Options for Securing RTP Sessions
RFC 7201

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Internet Engineering Task Force (IETF)                     M. Westerlund
Request for Comments: 7201                                      Ericsson
Category: Informational                                       C. Perkins
ISSN: 2070-1721                                    University of Glasgow
                                                              April 2014

                   Options for Securing RTP Sessions

Abstract

   The Real-time Transport Protocol (RTP) is used in a large number of
   different application domains and environments.  This heterogeneity
   implies that different security mechanisms are needed to provide
   services such as confidentiality, integrity, and source
   authentication of RTP and RTP Control Protocol (RTCP) packets
   suitable for the various environments.  The range of solutions makes
   it difficult for RTP-based application developers to pick the most
   suitable mechanism.  This document provides an overview of a number
   of security solutions for RTP and gives guidance for developers on
   how to choose the appropriate security mechanism.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see 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/rfc7201.

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RFC 7201            Options for Securing RTP Sessions         April 2014

Copyright Notice

   Copyright (c) 2014 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.

Westerlund & Perkins          Informational                     [Page 2]
RFC 7201            Options for Securing RTP Sessions         April 2014

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Point-to-Point Sessions . . . . . . . . . . . . . . . . .   5
     2.2.  Sessions Using an RTP Mixer . . . . . . . . . . . . . . .   5
     2.3.  Sessions Using an RTP Translator  . . . . . . . . . . . .   6
       2.3.1.  Transport Translator (Relay)  . . . . . . . . . . . .   6
       2.3.2.  Gateway . . . . . . . . . . . . . . . . . . . . . . .   7
       2.3.3.  Media Transcoder  . . . . . . . . . . . . . . . . . .   8
     2.4.  Any Source Multicast  . . . . . . . . . . . . . . . . . .   8
     2.5.  Source-Specific Multicast . . . . . . . . . . . . . . . .   8
   3.  Security Options  . . . . . . . . . . . . . . . . . . . . . .  10
     3.1.  Secure RTP  . . . . . . . . . . . . . . . . . . . . . . .  10
       3.1.1.  Key Management for SRTP: DTLS-SRTP  . . . . . . . . .  12
       3.1.2.  Key Management for SRTP: MIKEY  . . . . . . . . . . .  14
       3.1.3.  Key Management for SRTP: Security Descriptions  . . .  15
       3.1.4.  Key Management for SRTP: Encrypted Key Transport  . .  16
       3.1.5.  Key Management for SRTP: ZRTP and Other Solutions . .  17
     3.2.  RTP Legacy Confidentiality  . . . . . . . . . . . . . . .  17
     3.3.  IPsec . . . . . . . . . . . . . . . . . . . . . . . . . .  17
     3.4.  RTP over TLS over TCP . . . . . . . . . . . . . . . . . .  18
     3.5.  RTP over Datagram TLS (DTLS)  . . . . . . . . . . . . . .  18
     3.6.  Media Content Security/Digital Rights Management  . . . .  19
       3.6.1.  ISMA Encryption and Authentication  . . . . . . . . .  19
   4.  Securing RTP Applications . . . . . . . . . . . . . . . . . .  20
     4.1.  Application Requirements  . . . . . . . . . . . . . . . .  20
       4.1.1.  Confidentiality . . . . . . . . . . . . . . . . . . .  20
       4.1.2.  Integrity . . . . . . . . . . . . . . . . . . . . . .  21
       4.1.3.  Source Authentication . . . . . . . . . . . . . . . .  22
       4.1.4.  Identifiers and Identity  . . . . . . . . . . . . . .  23
       4.1.5.  Privacy . . . . . . . . . . . . . . . . . . . . . . .  24