Private Extensions to the Session Initiation Protocol (SIP) for Asserted Identity within Trusted Networks
RFC 3325
Network Working Group C. Jennings
Request for Comments: 3325 Cisco Systems
Category: Informational J. Peterson
NeuStar, Inc.
M. Watson
Nortel Networks
November 2002
Private Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document describes private extensions to the Session Initiation
Protocol (SIP) that enable a network of trusted SIP servers to assert
the identity of authenticated users, and the application of existing
privacy mechanisms to the identity problem. The use of these
extensions is only applicable inside an administrative domain with
previously agreed-upon policies for generation, transport and usage
of such information. This document does NOT offer a general privacy
or identity model suitable for use between different trust domains,
or use in the Internet at large.
Table of Contents
1. Applicability Statement . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Proxy Behavior . . . . . . . . . . . . . . . . . . . . . . . 5
6. Hints for Multiple Identities . . . . . . . . . . . . . . . 6
7. Requesting Privacy . . . . . . . . . . . . . . . . . . . . . 6
8. User Agent Server Behavior . . . . . . . . . . . . . . . . . 7
9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 7
9.1 The P-Asserted-Identity Header . . . . . . . . . . . . 8
9.2 The P-Preferred-Identity Header . . . . . . . . . . . . 8
9.3 The "id" Privacy Type . . . . . . . . . . . . . . . . . 9
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RFC 3325 SIP Asserted Identity November 2002
10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1 Network Asserted Identity passed to trusted gateway . . 9
10.2 Network Asserted Identity Withheld . . . . . . . . . . 11
11. Example of Spec(T) . . . . . . . . . . . . . . . . . . . . . 13
12. Security Considerations . . . . . . . . . . . . . . . . . . 14
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . 14
13.1 Registration of new SIP header fields . . . . . . . . . 14
13.2 Registration of "id" privacy type for SIP Privacy header 15
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
Normative References . . . . . . . . . . . . . . . . . . . . 15
Informational References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 17
Full Copyright Statement . . . . . . . . . . . . . . . . . . 18
1. Applicability Statement
This document describes private extensions to SIP [1] that enable a
network of trusted SIP servers to assert the identity of end users or
end systems, and to convey indications of end-user requested privacy.
The use of these extensions is only applicable inside a 'Trust
Domain' as defined in Short term requirements for Network Asserted
Identity [5]. Nodes in such a Trust Domain are explicitly trusted by
its users and end-systems to publicly assert the identity of each
party, and to be responsible for withholding that identity outside of
the Trust Domain when privacy is requested. The means by which the
network determines the identity to assert is outside the scope of
this document (though it commonly entails some form of
authentication).
A key requirement of [5] is that the behavior of all nodes within a
given Trust Domain 'T' is known to comply to a certain set of
specifications known as 'Spec(T)'. Spec(T) MUST specify behavior for
the following:
1. The manner in which users are authenticated
2. The mechanisms used to secure the communication among nodes within
the Trust Domain
3. The mechanisms used to secure the communication between UAs and
nodes within the Trust Domain
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RFC 3325 SIP Asserted Identity November 2002
4. The manner used to determine which hosts are part of the Trust
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