An Opportunistic Approach for Secure Real-time Transport Protocol (OSRTP)
RFC 8643

Document Type RFC - Informational (August 2019; No errata)
Last updated 2019-08-09
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Stream WG state Submitted to IESG for Publication
Document shepherd Gonzalo Camarillo
Shepherd write-up Show (last changed 2019-06-11)
IESG IESG state RFC 8643 (Informational)
Consensus Boilerplate Yes
Telechat date
Responsible AD Alexey Melnikov
Send notices to Gonzalo Camarillo <gonzalo.camarillo@ericsson.com>
IANA IANA review state Version Changed - Review Needed
IANA action state No IANA Actions
Internet Engineering Task Force (IETF)                       A. Johnston
Request for Comments: 8643                          Villanova University
Category: Informational                                         B. Aboba
ISSN: 2070-1721                                                Microsoft
                                                               A. Hutton
                                                                    Atos
                                                               R. Jesske
                                                        Deutsche Telekom
                                                                T. Stach
                                                            Unaffiliated
                                                             August 2019

   An Opportunistic Approach for Secure Real-time Transport Protocol
                                (OSRTP)

Abstract

   Opportunistic Secure Real-time Transport Protocol (OSRTP) is an
   implementation of the Opportunistic Security mechanism, as defined in
   RFC 7435, applied to the Real-time Transport Protocol (RTP).  OSRTP
   allows encrypted media to be used in environments where support for
   encryption is not known in advance and is not required.  OSRTP does
   not require Session Description Protocol (SDP) extensions or features
   and is fully backwards compatible with existing implementations using
   encrypted and authenticated media and implementations that do not
   encrypt or authenticate media packets.  OSRTP is not specific to any
   key management technique for Secure RTP (SRTP).  OSRTP is a
   transitional approach useful for migrating existing deployments of
   real-time communications to a fully encrypted and authenticated
   state.

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 candidates for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8643.

Johnston, et al.              Informational                     [Page 1]
RFC 8643                          OSRTP                      August 2019

Copyright Notice

   Copyright (c) 2019 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
   (https://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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Applicability Statement . . . . . . . . . . . . . . . . .   3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  SDP Offer/Answer Considerations . . . . . . . . . . . . . . .   3
     3.1.  Generating the Initial OSRTP Offer  . . . . . . . . . . .   4
     3.2.  Generating the Answer . . . . . . . . . . . . . . . . . .   4
     3.3.  Offerer Processing the Answer . . . . . . . . . . . . . .   4
     3.4.  Modifying the Session . . . . . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Opportunistic Security (OS) [RFC7435] is an approach to security that
   defines a third mode for security between "cleartext" and
   "comprehensive protection" that allows encryption and authentication
   of media to be used if supported but will not result in failures if
   it is not supported.  In the context of the transport of secure media
   streams using RTP and its secured derivatives, cleartext is
   represented by an RTP [RFC3550] media stream that is negotiated with
   the RTP/AVP (Audio-Visual Profile) [RFC3551] or the RTP/AVPF profile
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