Network Working Group                                   A. Jerichow, Ed.
Request for Comments: 5410                        Nokia Siemens Networks
Obsoletes: 4909                                                 L. Piron
Category: Informational                                 Nagravision S.A.
                                                            January 2009


      Multimedia Internet KEYing (MIKEY) General Extension Payload
                   for Open Mobile Alliance BCAST 1.0

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.

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Abstract

   This document specifies a new Multimedia Internet KEYing (MIKEY)
   General Extension payload to transport the short-term key message
   (STKM) and long-term key message (LTKM) payloads as well as the
   management data LTKM reporting message and parental control message
   payloads defined in the Open Mobile Alliance's (OMA) Broadcast
   (BCAST) group's Service and Content protection specification.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  MIKEY General Extension for OMA BCAST Usage . . . . . . . . . . 3
   4.  Interoperability Considerations . . . . . . . . . . . . . . . . 4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Changes since RFC 4909  . . . . . . . . . . . . . . . . . . . . 5
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     9.2.  Informative References  . . . . . . . . . . . . . . . . . . 6

1.  Introduction

   The Multimedia Internet KEYing (MIKEY) protocol specification (RFC
   3830 [RFC3830]) 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) Broadcast (BCAST) group's Service
   and Content Protection specification [SPCP] specifies the use of a
   short-term key message (STKM), a long-term key message (LTKM), an
   LTKM reporting message, and a parental control message that carry
   attributes related to Service and Content protection.  Note that any
   keys associated with the attributes, such as the Parental Control
   Pincode if present, are part of the MIKEY KEMAC payload.

   This document specifies the use of the General Extension payload of
   MIKEY to carry the messages mentioned above, as well as protection of
   the credentials using mechanisms supported by MIKEY with
   modifications in [RFC3830].

   RFC 3830 [RFC3830], the MIKEY General Extension payload defined in
   RFC 4563 [RFC4563], and the 3rd Generation Partnership Project
   (3GPP)'s Multimedia Broadcast/ Multicast Service (MBMS) document
   [3GPP.33.246] specify the transport of MIKEY messages via unicast or
   broadcast; the OMA BCAST 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 [RFC2119].

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

3.  MIKEY General Extension for OMA BCAST Usage

   The OMA BCAST Type (Type 5) formats the MIKEY General Extension
   payload as follows:

                       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 !      Type     !            Length            !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !       OMA BCAST Data Subtype  (variable length)             ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 1: OMA BCAST MIKEY General Extension

   Next Payload and Length are defined in Section 6.15 of [RFC3830].

   Type (8 bits): identifies the type of the General Extension Payload
   (see Section 6.15 of [RFC3830]).  This document adds a new type.  It
   specifies the use of Type 5 for OMA BCAST Service and Content
   Protection using the Smartcard Profile.

   Type        | Value | Comments
   ------------------------------------------------------------------
   OMA BCAST   |     5 | information on type and identity of messages

   Figure 2: Definition of the OMA BCAST MIKEY General Extension Payload

   OMA BCAST Data Subtype (variable length): defines a variable length
   Data field.  This field is formed by subtype-payloads.  The contents
   of the variable length OMA BCAST Data Subtype field are defined
   below.

                       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 3: STKM/LTKM/LTKM Reporting/Parental Control Subtype Payload

      Subtype: 8 bits.  This field indicates the subtype of the OMA
      BCAST payload.  In this specification, four values are specified:
      LTKM (1), STKM (2), LTKM Reporting (3), and Parental Control (4).

      Subtype Specific Data: Variable length.

         OMA BCAST Data Subtype | Value | Comment
         -----------------------------------------------------------
         LTKM                   |     1 | Long Term Key Message
         STKM                   |     2 | Short Term Key Message
         LTKM Reporting         |     3 | LTKM Reporting Message
         Parental Control       |     4 | Parental Control Message

           Figure 4: Subtype Definitions for OMA BCAST Messages

   The contents of the OMA BCAST Data Subtype payload field are defined
   in Section 6 of the OMA BCAST Service and Content Protection
   specification [SPCP].

4.  Interoperability Considerations

   This document specifies the use of MIKEY General Extension payload
   Type 5 and four subtype values: 1 and 2 for OMA BCAST Service and
   Content protection's LTKM and STKM payloads (respectively), 3 for
   LTKM Reporting payload, and 4 for Parental Control payload.
   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 [RFC3830] and RFC
   4563 [RFC4563].

5.  Security Considerations

   According to RFC 3830 [RFC3830], 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 also covers the
   General Extension payload.

6.  IANA Considerations

   IANA has allocated an OMA BCAST MIKEY General Extension Type --5--
   from the "General Extensions payload name space" for use by OMA BCAST
   as requested by RFC 4909 [RFC4909].  Furthermore, IANA has created a
   name space for the OMA BCAST payload subtype values defined in
   [RFC4909] and has assigned the following subtype values from this
   name space: LTKM (1), STKM (2).

   IANA has allocated two new subtypes from the OMA BCAST payload
   subtype name space.

   The subtypes are as follows:

      Subtype Name: LTKM Reporting

      Value: 3

   and

      Subtype Name: Parental Control

      Value: 4

7.  Changes since RFC 4909

   OMA BCAST Service and Content Protection specification [SPCP]
   contains messages that were created since RFC 4909 was written.  This
   document only adds the necessary assignments to support these new
   messages.  No modifications are made on values assigned by RFC 4909
   [RFC4909].

8.  Acknowledgments

   Many thanks to the authors of RFC 4909 [RFC4909] for allowing us to
   obsolete their RFC.

9.  References

9.1.  Normative References

   [3GPP.33.246]  3GPP, "3G Security; Security of Multimedia Broadcast/
                  Multicast Service (MBMS)", 3GPP TS 33.246 6.12.0,
                  October 2007.

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

   [RFC3830]      Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and
                  K. Norrman, "MIKEY: Multimedia Internet KEYing",
                  RFC 3830, August 2004.

   [RFC4563]      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.

   [SPCP]         Open Mobile Alliance, "Service and Content Protection
                  for Mobile Broadcast Services",
                  OMA-TS-BCAST_SvcCntProtection-V1_0,
                  <http://www.openmobilealliance.org>.

9.2.  Informative References

   [RFC4909]      Dondeti, L., Castleford, D., and F. Hartung,
                  "Multimedia Internet KEYing (MIKEY) General Extension
                  Payload for Open Mobile Alliance BCAST LTKM/STKM
                  Transport", RFC 4909, June 2007.

Authors' Addresses

   Anja Jerichow (editor)
   Nokia Siemens Networks
   Martinstr. 76
   81541 Munich
   Germany

   Phone: +49 89 636-45868
   EMail: anja.jerichow@nsn.com


   Laurent Piron
   Nagravision S.A.
   Case Postale 134
   1033 Cheseaux
   Switzerland

   Phone: +41 21 732 05 37
   EMail: laurent.piron@nagravision.com