Network Working Group                                    L. Dondeti, Ed.
Request for Comments: 4909                                QUALCOMM, Inc.
Category: Informational                                    D. Castleford
                                                         France Telecom
                                                             F. Hartung
                                                      Ericsson Research
                                                              June 2007


     Multimedia Internet KEYing (MIKEY) General Extension Payload
          for Open Mobile Alliance BCAST LTKM/STKM Transport

Status of This Memo

  This memo provides information for the Internet community.  It does
  not specify an Internet standard of any kind.  Distribution of this
  memo is unlimited.

Copyright Notice

  Copyright (C) The IETF Trust (2007).

Abstract

  This document specifies a new Multimedia Internet KEYing (MIKEY)
  General Extension payload (RFC 3830) to transport the short-term key
  message (STKM) and long-term key message (LTKM) payloads defined in
  the Open Mobile Alliance's (OMA) Browser and Content (BAC) Broadcast
  (BCAST) group's Service and Content protection specification.

Table of Contents

  1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
  2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
  3.  MIKEY General Extension for OMA BCAST Usage . . . . . . . . . . 3
  4.  Interoperability Considerations . . . . . . . . . . . . . . . . 3
  5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
  6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
  7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4
  8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
    8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
    8.2.  Informative References  . . . . . . . . . . . . . . . . . . 5









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1.  Introduction

  The Multimedia Internet Keying (MIKEY) protocol specification [1]
  defines a General Extension payload to allow possible extensions to
  MIKEY without having to allocate a new payload type.  The General
  Extension payload can be used in any MIKEY message and is part of the
  authenticated/signed data part.  There is an 8-bit type field in that
  payload.  The type code assignment is IANA-managed, and RFC 3830
  requires IETF consensus for assignments from the public range of
  0-240.

  The Open Mobile Alliance's (OMA) Browser and Content (BAC) Broadcast
  (BCAST) group's Service and Content Protection specification [2]
  specifies the use of a short-term key message (STKM) and a long-term
  key message (LTKM) that carry attributes related to Service and
  Content protection.  Note that any keys associated with the
  attributes are part of the MIKEY KEMAC payload.  This document
  specifies the use of the General Extension payload of MIKEY to carry
  the LTKMs or STKMs.

  RFC 3830 [1], the MIKEY General Extension payload defined in [3], and
  the 3rd Generation Partnership Project (3GPP)'s Multimedia Broadcast/
  Multicast Service (MBMS) document [4] specify the transport of MIKEY
  messages via unicast or broadcast and the OMA specifications use
  either for transport of MIKEY messages.

2.  Terminology

  The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
  "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
  document are to be interpreted as described in RFC 2119 [5].

  OMA BCAST STKM/LTKM MIKEY General Extension:  We refer to the General
     Extension type -- 5 -- as the OMA BCAST STKM/LTKM MIKEY General
     Extension .
















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3.  MIKEY General Extension for OMA BCAST Usage

                           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   !      Type     !            Length             !
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      !       OMA BCAST S/LTKM Subtype  (variable length)      ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 1: OMA BCAST MIKEY General Extension

  Section 6.1 of RFC 3830 specifies the first three fields of the
  General Extension Payload and defines a variable length Data field.
  This document specifies the use of Type 5 for OMA BCAST Service and
  Content Protection using the Smartcard Profile.  The contents of the
  variable length data field are defined below.

  Subtype:  8 bits.  This field indicates the type of the OMA BCAST
     payload.  In this specification, only two values are specified:
     LTKM (1), and STKM (2).

  Subtype Specific Data:  Variable length.  The contents of this field
     are defined in Section 6 of the OMA BCAST Service and Content
     Protection specification [2].


                        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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    !    Subtype    !   Subtype specific data (variable length)     ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 2: STKM/LTKM Subtype Payload

4.  Interoperability Considerations

  This document specifies the use of MIKEY General Extension Payload
  Type 5 and a couple of subtype values (1 and 2), one each for OMA
  BCAST Service and Content protection's STKM and LTKM payloads.
  Interoperability considerations span several standards bodies, with
  OMA BCAST 1.0 enabler compliance being the key aspect; as such, it is
  up to the OMA test planning to verify the interoperability and
  compliance of OMA BCAST 1.0 implementations.  This payload type
  assignment does not change MIKEY beyond RFC 3830 [1] and RFC 4563
  [3].





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5.  Security Considerations

  According to RFC 3830, the general extension payload can be used in
  any MIKEY message and is part of the authenticated/signed data part.
  The parameters proposed to be included in the OMA BCAST MIKEY General
  Extension payload (listed in Section 3) need only to be integrity
  protected, which is already allowed by the MIKEY specification.  The
  OMA BCAST MIKEY General Extension Payload SHALL be integrity
  protected.  Furthermore, keys or any parameters that require
  confidentiality MUST NOT be included in the General Extension
  Payload.  If keys or other confidential data are to be transported
  via the General Extension Payload, such data MUST be encrypted and
  encapsulated independently.  Finally, note that MIKEY already
  provides replay protection and that protection covers the General
  Extension Payload also.

6.  IANA Considerations

  IANA has allocated a new General Extension Type from the "General
  Extensions payload name spaces" in the IANA registry at
  http://www.iana.org/assignments/mikey-payloads for use by OMA BCAST.
  Furthermore, IANA maintains a list of corresponding subtypes (0-255)
  as follows:

     0 ...  Reserved

     1 ...  LTKM

     2 ...  STKM

     3 ... 191 (maintained by IANA and assigned by IETF Review [6])

     192 ... 255 (Private use)

7.  Acknowledgments

  Many thanks to Jari Arkko, Piron Laurent, and Steffen Fries for their
  reviews and suggestions for improvement.













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8.  References

8.1.  Normative References

  [1]  Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K.
       Norrman, "MIKEY: Multimedia Internet KEYing", RFC 3830,
       August 2004.

  [2]  Open Mobile Alliance, "Service and Content Protection for Mobile
       Broadcast Services", OMA TS-BCAST_SvcCntProtection-V1_0-
       20070529-C, 2007, <http://www.openmobilealliance.org/
       release_program/bcast_v1_0.html>.

  [3]  Carrara, E., Lehtovirta, V., and K. Norrman, "The Key ID
       Information Type for the General Extension Payload in Multimedia
       Internet KEYing (MIKEY)", RFC 4563, June 2006.

  [4]  3GPP, "3G Security; Security of Multimedia Broadcast/Multicast
       Service (MBMS)", 3GPP TS 33.246 6.6.0, March 2006.

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

8.2.  Informative References

  [6]  Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
       Considerations Section in RFCs", Work in Progress, March 2007.
























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Authors' Addresses

  Lakshminath Dondeti (editor)
  QUALCOMM, Inc.
  5775 Morehouse Dr
  San Diego, CA
  USA

  Phone: +1 858-845-1267
  EMail: [email protected]


  David Castleford
  France Telecom
  4, rue du Clos Courtel
  35512 Cesson Sevigne Cedex,
  France

  Phone: + 33 (0)2 99 12 49 27
  EMail: [email protected]


  Frank Hartung
  Ericsson Research
  Ericsson Allee 1
  52134 Herzogenrath,
  Germany

  Phone: +49 2407 575389
  EMail: [email protected]





















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Full Copyright Statement

  Copyright (C) The IETF Trust (2007).

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Acknowledgement

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