Connected Identity for STIR
draft-peterson-stir-rfc4916-update-01

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Network Working Group                                        J. Peterson
Internet-Draft                                                   Neustar
Intended status: Informational                                  C. Wendt
Expires: January 14, 2021                                        Comcast
                                                           July 13, 2020

                      Connected Identity for STIR
                 draft-peterson-stir-rfc4916-update-01

Abstract

   The SIP Identity header conveys cryptographic identity information
   about the originators of SIP requests.  The Secure Telephone Identity
   Revisited (STIR) framework however provides no means for determining
   the identity of the called party in a traditional telephone calling
   scenario.  This document updates prior guidance on the "connected
   identity" problem to reflect the changes to SIP Identity that
   accompanied STIR, and considers a revised problem space for connected
   identity as a means of detecting calls that have been retargeted to a
   party impersonating the intended destination.

Status of This Memo

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   This Internet-Draft will expire on January 14, 2021.

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   This document is subject to BCP 78 and the IETF Trust's Legal
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Peterson & Wendt        Expires January 14, 2021                [Page 1]
Internet-Draft               RFC4916 Update                    July 2020

   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Connected Identity Problem Statement for STIR . . . . . . . .   3
   4.  Authorization Policy for Callers  . . . . . . . . . . . . . .   4
   5.  Pre-Association with Destinations . . . . . . . . . . . . . .   5
   6.  Updates to RFC4916  . . . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   10. Informative References  . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Session Initiation Protocol (SIP) [RFC3261] initiates sessions,
   and as a step in establishing sessions, it exchanges information
   about the parties at both ends of a session.  Users review
   information about the calling party, for example, to determine
   whether to accept communications initiated by a SIP, in the same way
   that users of the telephone network assess "Caller ID" information
   before picking up calls.  This information may sometimes be consumed
   by automata to make authorization decisions.

   STIR [RFC8224] provides a cryptographic assurance of the identity of
   calling parties in order to prevent impersonation, which is a key
   enabler of unwanted robocalls, swatting, vishing, voicemail hacking,
   and similar attacks (see [RFC7340]).  There also exists a related
   problem: the identity of the party who answers a call can differ from
   that of the initial called party for various innocuous reasons such
   as call forwarding, but in certain network environments it is
   possible for attackers to hijack the route of a called number and
   direct it to a resource controlled by the attacker.  It can
   potentially be difficult to determine why a call reached a target
   other than the one originally intended, and whether the party
   ultimately reached by the call is one that the caller should trust.
   The property of providing identity in the backwards direction of a
   call is here called "connected identity."

   Previous work on connected identity focused on fixing the core
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