PASSporT Extension for Diverted Calls
draft-ietf-stir-passport-divert-03

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Network Working Group                                        J. Peterson
Internet-Draft                                                   Neustar
Intended status: Informational                              July 2, 2018
Expires: January 3, 2019

                 PASSporT Extension for Diverted Calls
                 draft-ietf-stir-passport-divert-03.txt

Abstract

   This document extends PASSporT, which conveys cryptographically-
   signed information about the people involved in personal
   communications, to include an indication that a call has been
   diverted from its original destination to a new one.  This
   information can greatly improve the decisions made by verification
   services in call forwarding scenarios.  Also specified here is an
   encapsulation mechanism for nesting a PASSporT within another
   PASSporT that assists relying parties in some diversion scenarios.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on January 3, 2019.

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
   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

Peterson                 Expires January 3, 2019                [Page 1]
Internet-Draft              PASSporT Diverted                  July 2018

   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  PASSporT 'div' Claim  . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Nesting the original PASSporT in 'div'  . . . . . . . . .   5
   4.  Using 'div' in SIP  . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Authentication Service Behavior . . . . . . . . . . . . .   6
     4.2.  Verification Service Behavior . . . . . . . . . . . . . .   6
   5.  Definition of 'opt' . . . . . . . . . . . . . . . . . . . . .   7
   6.  'div' and Redirection . . . . . . . . . . . . . . . . . . . .   7
   7.  Extending 'div' to work with Service Logic Tracking . . . . .   9
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  10
   11. Informative References  . . . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   PASSporT [RFC8225] is a token format based on JWT [RFC7519] for
   conveying cryptographically-signed information about the people
   involved in personal communications; it is used with STIR [RFC8224]
   to convey a signed assertion of the identity of the participants in
   real-time communications established via a protocol like SIP.  This
   specification extends PASSporT to include an indication that a call
   has been diverted from its originally destination to a new one.

   Although the STIR problem statement [RFC7340] is focused on
   preventing the impersonation of the caller's identity, which is a
   common enabler for threats such as robocalling and voicemail hacking
   on the telephone network today, it also provides a signature over the
   called number as the authentication service sees it.  As [RFC8224]
   Section 12.1 describes, this protection over the contents of the To
   header field is intended to prevent a class of cut-and-paste attacks.
   If Alice calls Bob, for example, Bob might attempt to cut-and-paste
   the Identity header field in Alice's INVITE into a new INVITE that
   Bob sends to Carol, and thus be able to fool Carol into thinking the
   call came from Alice and not Bob. With the signature over the To
   header field value, the INVITE Carol sees will clearly have been