Network Working Group L. Dondeti, Ed. Internet-Draft QUALCOMM, Inc. Intended status: Informational A. Jerichow Expires: August 30, 2007 Siemens Networks February 26, 2007 SDP Attributes for OMA BCAST Service and Content Protection draft-dondeti-oma-sip-sdp-attrs-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 30, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document provides descriptions of SDP attributes used by the Open Mobile Alliance's Broadcast Service and Content Protection specification. Dondeti & Jerichow Expires August 30, 2007 [Page 1] Internet-Draft OMA BCAST SDP Attributes February 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. New SDP Attributes . . . . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7.1. Normative References . . . . . . . . . . . . . . . . . . . 6 7.2. Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 8 Dondeti & Jerichow Expires August 30, 2007 [Page 2] Internet-Draft OMA BCAST SDP Attributes February 2007 1. Introduction The Open Mobile Alliance (OMA)'s Broadcast (BCAST) group is specifying service and content protection mechanisms for broadcast services over wireless networks. As part of that specification, several new SDP attributes are necessary to allow the broadcast server to signal the service and content protection parameters to clients. Section 8.2.4 of RFC 4566 [1] requires that new SDP attributes are registered through IANA with name, contact information and description (and other similar parameters). A standards track specification is RECOMMENDED if the new attribute(s) will have widespread use and interoperability considerations. OMA BCAST specifications are expected to be used by 3GPP MBMS, 3GPP2 BCMCS and DVB-H based broadcast wireless systems. Whereas that might qualify as widespread use, all of the networks compliant to those specifications will use the OMA specification as the point of reference for interoperability and inter-operation. Thus, it may be sufficient to simply document the attributes and the context in which they are used. This document provides descriptions of the SDP attributes used in the OMA BCAST Service and Content Protection specification. 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 [2]. 3. New SDP Attributes The following new SDP attributes have been specified: a=bcastversion:. This field specifies the OMA BCAST version "bcastversion" Value in the format x.y. The Value field is of XML data type Decimal. This is a session-level attribute and is not dependent on charset. Dondeti & Jerichow Expires August 30, 2007 [Page 3] Internet-Draft OMA BCAST SDP Attributes February 2007 a=control:streamid: Each stream declared in the SDP will be uniquely numbered. Only non-zero positive integers are acceptable. While it is recommended that streams are numbered in increasing order, this is NOT mandatory. Duplicate streamids SHALL be ignored, i.e. only the first one SHALL be used. a=kmsversion:. This field specifies the kmsversion Value in the format x.y. The Value field is of XML data type Decimal. This is a session-level attribute and is not dependent on charset. a=kmstype: The type of the value is String and it can take the values: * oma-bcast-drm-pki * oma-bcast-gba_u-mbms * oma-bcast-gba_me-mbms * oma-bcast-prov-bcmcs This is a session level attribute. This field is not dependent on chartset. a=keystreamtype: This field specifies the type of keystream as a string. The valid values are "stkm" and "ltkm" for short and long term key messages. This is a session or a media-level attribute and is not dependent on charset. a=stkmstream: The stkmstream attribute specifies mapping Short Term Key Message (STKM) streams to media streams in the SDP. The attribute can be at session level, in which case it applies to all media streams, or it can be at media level, in which case it only applies to the specified media and would overwrite possible session level attribute. Dondeti & Jerichow Expires August 30, 2007 [Page 4] Internet-Draft OMA BCAST SDP Attributes February 2007 Each session or media stream can have multiple stkmstream attributes. Using this attribute, the terminal can lookup the corresponding STKM stream announcements and figure out which one to listen to and process. We note that this attribute is optional and hence would not be there for unencrypted media streams. This field is not dependent on charset. a=encryptedstreamid: This field refers to the encrypted stream id and takes a non-zero positive integer. This is a session or a media-level attribute and is not dependent on charset. 4. Security Considerations In addition to the notes in Section 7 of RFC 4566 [1], the following considerations may be applicable: Some of the new SDP parameters indicate the version, type of the key management system used for service or content protection of broadcast content. Others provide references to relevant key management traffic streams so that receivers can map the media streams to key streams and retrieve the necessary keys to decrypt media. Modification of references to key streams will result in DoS attacks, but nothing more. However, if the kmsversion parameter is sent unprotected, there may be possibilities for downgrade attacks. 5. IANA Considerations This specification requests registration of the following SDP attributes: o a=bcastversion:. o a=control:streamid: o a=kmsversion:. o a=kmstype: o a=keystreamtype: o a=stkmstream: Dondeti & Jerichow Expires August 30, 2007 [Page 5] Internet-Draft OMA BCAST SDP Attributes February 2007 o a=encryptedstreamid: 6. Acknowledgments Many thanks to Charles Lo, Uwe Rauschenbach and David Castleford for their help and support. 7. References 7.1. Normative References [1] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K. Norrman, "MIKEY: Multimedia Internet KEYing", RFC 3830, August 2004. [4] 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. [5] Open Mobile Alliance, "Service and Content Protection for Mobile Broadcast Services", OMA TS-BCAST-SvcCntProtection-V1_0- 20060412-D, 2006. 7.2. Informative References [6] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Authors' Addresses Lakshminath Dondeti (editor) QUALCOMM, Inc. 5775 Morehouse Dr San Diego, CA USA Phone: +1 858-845-1267 Email: ldondeti@qualcomm.com Dondeti & Jerichow Expires August 30, 2007 [Page 6] Internet-Draft OMA BCAST SDP Attributes February 2007 Anja Jerichow Siemens Networks 81730 Munich, Germany Phone: +49 89 636-45868 Email: anja.jerichow@siemens.com Dondeti & Jerichow Expires August 30, 2007 [Page 7] Internet-Draft OMA BCAST SDP Attributes February 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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