              !  !     \--(2)---\
         !                   (2a)           (4)(3)
         !                    !              !  !
         !                    !              !  !
         !                    V              !  V
         !-------(4a)--- (Wait for  )       (Wait for  )
                         (Group     )       (Response  )
                         (Membership)       (from Key  )
                    /--> (Event     )       (Download  )
                   /         /
                  /         /
                 /--(3a)---/


                    Figure 28:  GSAKMP State Diagram


















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                        Table 28:  GSAKMP States
  ______________________________________________________________________

  Idle                 : GSAKMP Application waiting for input
  ______________________________________________________________________

  Wait for GC/KS Event : GC/KS up and running, waiting for events
  ______________________________________________________________________

  Wait for Response    : GC/KS has sent Key Download,
   from Key Download   :  waiting for response from GM
  ______________________________________________________________________

  Wait for Group       : GM in process of joining group
   Membership          :
  ______________________________________________________________________

  Wait for Group       : GM has group key, waiting for
   Membership Event    :  group management messages.
  ______________________________________________________________________

















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                   Table 29:  State Transition Events
  ____________________________________________________________________

  Transition 1  : Create group command
  ______________:_____________________________________________________
                :
  Transition 2  : Receive bad RTJ
                : Receive valid command to change group membership
                : Send Compromise message x times
                : Member Deregistration
  ______________:_____________________________________________________
                :
  Transition 3  : Receive valid RTJ
  ______________:_____________________________________________________
                :
  Transition 4  : Timeout
                : Receive Ack
                : Receive Nack
  ______________:_____________________________________________________
                :
  Transition 5  : Delete group command
  ______________:_____________________________________________________
                :
  Transition 1a : Join group command
  ______________:_____________________________________________________
                :
  Transition 2a : Send Ack
  ______________:_____________________________________________________
                :
  Transition 3a : Receipt of group management messages
  ______________:_____________________________________________________
                :
  Transition 4a : Delete group command
                : Deregistration command
  ______________:_____________________________________________________
                :
  Transition 5a : Time out
                : Msg failure
                : errors
                :

  ____________________________________________________________________






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9 IANA Considerations



9.1 IANA Port Number Assignment


  IANA has provided GSAKMP port number 3761 in both the UDP and TCP
  spaces.  All implementations MUST use this port assignment in the
  appropriate manner.


9.2 Initial IANA Registry Contents


  The following registry entries should be created:

  GSAKMP Group Identification Types (section  7.1.1)
  GSAKMP Payload Types (section  7.1.1)
  GSAKMP Exchange Types (section  7.1.1)
  GSAKMP Policy Token Types (section  7.3.1)
  GSAKMP Key Download Data Item Types (section  7.4.1)
  GSAKMP Cryptographic Key Types (section  7.4.1.1)
  GSAKMP Rekey Event Types (section  7.5.1)
  GSAKMP Identification Classification (section  7.6.1)
  GSAKMP Identification Types (section  7.6.1)
  GSAKMP Certificate Types (section  7.7.1)
  GSAKMP Signature Types (section  7.8.1)
  GSAKMP Notification Types (section  7.9.1)
  GSAKMP Acknowledgment Types (section  7.9.1.1)
  GSAKMP Mechanism Types (section  7.9.1.3)
  GSAKMP Nonce Hash Types (section  7.9.1.3)
  GSAKMP Key Creation Types (section  7.11.1)
  GSAKMP Nonce Types (section  7.12.1)

  Changes and additions to the following registries are by IETF
  Standards Action:

  GSAKMP Group Identification Types
  GSAKMP Payload Types
  GSAKMP Exchange Types
  GSAKMP Policy Token Types
  GSAKMP Key Download Data Item Types
  GSAKMP Rekey Event Types
  GSAKMP Identification Classification
  GSAKMP Notification Types
  GSAKMP Acknowledgment Types
  GSAKMP Mechanism Types
  GSAKMP Nonce Types

  Changes and additions to the following registries are by Expert
  Review:

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  GSAKMP Cryptographic Key Types
  GSAKMP Identification Types
  GSAKMP Certificate Types
  GSAKMP Signature Types
  GSAKMP Nonce Hash Types
  GSAKMP Key Creation Types



10 Acknowledgments


  This document is the collaborative effort of many individuals.  If
  there were no limit to the number of authors that could appear on an
  RFC, the following, in alphabetical order would have been listed:
  Haitham S. Cruickshank of University of Surrey, Sunil Iyengar of
  University Of Surrey Gavin Kenny of LogicaCMG, Patrick McDaniel of
  AT&T Labs Research, and Angela Schuett of NSA.

  The following individuals deserve recognition and thanks for their
  contributions which have greatly improved this protocol:  Eric Harder
  is an author to the Tunneled-GSAKMP, whose concepts are found in
  GSAKMP as well.  Rod Fleischer, also a Tunneled-GSAKMP author, and
  Peter Lough were both instrumental in coding a prototype of the
  GSAKMP software and helped define many areas of the protocol that
  were vague at best.  Andrew McFarland and Gregory Bergren provided
  critical analysis of early versions of the specification.  Ran
  Canetti analyzed the security of the protocol and provided denial of
  service suggestions leading to optional "cookie protection".


11 References


  The following references were used in the preparation of this
  document.



11.1 Normative References


  [CH02] Colegrove A., Harney H., ``Group Policy Token Version 1 with
  Application to GSAKMP'', draft-ietf-msec-policy-token-sec-02.txt,
  March 2005

  [DH77] Diffie, W., and M. Hellman, ``New Directions in
  Cryptography'', IEEE Transactions on Information Theory, June 1977

  [FIPS 186-2] NIST, "Digital Signature Standard", FIPS PUB 186-2,
  National Institute of Standards and Technology, U.S. Department of
  Commerce, January 2000

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  [FIPS 196] ``Entity Authentication Using Public Key Cryptography,''
  Federal Information Processing Standards Publication 196, NIST,
  February 1997

  [IKEv2] C. Kaufman, ``Internet Key Exchange (IKEv2) Protocol'',
  draft-ietf-ipsec-ikev2-12.txt, January 2004

  [OpenLDAP] Zeilenga, K., ``LDAP: String Representation of
  Distinguished Names'', draft-ietf-ldapbis-dn-16.txt, February 2005

  [RFC 2119] Bradner, S., "Key Words for use in RFCs to indicate
  Requirement Levels", BCP 14, March 1997

  [RFC 2409] Harkins D. and Carrel D., ``The Internet Key Exchange
  (IKE)'', RFC 2409, Proposed Standard, November 1998

  [RFC 2412] Orman H. K., ``The OAKLEY Key Determination Protocol'',
  RFC 2412, Informational, November 1998

  [RFC 2627] D. Wallner, E. Harder, R. Agee, Key Management for
  Multicast:  Issues and Architectures, June 1999

  [RFC 3280] R. Housley, W. Polk, W. Ford, D. Solo, Internet X.509
  Public Key Infrastructure Certificate and Certificate Revocation List
  (CRL) Profile, April 2002

  [RFC 3629] F. Yergeau, UTF-8, a transformation format of ISO 10646,
  November 2003



11.2 Informative References


  [BMS] Balenson D., McGrew D., Sherman A., ``Key Management for
  Large Dynamic Groups:  One-Way Function Trees and Amortized
  Initialization'', Internet Draft, February 1999

  [HCM] H. Harney, A. Colegrove, P. McDaniel, "Principles of Policy
  in Secure Groups", Proceedings of Network and Distributed Systems
  Security 2001 Internet Society, San Diego, CA, February 2001

  [HHMCD01] Thomas Hardjono, Hugh Harney, Pat McDaniel, Andrea
  Colgrove, Pete Dinsmore, Group Security Policy Token:  Definition and
  Payloads', draft-ietf-msec-gspt-00.txt, Work in progress

  [MSST98] Maughan, D., Schertler, M., Schneider, M., and J. Turner,
  ``Internet Security Association and Key Management Protocol
  (ISAKMP)'', RFC 2408, November 1998

  [RFC 1750] Eastlake D., Crocker S. Schiller J., ``Randomness
  Recommendations for Security'', RFC 1750, Informational, December

Harney, Meth, Colegrove, Gross                                [Page 99]

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  1994

  [RFC 2093] Harney H., Muckenhirn C., and Rivers T., ``Group Key,
  Management Protocol Specification'', RFC 2093, Experimental, July
  1997

  [RFC 2094] Harney H., Muckenhirn C., and Rivers T., ``Group Key
  Management Protocol Architecture'', RFC 2094, Experimental, July 1997

  [RFC 2104] Krawczyk H., Bellare M., and Canetti R., ``HMAC:
  Keyed-Hashing for Message Authentication'', RFC 2104, Informational,
  February

  [RFC 2401] Kent S. and Atkinson, R., ``Security Architecture for the
  Internet Protocol'', RFC 2401, November 1998, Proposed Standard

  [RFC 2402] Kent S. and Atkinson, R., ``IP Authentication Header'',
  RFC 2402, November 1998, Proposed Standard.1997

  [RFC 2406] Kent S. and Atkinson, R., ``IP Encapsulating Security
  Payload (ESP)'', RFC 2406, November 1998, Proposed Standard

  [RFC 2408] Maughan D., Schertler M., Schneider M., and Turner
  J., ``Internet Security Association and Key Management Protocol
  (ISAKMP)'', RFC 2408, Proposed Standard, November 1998

  [RFC 2451] Pereira R., Adams R., ``The ESP CBC-Mode Cipher
  Algorithms'', November 1998

  [RFC 2974] M. Handley, C. Perkins, E. Whelan, Session Announcement
  Protocol, October 2000

  [RFC 3161] C. Adams, P. Cain, D. Pinkas, R. Zuccherato, Internet
  X.509 Public Key Infrastructure Time-Stamp Protocol (TSP), August
  2001

  [RFC 3261] J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston,
  J. Peterson, R. Sparks, M. Handley, E. Schooler, `` SIP: Session
  Initiation Protocol'', June 2002

  [RFC 3447] J. Jonsson, B. Kaliski, Public-Key Cryptography Standards
  (PKCS) #1:  RSA Cryptography Specifications Version 2.1, February
  2003

  [RFC 3526] T. Kivinen, M. Kojo, More Modular Exponential (MODP)
  Diffie-Hellman groups for Internet Key Exchange (IKE), May 2003

  [RFC 3740] Hardjono T., Weis B., ``The Multicast Group Security
  Architecture'', RFC 3740, March 2004, Informational




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A APPENDIX A -- LKH Information


  This appendix will give an overview of LKH, define the values for
  fields within GSAKMP messages that are specific to LKH, and give an
  example of a Rekey Event Message using the LKH scheme.



A.1 LKH Overview


  LKH provides a topology for handling key distribution for a group
  rekey.  It rekeys a group based upon a tree structure and subgroup
  keys.  In the LKH tree shown in Figure 29, members are represented by
  the leaf nodes on the tree, while intermediate tree nodes represent
  abstract key groups.  A member will possess multiple keys:  the group
  traffic protection key (GTPK), subgroup keys for every node on its
  path to the root of the tree, and a personal key.  For example, the
  member labeled as #3 will have the GTPK, Key A, Key D, and Key 3.
                                      root
                            /                      \
                           /                        \
                        A                               B
                    /      \                        /      \
                   /        \                      /        \
                C               D               E               F
              /   \           /   \           /   \           /   \
             /     \         /     \         /     \         /     \
           1         2     3         4     5         6     7         8



                      Figure 29:   A. 1:  LKH Tree

  This keying topology provides for a rapid rekey to all but a
  compromised member of the group.  If member 3 were to be compromised,
  the new GTPK (GTPK') would need to be distributed to the group under
  a key not possessed by member 3.  Additionally, new Keys A and D
  (Key A' and Key D') would also need to be securely distributed to
  the other members of those subtrees.  Encrypting the GTPK' with Key B
  would securely distribute that key to members 5, 6, 7, and 8.  Key C
  can be used to encrypt both the GTPK' and Key A' for members 1 and 2.
  Member 3's nearest neighbor, Member 4 can obtain GTPK', Key D', and
  Key A' encrypted under its personal key, Key 4.  At the end of this
  process, the group is securely rekeyed with Member 3 fully excluded.







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A.2 LKH and GSAKMP


  When using LKH with GSAKMP the following issues require attention:



  1.  Rekey Version # - The Rekey Version # in the Rekey Array of the
      Key Download Payload MUST contain the value one (1).

  2.  Algorithm Version - The Algorithm Version in the Rekey Event
      Payload MUST contain the value one (1).

  3.  Degree of Tree - The LKH tree used can be of any degree, it need
      not be binary.

  4.  Node Identification - Each node in the tree is treated as a KEK.
      A KEK is just a special key.  As the rule stated for all keys in
      GSAKMP, the set of the KeyID and the KeyHandle MUST be unique.  A
      suggestion on how to do this will be given in this section.

  5.  Wrapping KeyID and Handle - This is the KeyID and Handle of the
      LKH node used to wrap/encrypt the data in a Rekey Event Data.


  For the following discussion, refer to Figure 30.

  Key:
  o: a node in the LKH tree
  N: this line contains the KeyID node number
  L: this line contains the MemberID number for all leaves ONLY

      LEVEL
      ----
      root                          o
  N:                         /      1     \
                            /              \
      1              o                             o
  N:              /  2  \                       /  3  \
                 /       \                     /       \
      2      o               o             o               o
  N:        /4\             /5\           /6\             /7\
           /   \           /   \         /   \           /   \
      3  o       o       o       o     o       o       o       o
  N:     8       9      10      11    12      13      14      15
  L:     1       2       3       4     5       6       7       8



                   Figure 30:   A. 2:  GSAKMP LKH Tree



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  To guarantee uniqueness of KeyID, the Rekey Controller SHOULD build a
  virtual tree and label the KeyID of each node doing a breadth first
  search of a fully populated tree regardless of whether or not the
  tree is actually full.  For simplicity of this example, the root
  of the tree was given KeyID value of one (1).  These KeyID values
  will be static throughout the life of this tree.  Additionally, the
  rekey arrays distributed to GMs requires a MemberID value associated
  with them to be distributed with the KeyDownload Payload.  These
  MemberID values MUST be unique.  Therefore, the set associated with
  each leaf node (the nodes from that leaf back to the root) are given
  a MemberID. In this example, the leftmost leaf node is given MemberID
  value of one (1).  These 2 sets of values, the KeyIDs (represented
  on lines N) and the MemberIDs (represented on line L) will give
  sufficient information in the KeyDownload and RekeyEvent Payloads
  to disseminate information.  The KeyHandle associated with these
  keys is regenerated each time the key is replace in the tree due to
  compromise.



A.3 LKH Examples


  Definition of values:
  0xLLLL          - length value
  0xHHHHHHH#      - handle value
  YYYYMMDDHHMMSSZ - Time Value


A.3.1 LKH Key Download Example


  This section will give an example of the data for the Key Download
  payload.  The GM will be given MemberID 1 and its associated keys.
  The data shown will be subsequent to the Generic Payload Header.

  | GTPK | MemberID 1 | KeyID 2 | KeyID 4 | KeyID 8



  Number of Items                   - 0x0002
    Item #1:
      Key Download Data Item Type   - 0x00 (GTPK)
      Key Download Data Item Length - 0xLLLL
        Key Type                    - 0x03 (3DES`CBC64`192)
        Key ID                      - KEY1
        Key Handle                  - 0xHHHHHHH0
        Key Creation Date           - YYYYMMDDHHMMSSZ
        Key Expiration Date         - YYYYMMDDHHMMSSZ
        Key Data                    - variable, based on key definition
    Item #2:
      Key Download Data Item Type   - 0x01 (Rekey - LKH)

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      Key Download Data Item Length - 0xLLLL
      Rekey Version Number          - 0x01
      Member ID                     - 0x00000001
      Number of KEK Keys            - 0x0003
        KEK #1:
          Key Type                  - 0x03 (3DES`CBC64`192)
          Key ID                    - 0x00000002
          Key Handle                - 0xHHHHHHH2
          Key Creation Date         - YYYYMMDDHHMMSSZ
          Key Expiration Date       - YYYYMMDDHHMMSSZ
          Key Data                  - variable, based on key definition
        KEK #2:
          Key Type                  - 0x03 (3DES`CBC64`192)
          Key ID                    - 0x00000004
          Key Handle                - 0xHHHHHHH4
          Key Creation Date         - YYYYMMDDHHMMSSZ
          Key Expiration Date       - YYYYMMDDHHMMSSZ
          Key Data                  - variable, based on key definition
        KEK #3:
          Key Type                  - 0x03 (3DES`CBC64`192)
          Key ID                    - 0x00000008
          Key Handle                - 0xHHHHHHH8
          Key Creation Date         - YYYYMMDDHHMMSSZ
          Key Expiration Date       - YYYYMMDDHHMMSSZ
          Key Data                  - variable, based on key definition



A.3.2 LKH Rekey Event Example


  This section will give an example of the data for the Rekey Event
  payload.  The GM with MemberID 6 will be keyed out of the group.  The
  data shown will be subsequent to the Generic Payload Header.

  | Rekey Event Type | GroupID | Date/Time | Rekey Type | Algorithm Ver|
  # of Packets| { (GTPK)2, (GTPK, 3', 6')12, (GTPK, 3')7 }

  This data shows that three packets are being transmitted.  Read each
  packet as:
  a) GTPK wrapped in LKH KeyID 2
  b) GTPK, LKH KeyIDs 3' & 6', all wrapped in LKH KeyID 12
  c) GTPK and LKH KeyID 3', all wrapped in LKH KeyID 7

  NOTE: Although in this example multiple keys are encrypted under one
  key, alternative pairings are legal (e.g., (GTPK)2, (GTPK)3', (3')6',
  (3')7', (6')12).

  We will show format for all header data, and packet (b).


  Rekey Event Type  - 0x01 (GSAKMP`LKH)

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  GroupID           - 0xAABBCCDD
                      0x12345678
  Time/Date Stamp   - YYYYMMDDHHMMSSZ
  Rekey Event Type  - 0x01 (GSAKMP`LKH)
  Algorithm Vers    - 0x01
  # of RkyEvt Pkts  - 0x0003
  For Packet (b):
  Packet Length       - 0xLLLL
  Wrapping KeyID      - 0x000C
  Wrapping Key Handle - 0xHHHHHHHD
  # of Key Packages   - 0x0003
    Key Package 1:
      Key Pkg Type  - 0x00 (GTPK)
      Pack Length   - 0xLLLL
        Key Type            - 0x03 (3DES`CBC64`192)
        Key ID              - KEY1
        Key Handle          - 0xHHHHHHH0
        Key Creation Date   - YYYYMMDDHHMMSSZ
        Key Expiration Date - YYYYMMDDHHMMSSZ
        Key Data            - variable, based on key definition
    Key Package 2:
      Key Pkg Type  - 0x01 (Rekey  - LKH)
      Pack Length   - 0xLLLL
        Key Type            - 0x03 (3DES`CBC64`192)
        Key ID              - 0x00000003
        Key Handle          - 0xHHHHHHH3
        Key Creation Date   - YYYYMMDDHHMMSSZ
        Key Expiration Date - YYYYMMDDHHMMSSZ
        Key Data            - variable, based on key definition
    Key Package 3:
      Key Pkg Type  - 0x01 (Rekey  - LKH)
      Pack Length   - 0xLLLL
        Key Type            - 0x03 (3DES`CBC64`192)
        Key ID              - 0x00000006
        Key Handle          - 0xHHHHHHH6
        Key Creation Date   - YYYYMMDDHHMMSSZ
        Key Expiration Date - YYYYMMDDHHMMSSZ
        Key Data            - variable, based on key definition



B APPENDIX B -- Change History (To Be Removed from RFC)


B.1 Changes from GSAKMP-00 to GSAKMP-01 February 2003


  This specification was based on two earlier versions of GSAKMP
  drafts, referred to to GSAKMP and GSAKMP-Light.  These two
  specifications were merged to incorporate all information necessary
  to allow the original GSAKMP-Light specification to stand on its own.


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  The original GSAKMP protocol no longer exists as a standard, it has
  been subsumed by GSAKMP-Light.  GSAKMP-Light is now called GSAKMP.

  Major modifications to the specification are



  Removed Payloads:   Authorization, Certificate Request, Vendor ID,
      and Hash.

  Removed Messages:   Group Removal/Destruction.

  Signature Processing:   The signature processing has been modified.


B.2 Changes from GSAKMP-01 to GSAKMP-02 June 2003


  1.  The specification was modified to confirm that key words are used
      as defined by RFC2119.

  2.  The Protocol Considerations section for IANA port number was
      added.

  3.  The Cookie section for mitigation of DoS attacks was added.

  4.  The Protocol State Diagram was added.


B.3 Changes from GSAKMP-02 to GSAKMP-03 August 2003


  1.  Clarified Nonce value in Request to Join With Cookie msg.

  2.  Added Signature ID Type to Security Suite 1 definition.

  3.  Clarified format of Identification information used in Signature
      and Identification Payloads.

  4.  Split Signature Type field into it's two appropriate fields.
      This was not a change in the payload, just cleaning up the
      definition.



B.4 Changes from GSAKMP-03 to GSAKMP-04 October 2003


  1.  Terminology Section


     (a)  Rekey definition was made more verbose.

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  2.  Security Considerations Section


     (a)  ISAKMP Section


          i.  Corrected GSAKMPs relationship definition to ISAKMP.


     (b)  Rekey Availability Section


          i.  Added this new section.


  3.  Architecture Section


     (a)  This section in its entirety was added for this revision of
          the specification.


  4.  Group Life Cycle Section


     (a)  Group Establishment Section


          i.  Introduced Verbose and Terse concept.


     (b)  Standard Group Establishment Section


          i.  Added messages Request to Join Error and Lack_of_Ack to
              ladder diagram to show verbose error messaging.

         ii.  Modified definition of Ack message on ladder diagram to
              be consistent with new naming convention.

        iii.  Reworked all section wording to convey the new message
              transmissions.


     (c)  Request to Join Section


          i.  Completely reworked to better define the process of
              building and processing the RTJ message by the GM and
              GC/KS.



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     (d)  Key Download Section


          i.  Completely reworked to better define the process of
              building and processing the KeyDL message by the GC/KS
              and GM.


     (e)  Request to Join Error Section


          i.  New section added for this new verbose message.


     (f)  Key Download = Ack/Failure Section


          i.  Completely reworked to better define the process of
              building and processing the KeyDL-A/F message by the GM
              and GC/KS.


     (g)  Lack_of_Ack Section


          i.  New section added for this new verbose message.


     (h)  Added the following new Sub-sections to this section.


          i.  Leaving Group

         ii.  Eviction

        iii.  Voluntary Departure without Notice

         iv.  De-registration

          v.  Request to Depart Message

         vi.  Departure Response Message

        vii.  Departure Ack Message


  5.  GSAKMP Payload Structure Section


     (a)  Added note that all all integer fields larger than one
          octet MUST be converted to Network Byte Order prior to


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          transmission.

     (b)  GSAKMP Header Section



          i.  Existing section became the Structure subsection.

         ii.  Added the Processing subsection.

        iii.  GroupID Type was modified to GroupID Length with the
              appropriate definitions.

         iv.  New Exchange Types added for verbose mode.

          v.  Sequence ID definition was modified for:


              A.  New initial value.

              B.  Rollover handling responsibility.


     (c)  GSAKMP Payload Header Section


          i.  Existing section became the Structure subsection.

         ii.  Added the Processing subsection.


     (d)  Policy Token Payload Section


          i.  The header paragraph was corrected to not levy any
              requirements from GSAKMP on the Policy Token.

         ii.  The PT Type field was expanded from one (1) to two (2)
              octets.

        iii.  The values of the PT Types were modified and defined to
              reflect the true purpose.


     (e)  Rekey Event Payload Section


          i.  Renamed Type field to be unique within specification.

         ii.  The values of the Rekey Type field were modified and
              defined to reflect their true purpose.


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     (f)  Signature Payload Section


          i.  Existing section became the Structure subsection.

         ii.  Added the Processing subsection.

        iii.  Removed the one (1) octet field Signature ID Role from
              the payload, it contained irrelevant data.

         iv.  Expanded the definition of Singer ID Data to inform the
              user how to interpret this field.


     (g)  Notification Payload Section


          i.  Removed the one (1) octet Status Type field from the
              payload.  It was irrelevant information.  Additionally,
              all references to Status Type were removed from the
              payload definition.

         ii.  Added new Notification Payload Type "Mechanism Choices".

        iii.  Added section "Notification Data - Mechanism Choices
              Payload Type" to define the format of a Notification
              Payload of type Mechanism Choices.


     (h)  Key Creation Payload Section


          i.  Existing section became the Structure subsection.

         ii.  Added the Processing subsection.

        iii.  Renamed Type field to be unique within specification.


     (i)  Nonce Payload Section


          i.  Existing section became the Structure subsection.

         ii.  Added the Processing subsection.








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B.5 Changes from GSAKMP-04 to GSAKMP-05 February 2004


B.5.1 Major Modification/Reorganization of Specification


B.5.1.1 Key Terms and Payloads Modified


  In the previous version of the specification, there was a lot of
  confusion with respect to the terminology used for anything to
  do with keys and rekey.  Therefore, all the terminology has been
  modified to make this more comprehensible.  Additionally, all key
  information that was found in the appendices was generalized and
  incorporated into the main sections of the specification.

  Following is a list of old terms mapped to new terms:


   -  LKH ID - Key ID, this field is now also in a GTPK, was not there
      previously.

   -  Key Pack - Key Datum

   -  Key Pack Data - Key Package

   -  Rekey Event Packet Data - Rekey Event Data


  To accommodate all these changes, the Key Download Payload, Rekey
  Event Payload, and LKH Appendix sections were completely reworked to
  reflect these changes.

  Other major changes in these sections with respect to bits on the
  wire:


   -  KeyID - All keys now have a 4 octet ID field.  This was not so
      before.  Also, this field is now 4 octets long, it was previously
      2 octets.

   -  Date Fields - These fields are now 15 bytes long and ascii
      format.


  THEREFORE, look closely at the Key Download Payload and Rekey
  Event Payload as the formats for these payloads have both changed
  dramatically the bits on the wire.





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B.5.2 Modification By Section


  1.  Protocol Considerations Section - Moved to new section entitled
      IANA Considerations Section.

  2.  Terminology Section


     (a)  Modified the following terms:  GTEK became GTPK

     (b)  Added the following terms:  Key Datum, KEK, Key Handle, Key
          ID, Key Package, Rekey Array, Rekey Key, Wrapping KeyID,
          Wrapping Key Handle


  3.  Security Considerations Section


     (a)  Security Assumptions Section


          i.  Added an assumption with respect to system clock.


     (b)  Rekey Availability Section


          i.  Stated retransmission of rekey messages required for
              implementations.


  4.  Group Establishment Section



     (a)  Added phrase concerning error message always indicates first
          error found.

     (b)  Key Download Section


          i.  Fixed second paragraph.


     (c)  Rekey Events Section - Made as subsection under new section
          Group Management.


  5.  GSAKMP Payload Structure Section



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     (a)  Added verbiage that no padding in any payloads.

     (b)  All processing sections updated to indicate error
          processing.


  6.  Split following sections into Structure and Processing
      subsections:


     (a)  Policy Token Payload

     (b)  Key Download Payload

     (c)  Rekey Event Payload

     (d)  Identification Payload

     (e)  Certificate Payload


  7.  GSAKMP Header Section


     (a)  Group ID Length and Sequence ID - Fixed definitions.

     (b)  Updated values in tables.

     (c)  Reworded processing section to be more precise.


  8.  Policy Token Payload Section


     (a)  PT Type field in diagram was updated to reflect that this is
          really a 2 octet field and not a 1 octet field.

     (b)  Updated tables.


  9.  Key Download and Rekey Event Payload Sections


     (a)  Completely reworked sections.  Refer to Section B.5.1.1
          above for the modifications to these sections.

     (b)  Basically, reread these sections closely as a lot has
          changed.


  10. Identification Payload Section


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     (a)  U-NAME Definition was incorporated directly into this
          section.

     (b)  Updated tables.


  11. Certificate Payload Section


     (a)  Added words to structure section about zero or multiple
          certificate payloads within a GSAKMP message.

     (b)  Updated tables.


  12. Signature Payload Section


     (a)  Updated Tables.

     (b)  Signature Type field is now 2 octets long.

     (c)  Signature Payload Span field has been removed, it no longer
          exists.

     (d)  Signature Timestamp field is now 15 bytes long to conform to
          the

     (e)  Processing section was updated.  new date/time format begin
          used throughout the spec.


  13. Notification Payload Section


     (a)  Updated Tables.

     (b)  Removed Length field from Notification Data Mechanism
          Choices Payload Types format.

     (c)  Made field Mechanism Choice Data field to be a static length
          of 2 octets.


  14. Key Creation Payload Section


     (a)  Updated Tables.

     (b)  Key Creation Type field is now 2 octets long.



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     (c)  Updated Processing subsection.


  15. Nonce Payload Section


     (a)  Updated Tables.

     (b)  Updated Processing subsection.


  16. Added new section IANA Considerations.



B.6 Changes from GSAKMP-05 to GSAKMP-06 May 2004


  NOTE: Minor editorial modifications are not listed here.


  1.  Security Considerations Section


     (a)  Security Assumptions Section


          i.  Added considerations as pointed out by gmg.


     (b)  Protocol Considerations Section


          i.  Fixed wording between subsections to remove contradiction
              of how and when to use Diffie-Hellman.



  2.  Architecture Section


     (a)  S-GC/KS Operations section replaced with Autonomous
          Distributed GSAKMP Operations Section

     (b)  GSAKMP Interactions with NAT Traversal section removed.


  3.  Group Life Cycle Section


     (a)  To all subsection, modified the message dissection and
          discussion for Nonces.  Nonces are now an optional payload

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          with a caveat.  Systems that have synchronized time do not
          use Nonce payloads.  Systems that do not have synchronized
          time MUST use Nonce payloads.

     (b)  Added information concerning Vendor ID payload processing.

     (c)  Added optional VendorID payload to all messages.

     (d)  Group Establishment Section


          i.  Added paragraph that Verbose mode is controlled by
              policy and how to handle it.

         ii.  Standard Group Establishment Section


              A.  Defined all possible error conditions.

              B.  Verbosely identified that message identification is
                  via the exchange type within the header.

              C.  Introduced concept of synchronized time.


        iii.  RTJ Section


              A.  Added the NotifPL of type IPValue and explanation to
                  this message type and discussion.


         iv.  Key Download - Ack/Failure Section


              A.  Added that upon successful registration all state
                  information should be removed.


          v.  Cookie Section


              A.  Added information for calculation of cookie value in
                  a NATted environment.


     (e)  Group Maintenance Section


          i.  Group Management Section



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              A.  Added sections Policy Update and Group Destruction.


         ii.  Leaving a Group Section


              A.  De-Registration Section - Added the GM SHOULD
                  support and GC/KS MUST support.

              B.  De-Registration Section - Fixed with respect to
                  Terse/Verbose mode processing.


  4.  GSAKMP Payload Structure Section


     (a)  Added pointed to VendorID section on how to process messages
          that contain this payload.

     (b)  GSAKMP Header Section


          i.  GSAKMP Header Structure Section


              A.  Updated GroupID Types table and added subsections to
                  define the format for each type.

              B.  Added VendorID value to Payload Types table.


         ii.  GSAKMP Header Processing Section


              A.  Updated processing rule for GroupID and Version.

              B.  Added discussion for interoperability with future
                  versions.


     (c)  Key Download Payload Section


          i.  Key Datum Structure Section


              A.  Fixed Key Type to be a 2 byte field as indicated by
                  the table which shows its values.

              B.  Updated structure definition for Key ID, Key Handle,
                  Key Creation Date, and Key Expiration Date.


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     (d)  Rekey Event Payload Section


          i.  Rekey Event Payload Structure Section


              A.  Defined how to break up the data across multiple
                  payloads.

              B.  Rekey Event Header Structure Section - Update
                  structure definition of Time/Date Stamp.

              C.  Rekey Event Data Structure Section - Clarified
                  information of which/how many Rekey Event Datas each
                  user is interested in.



          i.  Rekey Event Payload Processing Section


              A.  Updated Date/Time Stamp processing rules.


     (e)  Identification Payload Section


          i.  Added ID Classification octet to payload, associated
              table, and associated processing information.

         ii.  Updated Identification Types table.

        iii.  ID-U-NAME Structure Section


              A.  Updated DN Data definition for UTF-8.


         iv.  ID-U-NAME Processing Section


              A.  Updated Serial Number and DN Data processing rules.

              B.  Added a new rule for CA being a trust anchor.


     (f)  Certificate Payload Section


          i.  Certificate Payload Structure Section



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              A.  Updated Certificate Type values.


     (g)  Signature Payload Section


          i.  Signature Payload Structure Section


              A.  Updated Signature Timestamp definition for UTF-8 and
                  how to deal with time differential from local.

              B.  Updated Signature Type table values.

              C.  Signature ID type is now aligned with IdentificationPL
                  ID Type.


         ii.  Signature Payload Processing Section


              A.  Updated processing instructions for Signature
                  Timestamp, Signature ID Data, and Signature Data.


     (h)  Notification Payload Section


          i.  Notification Payload Structure Section


              A.  Updated Notification Types table.


     (i)  Vendor ID Payload Section


          i.  This whole section was added.


     (j)  Key Creation Payload Section


          i.  Key Creation Payload Structure Section


              A.  Updated Key Creation Type table.


         ii.  Key Creation Payload Processing Section



Harney, Meth, Colegrove, Gross                               [Page 119]

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              A.  Updated Key Creation Data processing instructions.


  5.  GSAKMP State Diagram Section


     (a)  Updated State Transition Events table.


  6.  IANA Considerations Section


     (a)  Updated all types sections for new values.



B.7 Changes from GSAKMP-06 to GSAKMP-07 December 2004


  NOTE: Minor editorial modifications are not listed here.


  1.  General/Global Revisions


     (a)  Wherever necessary, was more verbose in that LKH is an
          optional feature.

     (b)  Outstanding references fixed.

     (c)  Added/Modified references, both normative and informative.

     (d)  Replaced term 'trust anchor' with 'trusted policy creation
          authority'.

     (e)  Removed reference to draft policy token which is no longer
          in effect [HCLM00].


  2.  Overview section now has introductory remarks to the paper.

  3.  Security Considerations Section


     (a)  Security Assumptions Section


          i.  Updated information about Nonce with respect to replay
              attacks.


     (b)  Related Protocols - Diffie-Hellman

Harney, Meth, Colegrove, Gross                               [Page 120]

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          i.  Updated discussion on key size to be generic to more
              algorithm types.



B.8 Changes from GSAKMP-07 to GSAKMP-08 March 2005


  This draft was generated specifically to address the comments brought
  up during IESG review.  In addition to addressing these comments,
  some of the references were updated as some of the RFCs/Drafts had
  been replaced by newer RFCs.


  1.  Grp Life Cycle/Grp Est/Std Grp Est/Request to Join Section


     (a)  Added words to description that GM MUST be able to manually
          configure the destination of the RTJ.

     (b)  Fixed dissection and added words to description that Nonces
          are required and the GC/KS will determine if they will be
          used.

     (c)  Reordered GM resend of RTJ 3 times and GC/KS processing no
          more than one RTJ from this GM to clear up this interaction.


  2.  Cryptographic Key Types Table updated to make AES the MUST
      instead of 3DES.

  3.  Certificate Payload Processing section Certificate Data
      definition was fixed from root CA certificate to certificate of
      the trusted policy creation authority.

  4.  Identification Types was modified to add LDAP DN string
      representation.  This was made the MUST type.  Security Suite 1
      was updated to now use this type.  Reference to this document was
      added.


B.9 Changes from GSAKMP-08 to GSAKMP-09 April 2005


  This draft was generated to shore up the modification rules for IANA
  registry entries.  To accomplish this, the subsections of section 9.2
  were removed.  When this was done, modifications to tables within
  the payload definitions were modified where necessary to insure that
  they included the 'Defined In' information that used to be in these
  tables (only 2 entries in one table were missing).  Then general
  modifications rules for the registry entries were defined.


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  Also, it was recognized that one informative reference was missing
  and it was added.



B.10 Changes from GSAKMP-09 to GSAKMP-10 May 2005


  1.  The following IDNits issues were addressed:


     (a)  Line length was too long, corrected to max of 72 chars per
          line.

     (b)  Added correct boilerplate for front page, copyright, and
          IPR.


  2.  Insured that all terms were fully spelled out prior to initial
      use as an acronym.

  3.  Clarified in the Security Considerations Rekey Availability
      section that rekey capability is optional.  There was confusion
      with the MUST clause for retransmission, this MUST only applies
      when using the optional rekey capability.

  4.  Expanded section name to Creation of Policy Token from acronym
      PT.

  5.  Modified AES CBC key length from 192 bits to 128 both in the
      Security Suite 1 definition and in the Cryptographic Key Types
      table.


Authors' Addresses

  Hugh Harney (point-of-contact)
  SPARTA, Inc.
  7075 Samuel Morse Drive
  Columbia, MD 21046
  (410) 872-1515 ext 203
  FAX (410) 872-8079
  hh@sparta.com

  Uri Meth
  SPARTA, Inc.
  7075 Samuel Morse Drive
  Columbia, MD 21046
  (410) 872-1515 ext 233
  FAX (410) 872-8079
  umeth@sparta.com


Harney, Meth, Colegrove, Gross                               [Page 122]

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  Andrea Colegrove
  SPARTA, Inc.
  7075 Samuel Morse Drive
  Columbia, MD 21046
  (410) 872-1515 ext 232
  FAX (410) 872-8079
  acc@sparta.com

  George Gross
  IdentAware Security
  82 Old Mountain Road
  Lebanon, NJ 08833
  (908) 268 - 1629
  gmgross@identaware.com

Full Copyright Statement

  Copyright (C) The Internet Society (2005).  This document is subject
  to the rights, licenses and restrictions contained in BCP 78, and
  except as set forth therein, the authors retain all their rights.

  This document and the information contained herein are provided
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IPR Considerations

  By submitting this Internet-Draft, each author represents that any
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  at http://www.ietf.org/ipr.


Harney, Meth, Colegrove, Gross                               [Page 123]

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  The IETF invites any interested party to bring to its attention any
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  rights that may cover technology that may be required to implement
  this standard.  Please address the information to the IETF at ietf-
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Document expiration:  November 16, 2005














































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