Encrypted Key Transport for Secure RTP
draft-ietf-perc-srtp-ekt-diet-01

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Replaces draft-jennings-perc-srtp-ekt-diet
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PERC Working Group                                      J. Mattsson, Ed.
Internet-Draft                                                  Ericsson
Intended status: Standards Track                               D. McGrew
Expires: January 9, 2017                                         D. Wing
                                                            F. Andreasen
                                                             C. Jennings
                                                                   Cisco
                                                            July 8, 2016

                 Encrypted Key Transport for Secure RTP
                    draft-ietf-perc-srtp-ekt-diet-01

Abstract

   Encrypted Key Transport (EKT) is an extension to Secure Real-time
   Transport Protocol (SRTP) that provides for the secure transport of
   SRTP master keys, Rollover Counters, and other information within
   SRTP.  This facility enables SRTP to work for decentralized
   conferences with minimal control by allowing a common key to be used
   across multiple endpoints.

Status of This Memo

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   This Internet-Draft will expire on January 9, 2017.

Copyright Notice

   Copyright (c) 2016 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

Mattsson, et al.         Expires January 9, 2017                [Page 1]
Internet-Draft                  EKT SRTP                       July 2016

   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.  Conventions Used In This Document . . . . . . . . . . . .   3
   2.  Encrypted Key Transport . . . . . . . . . . . . . . . . . . .   3
     2.1.  EKT Field Formats . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Packet Processing and State Machine . . . . . . . . . . .   6
       2.2.1.  Outbound Processing . . . . . . . . . . . . . . . . .   7
       2.2.2.  Inbound Processing  . . . . . . . . . . . . . . . . .   7
     2.3.  Ciphers . . . . . . . . . . . . . . . . . . . . . . . . .   8
       2.3.1.  The Default Cipher  . . . . . . . . . . . . . . . . .   9
       2.3.2.  Other EKT Ciphers . . . . . . . . . . . . . . . . . .  10
     2.4.  Synchronizing
           Operation . . . . . . . . . . . . . . . . . . . . . . . .  10
     2.5.  Transport . . . . . . . . . . . . . . . . . . . . . . . .  10
     2.6.  Timing and Reliability Consideration  . . . . . . . . . .  11
   3.  Use of EKT with DTLS-SRTP . . . . . . . . . . . . . . . . . .  11
     3.1.  DTLS-SRTP Recap . . . . . . . . . . . . . . . . . . . . .  12
     3.2.  EKT Extensions to DTLS-SRTP . . . . . . . . . . . . . . .  12
     3.3.  Offer/Answer Considerations . . . . . . . . . . . . . . .  14
   4.  Sending the DTLS EKT_Key Reliably . . . . . . . . . . . . . .  14
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   6.  Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .  15
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   RTP is designed to allow decentralized groups with minimal control to
   establish sessions, such as for multimedia conferences.
   Unfortunately, Secure RTP (SRTP [RFC3711]) cannot be used in many
   minimal-control scenarios, because it requires that SSRC values and
   other data be coordinated among all of the participants in a session.
   For example, if a participant joins a session that is already in
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