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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 RFC 6738

Network Working Group                                         V. Cakulev
Internet-Draft                                            Alcatel Lucent
Intended status: Standards Track                                 A. Lior
Expires: September 9, 2010                           Bridgewater Systems
                                                           March 8, 2010


    Diameter IKEv2: Support for Interaction between IKEv2 Server and
                            Diameter Server
               draft-ietf-dime-ikev2-psk-diameter-01.txt

Abstract

   The Internet Key Exchange protocol version 2 (IKEv2) is a component
   of the IPsec architecture and is used to perform mutual
   authentication as well as to establish and to maintain IPsec security
   associations (SAs) between the respective parties.  IKEv2 supports
   several different authentication mechanisms, such as the Extensible
   Authentication Protocol (EAP), certificates, and pre-shared secrets.

   With [RFC 5778] the Diameter interworking for Mobile IPv6 between the
   Home Agent, as a Diameter client, and the Diameter server has been
   specified.  However, that specification focused on the usage of EAP
   and did not include support for pre-shared secret based
   authentication available with IKEv2.  This document therefore extends
   the functionality offered by [RFC 5778] with pre-shared key based
   authentication offered by IKEv2 when no EAP is used.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on September 9, 2010.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.























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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Requirements notation  . . . . . . . . . . . . . . . . . . . .  5
   3.  Application Identifier . . . . . . . . . . . . . . . . . . . .  6
   4.  Protocol Description . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Support for IKEv2 and Pre-Shared Secrets . . . . . . . . .  7
     4.2.  Session Management . . . . . . . . . . . . . . . . . . . .  7
       4.2.1.  Session-Termination-Request/Answer . . . . . . . . . .  8
       4.2.2.  AbortSession-Request/Answer  . . . . . . . . . . . . .  8
   5.  Command Codes for Diameter IKEv2 with PSK  . . . . . . . . . .  9
     5.1.  IKEv2-PSK-Request (IKEPSKR) Command  . . . . . . . . . . .  9
     5.2.  IKEv2-PSK-Answer (IKEPSKA) Command . . . . . . . . . . . . 10
   6.  Attribute Value Pair Definitions . . . . . . . . . . . . . . . 11
     6.1.  IKEv2-Nonces . . . . . . . . . . . . . . . . . . . . . . . 11
       6.1.1.  Ni . . . . . . . . . . . . . . . . . . . . . . . . . . 11
       6.1.2.  Nr . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   7.  AVP Occurrence Tables  . . . . . . . . . . . . . . . . . . . . 12
   8.  AVP Flag Rules . . . . . . . . . . . . . . . . . . . . . . . . 13
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
     9.1.  Command Codes  . . . . . . . . . . . . . . . . . . . . . . 14
     9.2.  AVP Codes  . . . . . . . . . . . . . . . . . . . . . . . . 14
     9.3.  AVP Values . . . . . . . . . . . . . . . . . . . . . . . . 14
     9.4.  Application Identifier . . . . . . . . . . . . . . . . . . 14
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 16
     11.2. Informative References . . . . . . . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17






















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1.  Introduction

   [RFC4306] defines Internet Key Exchange v2 as a protocol that
   performs mutual authentication between two parties and establishes a
   security association (SA) that includes shared secret information
   that can be used to efficiently establish SAs for Encapsulating
   Security Payload (ESP) [RFC4303] and/or Authentication Header (AH)
   [RFC4302], and a set of cryptographic algorithms to be used by the
   SAs to protect the traffic that they carry.  IKEv2 protocol allows
   several different mechanisms for authenticating a IKEv2 Peer to be
   used, such as the Extensible Authentication Protocol, certificates,
   and pre-shared secrets.

   From a service provider perspective it is important to ensure that a
   user is authorized to use the services.  Therefore, the IKEv2 Server
   must verify that the IKEv2 Peer is authorized for the requested
   services possibly with the assistance of the operator's Diameter
   servers.  [RFC 5778] defines the home agent as a Diameter client to
   the Diameter server communication when the mobile node authenticates
   using the IKEv2 protocol with the Extensible Authentication Protocol
   or using the Mobile IPv6 Authentication Protocol.  This document
   extends the functionality offered by [RFC 5778] with pre-shared key
   based authentication offered by IKEv2.  This document does not assume
   that the IKEv2 Server has the pre-shared secrets (PSK) with the IKEv2
   Peer.  Instead, it allows for PSK to be derived for a specific IKEv2
   session and exchanged between IKEv2 Server and HAAA.  This is
   accomplished through the use of a new Diameter application
   specifically designed for performing IKEv2 authorization decisions.























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2.  Requirements notation

   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 [RFC2119].














































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3.  Application Identifier

   This specification defines a new Diameter application and its
   respective Application Identifier:

      Diameter IKE PSK  (IKEPSK)  TBD1 by IANA


   The IKEPSK Application Identifier is used when the IKEv2 Peer is to
   be authenticated and authorized using IKEv2 with PSK-based
   authentication.








































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4.  Protocol Description

4.1.  Support for IKEv2 and Pre-Shared Secrets

   When IKEv2 is used with PSK-based initiator authentication, the
   Diameter commands IKEv2-PSK-Request and IKEv2-PSK-Answer defined in
   this document are used to authorize the IKEv2 Peer for the services.
   Upon receiving the IKE_AUTH message from the IKEv2 Peer, the IKEv2
   Server uses the information received in IDi to determine if it has
   the PSK for this IKEv2 Peer.  If there is no PSK found associated
   with this IKEv2 Peer, the IKEv2 Server MUST send an Authorize-Only
   (Auth-Request-Type set to "Authorize-Only") Diameter IKEv2-PSK
   message with the IKEv2 Peer's IDi payload to the HAAA to obtain the
   PSK.  The IDi payload extracted from the IKE_AUTH message has to
   contain an identity that is meaningful for the Diameter
   infrastructure, such as a Network Access Identifier (NAI), since it
   is used by the IKEv2 Server to populate the User-Name AVP in the
   Diameter message.  The IKEv2 Server also includes in the IKEv2-Nonces
   AVP of the same Diameter message the initiator and responder nonces
   (Ni and Nr) exchanged during initial IKEv2 exchange.

   This message is routed to the IKEv2 Peer's HAAA.  Upon receiving
   Diameter IKEv2-PSK-Request message from the IKEv2 Server, the HAAA
   SHALL use the User-Name AVP to retrieve the associated keying
   material.  The HAAA SHALL use the nonces Ni and Nr received in IKEv2-
   Nonces AVP to generate the PSK.  It is outside of scope of this
   document how the HAAA obtains or generates the PSK.  For example, if
   the HAAA previously performed EAP based access authentication and
   authorization of the IKEv2 Peer, it can use the available EMSK to
   generate the PSK [RFC5295].  The HAAA returns the PSK to the IKEv2
   Server using the Key AVP as specified in
   [I-D.ietf-dime-local-keytran].

   Once the IKEv2 Server receives the PSK from the HAAA, the IKEv2
   Server verifies the IKE_AUTH message received from the IKEv2 Peer.
   If the verification of AUTH is successful, the IKEv2 Server sends the
   IKE message back to the IKEv2 Peer.

4.2.  Session Management

   The HAAA may maintain state or may be stateless.  This is indicated
   by presence or absence of the Auth-Session-State AVP.  The IKEv2
   Server MUST support the Authorization Session State Machine defined
   in [RFC3588].

   This specification makes an assumption that each IKE_SA created
   between the IKEv2 Peer and the IKEv2 Server as a result of a
   successful IKEv2 negotiation exchange together with CHILD_SAs set up



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   through that particular IKE_SA correspond to one currently active PSK
   and one active Diameter session.

4.2.1.  Session-Termination-Request/Answer

   In the case where session tracking is being used, when the IKEv2
   Server terminates the SA it SHALL send a Session-Termination-Request
   (STR) message [RFC3588] to inform the HAAA that the authorized
   session has been terminated.

   The Session-Termination-Answer (STA) message [RFC3588] is sent by the
   HAAA to acknowledge the notification that the session has been
   terminated.

4.2.2.  AbortSession-Request/Answer

   The Abort-Session-Request (ASR) message [RFC3588] is sent by the HAAA
   to the IKEv2 Server to terminate the authorized session.  When the
   IKEv2 Server receives the ASR message, it MUST delete the
   corresponding IKE_SA and all CHILD_SAs set up through it.

   The Abort-Session-Answer (ASA) message [RFC3588] is sent by the IKEv2
   Server in response to an ASR message.




























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5.  Command Codes for Diameter IKEv2 with PSK

   This section defines new Command-Code values that MUST be supported
   by all Diameter implementations conforming to this specification.

    +-------------------+---------+------+-------------+-------------+
    |    Command-Name   | Abbrev. | Code |  Reference  | Application |
    +-------------------+---------+------+-------------+-------------+
    | IKEv2-PSK-Request | IKEPSKR | TBD2 | Section 5.1 |    IKEPSK   |
    |                   |         |      |             |             |
    |  IKEv2-PSK-Answer | IKEPSKA | TBD3 | Section 5.2 |    IKEPSK   |
    +-------------------+---------+------+-------------+-------------+

                          Table 1: Command Codes

5.1.  IKEv2-PSK-Request (IKEPSKR) Command

   The IKEv2-PSK-Request message, indicated with the Command-Code set to
   TBD2 and the 'R' bit set in the Command Flags field is sent from the
   IKEv2 Server to the HAAA to initiate IKEv2 with PSK authorization.
   In this case, the Application-ID field of the Diameter Header MUST be
   set to the Diameter IKE PSK Application ID (value of TDB1).

   Message format


         <IKEv2-PSK-Request> ::= < Diameter Header: TBD2, REQ, PXY >
                                 < Session-Id >
                                 { Auth-Application-Id }
                                 { Origin-Host }
                                 { Origin-Realm }
                                 { Destination-Realm }
                                 { Auth-Request-Type }
                                 [ Destination-Host ]
                                 [ NAS-Identifier ]
                                 [ NAS-IP-Address ]
                                 [ NAS-IPv6-Address ]
                                 [ NAS-Port ]
                                 [ Origin-State-Id ]
                                 { User-Name }
                                 [ Auth-Session-State ]
                                 { IKEv2-Nonces }
                               * [ Proxy-Info ]
                               * [ Route-Record ]
                                 ...
                               * [ AVP ]

   IKEv2-PSK-Request message MUST include a IKEv2-Nonces AVP containing



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   Ni and Nr nonces exchanged during initial IKEv2 exchange.

5.2.  IKEv2-PSK-Answer (IKEPSKA) Command

   The IKEv2-PSK-Answer (IKEPSKA) message, indicated by the Command-Code
   field set to TBD3 and the 'R' bit cleared in the Command Flags field,
   is sent by the HAAA to the IKEv2 Server in response to the IKEPSKR
   command.  In this case, the Application-ID field of the Diameter
   Header MUST be set to the Diameter IKE PSK Application ID (value of
   TDB1).

   Message format


           <IKEv2-PSK-Answer> ::= < Diameter Header: TBD3, PXY >
                                  < Session-Id >
                                  { Auth-Application-Id }
                                  { Auth-Request-Type }
                                  { Result-Code }
                                  { Origin-Host }
                                  { Origin-Realm }
                                  [ User-Name ]
                                  [ Key ]
                                  [ Error-Message ]
                                  [ Error-Reporting-Host ]
                                * [ Failed-AVP ]
                                  [ Origin-State-Id ]
                                * [ Redirect-Host ]
                                  [ Redirect-Host-Usage ]
                                  [ Redirect-Max-Cache-Time ]
                                * [ Proxy-Info ]
                                * [ Route-Record ]
                                  ...
                                * [ AVP ]

   If the authorization procedure was successful then the IKEv2-PSK-
   Answer message SHALL include the Key AVP as specified in
   [I-D.ietf-dime-local-keytran].  The value of the Key-Type AVP SHALL
   be set to TBD4.  The Keying-Material AVP SHALL contain the PSK.
   Exactly how the PSK is derived is beyond the scope of this document.
   The Key-Lifetime AVP may be included and if it is included then the
   associated key shall not be used if the lifetime has expired.









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6.  Attribute Value Pair Definitions

   This section defines new AVPs for the IKEv2 with PSK.

6.1.  IKEv2-Nonces

   The IKEv2-Nonces AVP (Code TBD5) is of type Grouped and contains the
   nonces exchanged between the IKEv2 Peer and the IKEv2 Server during
   IKEv2 initial exchange.  The nonces are used for PSK generation.


               IKEv2-Nonces ::= < AVP Header: TBD5>
                                {Ni}
                                {Nr}
                               *[AVP]

6.1.1.  Ni

   The Ni AVP (AVP Code TBD6) is of type Unsigned32 and contains the
   IKEv2 initiator nonce.

6.1.2.  Nr

   The Nr AVP (AVP Code TBD7) is of type Unsigned32 and contains the
   IKEv2 responder nonce.


























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7.  AVP Occurrence Tables

   The following tables present the AVPs defined or used in this
   document and their occurrences in Diameter messages.  Note that AVPs
   that can only be present within a Grouped AVP are not represented in
   this table.

   The table uses the following symbols:

   0:

      The AVP MUST NOT be present in the message.


   0+:

      Zero or more instances of the AVP MAY be present in the message.


   0-1:

      Zero or one instance of the AVP MAY be present in the message.


   1:

      One instance of the AVP MUST be present in the message.



                                     +-------------------+
                                     |   Command-Code    |
                                     |---------+---------+
      AVP Name                       | IKEPSKR | IKEPSKA |
      -------------------------------|---------+---------+
      Key                            |   0-1   |   0-1   |
      IKEv2-Nonces                   |   0-1   |    0    |
                                     +---------+---------+

                  IKEPSKR and IKEPSKA Commands AVP Table











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8.  AVP Flag Rules

   The following table describes the Diameter AVPs, their AVP Code
   values, types, possible flag values, and whether the AVP MAY be
   encrypted.  The Diameter base [RFC3588] specifies the AVP Flag rules
   for AVPs in Section 4.5.


                                             +--------------------+
                                             |   AVP Flag rules   |
                                             +----+---+------+----+----+
                    AVP  Defined             |    |   |SHOULD|MUST|MAY |
  Attribute Name    Code in       Value Type |MUST|MAY| NOT  | NOT|Encr|
 +-------------------------------------------+----+---+------+----+----+
 |Key               TBD  Note 1   Grouped    |  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+
 |Keying-Material   TBD  Note 1   OctetString|  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+
 |Key-Lifetime      TBD  Note 1   Integer64  |  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+
 |Key-SPI           TBD  Note 1   Unsigned32 |  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+
 |Key-Type          TBD  Note 1   Enumerated |  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+
 |Key-Name          TBD  Note 1   OctetString|  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+
 |IKEv2-Nonces      TBD5 6.2      Grouped    |  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+
 |Ni                TBD6 6.2.1    Unsigned32 |  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+
 |Nr                TBD7 6.2.2    Unsigned32 |  M | P |      | V  | Y  |
 +-------------------------------------------+----+---+------+----+----+

                           AVP Flag Rules Table

   Note 1: Key, Keying-Material, Key-Type, Key-SPI, Key-Name and Key-
   Lifetime AVPs are defined in [I-D.ietf-dime-local-keytran].














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9.  IANA Considerations

   This section contains the namespaces that have either been created in
   this specification or had their values assigned to existing
   namespaces managed by IANA.

9.1.  Command Codes

   IANA is requested to allocate a command code value for the IKEv2-PSK-
   Request message (IKEPSKR) and for the IKEv2-PSK-Answer message
   (IKEPSKA) from the Command Code namespace defined in [RFC3588].  See
   Section 5 for the assignment of the namespace in this specification.

9.2.  AVP Codes

   This specification requires IANA to register the following new AVPs
   from the AVP Code namespace defined in [RFC3588].


   o  IKEv2-Nonces

   o  Ni

   o  Nr


   The AVPs are defined in Section 6.

9.3.  AVP Values

   IANA is requested to create a new value for the Key-Type AVP.  The
   new value TBD4 signifies that IKEv2 PSK is being sent.

9.4.  Application Identifier

   This specification requires IANA to allocate one new value "Diameter
   IKE PSK" from the Application Identifier namespace defined in
   [RFC3588].

   Application Identifier         | Value
   -------------------------------+------
   Diameter IKE PSK (IKEPSK)      | TBD1









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10.  Security Considerations

   The security considerations of the Diameter Base protocol [RFC3588]
   are applicable to this document.

   The Diameter messages between the IKEv2 Server and the HAAA may be
   transported via one or more AAA brokers or Diameter agents.  In this
   case, the HA to the Diameter server AAA communication relies on the
   security properties of the intermediating AAA inter-connection
   networks, AAA brokers, and Diameter agents.  Furthermore, any agents
   that process IKEv2-PSK-Answer messages can see the contents of the
   Master-Security-Association AVP.  For this reason, this specification
   strongly recommends avoiding Diameter agents when they cannot be
   trusted to keep the keys secret.

   This specification expects that the HAAA derives and returns the
   associated session key to the IKEv2 Server.  For the key derivation
   this specification recommends the use of a short lived secrets,
   possibly based on a previous network access authentication run if
   such secrets are available.  To ensure key freshness, limit the key
   scope etc., this specification also recommends the use of nonces, if
   nonces are included in IKEv2-PSK-Request.  However, this
   specification does not define how the Diameter server actually
   derives required keys.  The details of the key derivation depends on
   the deployment where this specification is used and therefore the
   security properties of the system depend on how this is done.

























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11.  References

11.1.  Normative References

   [I-D.ietf-dime-local-keytran]
              Wu, W. and G. Zorn, "Diameter Attribute-Value Pairs for
              Cryptographic Key Transport",
              draft-ietf-dime-local-keytran-01 (work in progress),
              January 2010.

   [RFC3588]  Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
              Arkko, "Diameter Base Protocol", RFC 3588, September 2003.

   [RFC4302]  Kent, S., "IP Authentication Header", RFC 4302,
              December 2005.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, December 2005.

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

11.2.  Informative References

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

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

   [RFC5295]  Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri,
              "Specification for the Derivation of Root Keys from an
              Extended Master Session Key (EMSK)", RFC 5295,
              August 2008.
















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Authors' Addresses

   Violeta Cakulev
   Alcatel Lucent
   600 Mountain Ave.
   3D-517
   Murray Hill, NJ  07974
   US

   Phone: +1 908 582 3207
   Email: violeta.cakulev@alcatel-lucent.com


   Avi Lior
   Bridgewater Systems
   303 Terry Fox Drive
   Otawa, Ontario  K2K 3J1
   Canada

   Phone: +1 613-591-6655
   Email: avi@bridgewatersystems.com






























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