User-Agent-Driven Privacy Mechanism for SIP
RFC 5767

Document Type RFC - Informational (April 2010; No errata)
Last updated 2013-03-02
Replaces draft-munakata-sip-privacy-new
Stream IETF
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Stream WG state (None)
Consensus Unknown
Document shepherd No shepherd assigned
IESG IESG state RFC 5767 (Informational)
Telechat date
Responsible AD Cullen Jennings
Send notices to sip-chairs@ietf.org, draft-ietf-sip-ua-privacy@ietf.org
Internet Engineering Task Force (IETF)                       M. Munakata
Request for Comments: 5767                                   S. Schubert
Category: Informational                                          T. Ohba
ISSN: 2070-1721                                                      NTT
                                                              April 2010

              User-Agent-Driven Privacy Mechanism for SIP

Abstract

   This document defines a guideline for a User Agent (UA) to generate
   an anonymous Session Initiation Protocol (SIP) message by utilizing
   mechanisms such as Globally Routable User Agent URIs (GRUUs) and
   Traversal Using Relays around NAT (TURN) without the need for a
   privacy service defined in RFC 3323.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5767.

Copyright Notice

   Copyright (c) 2010 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
   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.

Munakata, et al.              Informational                     [Page 1]
RFC 5767           UA-Driven Privacy Mechanism for SIP        April 2010

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................3
   3. Concept of Privacy ..............................................3
   4. Treatment of Privacy-Sensitive Information ......................3
      4.1. Obtaining a Functional Anonymous URI Using the GRUU
           Mechanism ..................................................4
      4.2. Obtaining a Functional Anonymous IP Address Using
           the TURN Mechanism .........................................5
   5. UA Behavior .....................................................6
      5.1. Critical Privacy-Sensitive Information .....................6
           5.1.1. Contact Header Field ................................6
           5.1.2. From Header Field in Requests .......................7
           5.1.3. Via Header Field in Requests ........................8
           5.1.4. IP Addresses in SDP .................................8
      5.2. Non-Critical Privacy-Sensitive Information .................8
           5.2.1. Host Names in Other SIP Header Fields ...............8
           5.2.2. Optional SIP Header Fields ..........................9
   6. Security Considerations .........................................8
   7. References ......................................................9
      7.1. Normative References .......................................9
      7.2. Informative References ....................................10

1.  Introduction

   [RFC3323] defines a privacy mechanism for the Session Initiation
   Protocol (SIP) [RFC3261], based on techniques available at the time
   of its publication.  This mechanism relies on the use of a separate
   privacy service to remove privacy-sensitive information from SIP
   messages sent by a User Agent (UA) before forwarding those messages
   to the final destination.  Since then, numerous SIP extensions have
   been proposed and standardized.  Some of those enable a UA to
   withhold its user's identity and related information without the need
   for privacy services, which was not possible when RFC 3323 was
   defined.

   The purpose of this document is not to obsolete RFC 3323, but to
   enhance the overall privacy mechanism in SIP by allowing a UA to take
   control of its privacy, rather than being completely dependent on an
   external privacy service.

   The UA-driven privacy mechanism defined in this document will not
   eliminate the need for the RFC 3323 usage defined in [RFC3325], which
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