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Encrypted Key Transport for Secure RTP
draft-ietf-avtcore-srtp-ekt-03

Document type: Active Internet-Draft (avtcore WG)
Document stream: IETF
Last updated: 2014-10-22
Intended RFC status: Unknown
Other versions: plain text, xml, pdf, html

IETF State: WG Document Dec 2013
Revised I-D Needed - Issue raised by WG
Document shepherd: Magnus Westerlund

IESG State: I-D Exists
Responsible AD: (None)
Send notices to: No addresses provided

AVTCORE Working Group                                   J. Mattsson, Ed.
Internet-Draft                                                  Ericsson
Intended status: Standards Track                               D. McGrew
Expires: April 23, 2015                                          D. Wing
                                                            F. Andreasen
                                                                   Cisco
                                                        October 20, 2014

                 Encrypted Key Transport for Secure RTP
                     draft-ietf-avtcore-srtp-ekt-03

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.  This
   facility enables SRTP to work for decentralized conferences with
   minimal control.

   This note defines EKT, and also describes how to use it with SDP
   Security Descriptions, DTLS-SRTP, and MIKEY.  With EKT, these other
   key management protocols provide an EKT key to everyone in a session,
   and EKT coordinates the SRTP keys within the session.

Status of This Memo

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   This Internet-Draft will expire on April 23, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Mattsson, et al.         Expires April 23, 2015                 [Page 1]
Internet-Draft                  EKT SRTP                    October 2014

   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
     1.1.  History . . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Conventions Used In This Document . . . . . . . . . . . .   5
   2.  Encrypted Key Transport . . . . . . . . . . . . . . . . . . .   5
     2.1.  EKT Field Formats . . . . . . . . . . . . . . . . . . . .   6
     2.2.  Packet Processing and State Machine . . . . . . . . . . .   8
       2.2.1.  Outbound Processing . . . . . . . . . . . . . . . . .   8
       2.2.2.  Inbound Processing  . . . . . . . . . . . . . . . . .   9
     2.3.  Ciphers . . . . . . . . . . . . . . . . . . . . . . . . .  11
       2.3.1.  The Default Cipher  . . . . . . . . . . . . . . . . .  12
       2.3.2.  Other EKT Ciphers . . . . . . . . . . . . . . . . . .  13
     2.4.  Synchronizing Operation . . . . . . . . . . . . . . . . .  13
     2.5.  Transport . . . . . . . . . . . . . . . . . . . . . . . .  13
     2.6.  Timing and Reliability Consideration  . . . . . . . . . .  15
   3.  Use of EKT with SDP Security Descriptions . . . . . . . . . .  16
     3.1.  SDP Security Descriptions Recap . . . . . . . . . . . . .  16
     3.2.  Relationship between EKT and SDESC  . . . . . . . . . . .  17
     3.3.  Overview of Combined EKT and SDESC Operation  . . . . . .  19
     3.4.  EKT Extensions to SDP Security Descriptions . . . . . . .  19
     3.5.  Offer/Answer Considerations . . . . . . . . . . . . . . .  20
       3.5.1.  Generating the Initial Offer - Unicast Streams  . . .  20
       3.5.2.  Generating the Initial Answer - Unicast Streams . . .  21
       3.5.3.  Processing of the Initial Answer - Unicast Streams  .  22
     3.6.  SRTP-Specific Use Outside Offer/Answer  . . . . . . . . .  23
     3.7.  Modifying the Session . . . . . . . . . . . . . . . . . .  23
     3.8.  Backwards Compatibility Considerations  . . . . . . . . .  24
     3.9.  Grammar . . . . . . . . . . . . . . . . . . . . . . . . .  25
   4.  Use of EKT with DTLS-SRTP . . . . . . . . . . . . . . . . . .  25
     4.1.  DTLS-SRTP Recap . . . . . . . . . . . . . . . . . . . . .  26

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