Secure Telephone Identity Credentials: Certificates
draft-ietf-stir-certificates-18

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Last updated 2017-12-20 (latest revision 2017-12-18)
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Network Working Group                                        J. Peterson
Internet-Draft                                                   Neustar
Intended status: Standards Track                               S. Turner
Expires: June 21, 2018                                             sn3rd
                                                       December 18, 2017

          Secure Telephone Identity Credentials: Certificates
                    draft-ietf-stir-certificates-18

Abstract

   In order to prevent the impersonation of telephone numbers on the
   Internet, some kind of credential system needs to exist that
   cryptographically asserts authority over telephone numbers.  This
   document describes the use of certificates in establishing authority
   over telephone numbers, as a component of a broader architecture for
   managing telephone numbers as identities in protocols like SIP.

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 June 21, 2018.

Copyright Notice

   Copyright (c) 2017 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   include Simplified BSD License text as described in Section 4.e of

Peterson & Turner         Expires June 21, 2018                 [Page 1]
Internet-Draft                 STIR Certs                  December 2017

   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.  Authority for Telephone Numbers in Certificates . . . . . . .   4
   4.  Certificate Usage with STIR . . . . . . . . . . . . . . . . .   5
   5.  Enrollment and Authorization Using the TN Authorization List    6
     5.1.  Constraints on Signing PASSporTs  . . . . . . . . . . . .   8
     5.2.  Certificate Extension Scope and Structure . . . . . . . .   8
   6.  Provisioning Private Keying Material  . . . . . . . . . . . .   9
   7.  Acquiring Credentials to Verify Signatures  . . . . . . . . .   9
   8.  JWT Claim Constraints Syntax  . . . . . . . . . . . . . . . .  10
   9.  TN Authorization List Syntax  . . . . . . . . . . . . . . . .  11
   10. Certificate Freshness and Revocation  . . . . . . . . . . . .  13
     10.1.  Acquiring the TN List by Reference . . . . . . . . . . .  14
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
     11.1.  ASN.1 Registrations  . . . . . . . . . . . . . . . . . .  15
     11.2.  Media Type Registrations . . . . . . . . . . . . . . . .  16
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  16
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     13.2.  Informative References . . . . . . . . . . . . . . . . .  19
   Appendix A.  ASN.1 Module . . . . . . . . . . . . . . . . . . . .  20
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  22

1.  Introduction

   The Secure Telephone Identity Revisited (STIR) problem statement
   [RFC7340] identifies the primary enabler of robocalling, vishing
   (voicemail hacking), swatting, and related attacks as the capability
   to impersonate a calling party number.  The starkest examples of
   these attacks are cases where automated callees on the Public
   Switched Telephone Network (PSTN) rely on the calling number as a
   security measure -- for example, to access a voicemail system.
   Robocallers use impersonation as a means of obscuring identity.
   While robocallers can, in the ordinary PSTN, block (that is,
   withhold) their caller identity, callees are less likely to pick up
   calls from blocked identities; therefore, appearing to call from some
   number, any number, is preferable.  Robocallers, however, prefer not
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