Securing Session Initiation Protocol (SIP) based Messaging with S/MIME
draft-campbell-sip-messaging-smime-03

Document Type Active Internet-Draft (individual in art area)
Last updated 2018-07-30 (latest revision 2018-06-25)
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Network Working Group                                        B. Campbell
Internet-Draft                                         Standard Velocity
Updates: RFC 3261, RFC 3428, RFC 4975                         R. Housley
         (if approved)                                    Vigil Security
Intended status: Standards Track                           June 25, 2018
Expires: December 27, 2018

 Securing Session Initiation Protocol (SIP) based Messaging with S/MIME
                 draft-campbell-sip-messaging-smime-03

Abstract

   Mobile messaging applications used with the Session Initiation
   Protocol (SIP) commonly use some combination of the SIP MESSAGE
   method and the Message Session Relay Protocol (MSRP).  While these
   provide mechanisms for hop-by-hop security, neither natively provides
   end-to-end protection.  This document offers guidance on how to
   provide end-to-end authentication, integrity protection, and
   confidentiality using the Secure/Multipurpose Internet Mail
   Extensions (S/MIME).  It updates and provides clarifications for RFC
   3261, RFC 3428, and RFC 4975.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on December 27, 2018.

Copyright Notice

   Copyright (c) 2018 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

Campbell & Housley      Expires December 27, 2018               [Page 1]
Internet-Draft          S/MIME for SIP Messaging               June 2018

   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
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Problem Statement and Scope . . . . . . . . . . . . . . . . .   4
   4.  Applicability of S/MIME . . . . . . . . . . . . . . . . . . .   5
     4.1.  Signed Messages . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Encrypted Messages  . . . . . . . . . . . . . . . . . . .   6
     4.3.  Signed and Encrypted Messages . . . . . . . . . . . . . .   7
     4.4.  Certificate Handling  . . . . . . . . . . . . . . . . . .   8
       4.4.1.  Subject Alternative Name  . . . . . . . . . . . . . .   8
       4.4.2.  Certificate Validation  . . . . . . . . . . . . . . .   8
   5.  Transfer Encoding . . . . . . . . . . . . . . . . . . . . . .   8
   6.  User Agent Capabilities . . . . . . . . . . . . . . . . . . .   9
   7.  Using S/MIME with the SIP MESSAGE Method  . . . . . . . . . .   9
     7.1.  Size Limit  . . . . . . . . . . . . . . . . . . . . . . .  10
     7.2.  User Agent Capabilities . . . . . . . . . . . . . . . . .  10
     7.3.  Failure Cases . . . . . . . . . . . . . . . . . . . . . .  10
   8.  Using S/MIME with MSRP  . . . . . . . . . . . . . . . . . . .  11
     8.1.  Chunking  . . . . . . . . . . . . . . . . . . . . . . . .  11
     8.2.  Streamed Data . . . . . . . . . . . . . . . . . . . . . .  12
     8.3.  Indicating support for S/MIME . . . . . . . . . . . . . .  12
     8.4.  MSRP URIs . . . . . . . . . . . . . . . . . . . . . . . .  13
     8.5.  Failure Cases . . . . . . . . . . . . . . . . . . . . . .  13
   9.  S/MIME Interaction with other SIP Messaging Features  . . . .  13
     9.1.  Common Profile for Instant Messaging  . . . . . . . . . .  13
     9.2.  Instant Message Delivery Notifications  . . . . . . . . .  14
   10. Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  15
     10.1.  Signed Message in SIP Including the Sender's Certificate  15
     10.2.  Signed Message in SIP with No Certificate  . . . . . . .  17
     10.3.  MSRP Signed and Encrypted Message in a Single Chunk  . .  17
     10.4.  MSRP Signed and Encrypted Message sent in Multiple
            Chunks . . . . . . . . . . . . . . . . . . . . . . . . .  19
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
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