Network Working Group L. Dondeti, Ed. Internet-Draft QUALCOMM, Inc. Intended status: Informational A. Jerichow Expires: April 18, 2008 Nokia Siemens Networks GmbH and Co.KG October 16, 2007 Session Description Protocol (SDP) Attributes for OMA BCAST Service and Content Protection draft-dondeti-oma-sip-sdp-attrs-02 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 April 18, 2008. 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 April 18, 2008 [Page 1] Internet-Draft OMA BCAST SDP Attributes October 2007 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. New SDP Attributes . . . . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Registration of new SDP attributes . . . . . . . . . . . . 4 5.1.1. Registration of the attribute a=bcastversion:. . . . . . . . . . . . . 4 5.1.2. Registration of the attribute a=stkmstream: . . . . . . . . . . . . . . . . . . . 5 5.1.3. Registration of the attribute a=SRTPAuthentication: . . . . . . . . . . . . . . . . . . . 5 5.1.4. Registration of the attribute a=SRTPROCTxRate: . . . . . . . . 6 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 9 Dondeti & Jerichow Expires April 18, 2008 [Page 2] Internet-Draft OMA BCAST SDP Attributes October 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. This document provides descriptions of the SDP attributes used in the OMA BCAST Service and Content Protection specification [2]. 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 [3]. 3. New SDP Attributes The following new SDP attributes have been specified: o a=bcastversion:. o a=stkmstream: o a=SRTPAuthentication: o a=SRTPROCTxRate: See Section 5 for details on IANA considerations. 4. Security Considerations In addition to the notes in Section 7 of RFC 4566 [1], the following considerations may be applicable: Dondeti & Jerichow Expires April 18, 2008 [Page 3] Internet-Draft OMA BCAST SDP Attributes October 2007 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 document, following the guidelines of [5], instructs IANA to register a number of SDP attributes. 5.1. Registration of new SDP attributes This memo provides instructions to IANA to register a number of OMA BCAST only attributes in the Session Description Protocol Parameters registry [1]. The registration data, according to RFC 4566 [1] follows. Note to the RFC Editor: replace "RFC XXXX" with the RFC number of this specification. 5.1.1. Registration of the attribute a=bcastversion:. Contact: Anja Jerichow Phone: +49 89 636-45868 Attribute name: bcastversion:. Long-form attribute name: BCAST version Type of attribute: session-level This attribute is not dependent on charset. Description: This attribute specifies the OMA BCAST version "bcastversion" Value in the format x.y. The Value field is of XML data type Decimal. Specification: RFC XXXX and OMA-TS-BCAST_SvcCntProtection, Section 10.1.1 [2] Dondeti & Jerichow Expires April 18, 2008 [Page 4] Internet-Draft OMA BCAST SDP Attributes October 2007 5.1.2. Registration of the attribute a=stkmstream: Contact: Anja Jerichow Phone: +49 89 636-45868 Attribute name: stkmstream: Long-form attribute name: Short Term Key Message stream identifyer Type of attribute: session-level or media-level attribute 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. This attribute is not dependent on charset. Description: The stkmstream attribute specifies mapping Short Term Key Message streams to media streams in the SDP. 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 specifies the type of keystream as a string. The valid values are "stkm" for short term key messages and "ltkm" for long term key messages. Specification: RFC XXXX and OMA-TS-BCAST_SvcCntProtection, Section 10.1.3 [2] 5.1.3. Registration of the attribute a=SRTPAuthentication: Contact: Anja Jerichow Phone: +49 89 636-45868 Attribute name: SRTPAuthentication: Dondeti & Jerichow Expires April 18, 2008 [Page 5] Internet-Draft OMA BCAST SDP Attributes October 2007 Long-form attribute name: SRTP authentication algorithm value identifyer Type of attribute: media-level This attribute is not dependent on charset. Description: When SRTP is used, the attribute SRTPAuthentication states which authentication algorithm to use. Based on , the identifier is a transform-independent parameter of the cryptographic context for SRTP in integer format. One of the following three integrity transforms registered for the three modes MUST be used: value "2" for RCCm1, "3" for RCCm2 and "4" for RCCm3. Specification: RFC XXXX and OMA-TS-BCAST_SvcCntProtection, Section 10.4 [2] 5.1.4. Registration of the attribute a=SRTPROCTxRate: Contact: Anja Jerichow Phone: +49 89 636-45868 Attribute name: SRTPROCTxRate: Long-form attribute name: ROC transmission rate Type of attribute: media-level This attribute is not dependent on charset. Description: When SRTP is used, the attribute SRTPROCTxRate is used to define the ROC transmission rate, R, which is given in network byte order. R MUST be a non-zero unsigned integer between 1 and 65535 inclusive, as specified in [4]. If the ROC transmission rate is not included in the negotiation, the default value of 1 SHALL be used. Specification: RFC XXXX and OMA-TS-BCAST_SvcCntProtection, Section 10.4 [2] Dondeti & Jerichow Expires April 18, 2008 [Page 6] Internet-Draft OMA BCAST SDP Attributes October 2007 6. Acknowledgments Many thanks to Charles Lo, Uwe Rauschenbach, David Castleford, Hosame Abu-Amara, and Miguel Garcia 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] Open Mobile Alliance, "Service and Content Protection for Mobile Broadcast Services", OMA OMA-TS-BCAST_SvcCntProtection-V1_0- 20070504-D, 2007. [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [4] Lehtovirta, V., Naslund, M., and K. Norrman, "Integrity Transform Carrying Roll-Over Counter for the Secure Real-time Transport Protocol (SRTP)", RFC 4771, January 2007. 7.2. Informative References [5] 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 April 18, 2008 [Page 7] Internet-Draft OMA BCAST SDP Attributes October 2007 Anja Jerichow Nokia Siemens Networks GmbH and Co.KG Martinstr. 76 81541 Munich Germany Phone: +49 89 636-45868 Email: anja.jerichow@nsn.com Dondeti & Jerichow Expires April 18, 2008 [Page 8] Internet-Draft OMA BCAST SDP Attributes October 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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