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MSEC Working Group                                             S. Rowles
Internet-Draft                                             A. Yeung, Ed.
Intended status: Standards Track                                 P. Tran
Expires: May 08, 2014                                      Cisco Systems
                                                                  Y. Nir
                                  Check Point Software Technologies Ltd.
                                                       November 04, 2013


                    Group Key Management using IKEv2
                         draft-yeung-g-ikev2-07

Abstract

   This document presents a new group key distribution protocol.  The
   protocol is in conformance with MSEC key management architecture it
   contains two components: member registration and group rekeying, both
   downloading group security associations from the Group Controller Key
   Server to a member of the group.  The new protocol is similar to
   IKEv2 in message and payload formats as well as message semantics.

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 May 08, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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



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   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 and Overview . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     1.2.  Why do we need another GSA protocol?  . . . . . . . . . .   4
     1.3.  G-IKEv2 Payloads  . . . . . . . . . . . . . . . . . . . .   4
   2.  G-IKEv2 integration into IKEv2 protocol . . . . . . . . . . .   5
     2.1.  UDP port  . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  G-IKEv2 Protocol  . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  G-IKEv2 member registration and secure channel
           establishment . . . . . . . . . . . . . . . . . . . . . .   5
       3.1.1.  GSA_AUTH exchange . . . . . . . . . . . . . . . . . .   6
       3.1.2.  GSA_REGISTRATION Exchange . . . . . . . . . . . . . .   7
       3.1.3.  IKEv2 Header Initialization . . . . . . . . . . . . .   7
       3.1.4.  GM Registration Operations  . . . . . . . . . . . . .   8
       3.1.5.  GCKS Registration Operations  . . . . . . . . . . . .   9
     3.2.  Counter-based modes of operation  . . . . . . . . . . . .   9
     3.3.  G-IKEv2 group maintenance channel . . . . . . . . . . . .  11
       3.3.1.  G-IKEv2 GSA_REKEY exchange  . . . . . . . . . . . . .  11
       3.3.2.  Forward and Backward Access Control . . . . . . . . .  12
       3.3.3.  Forward Access Control Requirements . . . . . . . . .  13
       3.3.4.  Deletion of SAs . . . . . . . . . . . . . . . . . . .  14
       3.3.5.  GSA_REKEY GCKS Operations . . . . . . . . . . . . . .  14
       3.3.6.  GSA_REKEY GM Operations . . . . . . . . . . . . . . .  15
   4.  Header and Payload Formats  . . . . . . . . . . . . . . . . .  15
     4.1.  The G-IKEv2 Header  . . . . . . . . . . . . . . . . . . .  15
     4.2.  IDgroup Payload . . . . . . . . . . . . . . . . . . . . .  16
     4.3.  Group Security Association Payload  . . . . . . . . . . .  16
       4.3.1.  GSA policy  . . . . . . . . . . . . . . . . . . . . .  16
     4.4.  KEK Policy  . . . . . . . . . . . . . . . . . . . . . . .  18
       4.4.1.  KEK Attributes  . . . . . . . . . . . . . . . . . . .  19
       4.4.2.  KEK_MANAGEMENT_ALGORITHM  . . . . . . . . . . . . . .  19
       4.4.3.  KEK_ENCR_ALGORITHM  . . . . . . . . . . . . . . . . .  20
       4.4.4.  KEK_KEY_LENGTH  . . . . . . . . . . . . . . . . . . .  20
       4.4.5.  KEK_KEY_LIFETIME  . . . . . . . . . . . . . . . . . .  20
       4.4.6.  KEK_INTEGRITY_ALGORITHM . . . . . . . . . . . . . . .  20
       4.4.7.  KEK_AUTH_METHOD . . . . . . . . . . . . . . . . . . .  20
       4.4.8.  KEK_AUTH_ALGORITHM  . . . . . . . . . . . . . . . . .  21
       4.4.9.  KEK_MESSAGE_ID  . . . . . . . . . . . . . . . . . . .  21
     4.5.  GSA TEK Policy  . . . . . . . . . . . . . . . . . . . . .  21
       4.5.1.  TEK ESP and AH Protocol-Specific Policy . . . . . . .  22
     4.6.  GSA Group Associated Policy . . . . . . . . . . . . . . .  23
       4.6.1.  ACTIVATION_TIME_DELAY/DEACTIVATION_TIME_DELAY . . . .  24



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     4.7.  Key Download Payload  . . . . . . . . . . . . . . . . . .  25
       4.7.1.  TEK Download Type . . . . . . . . . . . . . . . . . .  26
       4.7.2.  KEK Download Type . . . . . . . . . . . . . . . . . .  27
       4.7.3.  LKH Download Type . . . . . . . . . . . . . . . . . .  28
       4.7.4.  SID Download Type . . . . . . . . . . . . . . . . . .  31
     4.8.  Delete Payload  . . . . . . . . . . . . . . . . . . . . .  33
     4.9.  Notify Payload  . . . . . . . . . . . . . . . . . . . . .  33
     4.10. Authentication Payload  . . . . . . . . . . . . . . . . .  33
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  33
     5.1.  GSA registration and secure channel . . . . . . . . . . .  33
     5.2.  GSA maintenance channel . . . . . . . . . . . . . . . . .  34
       5.2.1.  Authentication/Authorization  . . . . . . . . . . . .  34
       5.2.2.  Confidentiality . . . . . . . . . . . . . . . . . . .  34
       5.2.3.  Man-in-the-Middle Attack Protection . . . . . . . . .  34
       5.2.4.  Replay/Reflection Attack Protection . . . . . . . . .  34
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  34
     6.1.  New registries  . . . . . . . . . . . . . . . . . . . . .  34
     6.2.  New payload and exchange types to existing IKEv2 registry  35
     6.3.  Payload Types . . . . . . . . . . . . . . . . . . . . . .  35
     6.4.  New Name spaces . . . . . . . . . . . . . . . . . . . . .  35
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  36
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  36
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  36
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  36
   Appendix A.  Differences between G-IKEv2 and RFC 6407 . . . . . .  38
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  38

1.  Introduction and Overview

   This document presents a group key management protocol protected by
   IKEv2.  The data communications within the group are protected by a
   key pushed to the group members (GMs) by the Group Controller/Key
   Server (GCKS) using IKEv2 [RFC5996].  The GCKS pushes policy and keys
   for the group to the GM after authenticating it using new payloads
   added in the IKE_AUTH exchange.  This document references IKEv2
   [RFC5996] but it intended to be a separate document.  GDOI update
   document [RFC6407] presented GDOI using IKEv1 syntax.  This document
   uses IKEv2 syntax.  The message semantics of IKEv2 are preserved, in
   that all communications consists of message request-response pairs.
   The exception to this rule are the rekeying messages, which are sent
   in multicast without a response.  A number of payloads were deemed
   unnecessary since [RFC6407] are described in Appendix A









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1.1.  Requirements Language

   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].

1.2.  Why do we need another GSA protocol?

   GDOI protocol specified in [RFC6407] is protected by IKEv1 phase1
   security association defined in [RFC2407], [RFC2408] and [RFC2409];
   these documents are obsoleted and replaced by a new version of the
   IKE protocol defined in RFC 5996.  G-IKEv2 provides group key
   management between the group member and group controller key server
   using the new IKEv2 protocol and inherits the following key
   advantages over GDOI:

   1.  Provide a simple mechanism for the responder to keep minimal
       state and avoid DOS attack from forged IP address using cookie
       challenge exchange.

   2.  Improve performance and network latency by the reduced number of
       initial messages to complete the G-IKEv2 protocol from (10
       messages in main mode and quick mode, 7 messages in aggressive
       mode and quick) to 4 messages.

   3.  Fix cryptographic weakness with authentication HASH (ikev1
       authentication HASH specified in RFC-2409 does not include all
       ISAKMP payloads and does not include ISAKMP header).  This issue
       is documented at [IKE-HASH].

   4.  Improve protocol reliability where all unicast messages are
       ack'ed and sequenced.

   5.  Well defined behavior for error conditions to improve
       interoperability.

1.3.  G-IKEv2 Payloads

   1.  IDg (group ID) - The GM requests the GCKS for membership into the
       group by sending its IDg payload.

   2.  GSA (Group Security Association) - The GCKS sends the group
       policy to the GM using this payload.

   3.  KD (Key Download) - The GCKS sends the control and data keys to
       the GM using the KD payload.





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2.  G-IKEv2 integration into IKEv2 protocol

   The G-IKEv2 protocol provides the security mechanisms of IKEv2 (peer
   authentication, confidentiality, message integrity) to protect the
   group negotiations required for G-IKEv2.  The G-IKEv2 exchange
   further provides group authorization, and secure policy and key
   download from the GCKS to its group members.

2.1.  UDP port

   G-IKEv2 SHOULD use port 848, the same as GDOI [RFC6407] , because
   they serve a similar function, and can use the same ports, just as
   IKEv1 and IKEv2 can share port 500.  The version number in the IKEv2
   header distinguishes the G-IKEv2 protocol from GDOI protocol
   [RFC6407].

3.  G-IKEv2 Protocol

3.1.  G-IKEv2 member registration and secure channel establishment

   The registration protocol consists of minimum two exchanges
   IKE_SA_INIT and GSA_AUTH; member registration may have a few more
   messages exchanged if the EAP method, cookie challenge (for DoS) or
   invalid KE are used.  Each exchange consists of request/response
   pairs.  The first exchange IKE_SA_INIT is defined in IKEv2 [RFC5996].
   This exchange negotiates cryptographic algorithms, exchanges nonces
   and does a Diffie-Hellman exchange between the member and the Group
   Controller Key Server (GCKS).

   The second exchange GSA_AUTH authenticates the previous messages,
   exchange identities and certificates, . Parts of these messages are
   encrypted and integrity protected with keys established through the
   IKE_SA_INIT exchange, so the identities are hidden from eavesdroppers
   and all fields in all the messages are authenticated.  The GCKS MAY
   authorize group members to be allowed into the group as part of the
   GSA_AUTH exchange.  Once the GCKS accepted a group member to join a
   group it may downloads the data security keys (TEKs) and/or group key
   encrypting key (KEK) or KEK array as part of GSA_AUTH response
   message.  In the following descriptions, the payloads contained in
   the message are indicated by names as listed below.

     Notation      Payload
    ------------------------------------------------------------
     AUTH          Authentication
     CERT          Certificate
     CERTREQ       Certificate Request
     GSA           Group Security Association
     HDR           IKEv2 Header



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     IDg           Identification - Group
     IDi           Identification - Initiator
     IDr           Identification - Responder
     KD            Key Download
     KE            Key Exchange
     Ni, Nr        Nonce SA Security Association


   The details of the contents of each payload are described in
   Section 4.  Payloads that may optionally appear will be shown in
   brackets, such as [ CERTREQ], indicate that optionally a certificate
   request payload can be included.

3.1.1.  GSA_AUTH exchange

   After the group member and GCKS uses IKE_SA_INIT exchange to
   negotiate cryptographic algorithms, exchange nonces, and perform a
   Diffie-Hellman exchange as defined in IKEv2 [RFC5996], the GSA_AUTH
   MAY be used for the GCKS to download group policy and keys to the
   member.  The security properties of the GSA_AUTH exchange are the
   same as the properties of the IKE_AUTH exchange.  It is used to
   authenticate the IKE_SA_INIT messages, exchange identities and
   certificates.  G-IKEv2 also uses this exchange for group member
   registration and optionally authorization.  GSA_AUTH does not include
   SA2, TSi and TSr since policy is not negotiated between group member
   and GCKS but downloaded from the GCKS to the group member.

    Initiator (Member)                              Responder (GCKS)
   --------------------                            ------------------
    HDR, SK { IDi, [ CERT,] [ CERTREQ,] [ IDr,] AUTH,
              IDg, [N] }         -->


   After an unauthenticated secure channel is established by IKE_SA_INIT
   exchange, the member initiates a registration request to join a group
   indicated by the IDg payload.  The GM can include 0 or more Notify
   payload.  Notify payload status type SENDER_ID_REQUEST is indicate a
   request SIDs for Counter-based cipher from the GCKS.

                          <-- HDR, SK { IDr, [ CERT,] AUTH, [GSA, KD,] [D,]  }


   Besides response with IDr, optional CERT, and AUTH material, the GCKS
   MAY also informs the member the cryptographic policies of the group
   in the GSA payload and key material in the KD payload.  GCKS can also
   include Delete payload instructing the group member to delete
   existing SAs it might have.




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   In addition to the IKEv2 error handling, GCKS can reject the
   registration request when IDg is invalid or authorization fail, etc.
   In these cases, see Section 4.9, the GSA_AUTH response will include
   notify indicate errors.  The member SHOULD delete the registration
   IKE SA.

     Initiator (Member)               Responder (GCKS)
   --------------------              ------------------
                              <--    HDR, SK { N }


   When the group member found the policy sent by the GCKS is
   unacceptable, the member SHOULD send an IKEv2 delete using the
   INFORMATION message exchange to bring down the authenticated IKE SA.

3.1.2.  GSA_REGISTRATION Exchange

   When a secure channel is already established between GM and KS, the
   GM registration for a group can reuse the established secure channel.
   In this scenario the GM will use the GSA_REGISTRATION exchange by
   including the desired group ID (IDg) to request data security keys
   (TEKs) and/or group key encrypting keys (KEKs) from the GCKS.  The GM
   MAY also include the Notify payload status type SENDER_ID_REQUEST to
   request SIDs for Counter-based cipher from the GCKS.

       Initiator (Member)                             Responder (GCKS)
      --------------------                            ------------------
       HDR, SK {IDg, [N] } -->

                                         <--  HDR, SK { GSA, KD, [D] }


   This exchange can also be used when the group member found the policy
   sent by the GCKS is unacceptable.  The group member can notify the
   GCKS by sending IDg and the NOTIFY type NO_PROPOSAL_CHOSEN as shown
   below.  The GCKS MUST unregister the group member.

       Initiator (Member)                 Responder (GCKS)
      --------------------               ------------------
       HDR, SK {IDg [N,]}      -->

                               <--        HDR, SK {}


3.1.3.  IKEv2 Header Initialization

   The Major Version is (2) and Minor Version number (0) according to
   IKEv2 [RFC5996], and maintained in this document.  The G-IKEv2



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   IKE_SA_INIT, GSA_AUTH and GSA_REGISTRATION use the SPI according to
   IKEv2 [RFC5996],section 2.6.

3.1.4.  GM Registration Operations

   A G-IKEv2 Initiator (GM) requesting registration contacts the GCKS
   using the IKE_SA_INIT exchange and receives the response from the
   GCKS.  This exchange is unchanged from the IKE_SA_INIT in IKEv2
   protocol.

   Upon completion of parsing and verifying the IKE_SA_INIT response,
   the GM sends the GSA_AUTH message with the IKEv2 payloads from
   IKE_AUTH (without the SAi2, TSi and TSr) along with the Group ID
   informing the GCKS of the group the initiator wishes to join.  The
   initiator MAY specify how many Sender-ID values it would like to
   receive in the Notify payload status type SENDER_ID_REQUEST in case
   the Data Security SA supports a counter mode cipher [section 3.2].

   Upon receiving the GSA_AUTH, the initiator then parses the response
   from the GCKS authenticating the exchange using the IKEv2 method,
   then processing the GSA, and KD.

   The GSA payload contains the security protocol and cryptographic
   protocols used by the group.  This policy describes the Re-key SA
   (KEK), if present, Data-security SAs (TEK), and other group policy
   (GAP).  If the policy in the GSA payload is not acceptable to the GM,
   it SHOULD tear down the session after notifying the GCKS.  Finally
   the KD is parsed providing the keying material for the TEK and/or
   KEK.  The GM interprets the KD key packets, where each key packet
   includes the keying material for SAs distributed in the GSA payload.
   Keying material is matched by comparing the SPIs in the key packets
   to SPIs previously included in the GSA payloads.  Once TEK keys and
   policy are matched, the GM provides them to the data security
   subsystem, and it is ready to send or receive packets matching the
   TEK policy.

   The GSA KEK policy MUST include KEK attribute KEK_MESSAGE_ID with a
   message id.  The message id in the KEK_MESSAGE_ID attribute MUST be
   checked against any previously received message id for this group.
   If it is less than the previously received number, it should be
   considered stale and ignored.  This could happen if two GSA_AUTH
   exchanges happened in parallel, and the message id changed.  This
   KEK_MESSAGE_ID is used by the GM to prevent GSA_REKEY message replay
   attacks.  The first GSA_REKEY message that the GM receives from the
   GCKS has to have message id greater or equal to the message id
   received in the KEK_MESSAGE_ID attribute.





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3.1.5.  GCKS Registration Operations

   A G-IKEv2 GCKS passively listens for incoming requests from group
   members.  The GCKS receives the IKE_SA_INIT request, select the IKE
   proposal, generates nonce and DH to include them in the IKE_SA_INIT
   response.

   Upon receiving the GSA_AUTH request, and after authenticate the group
   member using the same properties as IKEv2, the GCKS locates the group
   the GM wishes to join, extracts the policy for that group.  If the
   GCKS policy desires authorization, the GCKS authorizes the group
   member against the specified credentials before preparing to send
   GSA_AUTH response.  The GSA_AUTH response MAY include group policy in
   GSA payload and keys in the KD payload.  If the GCKS policy include
   group rekey option, this policy is constructed in the GSA KEK and the
   key is constructed in the KD KEK.  The GSA KEK MUST include attribute
   KEK_MESSAGE_ID specify the starting message id the GCKS will be using
   when sending the GSA_REKEY message to the group member.  This message
   id is used prevent replay attacks of the GSA_REKEY message and will
   be increasing each time a GSA_REKEY message is sent to the group.
   The GCKS data traffic policy is included in the GSA TEK and keys are
   included in KD TEK.  GSA GAP MAY also included to provide the ATD and
   /or DTD [section 4.6.1] specifying activation and deactivation delays
   for SAs generated from the TEKs.  If one or more Data Security SAs
   distributed in the GSA payload included a counter mode of operation,
   the GCKS includes at least one SID value in the KD payload, and
   possibly more depending on the request received in the NOTIFY payload
   status type SENDER_ID_REQUEST requesting the number of SIDs from the
   group member.

   If the GCKS receives a GSA_REGISTRATION exchange with a request to
   register a GM to a group, the GCKS will need to authorize the GM with
   the new group (IDg) and respond with corresponding group policy and
   keys.  If the GCKS fails to authorize the GM, it will respond with
   the AUTHORIZATION_FAILED notify message.

3.2.  Counter-based modes of operation

   Several new counter-based modes of operation have been specified for
   ESP (e.g., AES-CTR [RFC3686], AES-GCM [RFC4106], AES-CCM [RFC4309],
   AES-GMAC [RFC4543]) and AH (e.g., AES-GMAC [RFC4543]).  These
   counter-based modes require that no two senders in the group ever
   send a packet with the same Initialization Vector (IV) using the same
   cipher key and mode.  This requirement is met in G-IKEv2 when the
   following requirements are met:

   o The GCKS distributes a unique key for each Data-Security SA.




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   o The GCKS uses the method described in [RFC6054], which assigns each
   sender a portion of the IV space by provisioning each sender with one
   or more unique SID values.

   When at least one Data-Security SA included in the group policy
   includes a counter-mode, the GCKS automatically allocates and
   distributes one SID to each group member acting in the role of sender
   on the Data-Security SA.  The SID value is used exclusively by the
   group member to which it was allocated.  The group member uses the
   same SID for each Data-Security SA specifying the use of a counter-
   based mode of operation.  A GCKS MUST distribute unique keys for each
   Data-Security SA including a counter-based mode of operation in order
   to maintain a unique key and nonce usage.

   During registration, the group member can choose to request one or
   more SID values.  Requesting a value of 1 is not necessary since the
   GCKS will automatically allocate exactly one to the sending group
   member.  A group member MUST request as many SIDs matching the number
   of encryption modules in which it will be installing the TEKs in the
   outbound direction.  Alternatively, a group member MAY request more
   than one SID and use them serially.  This could be useful when it is
   anticipated that the group member will exhaust their range of Data-
   Security SA nonces using a single SID too quickly (e.g., before the
   time-based policy in the TEK expires).

   When group policy includes a counter-based mode of operation, a GCKS
   SHOULD use the following method to allocate SID values, which ensures
   that each SID will be allocated to just one group member.

   1.  A GCKS maintains an SID-counter, which records the SIDs that have
   been allocated.  SIDs are allocated sequentially, with the first SID
   allocated to be zero.

   2.  Each time an SID is allocated, the current value of the counter
   is saved and allocated to the group member.  The SID-counter is then
   incremented in preparation for the next allocation.

   3.  When the GCKS specifies a counter-based mode of operation in the
   Data Security SA, and a group member is a sender, a group member may
   request a count of SIDs during registration in a NOTIFY payload
   information type SEND_ID_REQUEST.  When the GCKS receives this
   request, it increments the SID- counter once for each requested SID,
   and distributes each SID value to the group member.

   4.  A GCKS allocates new SID values for each GSA_REGISTRATION
   exchange originated by a sender, regardless of whether a group member
   had previously contacted the GCKS.  In this way, the GCKS does not
   have a requirement of maintaining a record of which SID values it had



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   previously allocated to each group member.  More importantly, since
   the GCKS cannot reliably detect whether the group member had sent
   data on the current group Data-Security SAs it does not know what
   Data-Security counter-mode nonce values that a group member has used.
   By distributing new SID values, the key server ensures that each time
   a conforming group member installs a Data- Security SA it will use a
   unique set of counter-based mode nonces.

   5.  When the SID-counter maintained by the GCKS reaches its final SID
   value, no more SID values can be distributed.  Before distributing
   any new SID values, the GCKS MUST delete the Data- Security SAs for
   the group, followed by creation of new Data- Security SAs, and
   resetting the SID-counter to its initial value.

   6.  The GCKS SHOULD send a GSA_REKEY message deleting all Data-
   Security SAs and the Rekey SA for the group.  This will result in the
   group members initiating a new GSA_REGISTRATION exchange, in which
   they will receive both new SID values and new Data-Security SAs.  The
   new SID values can safely be used because they are only used with the
   new Data-Security SAs.  Note that deletion of the Rekey SA is
   necessary to ensure that group members receiving a GSA_REKEY exchange
   before the re-register do not inadvertently use their old SIDs with
   the new Data-Security SAs.  Using the method above, at no time can
   two group members use the same IV values with the same Data-Security
   SA key.

3.3.  G-IKEv2 group maintenance channel

   The GCKS indicates that it will be delivering group rekey messages
   when the KEK poilcy and keys are present in the G-IKEv2 GSA and KD
   payloads.  Though the G-IKEv2 Rekey is optional, it plays a crucial
   role for large and dynamic groups.  The GCKS is responsible for
   rekeying of the secure group per the group policy.  The GCKS uses
   multicast to transport the rekey message.  The G-IKEv2 protocol uses
   GSA_REKEY exchange type in G-IKEv2 header identifying it as a rekey
   message.  This rekey message is protected by the registration
   exchanges.

3.3.1.  G-IKEv2 GSA_REKEY exchange












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   The GCKS initiates the G-IKEv2 Rekey securely using IP multicast.
   Since multicast rekey does not require a response and it sends to
   multiple GMs, G-IKEv2 rekeying MUST NOT support windowing.  The GCKS
   rekey message replaces the rekey GSA KEK or KEK array, and/or creates
   a new Data-Security GSA TEK.  The SID Download attribute [section
   4.7.4] in the Key Download payload MUST NOT be part of the Rekey
   Exchange as this is sender specific information and the Rekey
   Exchange is group specific.  The GCKS initiates the GSA_REKEY
   exchange as following:

    Members (Responder)            GCKS (Initiator)
   --------------------           ------------------
                           <-- HDR, SK {GSA, KD, [D,] AUTH }


   HDR is defined in Section 4.1.  The message id in this message will
   start with the same value the GCKS sent to group member in the KEK
   attribute KEK_MESSAGE_ID during registration; this message id will be
   increasing each time a new GSA_REKEY message is sent to the group
   members.

   The GSA payload contains the current rekey and data security SAs.
   The GSA may contain a new data security SA and/or a new rekey SA,
   which, optionally contains an LKH rekey SA, Section 4.3.

   The KD represents the keys for the policy included in the GSA.  If
   the data security SA is being refreshed in this rekey message, the
   IPSec keys are updated in the KD, and/or if the rekey SA is being
   refreshed in this rekey message, the rekey Key or the LKH KEK array
   is updated in the KD payload.

   The Delete payload is included to instruct the GM to delete existing
   SAs.

   The AUTH payload is a signature of the hash of the entire GSA_REKEY
   message before it has been encrypted.

   After adding the Signature of the above Hash to the rekey message,
   the current KEK encryption key encrypts all the payloads following
   the HDR.

3.3.2.  Forward and Backward Access Control

   Through G-IKEv2 rekey, the G-IKEv2 supports algorithms such as LKH
   that have the property of denying access to a new group key by a
   member removed from the group (forward access control) and to an old
   group key by a member added to the group (backward access control).
   An unrelated notion to PFS, "forward access control" and "backward



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   access control" have been called "perfect forward security" and
   "perfect backward security" in the literature [RFC2627].

   Group management algorithms providing forward and backward access
   control other than LKH have been proposed in the literature,
   including OFT [OFT] and Subset Difference [NNL].  These algorithms
   could be used with G-IKEv2, but are not specified as a part of this
   document.

   Support for group management algorithms is supported via the
   KEY_MANAGEMENT_ALGORITHM attribute which is sent in the GSA KEK
   policy.  G-IKEv2 specifies one method by which LKH can be used for
   forward and backward access control.  Other methods of using LKH, as
   well as other group management algorithms such as OFT or Subset
   Difference may be added to G-IKEv2 as part of a later document.  Any
   such addition MUST be due to a Standards Action as defined in
   [RFC2434].

3.3.3.  Forward Access Control Requirements

   When group membership is altered using a group management algorithm
   new GSA TEKs (and their associated keys) are usually also needed.
   New GSAs and keys ensure that members who were denied access can no
   longer participate in the group.

   If forward access control is a desired property of the group, new GSA
   TEKs and the associated key packets in the KD payload MUST NOT be
   included in a G-IKEv2 rekey message which changes group membership.
   This is required because the GSA TEK policy and the associated key
   packets in the KD payload are not protected with the new KEK.  A
   second G-IKEv2 rekey message can deliver the new GSA TEKS and their
   associated keys because it will be protected with the new KEK, and
   thus will not be visible to the members who were denied access.

   If forward access control policy for the group includes keeping group
   policy changes from members that are denied access to the group, then
   two sequential G-IKEv2 rekey messages changing the group KEK MUST be
   sent by the GCKS.  The first G-IKEv2 rekey message creates a new KEK
   for the group.  Group members, which are denied access, will not be
   able to access the new KEK, but will see the group policy since the
   G-IKEv2 rekey message is protected under the current KEK.  A
   subsequent G-IKEv2 rekey message containing the changed group policy
   and again changing the KEK allows complete forward access control.  A
   G-IKEv2 rekey message MUST NOT change the policy without creating a
   new KEK.

   If other methods of using LKH or other group management algorithms
   are added to G-IKEv2, those methods MAY remove the above restrictions



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   requiring multiple G-IKEv2 rekey messages, providing those methods
   specify how forward access control policy is maintained within a
   single G-IKEv2 rekey message.

3.3.4.  Deletion of SAs

   There are occasions the GCKS may want to signal to receivers to
   delete policy at the end of a broadcast, or if group policy has
   changed.  Deletion of keys MAY be accomplished by sending the G-IKEv2
   Delete Payload [RFC5996], section 3.11 as part of the G-IKEv2
   GSA_AUTH or GSA_REKEY Exchange.

   When a policy delete is required the GCKS sends a rekey of the
   following format:

    Members (Responder)            GCKS (Initiator)
   --------------------           ------------------
                          <--   HDR, SK {
                                 [ GSA], [ KD], [D,] AUTH }


   The GSA MAY specify the remaining active time of the remaining policy
   by using the DTD attribute in the GSA GAP.  If a GCKS has no further
   SAs to send to group members, the SA and KD payloads MUST be omitted
   from the message.  There may be circumstances where the GCKS may want
   to start over with a clean slate.  If the administrator is no longer
   confident in the integrity of the group, the GCKS can signal deletion
   of all policy of a particular TEK protocol by sending a TEK with a
   SPI value equal to zero in the delete payload.  For example, if the
   GCKS wihses to remove all the KEKs and all the TEKs in the group, the
   GCKS SHOULD send a delete payload with a spi of zero and a
   protocol_id of a TEK protocol_id value define in Section 4.5,
   followed by another delete payload with a spi of zero and protocol_id
   of zero, indicating that the KEK SA should be deleted.

3.3.5.  GSA_REKEY GCKS Operations

   The GCKS may initiate a rekey message if group membership and/or
   policy has changed, or if the keys are about to expire.  The GCKS
   builds the rekey message with value of the message id that is one
   greater than the previous rekey.  If the message is using a new KEK
   attribute, the message id is reset to 1 in this message.  The GSA and
   KD follow with the same characteristics as in the GSA Registration
   exchange.  The AUTH payload is created by hashing the string
   "G-IKEv2" and the message created so far, and then digitally signed.
   Finally, the payloads following the HDR are encrypted using the
   current KEK encryption key.




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3.3.6.  GSA_REKEY GM Operations

   The group member receives the Rekey Message from the GCKS, decrypts
   the message using the current KEK, validates the signature using the
   public key retrieved in a previous G-IKEv2 exchange, verifies the
   message id, and processes the GSA and KD payloads.  The group member
   then downloads the new data security SA and/or new Rekey GSA.  The
   parsing of the payloads is identical to the registration exchange.

   Anti-replay protection is achieved when the group member rejects
   GSA_REKEY message which has message id smaller than the current
   message id that the GM is expecting.  The GM expects the message id
   in the first GSA_REKEY message it receives to be equal or greater
   than the message id it receives in the KEK_MESSAGE_ID attribute.  The
   GM expects the message id in the subsequence GSA_REKEY message to be
   greater than the last valid GSA_REKEY message it received.

   If the SA payload includes Data-Security SA including a counter-modes
   of operation and the receiving group member is a sender for that SA,
   the group member uses its current SID value with the Data-Security
   SAs to create counter-mode nonces.  If it is a sender and does not
   hold a current SID value, it MUST NOT install the Data-Security SAs.
   It MAY initiate a GSA_REGISTRATION exchange to the GCKS in order to
   obtain an SID value (along with current group policy).

4.  Header and Payload Formats

   Refer to IKEv2 [RFC5996] for existing payloads.

4.1.  The G-IKEv2 Header

   G-IKEv2 uses the same IKE header format as specified in RFC 5996
   section 3.1.

   Several new payload formats are required in the group security
   exchanges.

           Next Payload Type                   Value
           -----------------                   -----
           Group Identification (IDg)           TBD
           Group Security Association (GSA)     TBD
           Key Download (KD)                    TBD


   New exchange types GSA_AUTH, GSA_REGISTRATION and GSA_REKEY are added
   to the IKEv2 [RFC5996] protocol.





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           Exchange Type           Value
           --------------          -----
           GSA_AUTH                 TBD
           GSA_REGISTRATION         TBD
           GSA_REKEY                TBD


   Major Version is 2 and Minor Version is 0 as in IKEv2 [RFC5996].  IKE
   SA initiator SPI, IKE SA responder SPI, Flags, Message Id are as
   specified in [RFC5996].

4.2.  IDgroup Payload

   The IDg Payload allows the group member to indicate which group it
   wants to join.  The payload is constructed by using the IKEv2
   [RFC5996] Identification Payload.  ID type ID_KEY_ID MUST be
   supported.  ID types ID_IPV4_ADDR, ID_FQDN, ID_RFC822_ADDR,
   ID_IPV6_ADDR SHOULD be supported.  ID types ID_DER_ASN1_DN and
   ID_DER_ASN1_GN are not expected to be used.

4.3.  Group Security Association Payload

   The Group Security Association payload is used by the GCKS to assert
   security attributes for both Re-key and Data-security SAs.

    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        !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The Security Association Payload fields are defined as follows:

   o  Next Payload (1 octet) -- Identifies the next payload type for the
      G-IKEv2 registration or the G-IKEv2 rekey message.

   o  RESERVED (1 octet) -- Must be zero.

   o  Payload Length (2 octets) -- Is the octet length of the current
      payload including the generic header and all TEK and KEK policies.

4.3.1.  GSA policy








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   Following GSA generic payload header are GSA policies for group
   rekeying (KEK) and/or data traffic SAs (TEK).  There may be zero or
   one GSA KEK policy, zero or more GAP policy, and zero or more GSA TEK
   policies, where either one GSA KEK or GSA TEK payload MUST be
   present.

   This latitude allows various group policies to be accommodated.  For
   example if the group policy does not require the use of a Re-key SA,
   the GCKS would not need to send an GSA KEK attribute to the group
   member since all SA updates would be performed using the Registration
   SA.  Alternatively, group policy might use a Re-key SA but choose to
   download a KEK to the group member only as part of the Registration
   SA.  Therefore, the GSA KEK policy would not be necessary as part of
   the GSA_REKEY message.

   Specifying multiple GSA TEKs allows multiple sessions to be part of
   the same group and multiple streams to be associated with a session
   (e.g., video, audio, and text) but each with individual security
   association policy.

   A GAP payload allows for the distribution of group-wise policy, such
   as instructions as to when to activate and de-activate SAs.

   Policies following the GSA payload has common header

       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

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !    Type       !   RESERVED    !                 Length        !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!


   Type is defined as follow:

   0 - RESERVED
   1 - KEK
   2 - GAP
   3 - TEK
   4-240 - RESERVED
   241-255 - private and experimental










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4.4.  KEK Policy

   The GSA KEK (GSAK) policy contains security attributes for the KEK
   method for a group and parameters specific to the G-IKEv2
   registration operation.  The source and destination identities
   describe the identities used for the G-IKEv2 registration datagram.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !     Type      !   RESERVED    !                 Length        !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !                                                               !
   ~                              SPI                              ~
   !                                                               !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !                                                               !
   ~                 <Source Traffic Selector>                     ~
   !                                                               !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !                                                               !
   ~               <Destination Traffic Selector>                  ~
   !                                                               !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   ~                        KEK Attributes                         ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!


   The GSAK Payload fields are defined as follows:

   o  Type (1 octet) -- Identifies the GSA payload type KEK present in
      the G-IKEv2 registration or the G-IKEv2 rekey message.

   o  RESERVED (1 octet) -- Must be zero.

   o  Length (2 octets) -- Length of this structure including KEK
      attributes.

   o  SPI (16 octets) -- Security Parameter Index for the KEK.  The SPI
      must be the IKEv2 Header SPI pair where the first 8 octets become
      the "Initiator's SPI" field of the G-IKEv2 rekey message IKEv2
      HDR, and the second 8 octets become the "Responder's SPI" in the
      same HDR.  As described above, these SPIs are assigned by the
      GCKS.

   o  Source & Destination Traffic Selectors - Substructures describing
      the source and destination of the identities.  These identities
      refer to the source and destination of the next KEK rekey SA.



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      Defined format and values are specified by IKEv2 [RFC5996],
      section 3.13.1.

   o  KEK Attributes -- Contains KEK policy attributes associated with
      the group.  The following sections describe the possible
      attributes.  Any or all attributes may be optional, depending on
      the group policy.

4.4.1.  KEK Attributes

   The following attributes may be present in a GSA KEK policy.  The
   attributes must follow the format defined in IKEv2 [RFC5996] section
   3.3.5.  In the table, attributes that are defined as TV are marked as
   Basic (B); attributes that are defined as TLV are marked as Variable
   (V).

             ID Class                   Value    Type
             --------                   -----    ----
             RESERVED                     0
             KEK_MANAGEMENT_ALGORITHM     1        B
             KEK_ENCR_ALGORITHM           2        B
             KEK_KEY_LENGTH               3        B
             KEK_KEY_LIFETIME             4        V
             KEK_INTEGRITY_ALGORITHM      5        B
             KEK_AUTH_METHOD              6        B
             KEK_AUTH_ALGORITHM           7        B
             KEK_MESSAGE_ID               8        B


   The following attributes may only be included in a G-IKEv2
   registration message: KEK_MANAGEMENT_ALGORITHM.

   Minimum attributes that must be sent as part of an GSA KEK:
   KEK_ENCR_ALGORITHM, KEK_KEY_LENGTH (if the cipher definition includes
   a variable length key), KEK_MESSAGE_ID, KEK_KEY_LIFETIME,
   KEK_INTEGRITY_ALGORITHM, KEK_AUTH_METHOD and KEK_AUTH_ALGORITHM
   (except for DSA based algorithms).

4.4.2.  KEK_MANAGEMENT_ALGORITHM

   The KEK_MANAGEMENT_ALGORITHM class specifies the group KEK management
   algorithm used to provide forward or backward access control (i.e.,
   used to exclude group members).  Defined values are specified in the
   following table.

               KEK Management Type               Value
               -------------------               -----
               RESERVED                            0



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               LKH                                 1
               Standards Action                   2-127
               Private Use                       128-255


4.4.3.  KEK_ENCR_ALGORITHM

   The KEK_ENCR_ALGORITHM class specifies the encryption algorithm using
   with the KEK.  This is the same as IKEv2 encryption algorithm defined
   in [RFC5996] section 3.3.2.  If a KEK_MANAGEMENT_ALGORITHM is defined
   which defines multiple keys (e.g., LKH), and if the management
   algorithm does not specify the algorithm for those keys, then the
   algorithm defined by the KEK_ENCR_ALGORITHM attribute MUST be used
   for all keys which are included as part of the management.

4.4.4.  KEK_KEY_LENGTH

   The KEK_KEY_LENGTH class specifies the KEK Algorithm key length (in
   bits).

   The Group Controller/Key Server (GCKS) adds the KEK_KEY_LENGTH
   attribute to the GSA payload when distributing KEK policy to group
   members.  The group member verifies whether or not it has the
   capability of using a cipher key of that size.  If the cipher
   definition includes a fixed key length, the group member can make its
   decision solely using KEK_ENCR_ALGORITHM attribute and does not need
   the KEK_KEY_LENGTH attribute.  Sending the KEK_KEY_LENGTH attribute
   in the GSA payload is OPTIONAL if the KEK cipher has a fixed key
   length.

4.4.5.  KEK_KEY_LIFETIME

   The KEK_KEY_LIFETIME class specifies the maximum time for which the
   KEK is valid.  The GCKS may refresh the KEK at any time before the
   end of the valid period.  The value is a four (4) octet number
   defining a valid time period in seconds.

4.4.6.  KEK_INTEGRITY_ALGORITHM

   KEK_INTEGRITY specifies the integrity algorithm.  This integrity
   algorithm is specified in IKEv2 RFC 5996 section 3.3.2.

4.4.7.  KEK_AUTH_METHOD

   KEK_AUTH_METHOD specifies the method of authentication used.  This is
   the same as IKEv2 Auth Method specified in IKEv2 RFC 5996 section 3.8





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4.4.8.  KEK_AUTH_ALGORITHM

   KEK_AUTH_ALGORITHM specifies the hash algorithm uses to sign the AUTH
   payload as defined in IKEv2 [RFC5996] section 3.8 for RSA Digital
   Signature.  The following tables define the algorithms for
   KEK_AUTHALGORITHM.

                Algorithm Type       Value
                --------------       -----
                RESERVED               0
                AUTH_HASH_SHA256        1
                AUTH_HASH_SHA384        2
                AUTH_HASH_SHA512        3
                Standards Action      4-127
                Private Use         128-255


4.4.9.  KEK_MESSAGE_ID

   KEK_MESSAGE_ID define the start message id to be used by the GCKS in
   the GSA_REKEY message.  Message ID is 4 octets unsigned integer.

4.5.  GSA TEK Policy

   The GSA TEK (GSAT) policy contains security attributes for a single
   TEK associated with a group.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !    Type       !   RESERVED    !                 Length        !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   ! Protocol-ID   !       TEK Protocol-Specific Payload           !
   +-+-+-+-+-+-+-+-+                                               ~
   ~                                                               !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!


   The GSAT Payload fields are defined as follows:

   o  Type (1 octet) -- Identifies the GSA payload type TEK present in
      the G-IKEv2 registration or the G-IKEv2 rekey message.

   o  RESERVED (1 octet) -- Must be zero.

   o  Length (2 octets) -- Length of this structure, including the TEK
      Protocol-Specific Payload.




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   o  Protocol-ID (1 octet) -- Value specifying the Security Protocol.
      The following table defines values for the Security Protocol

             Protocol ID                       Value
             -----------                       -----
             RESERVED                            0
             GSA_PROTO_IPSEC_ESP                 1
             GSA_PROTO_IPSEC_AH                  2
             Standards Action                   3-127
             Private Use                      128-255

   Support for the GSA_PROTO_IPSEC_AH GSA TEK is OPTIONAL.


   o  TEK Protocol-Specific Payload (variable) -- Payload which
      describes the attributes specific for the Protocol-ID.

4.5.1.  TEK ESP and AH Protocol-Specific Policy

   The TEK Protocol-Specific policy contains of two traffic selectors
   for source and destination of the protecting traffic, SPI, Transform,
   and Attributes.

   The TEK Protocol-Specific policy for ESP is 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !                             SPI                               !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   |                                                               |
   ~                 <Source Traffic Selector>                     ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~               <Destination Traffic Selector>                  |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   |                                                               |
   ~                         <Transform>                           ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !                        TEK Attributes                         ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!


   The GSAT Policy fields are defined as follows:




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   o  SPI (4 octets) -- Security Parameter Index.

   o  Source & Destination Traffic Selectors - The traffic selectors
      describe the source and the destination of the protecting traffic.
      The format and values are defined in IKEv2 [RFC5996], section
      3.13.1.

   o  Transform -- A substructure specifies the transform information.
      The format and values are defined in IKEv2 [RFC5996], section
      3.3.2.

   o  TEK Attributes -- Contains TEK policy attributes associated with
      the group.  The following sections describe the possible
      attributes.  Any or all attributes may be optional, depending on
      the group policy.  [RFC5996], section 3.3.5.

   Attribute Types

                class               value           type
          -------------------------------------------------
          Life Duration              1               V

              Specifies the time-to-live for the overall security
              association.  When the TEK expires, all keys downloaded under
              the association (AH or ESP) must be re-rekeyed.  The life
              duration attribute defines the actual length of the
              component lifetime in secondsthat can be protected.

              If unspecified, the default value shall be assumed to be
              28800 seconds (8 hours).

          Transport mode             2               B
              Specifies to use transport mode rather than tunnel mode




4.6.  GSA Group Associated Policy

   Group specific policy that does not belong to rekey policy (GSA KEK)
   or traffic encryption policy (GSA TEK) can be distributed to all
   group member using GSA GAP (Group Associated Policy).

   The GSA GAP payload is 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!



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   !    Type       !   RESERVED    !                 Length        !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !               Group Associated Policy Attributes              ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!


   The GSA GAP payload fields are defined as follows:

   o  Type (1 octet) -- Identifies the GSA payload type GAP present in
      the G-IKEv2 registration or the G-IKEv2 rekey message.

   o  RESERVED (1 octet) -- Must be zero.

   o  Length (2 octets) -- Length of this structure, including the GSA
      GAP header and Attributes.

   o  Group Associated Policy Attributes (variable) -- Contains
      attributes following the format defined in Section 3.3.5 of
      [RFC5996].

   Several group associated policy attributes are defined below.  A
   G-IKEv2 implementation MUST abort if it encounters an attribute or
   capability that it does not understand.

4.6.1.  ACTIVATION_TIME_DELAY/DEACTIVATION_TIME_DELAY

   Section 4.2.1 of RFC 5374 specifies a key rollover method that
   requires two values be given it from the group key management
   protocol.  The ACTIVATION_TIME_DELAY attribute allows a GCKS to set
   the Activation Time Delay (ATD) for SAs generated from TEKs.  The ATD
   defines how long after receiving new SAs that they are to be
   activated by the GM.  The ATD value is in seconds.

   The DEACTIVATION_TIME_DELAY allows the GCKS to set the Deactivation
   Time Delay (DTD) for previously distributed SAs.  The DTD defines how
   long after receiving new SAs that it should deactivate SAs that are
   destroyed by the re-key event.  The value is in seconds.

   The values of ATD and DTD are independent.  However, the DTD value
   should be larger, which allows new SAs to be activated before older
   SAs are deactivated.  Such a policy ensures that protected group
   traffic will always flow without interruption.









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4.7.  Key Download Payload

   The Key Download Payload contains group keys for the group specified
   in the GSA Payload.  These key download payloads can have several
   security attributes applied to them based upon the security policy of
   the group as defined by the associated GSA 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    !                 Length        !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Number of Key Packets         !            RESERVED2          !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ~                    Key Packets                                ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!


   The Key Download Payload fields are defined as follows:

   o  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 zero.

   o  RESERVED (1 octet) -- Unused, set to zero.

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

   o  Number of Key Packets (2 octets) -- Contains the total number of
      both TEK and Rekey arrays being passed in this data block.

   o  Key Packets Several types of key packets are defined.  Each Key
      Packet has the following format.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !   KD Type     !   RESERVED    !            KD Length          !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   !    SPI Size   !                   SPI (variable)              ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
   ~                    Key Packet Attributes                      ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!


   o  Key Download (KD) Type (1 octet) -- Identifier for the Key Data
      field of this Key Packet.



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                          Key Download Type        Value
                          -----------------        -----
                          RESERVED                   0
                          TEK                        1
                          KEK                        2
                          LKH                        3
                          SID                       TBD-7
                          Standards Action          4-127
                          Private Use             128-255

   "KEK" is a single key whereas LKH is an array of key-encrypting keys.


   o  RESERVED (1 octet) -- Unused, set to zero.

   o  Key Download Length (2 octets) -- Length in octets of the Key
      Packet data, including the Key Packet header.

   o  SPI Size (1 octet) -- Value specifying the length in octets of the
      SPI as defined by the Protocol-Id.

   o  SPI (variable length) -- Security Parameter Index which matches a
      SPI previously sent in an GSAK or GSAT Payload.

   o  Key Packet Attributes (variable length) -- Contains Key
      information.  The format of this field is specific to the value of
      the KD Type field.  The following sections describe the format of
      each KD Type.

4.7.1.  TEK Download Type

   The following attributes may be present in a TEK Download Type.
   Exactly one attribute matching each type sent in the GSAT payload
   MUST be present.  The attributes must follow the format defined in
   IKEv2 (Section 3.3.5 of [RFC5996]).  In the table, attributes defined
   as TV are marked as Basic (B); attributes defined as TLV are marked
   as Variable (V).

             TEK Class                 Value      Type
             ---------                 -----      ----
             RESERVED                     0
             TEK_ALGORITHM_KEY            1        V
             TEK_INTEGRITY_KEY            2        V
             TEK_SOURCE_AUTH_KEY          3        V


   If no TEK key packets are included in a Registration KD payload, the
   group member can expect to receive the TEK as part of a Re-key SA.



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   At least one TEK must be included in each Re-key KD payload.
   Multiple TEKs may be included if multiple streams associated with the
   SA are to be rekeyed.

4.7.1.1.  TEK_ALGORITHM_KEY

   The TEK_ALGORITHM_KEY class declares that the encryption key for this
   SPI is contained as the Key Packet Attribute.  The encryption
   algorithm that will use this key was specified in the GSAT payload.

   In the case that the algorithm requires multiple keys, all keys will
   be included in one attribute.

4.7.1.2.  TEK_INTEGRITY_KEY

   The TEK_INTEGRITY_KEY class declares that the integrity key for this
   SPI is contained as the Key Packet Attribute.  The integrity
   algorithm that will use this key was specified in the GSAT payload.
   Thus, G-IKEv2 assumes that both the symmetric encryption and
   integrity keys are pushed to the member.  SHA256 keys will consist of
   256 bits.

4.7.1.3.  TEK_SOURCE_AUTH_KEY

   The TEK_SOURCE_AUTH_KEY class declares that the source authentication
   key for this SPI is contained in the Key Packet Attribute.  The
   source authentication algorithm that will use this key was specified
   in the GSAT payload.

4.7.2.  KEK Download Type

   The following attributes may be present in a KEK Download Type.
   Exactly one attribute matching each type sent in the GSAK payload
   MUST be present.  The attributes must follow the format defined in
   IKEv2 (Section 3.3.5 of [RFC5996]).  In the table, attributes defined
   as TV are marked as Basic (B); attributes defined as TLV are marked
   as Variable (V).

             KEK Class                 Value      Type
             ---------                 -----      ----
             RESERVED                     0
             KEK_ALGORITHM_KEY            1        V
             KEK_AUTH_KEY                 2        V


   If the KEK key packet is included, there MUST be only one present in
   the KD payload.




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4.7.2.1.  KEK_ALGORITHM_KEY

   The KEK_ALGORITHM_KEY class declares key for this SPI is contained in
   the Key Packet Attribute.  The encryption and integrity algorithm
   that will use this key were specified in the GSAK payload.  Then
   encryption and integrity keys can be derived using the following
   formula

   { SK_ai | SK_ar | SK_ei | SK_er } = prf+(KEK key, "G-IKEv2 REKEY" |
   SPIi | SPIr)

   If the mode of operation for the algorithm requires an Initialization
   Vector (IV), an explicit IV MUST be included in the KEK_ALGORITHM_KEY
   before the actual key.

4.7.2.2.  KEK_AUTH_KEY

   The KEK_AUTH_KEY class declares that the public key for this SPI is
   contained in the Key Packet Attribute, which may be useful when no
   public key infrastructure is available.  The signature algorithm that
   will use this key was specified in the GSAK payload.

4.7.3.  LKH Download Type

   The LKH key packet is comprised of attributes representing different
   leaves in the LKH key tree.

   The following attributes are used to pass an LKH KEK array in the KD
   payload.  The attributes must follow the format defined in IKEv2
   (Section 3.3.5 of [RFC5996]).  In the table, attributes defined as TV
   are marked as Basic (B); attributes defined as TLV are marked as
   Variable (V).

             KEK Class                 Value      Type
             ---------                 -----      ----
             RESERVED                     0
             LKH_DOWNLOAD_ARRAY           1        V
             LKH_UPDATE_ARRAY             2        V
             AUTH_ALGORITHM_KEY           3        V
             Standards Action            4-127
             Private Use               128-255


   If an LKH key packet is included in the KD payload, there must be
   only one present.

4.7.3.1.  LKH_DOWNLOAD_ARRAY




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   This attribute is used to download a set of keys to a group member.
   It MUST NOT be included in a IKEv2 rekey message KD payload if the
   IKEv2 rekey is sent to more than the group member.  If an
   LKH_DOWNLOAD_ARRAY attribute is included in a KD payload, there must
   be only one present.

   This attribute consists of a header block, followed by one or more
   LKH keys.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !  LKH Version  !          # of LKH Keys        !  RESERVED     !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !                             LKH Keys                          !
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The KEK_LKH attribute fields are defined as follows:

   o  LKH version (1 octet) -- Contains the version of the LKH protocol
      which the data is formatted in.  Must be one.

   o  Number of LKH Keys (2 octets) -- This value is the number of
      distinct LKH keys in this sequence.

   o  RESERVED (1 octet) -- Unused, set to zero.

   Each LKH Key is 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !             LKH ID            !    Key Type   !    RESERVED   !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                        Key Creation Date                      !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                       Key expiration Date                     !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                           Key Handle                          !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !                                                               !
   ~                            Key Data                           ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+






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   o  LKH ID (2 octets) -- This is the position of this key in the
      binary tree structure used by LKH.

   o  Key Type (1 octet) -- This is the encryption algorithm for which
      this key data is to be used.  This value is specified in
      Section 4.4.3.

   o  RESERVED (1 octet) -- Unused, set to zero.

   o  Key Creation Date (4 octets) -- This is the time value of when
      this key data was originally generated.  A time value of zero
      indicates that there is no time before which this key is not
      valid.

   o  Key Expiration Date (4 octets) -- This is the time value of when
      this key is no longer valid for use.  A time value of zero
      indicates that this key does not have an expiration time.

   o  Key Handle (4 octets) -- This is the randomly generated value to
      uniquely identify a key within an LKH ID.

   o  Key Data (variable length) -- This is the actual encryption key
      data, which is dependent on the Key Type algorithm for its format.
      If the mode of operation for the algorithm requires an
      Initialization Vector (IV), an explicit IV MUST be included in the
      Key Data field before the actual key.

   The Key Creation Date and Key expiration Dates MAY be zero.  This is
   necessary in the case where time synchronization within the group is
   not possible.

   The first LKH Key structure in an LKH_DOWNLOAD_ARRAY attribute
   contains the Leaf identifier and key for the group member.  The rest
   of the LKH Key structures contain keys along the path of the key tree
   in order from the leaf, culminating in the group KEK.

4.7.3.2.  LKH_UPDATE_ARRAY

   This attribute is used to update the keys for a group.  It is most
   likely to be included in a G-IKEv2 rekey message KD payload to rekey
   the entire group.  This attribute consists of a header block,
   followed by one or more LKH keys, as defined in Section 4.7.3.1.

   There may be any number of UPDATE_ARRAY attributes included in a KD
   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



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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !  LKH Version  !          # of LKH Keys        !  RESERVED     !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !            LKH ID             !           RESERVED2           !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !                           Key Handle                          !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !                            LKH Keys                           !
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  LKH version (1 octet) -- Contains the version of the LKH protocol
      which the data is formatted in.  Must be one.

   o  Number of LKH Keys (2 octets) -- This value is the number of
      distinct LKH keys in this sequence.

   o  RESERVED (1 octet) -- Unused, set to zero.

   o  LKH ID (2 octets) -- This is the node identifier associated with
      the key used to encrypt the first LKH Key.

   o  RESERVED2 (2 octets) -- Unused, set to zero.

   o  Key Handle (4 octets) -- This is the value to uniquely identify
      the key within the LKH ID which was used to encrypt the first LKH
      key.

   The LKH Keys are as defined in Section 4.7.3.1.  The LKH Key
   structures contain keys along the path of the key tree in order from
   the LKH ID found in the LKH_UPDATE_ARRAY header, culminating in the
   group KEK.  The Key Data field of each LKH Key is encrypted with the
   LKH key preceding it in the LKH_UPDATE_ARRAY attribute.  The first
   LKH Key is encrypted under the key defined by the LKH ID and Key
   Handle found in the LKH_UPDATE_ARRAY header.

4.7.4.  SID Download Type

   This attribute is used to download one or use more Sender-ID (SID)
   values for the exclusive use of a group member.

             KEK Class                 Value      Type
             ---------                 -----      ----
             RESERVED                     0
             NUMBER_OF_SID_BITS           1        V
             SID_VALUE                    2        V
             Standards Action            3-128



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             Private Use               129-255
             Unassigned                256-32767


   Because a SID value is intended for a single group member, the SID
   Download type MUST NOT be distributed in a GROUPKEY_PUSH message
   distributed to multiple group members.

4.7.4.1.  NUMBER_OF_SID_BITS

   The NUMBER_OF_SID_BITS class declares how many bits of the cipher
   nonce in which to represent an SID value.  This value applied to each
   SID value is distributed in the SID Download.

4.7.4.2.  SID_VALUE

   The SID_VALUE class declares a single SID value for the exclusive use
   of the a group member.  Multiple SID_VALUE attributes MAY be included
   in a SID Download.

4.7.4.3.  GM Semantics

   The SID_VALUE attribute value distributed to the group member MUST be
   used by that group member as the SID field portion of the IV for all
   Data-Security SAs including a counter-based mode of operation
   distributed by the GCKS as a part of this group.  When the Sender-
   Specific IV (SSIV) field for any Data-Security SA is exhausted, the
   group member MUST no longer act as a sender on that SA using its
   active SID.  The group member SHOULD re-register, at which time the
   GCKS will issue a new SID to the group member, along with either the
   same Data-Security SAs or replacement ones.  The new SID replaces the
   existing SID used by this group member, and also resets the SSIV
   value to its starting value.  A group member MAY re-register prior to
   the actual exhaustion of the SSIV field to avoid dropping data
   packets due to the exhaustion of available SSIV values combined with
   a particular SID value.

   A group member MUST NOT process an SID Download Type KD payload
   present in a GSA-REKEY message.

4.7.4.4.  GCKS Semantics

   If any KD payload includes keying material that is associated with a
   counter-mode of operation, an SID Download Type KD payload containing
   at least one SID_VALUE attribute MUST be included.  The GCKS MUST NOT
   send the SID Download Type KD payload as part of a GSA-REKEY message,
   because distributing the same sender-specific policy to more than one
   group member will reduce the security of the group.



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4.8.  Delete Payload

   There are occasions the GCKS may want to signal to receivers to
   delete policy at the end of a broadcast, or if policy has changed.
   Deletion of keys MAY be accomplished by sending an IKEv2 Delete
   Payload, section 3.11 of [RFC5996] as part of the GSA_AUTH or
   GSA_REKEY Exchange.  One or more Delete payloads MAY be placed
   following the HDR payload in the GSA_AUTH or GSA_REKEY Exchange.

   The Protocol ID MUST be 1 for KEK SA, 2 for TEK AH or 3 for TEK ESP.
   Note that only one protocol id value can be defined in a Delete
   payload.  If a TEK and a KEK SA must be deleted, they must be sent in
   different Delete payloads.  Similarly, if a TEK specifying ESP and a
   TEK specifying AH need to be deleted, they must be sent in different
   Delete payloads.

4.9.  Notify Payload

   G-IKEv2 uses the same notify payload as specified in [RFC5996],
   section 3.10.

   There are additional notify message types introduced by G-IKEv2 to
   communicate error conditions and status.

   NOTIFY MESSAGES - ERROR TYPES          Value
   -------------------------------------------------------------------
   INVALID_GROUP_ID -                      TBD
   Indicates the group id sent during registration process is invalid.

   AUTHORIZATION_FAILED -                  TBD
   Sent in the response to GSA_AUTH message when authorization failed.


   NOTIFY MESSAGES - STATUS TYPES          Value
   -------------------------------------------------------------------
   SENDER_REQUEST_ID   -                    TBD
   Sent in GSA_AUTH or GSA_REGISTRATION to request SIDs from GCKS.  The data includes a count of how many SID values it desires.


4.10.  Authentication Payload

   G-IKEv2 uses the same Authentication payload as specified in
   [RFC5996], section 3.8, to sign the rekey message.

5.  Security Considerations

5.1.  GSA registration and secure channel




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   G-IKEv2 registration exchange uses IKEv2 IKE_SA_INIT, GSA_AUTH and
   GSA_REGISTRATION inheriting all the security considerations
   documented in [RFC5996] section 5 Security Considerations, including
   authentication, confidentiality, protection against man-in-the
   middle, protection against replay/reflection attacks, and denial of
   service protection.  In addition, G-IKEv2 brings in the capability to
   authorize a particular group member regardless of whether they have
   the IKEv2 credentials.

5.2.  GSA maintenance channel

   The GSA maintenance channel is cryptographically and integrity
   protected using the cryptographic algorithm and key negotiated in the
   GSA member registration exchanged.

5.2.1.  Authentication/Authorization

   Authentication is implicit, the public key of the identity is
   distributed during the registration, and the receiver of the rekey
   message uses that public key and identity to verify the message is
   come from the authorized GCKS.

5.2.2.  Confidentiality

   Confidentiality is provided by distributing a confidentiality key as
   part of the GSA member registration exchange.

5.2.3.  Man-in-the-Middle Attack Protection

   GSA maintenance channel is integrity protected by using digital
   signature.

5.2.4.  Replay/Reflection Attack Protection

   The GSA rekey message includes a monotonically increasing sequence
   number to protect against replay and reflection attacks.  A group
   member will recognize a replayed message by comparing the message id
   number to that of the last received rekey message, any rekey message
   contains message id number less than or equal to the last received
   value SHOULD be discarded.  Implementations SHOULD keep a record of
   recently received GSA rekey messages for this comparison.

6.  IANA Considerations

6.1.  New registries

   A new set of registries are created for this draft.




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   KEK Attributes Registry, see Section 4.4.1

   KEK Management Algorithm Registry, see Section 4.4.2

   GSA TEK Payload Protocol ID Type Registry, see Section 4.5

   TEK Attributes Registry, see Section 4.5

   Key Download Type Registry, see Section 4.7

   TEK Download Type Registry, see Section 4.7.1

   KEK Download Type Registry, see Section 4.7.2

   LKH Download Type Registry, see Section 4.7.3

   SID Download Type Registry, see Section 4.7.4

6.2.  New payload and exchange types to existing IKEv2 registry

   The present document describes new IKEv2 Next Payload types, see
   Section 4.1

   The present document describes new IKEv2 Exchanges types, see
   Section 4.1

   The present document describes new IKEv2 Notify Payload types, see
   Section 4.9

6.3.  Payload Types

   The present document defines new IKEv2 Next Payload types.  See
   Section 4.0 for the payloads defined in this document, including the
   Next Payload values defined by the IANA to identify these payloads.

6.4.  New Name spaces

   The present document describes many new name spaces for use in the
   G-IKEv2 payloads.  Those may be found in subsections under
   Section 4.0.  A new G-IKEv2 registry has been created for these name
   spaces.

   Portions of name spaces marked "RESERVED" are reserved for IANA
   allocation.  New values MUST be added due to a Standards Action as
   defined in [RFC2434].

   Portions of name spaces marked "Private Use" may be allocated by
   implementations for their own purposes.



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7.  Acknowledgements

   The authors thank Lakshminath Dondeti and Jing Xiang for originating
   the GKDP document and providing the basis behind the protocol.

   The authors also thank reviewers: Brian Weis, Kavitha Kamarthy, Lewis
   Chen, Cheryl Madson, and Raghunandan P.

8.  References

8.1.  Normative References

   [FIPS197]  , "Advanced Encryption Standard (AES)", United States of
              America, National Institute of Science and Technology
              Federal Information Processing Standard (FIPS) 197,
              November 2001.

   [RFC6054]  McGrew, D. and B. Weis, "Using Counter Modes with
              Encapsulating Security Payload (ESP) and Authentication
              Header (AH) to Protect Group Traffic", RFC 6054, November
              2010.

   [SP800-38A]
              Dworkin, M., "Recommendation for Block Cipher Modes of
              Operation", United States of America, National Institute
              of Science and Technology NIST Special Publication 800-38A
              2001 Edition, December 2001.

   [SP800-38D]
              Dworkin, M., "Recommendation for Block Cipher Modes of
              Operation", United States of America, National Institute
              of Science and Technology NIST Special Publication 800-38D
              2007 Edition, December 2001.

8.2.  Informative References

   [IKE-HASH]
              Kivinen, T., "Fixing IKE Phase 1 & 2 Authentication
              HASHs", November 2001, <http://tools.ietf.org/html/draft-
              ietf-ipsec-ike-hash-revised-03>.

   [NNL]      Naor, D., Noal, M., and J. Lotspiech, "Revocation and
              Tracing Schemes for Stateless Receivers", Advances in
              Cryptology, Crypto '01, Springer-Verlag LNCS 2139, 2001,
              pp. 41-62, 2001,
              <http://www.wisdom.weizmann.ac.il/~naor/>.





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   [OFT]      McGrew, D. and A. Sherman, "Key Establishment in Large
              Dynamic Groups Using One-Way Function Trees", Manuscript,
              submitted to IEEE Transactions on Software Engineering,
              1998, <http://download.nai.com/products/media/nai/misc/
              oft052098.ps>.

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

   [RFC2407]  Piper, D., "The Internet IP Security Domain of
              Interpretation for ISAKMP", RFC 2407, November 1998.

   [RFC2408]  Maughan, D., Schneider, M., and M. Schertler, "Internet
              Security Association and Key Management Protocol
              (ISAKMP)", RFC 2408, November 1998.

   [RFC2409]  Harkins, D. and D. Carrel, "The Internet Key Exchange
              (IKE)", RFC 2409, November 1998.

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.

   [RFC2627]  Wallner, D., Harder, E., and R. Agee, "Key Management for
              Multicast: Issues and Architectures", RFC 2627, June 1999.

   [RFC3686]  Housley, R., "Using Advanced Encryption Standard (AES)
              Counter Mode With IPsec Encapsulating Security Payload
              (ESP)", RFC 3686, January 2004.

   [RFC4106]  Viega, J. and D. McGrew, "The Use of Galois/Counter Mode
              (GCM) in IPsec Encapsulating Security Payload (ESP)", RFC
              4106, June 2005.

   [RFC4309]  Housley, R., "Using Advanced Encryption Standard (AES) CCM
              Mode with IPsec Encapsulating Security Payload (ESP)", RFC
              4309, December 2005.

   [RFC4543]  McGrew, D. and J. Viega, "The Use of Galois Message
              Authentication Code (GMAC) in IPsec ESP and AH", RFC 4543,
              May 2006.

   [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
              "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC
              5996, September 2010.

   [RFC6407]  Weis, B., Rowles, S., and T. Hardjono, "The Group Domain
              of Interpretation", RFC 6407, October 2011.



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Appendix A.  Differences between G-IKEv2 and RFC 6407

   KE Payload - The KE payload is no longer needed with the availability
   of newer algorithms such as AES and GCM which provide adequate
   protection therefore not needing the PFS capability the KE payload
   offers.

   SIG Payload - The AUTH payload is used for the same purpose instead.

   DOI/Situation - The DOI and Situation fields in the SA payload are no
   longer needed in the G-IKEv2 protocol as port 848 will distinguish
   the IKEv2 messages from the G-IKEv2 messages.

   SEQ Payload - The SEQ payload is no longer needed since IKEv2 header
   has message id which is used to prevent message replay attacks.

Authors' Addresses

   Sheela Rowles
   Cisco Systems
   170 W. Tasman Drive
   San Jose, California  95134-1706
   USA

   Phone: +1-408-527-7677
   Email: sheela@cisco.com


   Aldous Yeung (editor)
   Cisco Systems
   170 W. Tasman Drive
   San Jose, California  95134-1706
   USA

   Phone: +1-408-853-2032
   Email: cyyeung@cisco.com


   Paulina Tran
   Cisco Systems
   170 W. Tasman Drive
   San Jose, California  95134-1706
   USA

   Phone: +1-408-526-8902
   Email: ptran@cisco.com





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   Yoav Nir
   Check Point Software Technologies Ltd.
   5 Hasolelim St.
   Tel Aviv  67897
   Israel

   Email: ynir@checkpoint.com












































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