SRTP Double Encryption Procedures
draft-ietf-perc-double-07

Document Type Active Internet-Draft (perc WG)
Last updated 2017-09-01
Replaces draft-jennings-perc-double
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Network Working Group                                        C. Jennings
Internet-Draft                                                  P. Jones
Intended status: Standards Track                               R. Barnes
Expires: March 5, 2018                                     Cisco Systems
                                                                A. Roach
                                                                 Mozilla
                                                       September 1, 2017

                   SRTP Double Encryption Procedures
                       draft-ietf-perc-double-07

Abstract

   In some conferencing scenarios, it is desirable for an intermediary
   to be able to manipulate some RTP parameters, while still providing
   strong end-to-end security guarantees.  This document defines SRTP
   procedures that use two separate but related cryptographic operations
   to provide hop-by-hop and end-to-end security guarantees.  Both the
   end-to-end and hop-by-hop cryptographic algorithms can utilize an
   authenticated encryption with associated data scheme or take
   advantage of future SRTP transforms with different properties.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on March 5, 2018.

Copyright Notice

   Copyright (c) 2017 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

Jennings, et al.          Expires March 5, 2018                 [Page 1]
Internet-Draft                 Double SRTP                September 2017

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Cryptographic Context . . . . . . . . . . . . . . . . . . . .   4
   4.  Original Header Block . . . . . . . . . . . . . . . . . . . .   4
   5.  RTP Operations  . . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Encrypting a Packet . . . . . . . . . . . . . . . . . . .   5
     5.2.  Relaying a Packet . . . . . . . . . . . . . . . . . . . .   6
     5.3.  Decrypting a Packet . . . . . . . . . . . . . . . . . . .   7
   6.  RTCP Operations . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Use with Other RTP Mechanisms . . . . . . . . . . . . . . . .   8
     7.1.  RTX . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.2.  RED . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.3.  FEC . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     7.4.  DTMF  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Recommended Inner and Outer Cryptographic Algorithms  . . . .   9
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
     10.1.  RTP Header Extension . . . . . . . . . . . . . . . . . .  11
     10.2.  DTLS-SRTP  . . . . . . . . . . . . . . . . . . . . . . .  11
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  12
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     12.2.  Informative References . . . . . . . . . . . . . . . . .  13
   Appendix A.  Encryption Overview  . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Cloud conferencing systems that are based on switched conferencing
   have a central Media Distributor device that receives media from
   endpoints and distributes it to other endpoints, but does not need to
   interpret or change the media content.  For these systems, it is
   desirable to have one cryptographic key from the sending endpoint to
   the receiving endpoint that can encrypt and authenticate the media
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