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Versions: (draft-wasserman-pcp-authentication) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 RFC 7652

Network Working Group                                       M. Wasserman
Internet-Draft                                                S. Hartman
Intended status: Experimental                          Painless Security
Expires: August 11, 2014                                        D. Zhang
                                                                  Huawei
                                                        February 7, 2014


          Port Control Protocol (PCP) Authentication Mechanism
                    draft-ietf-pcp-authentication-03

Abstract

   An IPv4 or IPv6 host can use the Port Control Protocol (PCP) to
   flexibly manage the IP address and port mapping information on
   Network Address Translators (NATs) or firewalls, to facilitate
   communications with remote hosts.  However, the un-controlled
   generation or deletion of IP address mappings on such network devices
   may cause security risks and should be avoided.  In some cases the
   client may need to prove that it is authorized to modify, create or
   delete PCP mappings.  This document proposes an in-band
   authentication mechanism for PCP that can be used in those cases.
   The Extensible Authentication Protocol (EAP) is used to perform
   authentication between PCP devices.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 11, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Protocol Details  . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Session Initiation  . . . . . . . . . . . . . . . . . . .   5
     3.2.  Session Termination . . . . . . . . . . . . . . . . . . .   8
     3.3.  Session Re-Authentication . . . . . . . . . . . . . . . .   8
   4.  PA Security Association . . . . . . . . . . . . . . . . . . .   9
   5.  Result Code . . . . . . . . . . . . . . . . . . . . . . . . .  10
   6.  Packet Format . . . . . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Packet Format of PCP Auth Messages  . . . . . . . . . . .  10
     6.2.  Authentication OpCode . . . . . . . . . . . . . . . . . .  11
     6.3.  Nonce Option  . . . . . . . . . . . . . . . . . . . . . .  12
     6.4.  Authentication Tag Option for Common PCP  . . . . . . . .  12
     6.5.  Authentication Tag Option for PCP Auth Messages . . . . .  13
     6.6.  EAP Payload Option  . . . . . . . . . . . . . . . . . . .  14
     6.7.  PRF Option  . . . . . . . . . . . . . . . . . . . . . . .  15
     6.8.  MAC Algorithm Option  . . . . . . . . . . . . . . . . . .  15
     6.9.  Session Lifetime Option . . . . . . . . . . . . . . . . .  15
     6.10. Received Packet Option  . . . . . . . . . . . . . . . . .  16
   7.  Processing Rules  . . . . . . . . . . . . . . . . . . . . . .  16
     7.1.  Authentication Data Generation  . . . . . . . . . . . . .  16
     7.2.  Authentication Data Validation  . . . . . . . . . . . . .  17
     7.3.  Retransmission Policies for PCP Auth Messages . . . . . .  18
     7.4.  Sequence Numbers for PCP Auth Messages  . . . . . . . . .  18
     7.5.  Sequence Numbers for Common PCP Messages  . . . . . . . .  19
     7.6.  MTU Considerations  . . . . . . . . . . . . . . . . . . .  20
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  20
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  21
   11. Change Log  . . . . . . . . . . . . . . . . . . . . . . . . .  21
     11.1.  Changes from wasserman-pcp-authentication-02 to ietf-
            pcp-authentication-00  . . . . . . . . . . . . . . . . .  21
     11.2.  Changes from wasserman-pcp-authentication-01 to -02  . .  21
     11.3.  Changes from ietf-pcp-authentication-00 to -01 . . . . .  21
     11.4.  Changes from ietf-pcp-authentication-01 to -02 . . . . .  21
     11.5.  Changes from ietf-pcp-authentication-02 to -03 . . . . .  22



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   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  22
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  22
     12.2.  Informative References . . . . . . . . . . . . . . . . .  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  23

1.  Introduction

   Using the Port Control Protocol (PCP) [RFC6887], an IPv4 or IPv6 host
   can flexibly manage the IP address mapping information on its network
   address translators (NATs) and firewalls, and control their policies
   in processing incoming and outgoing IP packets.  Because NATs and
   firewalls both play important roles in network security
   architectures, there are many situations in which authentication and
   access control are required to prevent un-authorized users from
   accessing such devices.  This document proposes a PCP security
   extension which enables PCP servers to authenticate their clients
   with Extensible Authentication Protocol (EAP).  The EAP messages are
   encapsulated within PCP packets during transportation.

   The following issues are considered in the design of this extension:

   o  Loss of EAP messages during transportation

   o  Disordered delivery of EAP messages

   o  Generation of transport keys

   o  Integrity protection and data origin authentication for PCP
      messages

   o  Algorithm agility

   The mechanism described in this document meets the security
   requirements to address the Advanced Threat Model described in the
   base PCP specification [RFC6887].  This mechanism can be used to
   secure PCP in the following situations::

   o  On security infrastructure equipment, such as corporate firewalls,
      that does not create implicit mappings.

   o  On equipment (such as CGNs or service provider firewalls) that
      serve multiple administrative domains and do not have a mechanism
      to securely partition traffic from those domains.

   o  For any implementation that wants to be more permissive in
      authorizing explicit mappings than it is in authorizing implicit
      mappings.




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   o  For implementations that support the THIRD_PARTY Option (unless
      they can meet the constraints outlined in Section 14.1.2.2).

   o  For implementations that wish to support any deployment scenario
      that does not meet the constraints described in Section 14.1.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   Most of the terms used in this document are introduced in [RFC6887].

   PCP Client: A PCP device (e.g., a host) which is responsible for
   issuing PCP requests to a PCP server.  In this document, a PCP client
   is also a EAP peer [RFC3748], and it is the responsibility of a PCP
   client to provide the credentials when authentication is required.

   PCP Server: A PCP device (e.g., a NAT or a firewall) that implements
   the server-side of the PCP protocol, via which PCP clients request
   and manage explicit mappings.  In this document, a PCP server is
   integrated with an EAP authenticator [RFC3748].  Therefore, when
   necessary, a PCP server can verify the credentials provided by a PCP
   client and make an access control decision based on the
   authentication result.

   PCP-Authentication (PCP-Auth) Session: A series of PCP message
   exchanges transferred between a PCP client and a PCP server.  The PCP
   message involved within a session includes the PCP-Auth messages used
   to perform EAP authentication, key distribution and session
   management, and the common PCP messages secured with the keys
   distributed during authentication.  Each PCP-Auth session is assigned
   a distinctive Session ID.

   Session Partner: A PCP device involved within a PCP-Auth session.
   Each PCP-Auth session has two session partners (a PCP server and a
   PCP client).

   Session Lifetime: The life period associated with a PCP-Auth session,
   which decides the lifetime of the current authorization given to the
   PCP client.

   PCP Security Association (PCP SA): A PCP security association is
   formed between a PCP client and a PCP server by sharing cryptographic
   keying material and associated context.  The formed duplex security
   association is used to protect the bidirectional PCP signaling
   traffic between the PCP client and PCP server.



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   Master Session Key (MSK): A key derived by the partners of a PCP-Auth
   session, using an EAP key generating method (e.g., the one defined in
   [RFC5448]).

   PCP-Authentication (PCP-Auth) message: A PCP message containing an
   Authentication OpCode.  Particularly, a PCP-Auth message sent from a
   PCP server to a PCP client is referred to as a PCP-Auth-Server, while
   PCP-Auth message sent from a PCP client to a PCP server is referred
   to as a PCP-Auth-Client.  Therefore, a PCP-Auth-Server is actually a
   PCP response message specified in [RFC6887], and a PCP-Auth-Client is
   a PCP request message.  This document specifies an option, the
   Authentication Tag Option for PCP Auth, to provide integrity
   protection and message origin authentication for PCP-Auth messages.

   Common PCP message: A PCP message which does not contain an
   Authentication OpCode.  This document specifies an option, the
   Authentication Tag Option for Common PCP, to provide integrity
   protection and message origin authentication for the common PCP
   messages.

3.  Protocol Details

3.1.  Session Initiation

   At be beginning of a PCP-Auth session, a PCP client and a PCP server
   need to exchange a series of PCP-Auth messages in order to perform an
   EAP authentication process.  Each PCP-Auth message is attached with
   an Authentication OpCode and may optionally contain a set of Options
   for various purposes (e.g., transporting authentication messages and
   session managements).  The Authentication OpCode consists of two
   fields: Session ID and Sequence Number.  The Session ID field is used
   to identify the session to which the message belongs.  The sequence
   number field is used to detect the disorder or the duplication
   occurred during packet delivery.

   When a PCP client intends to proactively initiate a PCP-Auth session
   with a PCP server, it sends a PCP-Auth-Initiation message (a PCP-
   Auth-Client message with the result code "INITIATION") to the PCP
   server.  In the message, the Session ID and Sequence Number fields of
   the Authentication OpCode are set as 0.  The PCP client MAY also
   optionally append a nonce option which consists of a random nonce
   with the message.

   After receiving the PCP-Auth-Initiation, if the PCP server agrees to
   initiate a PCP-Auth session with the PCP client, it will reply with a
   PCP-Auth-Server message which contains an EAP Identity Request, and
   the result code field of this PCP-Auth-Server message is set as
   AUTHENTICATION-REQUIRED.  In addition, the server MUST assign a



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   session identifier which can distinctly identify this session, and
   fill the identifier into the Session ID field of the Authentication
   OpCode in the PCP-Auth-Server message.  The Sequence Number field of
   the Authentication OpCode is set as 0.  If there is a nonce option in
   the received PCP-Auth-Initiation message, the PCP-Auth-Server MUST be
   attached with a nonce option so as to send the nonce value back.  The
   nonce will then be used by the PCP client to check the freshness of
   the PCP-Auth-Server message.  From now on, every PCP message within
   this session will be attached with this session identifier.  When
   receiving a PCP-Auth message from an unknown session, a PCP device
   MUST discard the message silently.  If the PCP client intends to
   simplify the authentication process, it MAY append an EAP Identity
   Response message within the PCP-Auth-Initiation message so as to
   inform the PCP server that it would like to perform EAP
   authentication and skip the step of waiting for the EAP Identity
   Request.

   In the scenario where a PCP server receives a common PCP request
   message from a PCP client which needs to be authenticated, the PCP
   server can reply with a PCP-Auth-Server message to initiate a PCP-
   Auth session.  The result code field of this PCP-Auth-Server message
   is set as AUTHENTICATION-REQUIRED.  In addition, the PCP server MUST
   assign a session ID for the session and transfer it within the PCP-
   Auth-Server message.  The Sequence Number field in the PCP-Auth-
   Server is set as 0.  In the PCP-Auth messages exchanged afterwards in
   this session, the session ID MUST be used in order to help session
   partners distinguish the messages within this session from those not
   within.  When the PCP client receives this initial PCP-Auth-Server
   message from the PCP server, it can reply with a PCP-Auth-Client
   message or silently discard the request message according to its
   local policies.  In the PCP-Auth-Client message, a nonce option which
   consists of a random nonce MAY be appended.  If so, in the next PCP-
   Auth-Server message, the PCP sever MUST forward the nonce back within
   a nonce option.

   In a PCP-Auth session, an EAP request message is transported within a
   PCP-Auth-Server message, and an EAP answer message is transported
   within a PCP-Auth-Client message.  EAP relies on the underlying
   protocol to provide reliable transmission; any disordered delivery or
   loss of packets occurred during transportation must be detected and
   addressed.  Therefore, after sending out a PCP-Auth-Server message,
   the PCP server will not send a new PCP-Auth-Server message until it
   receives a PCP-Auth-Client message with a proper sequence number from
   the PCP client, and vice versa.  If a PCP device receives a PCP-Auth
   message from its partner and cannot generate a EAP response within a
   pre-specified period due to certain reasons (e.g., waiting for human
   input to construct a EAP message or waiting for the additional PCP-
   Auth messages in order to construct a complete EAP message), the PCP



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   device MUST reply with a PCP-Auth-Acknowledge message (PCP-Auth
   messages with a Received Packet Option) to notify the packet has been
   received.  This approach not only can avoid un-necessarily
   retransmission of the PCP-Auth message but also can guarantee the
   reliable packet delivery in the conditions where a PCP device needs
   to receive multiple PCP-Auth messages before generating an EAP
   response.

   In this approach, it is mandated for a PCP client and a PCP server to
   perform a key-generating EAP method in authentication.  Therefore,
   after a successful authentication procedure, a Master Session Key
   (MSK) will be generated.  If the PCP client and the PCP server want
   to generate a traffic key using the MSK, they need to agree upon a
   Pseudo-Random Function (PRF) for the transport key derivation and a
   MAC algorithm to provide data origin authentication for subsequent
   PCP packets.  In order to do this, the PCP server needs to append a
   set of PRF Options and MAC Algorithm Options to the initial PCP-Auth-
   Server message.  Each PRF Option contains a PRF that the PCP server
   supports, and each MAC Algorithm Option contains a MAC (Message
   Authentication Code) algorithm that the PCP server supports.  After
   receiving the options, the PCP client selects the PRF and the MAC
   algorithm which it would like to use, and then attach the associated
   PRF and MAC Algorithm Options to the next PCP-Auth-Client message.

   After the EAP authentication, the PCP server sends out a PCP-Auth-
   Server message to indicate the EAP authentication and PCP
   authorization results.  If the EAP authentication succeeds, the
   result code of the PCP-Auth-Server message is AUTHENTICATION-SUCCEED.
   In this case, before sending out the PCP-Auth-Server message, the PCP
   server MUST generate a PCP SA and use the derived transport key to
   generate a digest for the message.  The digest is transported within
   an Authentication Tag Option for PCP Auth.  A more detailed
   description of generating the authentication data can be found in
   Section 7.1.  In addition, the PCP-Auth-Server MAY also contain a
   Session Lifetime Option which indicates the life-time of the PCP-Auth
   session (i.e., the life-time of the MSK).  After receiving the PCP-
   Auth-Server message, the PCP client then needs to generate a PCP-
   Auth-Client message as response.  If the PCP client also
   authenticates the PCP server, the result code of the PCP-Auth-Client
   is AUTHENTICATION-SUCCEED.  In addition, the PCP client needs to
   generate a PCP SA and uses the derived traffic key to secure the
   message.  From then on, all the PCP messages within the session are
   secured with the traffic key and the MAC algorithm specified in the
   PCP SA, unless a re-authentication is performed.

   If a PCP client/server cannot authenticate its session partner, the
   device sends out a PCP-Auth message with the result code,
   AUTHENTICATION-FAILED.  If the EAP authentication succeeds but



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   Authorization fails, the device making the decision sends out a PCP-
   Auth message with the result code, AUTHORIZATION-FAILED.  In these
   two cases, after the PCP-Auth message is sent out, the PCP-Auth
   session MUST be terminated immediately.

3.2.  Session Termination

   A PCP-Auth session can be explicitly terminated by sending a
   termination-indicating PCP-Auth message (a PCP-Auth message with a
   result code "SESSION-TERMINATION" ) from either session partner.
   After receiving a Termination-Indicating message from the session
   partner, a PCP device MUST respond with a Termination-Indicating PCP-
   Auth message and remove the PCP-Auth SA immediately.  When the
   session partner initiating the termination process receives the PCP-
   Auth message, it will remove the associated PCP-Auth SA immediately.

3.3.  Session Re-Authentication

   A session partner may select to perform EAP re-authentication if it
   would like to update the PCP SA (e.g., update the MSK and rollback
   the sequence numbers, or extend the session life period) without
   initiating a new PCP-Auth session.

   When the PCP server would like to initiate a re-authentication, it
   sends the PCP client a PCP-Auth-Server message.  The result code of
   the message is set to "RE-AUTHENTICATION", which indicates the
   message is for an re-authentication process.  If the PCP client would
   like to start the re-authentication, it will send an PCP-Auth-Client
   message to the PCP server, the result code of the PCP-Auth-Client
   message is set to "RE-AUTHENTICATION".  Then, the session partners
   exchange PCP-Auth messages to transfer EAP messages for the re-
   authentication.  During the re-authentication procedure, the session
   partners protect the integrity of PCP-Auth messages with the key and
   MAC algorithm specified in the current PCP SA; the sequence numbers
   associated with the packet will never be rolled back and keep
   increasing according to Section 7.3.

   If the EAP re-authentication succeeds, the result code of the last
   PCP-Auth-Server is "AUTHENTICATION-SUCCEED".  In this case, before
   sending out the PCP-Auth-Server, the PCP server must update the SA
   and use the new key to generate digests to protect the integrity and
   authenticity of the PCP-Auth-Server and any subsequent PCP message.
   In addition, the PCP-Auth-Server MAY be appended with a Session
   Lifetime Option which indicates the new life-time of the PCP-Auth
   session.

   If the EAP authentication fails, the result code of the last PCP-
   Auth-Server is "AUTHENTICATION-FAILED".  If the EAP authentication



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   succeeds but Authorization fails, the result code of the last PCP-
   Auth-Server is "AUTHORIZATION-FAILED".  In the latter two cases, the
   PCP-Auth session MUST be terminated immediately after the last PCP-
   Auth message exchange.

4.  PA Security Association

   At the beginning of a PCP-Auth session, a session SHOULD generate a
   PCP-Auth SA to maintain its state information during the session.
   The parameters of a PCP-Auth SA are listed as follows:

   o  IP address and UDP port number of the PCP client

   o  IP address and UDP port number of the PCP server

   o  Session Identifier

   o  Sequence number for the next outgoing PCP-Auth message

   o  Sequence number for the next incoming PCP-Auth message

   o  Sequence number for the next outgoing common PCP message (included
      in the SA for PCP slient)

   o  Sequence number for the next incoming common PCP message (included
      in the SA for PCP slient)

   o  Last outgoing message payload

   o  Retransmission interval

   o  MSK: The master session key generated by the EAP method.

   o  MAC algorithm: The algorithm that the transport key should use to
      generate digests for PCP messages.

   o  Pseudo-random function: The pseudo random function negotiated in
      the initial PCP-Auth-Server and PCP-Auth-Client exchange for the
      transport key derivation

   o  Transport key: the key derived from the MSK to provide integrity
      protection and data origin authentication for the messages in the
      PCP-Auth session.  The life-time of the transport key SHOULD be
      identical to the life-time of the session.

   o  The nonce selected by the PCP client at the initiation of the
      session.




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   o  Key ID: the ID associated with Transport key.

   Particularly, the transport key is computed in the following way:
   Transport key = prf(MSK, "IETF PCP"| Session_ID| Nonce| key ID),
   where:

   o  The prf: The pseudo-random function assigned in the Pseudo-random
      function parameter.

   o  MSK: The master session key generated by the EAP method.

   o  "IETF PCP": The ASCII code representation of the non-NULL
      terminated string (excluding the double quotes around it).

   o  Session_ID: The ID of the session which the MSK is derived from.

   o  Nonce: The nonce selected by the client and transported in the
      Initial PCP-Auth-Client packet.  If the PCP client does not select
      one, this value is set as 0.

   o  Key ID: The ID assigned for the traffic key.

5.  Result Code

   This message use the result code field specified in the PCP headers
   to transport the information for authentication and session
   management.  Particularly, the values of following result codes are
   specified.

      TBD INITIATION

      TBD AUTHENTICATION-REQUIRED

      TBD AUTHENTICATION-FAILED

      TBD AUTHENTICATION-SUCCEED

      TBD AUTHORIZATION-FAILED

      TBD SESSION-TERMINATION

6.  Packet Format

6.1.  Packet Format of PCP Auth Messages

   The format of PCP-Auth-Server messages is identical to the response
   packet format specified in Section 7.2 of [RFC6887].




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   As illustrated in Figure 1, the PCP-Auth-Client messages use the
   requester header specified in Section 7.1 of[RFC6887].  The only
   difference is that eight reserved bits are used to transfer the
   result codes (e.g., "INITIATION", "AUTHENTICATION-FAILED").  Other
   fields in Figure 1 are described in Section 7.1 of [RFC6887].

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Version = 2  |R|   Opcode    |   Reserved    |  Result Code  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 Requested Lifetime (32 bits)                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       |            PCP Client's IP Address (128 bits)                 |
       |                                                               |
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       :                                                               :
       :                  Opcode-specific information                  :
       :                                                               :
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       :                                                               :
       :                   (optional) PCP Options                      :
       :                                                               :
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                    Figure 1.  PCP-Auth-Client message Format

6.2.  Authentication OpCode

   The following figure illustrates the format of an authentication
   OpCode:

         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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                       Session ID                              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Sequence Number                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Session ID: This field contains a 32-bit PCP-Auth session
      identifier.

      Sequence Number: This field contains a 32-bit sequence number.  In
      this solution, a sequence number needs to be incremented on every



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      new (non-retransmission) outgoing packet in order to provide
      ordering guarantee for PCP.

6.3.  Nonce Option

   Because the session identifier of PCP-Auth session is determined by
   the PCP server, a PCP client does not know the session identifier
   which will be used when it sends out a PCP-Auth-Initiation message.
   In order to prevent an attacker from interrupting the authentication
   process by sending off-line generated PCP-Auth-Server messages, the
   PCP client needs to generate a random number as nonce in the PCP-
   Auth-Initiation message.  The PCP server will append the nonce within
   the initial PCP-Auth-Server message.  If the PCP-Auth-Server message
   does not carry the correct nonce, the message will be discarded
   silently.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Option Code  |  Reserved     |       Option-Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Nonce                                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Option-Length: The length of the Nonce Option (in octet),
      including the 4 octet fixed header and the variable length of the
      authentication data.

      Nonce: A random 32 bits number which is transported within a PCC-
      Initiate message and the corresponding reply message from the PCP
      server.

6.4.  Authentication Tag Option for Common PCP


















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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Option Code  |  Reserved     |       Option-Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                       Session ID                              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Sequence Number                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                          Key ID                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       |                Authentication Data (Variable)                 |
       ~                                                               ~
       |                                                               |
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Option-Length: The length of the Authentication Tag Option for
      Common PCP (in octet), including the 12 octet fixed header and the
      variable length of the authentication data.

      Session ID: A 32-bit field used to indicates the identifier of the
      session that the message belongs to and identifies the secret key
      used to create the message digest appended to the PCP message.

      Sequence Number: This field contains a 32-bit sequence number.  In
      this solution, a sequence number needs to be incremented on every
      new (non-retransmission) outgoing packet in order to provide
      ordering guarantee for common PCP messages.

      Key ID: The ID associated with the traffic key used to generate
      authentication data.  This field is filled with zero if MSK is
      directly used to secure the message.

      Authentication Data: A variable-length field that carries the
      Message Authentication Code for the PCP packet.  The generation of
      the digest can be various according to the algorithms specified in
      different PCP SAs.  This field MUST end on a 32-bit boundary,
      padded with 0's when necessary.

6.5.  Authentication Tag Option for PCP Auth Messages

   This option is used to provide message authentication for PCP-Auth
   messages.  Compared with the Authentication Tag Option for Common
   PCP, the session ID field and the sequence number field are removed
   because such information is provided in the Authentication OpCode.




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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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Option Code  |  Reserved     |       Option-Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                          Key ID                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       |                Authentication Data (Variable)                 |
       ~                                                               ~
       |                                                               |
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Option-Length: The length of the Authentication Tag Option for PCP
      Auth (in octet), including the 12 octet fixed header and the
      variable length of the authentication data.

      Key ID: The ID associated with the traffic key used to generate
      authentication data.  This field is filled with zero if MSK is
      directly used to secure the message.

      Authentication Data: A variable-length field that carries the
      Message Authentication Code for the PCP packet.  The generation of
      the digest can be various according to the algorithms specified in
      different PCP SAs.  This field MUST end on a 32-bit boundary,
      padded with 0's when necessary.

6.6.  EAP Payload Option

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Option Code  |  Reserved     |       Option-Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       |                           EAP Message                         |
       ~                                                               ~
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Option-Length: The length of the EAP Payload Option (in octet),
      including the 4 octet fixed header and the variable length of the
      EAP message.

      EAP Message: The EAP message transferred.  Note this field MUST
      end on a 32-bit boundary, padded with 0's when necessary.




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6.7.  PRF Option

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Option Code  |  Reserved     |       Option-Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                          PRF                                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-Length: The length of the PRF Option (in octet), including the
   4 octet fixed header and the variable length of the EAP message.

   PRF: The Pseudo-Random Function which the sender supports to generate
   an MSK.  This field contains an IKEv2 Transform ID of Transform Type
   2 [RFC4306][RFC4868].  A PCP implementation MUST support
   PRF_HMAC_SHA2_256 (5).

6.8.  MAC Algorithm Option

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Option Code  |  Reserved     |       Option-Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    MAC Algorithm ID                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-Length: The length of the MAC Algorithm Option (in octet),
   including the 4 octet fixed header and the variable length of the EAP
   message.

   MAC Algorithm ID: Indicate the MAC algorithm which the sender
   supports to generate authentication data.  The MAC Algorithm ID field
   contains an IKEv2 Transform ID of Transform Type 3
   [RFC4306][RFC4868].A PCP implementation MUST support
   AUTH_HMAC_SHA2_256_128 (12).

6.9.  Session Lifetime Option

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Option Code  |  Reserved     |       Option-Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Session Lifetime                            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+




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   Option-Length: The length of the Session Lifetime Option (in octet),
   including the 4 octet fixed header and the variable length of the EAP
   message.

   Session Lifetime: The life time of the PCP-Auth Session, which is
   decided by the authorization result.

6.10.  Received Packet Option

   This option is used in a PCP-Auth-Acknowledgement message to indicate
   a packet with the contained sequence number has been received.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Option Code  |  Reserved     |       Option-Length           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Received Sequence Number                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Option-Length: The length of the Received Packet Option (in octet),
   including the 4 octet fixed header and the variable length of the EAP
   message.

   Received Sequence Number: The sequence number of the last received
   PCP packet.

7.  Processing Rules

7.1.  Authentication Data Generation

   If a PCP SA is generated as the result of a successful EAP
   authentication process, every subsequent PCP message within the
   session MUST carry an Authentication Tag Option which contains the
   digest of the PCP message for data origin authentication and
   integrity protection.

   Before generating a digest for a PCP-Auth message, a device needs to
   first locate the PCP SA according to the session identifier and then
   get the traffic key.  Then the device appends an Authentication Tag
   Option for PCP Auth at the end of the PCP Auth message.  The length
   of the Authentication Data field is decided by the MAC algorithm
   adopted in the session.  The device then fills the Key ID field with
   the key ID of the traffic key, and sets the Authentication Data field
   to 0.  After this, the device generates a digest for the entire PCP
   message (including the PCP header and Authentication Tag Option)
   using the traffic key and the associated MAC algorithm, and insert
   the generated digest into the Authentication Data field.



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   Similar to generating a digest for a PCP-Auth message, before
   generating a digest for a common PCP message, a device needs to first
   locate the PCP SA according to the session identifier and then get
   the traffic key.  Then the device appends the Authentication Tag
   Option for common PCP at the end of the message.  The length of the
   Authentication Data field is decided by the MAC algorithm adopted in
   the session.  The device then use the corresponding values derived
   from the SA to fills the Session ID field, the Sequence Number field,
   and the Key ID field, and sets the Authentication Data field to 0.
   After this, the device generates a digest for the entire PCP message
   (including the PCP header and Authentication Tag Option) using the
   traffic key and the associated MAC algorithm, and inputs the
   generated digest into the Authentication Data field.

7.2.  Authentication Data Validation

   When a device receives a common PCP packet with an Authentication Tag
   Option for Common PCP, the device needs to use the session ID
   transported in the option to locate the proper SA, and then find the
   associated transport key (using key ID in the option) and the MAC
   algorithm.  If no proper SA or traffic key is found, the PCP packet
   MUST be discarded silently.  After storing the value of the
   Authentication field of the Authentication Tag Option, the device
   fills the Authentication field with zeros.  Then, the device
   generates a digest for the packet (including the PCP header and
   Authentication Tag Option) with the transport key and the MAC
   algorithm found in the first step.  If the value of the newly
   generated digest is identical to the stored one, the device can
   ensure that the packet has not been tampered with, and the validation
   succeeds.  Otherwise, the packet MUST be discarded.

   Similarly, when a device receives a PCP Auth packet with an
   Authentication Tag Option for PCP Auth, the device needs to use the
   session ID transported in the opcode to locate the proper SA, and
   then find the associated transport key (using key ID in the option)
   and the MAC algorithm.  If no proper SA or traffic key is found, the
   PCP packet MUST be discarded silently.  After storing the value of
   the Authentication field of the Authentication Tag Option, the device
   fills the Authentication field with zeros.  Then, the device
   generates a digest for the packet (including the PCP header and
   Authentication Tag Option) with the transport key and the MAC
   algorithm found in the first step.  If the value of the newly
   generated digest is identical to the stored one, the device can
   ensure that the packet has not been tampered with, and the validation
   succeeds.  Otherwise, the packet MUST be discarded.






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7.3.  Retransmission Policies for PCP Auth Messages

   Because EAP relies on the underlying protocols to provide reliable
   transmission, after sending a PCP-Auth message, a PCP client/server
   MUST NOT send out any subsequent messages until receiving an expect
   PCP-Auth message (the PCP-Auth message with a proper sequence number)
   from the peer.  If no such a message is received in a certain period,
   the PCP device will re-send the last message according to certain
   retransmission policies.  This work reuses the retransmission
   policies specified in the base PCP protocol (Section 8.1.1 of
   [RFC6887]).  In the base PCP protocol, such retransmission policies
   are only applied by PCP clients.  However, in this work, such
   retransmission policies are also applied by the PCP servers.

   Note that the last PCP-Auth messages transported within the phases of
   session initiation, session re-authentication, and session
   termination do not have to follow the above policies since the
   devices sending out those messages do not expect any further PCP-Auth
   messages.

   When a device receives such a duplicate PCP-Auth message from its
   session partner, it MUST try to answer it by sending the last
   outgoing PCP-Auth message again.  The rate of replying the duplicate
   PCP-Auth messages MUST be limited.

7.4.  Sequence Numbers for PCP Auth Messages

   PCP adopts UDP to transport signaling messages.  As an un-reliable
   transport protocol, UDP does not guarantee ordered packet delivery
   and does not provide any protection from packet loss.  In order to
   ensure the EAP messages are exchanged in a reliable way, every PCP
   packet exchanged during EAP authentication must carry an
   monotonically increasing sequence number.  During a PCP-Auth session,
   a PCP device needs to maintain two sequence numbers for PCP-Auth
   messages, one for incoming PCP-Auth messages and one for outgoing
   PCP-Auth messages.  When generating an outgoing PCP-Auth packet, the
   device attaches the associated outgoing sequence number to the packet
   and increments the sequence number maintained in the SA by 1.  When
   receiving a PCP-Auth packet from its session partner, the device will
   not accept it if the sequence number carried in the packet does not
   match the incoming sequence number the device maintains.  After
   confirming that the received packet is valid, the device increments
   the incoming sequence number maintained in the SA by 1.

   The above rules are not applied to PCP-Auth-Acknowledgement messages
   (i.e., PCP-Auth messages containing a Received Packet Option).  A
   PCP-Auth-Acknowledgement message does not transport any EAP message
   and only indicate at a PCP-Auth message is received.  Therefore, the



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   reliable transmission of PCP-Auth-Acknowledgement message does not
   have to be guaranteed.  Therefore, when receiving or sending out a
   PCP-Auth-Acknowledgement message, the device MUST not increase the
   corresponding sequence number stored in the SA.  Otherwise, the lost
   of a PCP-Auth-Acknowledgement message during transportation will
   cause the mismatching issues with the sequence numbers.

   Another exception is in the message retransmission scenarios.  When a
   device does not receive any response from its session partner in a
   certain period, it needs to retransmit the last outgoing PCP-Auth
   message with a limited rate.  The duplicate messages and the original
   message MUST use the identical sequence number.  When the device
   receives such a duplicate PCP-Auth message from its session partner,
   it MUST try to answer it by sending the last outgoing PCP-Auth
   message again.  Note the rate of replying the duplicate PCP-Auth
   messages must be limited.  In such cases, the maintained incoming and
   outgoing sequence numbers will not be affected by the message
   retransmission.

7.5.  Sequence Numbers for Common PCP Messages

   When transporting common PCP messages within a PCP-Auth session, a
   PCP device needs to maintain a sequence number for outgoing common
   PCP messages and a sequence number for incoming common PCP messages.
   When generating a new outgoing PCP messages, the PCP device attaches
   the outgoing sequence number for common PCP messages to the messages
   and increments the sequence number maintained in the SA by 1.

   When receiving a PCP packet from its session partner, the PCP device
   will not accept it if the sequence number carried in the packet is
   smaller than the incoming sequence number the server maintains.  This
   approach can protect the PCP server from replay attacks.  After
   confirming that the received packet is valid, the PCP server will use
   the sequence number in the incoming packet to take place the incoming
   sequence number for common PCP messages maintained in the SA.

   Note that the sequence number in the incoming packet may not exactly
   match the incoming sequence number maintained locally.  In the base
   PCP specification [RFC6887], a PCP client may stop retransmitting a
   PCP request without receiving any expected PCP answer when the client
   is no longer interested in the PCP transaction.  After that, the PCP
   client will try to generate new PCP requests for other purposes.  In
   this case, the sequence number in the new request will be larger than
   the incoming sequence number maintained in the PCP server.







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7.6.  MTU Considerations

   EAP methods are responsible for MTU handling, so no special
   facilities are required in this protocol to deal with MTU issues.  If
   an EAP message is too long for a single PCP-Auth message to
   transport, it will be divided into multiple sections and transport
   them within different PCP-Auth messages.  Note that the receiver may
   not be able to know what to do in the next step until receiving all
   the sections and constructing the complete EAP message.  In this
   case, in order to guarantee reliable message transmission, after
   receiving a PCP-Auth message, the receiver MUST reply with a PCP-
   Auth-Acknowledgement message until all the sections have been
   received.

8.  IANA Considerations

   TBD

9.  Security Considerations

   This section applies only to the in-band key management mechanism.
   It will need to be updated if the WG choose to pursue the out-of-band
   key management mechanism discussed above.

   In this work, after a successful EAP authentication process performed
   between two PCP devices, a MSK will be exported.  The MSK can be used
   to derive the transport keys to generate MAC digests for subsequent
   PCP message exchanges.  However, before a transport key has been
   generated, the PCP-Auth messages exchanged within a PCP-Auth session
   have little cryptographic protection, and if there is no already
   established security channel between two session partners, these
   messages are subject to man-in-the-middle attacks and DOS attacks.
   For instance, the initial PCP-Auth-Server and PCP-Auth-Client
   exchange is vulnerable to spoofing attacks as these messages are not
   authenticated and integrity protected.  In addition, because the PRF
   and MAC algorithms are transported at this stage, an attacker may try
   to remove the PRF and MAC options containing strong algorithms from
   the initial PCP-Auth-Server message and force the client choose the
   weakest algorithms.  Therefore, the server needs to guarantee that
   all the PRF and MAC algorithms it provides support are strong enough.

   In order to prevent very basic DOS attacks, a PCP device SHOULD
   generate state information as little as possible in the initial PCP-
   Auth-Server and PCP-Auth-Client exchanges.  The choice of EAP method
   is also very important.  The selected EAP method must be resilient to
   the attacks possibly in an insecure network environment, and the
   user-identity confidentiality, protection against dictionary attacks,
   and session-key establishment must be supported.



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10.  Acknowledgements

11.  Change Log

11.1.  Changes from wasserman-pcp-authentication-02 to ietf-pcp-
       authentication-00

   o  Added discussion of in-band and out-of-band key management
      options, leaving choice open for later WG decision.

   o  Removed support for fragmenting EAP messages, as that is handled
      by EAP methods.

11.2.  Changes from wasserman-pcp-authentication-01 to -02

   o  Add a nonce into the first two exchanged PCP-Auth message between
      the PCP client and PCP server.  When a PCP client initiate the
      session, it can use the nonce to detect offline attacks.

   o  Add the key ID field into the authentication tag option so that a
      MSK can generate multiple traffic keys.

   o  Specify that when a PCP device receives a PCP-Auth-Server or a
      PCP-Auth-Client message from its partner the PCP device needs to
      reply with a PCP-Auth-Acknowledge message to indicate that the
      message has been received.

   o  Add the support of fragmenting EAP messages.

11.3.  Changes from ietf-pcp-authentication-00 to -01

   o  Editorial changes, added use cases to introduction.

11.4.  Changes from ietf-pcp-authentication-01 to -02

   o  Add the support of re-authentication initiated by PCP server.

   o  Specify that when a PCP device receives a PCP-Auth-Server or a
      PCP-Auth-Client message from its partner the PCP device MAY reply
      with a PCP-Auth-Acknowledge message to indicate that the message
      has been received.

   o  Discuss the format of the PCP-Auth-Acknowledge message.

   o  Remove the redundant information from the Auth OpCode, and specify
      new result codes transported in PCP packet headers

   o



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11.5.  Changes from ietf-pcp-authentication-02 to -03

   o  Change the name "PCP-Auth-Request" to "PCP-Auth-Server"

   o  Change the name "PCP-Auth-Response" to "PCP-Auth-Client"

   o  Specify two new sequence numbers for common PCP messages in the
      PCP SA, and describe how to use them

   o  Specify a Authentication Tag Option for PCP Common Messages

   o  Introduce the scenario where a EAP message has to be divided into
      multiple sections and transported in different PCP-Auth messages
      (for the reasons of MTU), and introduce how to use PCP-Auth-
      Acknowledge messages to ensure reliable packet delivery in this
      case.

12.  References

12.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

12.2.  Informative References

   [RFC3748]  Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
              Levkowetz, "Extensible Authentication Protocol (EAP)", RFC
              3748, June 2004.

   [RFC4306]  Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", RFC
              4306, December 2005.

   [RFC4868]  Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-
              SHA-384, and HMAC-SHA-512 with IPsec", RFC 4868, May 2007.

   [RFC5191]  Forsberg, D., Ohba, Y., Patil, B., Tschofenig, H., and A.
              Yegin, "Protocol for Carrying Authentication for Network
              Access (PANA)", RFC 5191, May 2008.

   [RFC5448]  Arkko, J., Lehtovirta, V., and P. Eronen, "Improved
              Extensible Authentication Protocol Method for 3rd
              Generation Authentication and Key Agreement (EAP-AKA')",
              RFC 5448, May 2009.

   [RFC6887]  Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
              Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
              2013.



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Authors' Addresses

   Margaret Wasserman
   Painless Security
   356 Abbott Street
   North Andover, MA  01845
   USA

   Phone: +1 781 405 7464
   Email: mrw@painless-security.com
   URI:   http://www.painless-security.com


   Sam Hartman
   Painless Security
   356 Abbott Street
   North Andover, MA  01845
   USA

   Email: hartmans@painless-security.com
   URI:   http://www.painless-security.com


   Dacheng Zhang
   Huawei
   Beijing
   China

   Email: zhangdacheng@huawei.com






















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