stir                                                            C. Wendt
Internet-Draft                                                   Comcast
Intended status: Standards Track                               M. Barnes
Expires: March 24, 2019                                        iconectiv
                                                      September 20, 2018


                   PASSporT SHAKEN Extension (SHAKEN)
                   draft-ietf-stir-passport-shaken-03

Abstract

   This document extends PASSporT, which is a token object that conveys
   cryptographically-signed information about the participants involved
   in communications, to include information defined as part of the
   SHAKEN specification from ATIS (Alliance for Telecommunications
   Industry Solutions) and the SIP Forum IP-NNI Joint Task Force.  These
   extensions provide a level of confidence in the correctness of the
   originating identity for a telephone network that has communications
   coming from both STIR participating originating communications as
   well as communications that does not include STIR information.

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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   This Internet-Draft will expire on March 24, 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



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   carefully, as they describe your rights and restrictions with respect
   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 . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Overview of 'shaken' PASSporT extension . . . . . . . . . . .   3
   4.  PASSporT 'attest' Claim . . . . . . . . . . . . . . . . . . .   3
   5.  PASSporT 'origid' Claim . . . . . . . . . . . . . . . . . . .   4
   6.  Example "shaken" PASSporT . . . . . . . . . . . . . . . . . .   4
   7.  Using 'shaken' in SIP . . . . . . . . . . . . . . . . . . . .   5
   8.  Order of Claim Keys . . . . . . . . . . . . . . . . . . . . .   5
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  JSON Web Token claims . . . . . . . . . . . . . . . . . .   5
     9.2.  PASSporT Types  . . . . . . . . . . . . . . . . . . . . .   6
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     11.1.  Normative References . . . . . . . . . . . . . . . . . .   6
     11.2.  Informative References . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

.  Introduction

   The SHAKEN [ATIS-1000074] specification defines a framework for using
   STIR protocols including PASSporT [RFC8225], RFC4474bis [RFC8224] and
   the STIR certificate framework [RFC8226] for implementing the
   cryptographic validation of an authorized originator of telephone
   calls using SIP.  Because the current telephone network contains both
   VoIP and TDM/SS7 originated traffic, there are many scenarios that
   need to be accounted for where PASSporT signatures may represent
   either direct or indirect call origination scenarios.  The SHAKEN
   [ATIS-1000074] specification defines levels of attestation of the
   origination of the call as well as an origination identifier that can
   help create a unique association with the origination of calls from
   various parts of the VoIP or TDM telephone network.  This document
   specifies these indicators as a specified PASSporT extension.

.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].





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.  Overview of 'shaken' PASSporT extension

   The SHAKEN framework is designed to use PASSporT [RFC8225] as a
   method of asserting the telephone number calling identity.  In
   addition to the PASSporT base claims, there are two additional claims
   that have been defined for the needs of a service provider to signal
   information beyond just the telephone identity.  First, in order to
   help bridge the transition of the state of the current telephone
   network which has calls with no authentication and non-SIP [RFC3261]
   signaling not compatible with the use of PASSporT and Secure
   Telephone Identity (STI) in general, there is an attestation claim.
   This provides three levels of attestation, including a full
   attestation when the service provider can fully attest to the calling
   identity, a partial attestation, when the service provider originated
   a telephone call but can not fully attest to the calling identity,
   and a gateway attestation which is the lowest level of attestation
   and represents the service provider receiving a call from a non
   PASSporT or STI supporting telephone gateway.

   The second claim is a unique origination identifier that should be
   used by the service provider to identify different sources of
   telephone calls to support a traceback mechanism that can be used for
   enforcement and identification of a source of illegitimate calls.

   The use of the compact form of PASSporT is not specified in this
   document and is not specified for use in SHAKEN [ATIS-1000074].

   The next two sections define these new claims.

.  PASSporT 'attest' Claim

   This indicator allows for both identifying the service provider that
   is vouching for the call as well as clearly indicating what
   information the service provider is attesting to.  The 'attest' claim
   can be one of the following three values, 'A', 'B', or 'C' as defined
   in [ATIS-1000074].

   'A' represents 'Full Attestation' where the signing provider MUST
   satisfy all of the following conditions:

   o  Is responsible for the origination of the call onto the IP based
      service provider voice network.

   o  Has a direct authenticated relationship with the initiator of the
      call and can identify the customer associated with the initiator.

   o  Has established a verified association with the calling party
      telephone number used for the call.



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   'B' represents 'Partial Attestation' where the signing provider MUST
   satisfy all of the following conditions:

   o  Is responsible for the origination of the call onto its IP-based
      voice network.

   o  Has a direct authenticated relationship with the initiator of the
      call and can identify the customer associated with the initiator.

   o  Has NOT established a verified association with the calling party
      telephone number being used for the call.

   'C' represents 'Gateway Attestation' where the signing provider MUST
   satisfy all of the following conditions:

   o  Is the entry point of the call into its VoIP network.

   o  Has no relationship with the initiator of the call (e.g.,
      international gateways)

.  PASSporT 'origid' Claim

   The purpose of the unique origination identifier is to assign an
   opaque identifier corresponding to the service provider-initiated
   calls themselves, customers, classes of devices, or other groupings
   that a service provider might want to use for determining things like
   reputation or trace back identification of customers or gateways.
   The value of 'origid' claim is a UUID as defined in [RFC4122].
   SHAKEN isn't prescriptive in the exact usage of origid other than the
   UUID format as a globally unique identifier representing the
   originator of the call to whatever granularity the PASSporT signer
   determines is sufficient for the ability to trace the original
   origination point of the call.  There will likely be best practices
   documents that more precisely guide it's usage in real deployments.

.  Example "shaken" PASSporT















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   Protected Header
   {
      "alg":"ES256",
      "typ":"passport",
      "ppt":"shaken",
      "x5u":"https://cert.example.org/passport.cer"
   }
   Payload
   {
      "attest":"A"
      "dest":{"uri":["sip:alice@example.com"]}
      "iat":"1443208345",
      "orig":{"tn":"12155551212"},
      "origid":"123e4567-e89b-12d3-a456-426655440000"
   }

.  Using 'shaken' in SIP

   The use of the 'shaken' PASSporT type and the claims 'attest' and
   'origid' are formally defined in [ATIS-1000074] for usage in SIP
   [RFC3261] aligned with the use of the identity header defined in
   [RFC8224].

.  Order of Claim Keys

   The order of the claim keys MUST follow the rules of [RFC8225]
   Section 9; the claim keys MUST appear in lexicographic order.
   Therefore, the claim keys discussed in this document appear in the
   PASSporT Payload in the following order,

   o  attest

   o  dest

   o  iat

   o  orig

   o  origid

.  IANA Considerations

9.1.  JSON Web Token claims

   This specification requests that the IANA add two new claims to the
   JSON Web Token Claims registry as defined in [RFC7519].

   Claim Name: "attest"



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   Claim Description: Attestation level as defined in SHAKEN framework

   Change Controller: IESG

   Specification Document(s): [RFCThis]

   Claim Name: "origid"

   Claim Description: Originating Identifier as defined in SHAKEN
   framework

   Change Controller: IESG

   Specification Document(s): [RFCThis]

9.2.  PASSporT Types

   This specification requests that the IANA add a new entry to the
   PASSporT Types registry for the type "shaken" which is specified in
   [RFCThis].

.  Acknowledgements

   The authors would like to thank those that helped review and
   contribute to this document including specific contributions from Jon
   Peterson, Russ Housley, and Andrew Jurczak.  The authors would like
   acknowledge the work of the ATIS/SIP Forum IP-NNI Task Force to
   develop the concepts behind this document.

.  References

11.1.  Normative References

   [ATIS-1000074]
              ATIS/SIP Forum NNI Task Group, "Signature-based Handling
              of Asserted information using toKENs (SHAKEN)", January
              2017.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              DOI 10.17487/RFC4122, July 2005,
              <https://www.rfc-editor.org/info/rfc4122>.

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <https://www.rfc-editor.org/info/rfc7519>.





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   [RFC8224]  Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
              "Authenticated Identity Management in the Session
              Initiation Protocol (SIP)", RFC 8224,
              DOI 10.17487/RFC8224, February 2018,
              <https://www.rfc-editor.org/info/rfc8224>.

   [RFC8225]  Wendt, C. and J. Peterson, "PASSporT: Personal Assertion
              Token", RFC 8225, DOI 10.17487/RFC8225, February 2018,
              <https://www.rfc-editor.org/info/rfc8225>.

   [RFC8226]  Peterson, J. and S. Turner, "Secure Telephone Identity
              Credentials: Certificates", RFC 8226,
              DOI 10.17487/RFC8226, February 2018,
              <https://www.rfc-editor.org/info/rfc8226>.

11.2.  Informative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              DOI 10.17487/RFC3261, June 2002,
              <https://www.rfc-editor.org/info/rfc3261>.

Authors' Addresses

   Chris Wendt
   Comcast
   One Comcast Center
   Philadelphia, PA  19103
   USA

   Email: chris-ietf@chriswendt.net


   Mary Barnes
   iconectiv

   Email: mary.ietf.barnes@gmail.com








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