MIKEY General Extension Payload for OMA BCAST 1.0
draft-jerichow-msec-mikey-genext-oma-00

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Abstract

This document extends the General Extension Payload for OMA BCAST usage defined in RFC 4909 [1] (, “Multimedia Internet KEYing (MIKEY) General Extension,” June 2007.). It adds necessary support for the newly specified management data as defined in the Open Mobile Alliance's (OMA) Broadcast (BCAST) group's Service and Content protection specification [2] (Open Mobile Alliance, “Service and Content Protection for Mobile Broadcast Services,” 2008.).

Table of Contents

1.  Introduction
2.  Terminology
3.  MIKEY General Extension for OMA BCAST Usage
4.  Interoperability considerations
5.  Security Considerations
6.  IANA Considerations
7.  Changes since RFC 4909
8.  Acknowledgments
9.  Normative References
§  Authors' Addresses
§  Intellectual Property and Copyright Statements

1.  Introduction

The Multimedia Internet Keying (MIKEY) protocol specification (RFC 3830 [3] (Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K. Norrman, “MIKEY: Multimedia Internet KEYing,” August 2004.)) 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 [2] (Open Mobile Alliance, “Service and Content Protection for Mobile Broadcast Services,” 2008.) specifies the use of a short- term key message (STKM), a long-term key message (LTKM), a LTKM reporting message, as well as 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 [3] (Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K. Norrman, “MIKEY: Multimedia Internet KEYing,” August 2004.).

RFC 3830 [3] (Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K. Norrman, “MIKEY: Multimedia Internet KEYing,” August 2004.), the MIKEY General Extension payload defined in RFC 4563 [4] (Carrara, E., Lehtovirta, V., and K. Norrman, “The Key ID Information Type for the General Extension Payload in Multimedia Internet KEYing (MIKEY),” June 2006.), and the 3rd Generation Partnership Project (3GPP)'s Multimedia Broadcast/ Multicast Service (MBMS) document [5] (3GPP, “3G Security; Security of Multimedia Broadcast/Multicast Service (MBMS),” March 2006.) 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 [6] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).

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

Section 6.1 of RFC 3830 [3] (Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K. Norrman, “MIKEY: Multimedia Internet KEYing,” August 2004.) specifies the first three fields of the General Extension Payload and defines a variable length Data field.

                    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 Payload Subtype  (variable length)            ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

This document 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

The contents of the variable length data 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
!   Sub Type    ! Subtype Specific Data (variable length)       ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Sub Type: 8 bits. This field indicates the type of the OMA BCAST payload. In this specification, four values are specified: LTKM (1), STKM (2), LTKM Reporting (TBD1), and Parental Control (TBD2).

Sub Type Specific Data: Variable length.

      OMA BCAST Type        | Value | Comment
      -----------------------------------------------------------
      LTKM                  |     1 | Long Term Key Message
      STKM                  |     2 | Short Term Key Message
      LTKM Reporting        |  TBD1 | LTKM Reporting Message
      Parental Control      |  TBD2 | Parental Control Message

The contents of the OMA BCAST payload field are defined in Section 6 of the OMA BCAST Service and Content Protection specification [2] (Open Mobile Alliance, “Service and Content Protection for Mobile Broadcast Services,” 2008.).

4.  Interoperability considerations

This document specifies the use of MIKEY General Extension Payload Type 5 and four subtype values (1, 2, TBD1 and TBD2), 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 [3] (Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K. Norrman, “MIKEY: Multimedia Internet KEYing,” August 2004.) and RFC 4563 [4] (Carrara, E., Lehtovirta, V., and K. Norrman, “The Key ID Information Type for the General Extension Payload in Multimedia Internet KEYing (MIKEY),” June 2006.).

5.  Security Considerations

According to RFC 3830 [3] (Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K. Norrman, “MIKEY: Multimedia Internet KEYing,” August 2004.), 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 also 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" in the IANA registry at http://www.iana.org/assignments/mikey-payloads for use by OMA BCAST as requested by RFC 4909 [1] (, “Multimedia Internet KEYing (MIKEY) General Extension,” June 2007.). Furthermore, IANA has created a name space for the OMA BCAST payload subtype values defined in [1] (, “Multimedia Internet KEYing (MIKEY) General Extension,” June 2007.) and has assigned the following subtype values from this name space: LTKM (1), STKM (2).

IANA is requested to allocate two new subtypes from the OMA BCAST payload subtype name space, referenced above, in the IANA registry at http://www.iana.org/assignments/mikey-payloads.

The requested subtypes are as follows:

Subtype Name: LTKM Reporting

Value: TBD1

Suggested value: 3

and

Subtype Name: Parental Control

Value: TBD2

Suggested value: 4

Note to Editor: Please replace all TBD1 and TBD2 in this specification with the values assigned by IANA.

7.  Changes since RFC 4909

OMA BCAST Service and Content Protection specification [2] (Open Mobile Alliance, “Service and Content Protection for Mobile Broadcast Services,” 2008.) 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 [1] (, “Multimedia Internet KEYing (MIKEY) General Extension,” June 2007.).

8.  Acknowledgments

Many thanks to the authors of RFC 4909 [1] (, “Multimedia Internet KEYing (MIKEY) General Extension,” June 2007.) for allowing to update their RFC.

9. Normative References

Authors' Addresses

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