MIKEY-RSA-R: An Additional Mode of Key Distribution in Multimedia Internet KEYing (MIKEY)
RFC 4738

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• 07

Network Working Group                                        D. Ignjatic
Request for Comments: 4738                                       Polycom
Updates: 3830                                                 L. Dondeti
Category: Standards Track                                       QUALCOMM
                                                                F. Audet
                                                                  P. Lin
                                                                  Nortel
                                                           November 2006

          MIKEY-RSA-R: An Additional Mode of Key Distribution
                 in Multimedia Internet KEYing (MIKEY)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2006).

Abstract

   The Multimedia Internet Keying (MIKEY) specification describes
   several modes of key distribution solution that address multimedia
   scenarios (e.g., SIP calls and Real Time Streaming Protocol (RTSP)
   sessions) using pre-shared keys, public keys, and optionally a
   Diffie-Hellman key exchange.  In the public-key mode, the Initiator
   encrypts a random key with the Responder's public key and sends it to
   the Responder.  In many communication scenarios, the Initiator may
   not know the Responder's public key, or in some cases the Responder's
   ID (e.g., call forwarding) in advance.  We propose a new MIKEY mode
   that works well in such scenarios.  This mode also enhances the group
   key management support in MIKEY; it supports member-initiated group
   key download (in contrast to group manager pushing the group keys to
   all members).  This document updates RFC 3830 with the RSA-R mode.

Ignjatic, et al.            Standards Track                     [Page 1]
RFC 4738                      MIKEY-RSA-R                  November 2006

Table of Contents

   1. Introduction ....................................................3
      1.1. Terminology Used in This Document ..........................3
   2. Motivation ......................................................3
      2.1. Description of the MIKEY Modes .............................3
      2.2. Use Case Motivating the Proposed Mode ......................5
   3. A New MIKEY-RSA Mode: MIKEY-RSA-R ...............................5
      3.1. Outline ....................................................5
      3.2. Group Communication Using the MIKEY RSA-R Mode .............6
      3.3. Preparing RSA-R Messages ...................................6
      3.4. Components of the I_MESSAGE ................................6
      3.5. Processing the I_MESSAGE ...................................8
      3.6. Components of the R_MESSAGE ................................9
      3.7. Processing the R_MESSAGE ..................................10
      3.8. Certificate Handling ......................................10
      3.9. Additions to RFC 3830 Message Types and Other Values ......11
           3.9.1. Modified Table 6.1a from RFC 3830 ..................11
           3.9.2. Modified Table 6.12 from RFC 3830 ..................12
           3.9.3. Modified Table 6.15 from RFC 3830 ..................12
   4. Applicability of the RSA-R and RSA Modes .......................13
      4.1. Limitations ...............................................13
   5. Security Considerations ........................................14
      5.1. Impact of the Responder Choosing the TGK ..................15
      5.2. Updates to Security Considerations in RFC 3830 ............15
   6. IANA Considerations ............................................15
   7. Acknowledgments ................................................16
   8. References .....................................................16
      8.1. Normative References ......................................16
      8.2. Informative References ....................................16

Ignjatic, et al.            Standards Track                     [Page 2]
RFC 4738                      MIKEY-RSA-R                  November 2006

1.  Introduction

   The MIKEY protocol [RFC3830] has three different methods for key
   transport or exchange: a pre-shared key mode (PSK), a public-key
   (RSA) mode, and an optional Diffie-Hellman exchange (DHE) mode.  In
   addition, there is also an optional DH-HMAC mode [RFC4650], bringing
   the total number of modes to four.  The primary motivation for the
   MIKEY protocol design is low-latency requirements of real-time
   communication, and thus all the exchanges finish in one-half to 1
   roundtrip; note that this offers no room for security parameter