STIR Out-of-Band Architecture and Use Cases
draft-ietf-stir-oob-05

Document Type Active Internet-Draft (stir WG)
Last updated 2019-07-11 (latest revision 2019-07-08)
Replaces draft-rescorla-stir-fallback
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On Agenda stir at IETF-105
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Network Working Group                                        E. Rescorla
Internet-Draft                                                   Mozilla
Intended status: Informational                               J. Peterson
Expires: January 9, 2020                                         Neustar
                                                            July 8, 2019

              STIR Out-of-Band Architecture and Use Cases
                         draft-ietf-stir-oob-05

Abstract

   The PASSporT format defines a token that can be carried by signaling
   protocols, including SIP, to cryptographically attest the identify of
   callers.  Not all telephone calls use Internet signaling protocols,
   however, and some calls use them for only part of their signaling
   path, or cannot reliably deliver SIP header fields end-to-end.  This
   document describes use cases that require the delivery of PASSporT
   objects outside of the signaling path, and defines architectures and
   semantics to provide this functionality.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on January 9, 2020.

Copyright Notice

   Copyright (c) 2019 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

Rescorla & Peterson      Expires January 9, 2020                [Page 1]
Internet-Draft              STIR Out-of-Band                   July 2019

   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Operating Environments  . . . . . . . . . . . . . . . . . . .   4
   4.  Dataflows . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  Case 1: VoIP to PSTN Call . . . . . . . . . . . . . . . .   7
     5.2.  Case 2: Two Smart PSTN endpoints  . . . . . . . . . . . .   7
     5.3.  Case 3: PSTN to VoIP Call . . . . . . . . . . . . . . . .   7
     5.4.  Case 4: Gateway Out-of-band . . . . . . . . . . . . . . .   8
     5.5.  Case 5: Enterprise Call Center  . . . . . . . . . . . . .   8
   6.  Storing and Retrieving PASSporTs  . . . . . . . . . . . . . .   9
     6.1.  Storage . . . . . . . . . . . . . . . . . . . . . . . . .  10
     6.2.  Retrieval . . . . . . . . . . . . . . . . . . . . . . . .  11
   7.  Solution Architecture . . . . . . . . . . . . . . . . . . . .  12
     7.1.  Credentials and Phone Numbers . . . . . . . . . . . . . .  12
     7.2.  Call Flow . . . . . . . . . . . . . . . . . . . . . . . .  12
     7.3.  Security Analysis . . . . . . . . . . . . . . . . . . . .  13
     7.4.  Substitution Attacks  . . . . . . . . . . . . . . . . . .  14
     7.5.  Rate Control for CPS Storage  . . . . . . . . . . . . . .  15
   8.  Authentication and Verification Service Behavior for Out-of-
       Band  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
     8.1.  Authentication Service  . . . . . . . . . . . . . . . . .  16
     8.2.  Verification Service  . . . . . . . . . . . . . . . . . .  17
     8.3.  Gateway Placement Services  . . . . . . . . . . . . . . .  18
   9.  Example HTTPS Interface to the CPS  . . . . . . . . . . . . .  19
   10. CPS Discovery . . . . . . . . . . . . . . . . . . . . . . . .  21
   11. Encryption Key Lookup . . . . . . . . . . . . . . . . . . . .  22
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  23
   13. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  23
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  23
   15. Informative References  . . . . . . . . . . . . . . . . . . .  24
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  26

1.  Introduction

   The STIR problem statement [RFC7340] describes widespread problems
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