SIP WG J . Peterson Internet - Draft NeuStar Expires : December 27 , 2003 June 28 , 2003 SIP

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." Abstract RFC3261 introduces the concept of adding an S/MIME body to a SIP request or response in order to provide reference integrity over its headers. This document provides a more specific mechanism to derive integrity and authentication properties from an 'authenticated identity body', a digitally-signed SIP message or message fragment. A standard format for such bodies (known as Authenticated Identity Bodies, or AIBs) is given in this document. Some considerations for the processing of AIBs by recipients of SIP messages with such bodies are also given.