Encryption of Header Extensions in the Secure Real-time Transport Protocol (SRTP)
RFC 6904
| Document | Type |
RFC - Proposed Standard
(April 2013; No errata)
Updates RFC 3711
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-lennox-avtcore-srtp-encrypted-header-ext | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Roni Even | ||
| IESG | IESG state | RFC 6904 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Robert Sparks | ||
| IESG note | Roni Even (ron.even.tlv@gmail.com) is the Document Shepherd. | ||
| Send notices to | (None) | ||
Internet Engineering Task Force (IETF) J. Lennox
Request for Comments: 6904 Vidyo
Updates: 3711 April 2013
Category: Standards Track
ISSN: 2070-1721
Encryption of Header Extensions
in the Secure Real-time Transport Protocol (SRTP)
Abstract
The Secure Real-time Transport Protocol (SRTP) provides
authentication, but not encryption, of the headers of Real-time
Transport Protocol (RTP) packets. However, RTP header extensions may
carry sensitive information for which participants in multimedia
sessions want confidentiality. This document provides a mechanism,
extending the mechanisms of SRTP, to selectively encrypt RTP header
extensions in SRTP.
This document updates RFC 3711, the Secure Real-time Transport
Protocol specification, to require that all future SRTP encryption
transforms specify how RTP header extensions are to be encrypted.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6904.
Lennox Standards Track [Page 1]
RFC 6904 Encrypted SRTP Header Extensions April 2013
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Encryption Mechanism . . . . . . . . . . . . . . . . . . . . 4
3.1. Example Encryption Mask . . . . . . . . . . . . . . . . . 6
3.2. Header Extension Keystream Generation for Existing
Encryption Transforms . . . . . . . . . . . . . . . . . . 7
3.3. Header Extension Keystream Generation for Future
Encryption Transforms . . . . . . . . . . . . . . . . . . 8
4. Signaling (Setup) Information . . . . . . . . . . . . . . . . 8
4.1. Backward Compatibility . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. Test Vectors . . . . . . . . . . . . . . . . . . . . 13
A.1. Key Derivation Test Vectors . . . . . . . . . . . . . . . 13
A.2. Header Encryption Test Vectors Using AES-CM . . . . . . . 14
Lennox Standards Track [Page 2]
RFC 6904 Encrypted SRTP Header Extensions April 2013
1. Introduction
The Secure Real-time Transport Protocol [RFC3711] specification
provides confidentiality, message authentication, and replay
protection for multimedia payloads sent using the Real-time Protocol
(RTP) [RFC3550]. However, in order to preserve RTP header
compression efficiency, SRTP provides only authentication and replay
protection for the headers of RTP packets, not confidentiality.
For the standard portions of an RTP header, providing only
authentication and replay protection does not normally present a
problem, as the information carried in an RTP header does not provide
much information beyond that which an attacker could infer by
observing the size and timing of RTP packets. Thus, there is little
need for confidentiality of the header information.
However, the security requirements can be different for information
carried in RTP header extensions. A number of recent proposals for
header extensions using the mechanism described in "A General
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