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STIR                                                          T. Asveren
Internet-Draft                                                    Ribbon
Intended status: Standards Track                             May 8, 2018
Expires: November 9, 2018


              PASSPorT Extension for P-Charge-Info Header
                  draft-asveren-stir-p-charge-info-00

Abstract

   This document extends the PASSporT (Personal Assertion Token)
   specification defined in [RFC8225] to allow the inclusion of
   cryptographically signed assertions of authorization for the values
   populated in the 'Session Initiation Protocol (SIP) P-Charge-Info'
   header, which is used for conveying information about the entity to
   be charged for a particular real time session.

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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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 9, 2018.

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
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   include Simplified BSD License text as described in Section 4.e of




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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   2
   3.  PASSPortT 'pci' Claim . . . . . . . . . . . . . . . . . . . .   3
   4.  Using 'pci' in SIP  . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Authentication Service Behavior . . . . . . . . . . . . .   4
     4.2.  Verification Service Behavior . . . . . . . . . . . . . .   4
     4.3.  Other Behavior  . . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   PASSporT RFC 8225 [RFC8225] is a token format based on JSON Web Token
   (JWT) RFC 7519 [RFC7519] for conveying cryptographically signed
   information about the identities involved in personal communications;
   it is used with STIR RFC 8224 [RFC8224] to convey a signed assertion
   of the identity of the participants in real-time communications
   established via a protocol like SIP RFC 3261 [RFC3261].  This
   specification extends PASSporT to allow cryptographic-signing of the
   'SIP P-Charge-Info' header [RFCXXX], which is used to provide
   information about the party to be charged for a real time session.

   'SIP P-Charge-Info' header could be spoofed and abused by
   unauthorized entities.  Compromise of the 'SIP P-Charge-Info' header
   would allow charging fraud.

   Extension mechanisms defined in RFC8225 can be utilized to
   cyrptographically sign the 'SIP P-Charge-Info' header.  This would
   allow a receiving entity to verify the validity of this header.

   This specification documents an extension to PASSporT and the
   associated STIR mechanisms to provide a function to sign the 'SIP P-
   Charge-Info' header.

2.  Requirements Language

   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 RFC 2119.




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3.  PASSPortT 'pci' Claim

   This specification defines a new JSON Web Token claim for "pci",
   which provides an assertion for information in 'SIP P-Charge-Info'
   header.

   The creator of a PASSporT object adds a "ppt" value of "pci" to the
   header of a PASSporT object, in which case the PASSporT claims MUST
   contain a "pci" claim, and any entities verifying the PASSporT object
   will be required to understand the "ppt" extension in order to
   process the PASSporT in question.  A PASSPorT header with the "ppt"
   included will look as follows:

      {
      "typ":"passport",
        "ppt":"pci",
        "alg":"ES256",
        "x5u":"https://www.example.org/cert.cer"
      }

   The "pci" claim will provide an assertion for information in the 'SIP
   P-Charge-Info' header as defined in [RFCXXX] .

   After the header and claims PASSporT objects have been constructed,
   their signature is generated normally per the guidance in [RFC8225].
   The credentials (i.e., Certificate) used to create the signature must
   have authority over the "pci" claim and there is only one authority
   per claim.  If P-Charge-Info header is added or by the intermediaries
   along the path, intermediaries must generate a new "pci" header and
   sign the claim with its own authority.

   The following is an example "pci" claim for a 'SIP P-Charge-Info'
   header field with a value of "12125550100"

       {
        "orig":{"tn":"12155550112"},
        "dest":{["tn":"12125550113"]},
        "iat":1443208345,
        "pci":{["tn": "12125550100"]}
       }

4.  Using 'pci' in SIP

   This section specifies SIP-specific usage for the "pci" PASSporT type
   and its handling in the SIP Identity header field "ppt" parameter
   value.  Other using protocols of PASSporT may define behavior
   specific to their use of the "pci" claim.




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4.1.  Authentication Service Behavior

   An authentication service adds an Identity header field containing
   the "pci" PASSporT type to an SIP request only if it adds a P-Charge-
   Info header to the request.  Whether to add such an Identity header
   is controlled by local policy.  When adding an Identity header field
   with a PASSporT object containing a "pci" claim, SIP authentication
   services MUST also add a "ppt" parameter to that Identity header with
   a value of "pci".  The resulting Identity header field to add to the
   message might look as follows:

      Identity: eyJhbGciOiJFUzI1NiIsInR5cCI6InBhc3Nwb3J0IiwieDV1I \
      joiaHR0cHM6Ly9jZXJ0LmV4YW1wbGUub3JnL3Bhc3Nwb3J0LmNlciJ9.eyJ \
      kZXN0Ijp7InVyaSI6WyJzaXA6YWxpY2VAZXhhbXBsZS5jb20iXX0sImlhdC \
      I6IjE0NDMyMDgzNDUiLCJvcmlnIjp7InRuIjoiMTIxNTU1NTEyMTIifX0.r \
      q3pjT1hoRwakEGjHCnWSwUnshd0-zJ6F1VOgFWSjHBr8Qjpjlk-cpFYpFYs \
      ojNCpTzO3QfPOlckGaS6hEck7w;info=<https://biloxi.example.org \
      /biloxi.cert>;alg=ES256;ppt="pci"

4.2.  Verification Service Behavior

   RFC 8224 [RFC8224] Section 6.2 Step 5 requires that specifications
   defining "ppt" values describe any additional verifier behavior.  The
   behavior specified for the "pci" value of "ppt" is as follows.  The
   verification service MUST extract the value associated with the "pci"
   key in a PASSPorT with a "ppt" value of "pci".  If the signature
   validates, then the verification service can use the value of the
   "pci" claim as validation that P-Charge-Info in the received request
   is authentic.  The verifier MUST also ensure that the generator of
   Identity header is authorized to declare the value used for P-Charge-
   Info as the party to be charged.  How this can be achieved is out of
   the scope of this specification.

4.3.  Other Behavior

   An entity dropping P-Charge-Info MUST drop the corresponding Identity
   header with "ppt" parameter value of "pci".

5.  IANA Considerations

   This specification requests that the IANA add a new claim to the JSON
   Web Token Claims registry as defined in RFC 7519 [RFC7519].









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        Claim Name: "pci"

        Claim Description: Party to be charged for a session

        Change Controller: IESG

        Specification Document(s): [RFCThis]

6.  Security Considerations

   This specification describes a security feature, and is primarily
   concerned with increasing security for information regarding the
   party to be charged for a real time session.

   A malicious entity may add a P-Charge-Info value and a corresponding
   Identity header for charge abuse.  This would be detected either
   because the signature validation fails or because the malicious
   entity does not have authority to declare the value of P-Charge-Info
   as the party to be charged.

   A malicious entity may drop the P-Charge-Info and the corresponding
   Identity header.  This would cause infoirmation about the actual
   party to cherge not being present for a receiver entity which
   otherwise would use it for billing purposes.  One way to avoid this
   type of attack would be, for example, to enforce presence of P-
   Charge-Info header by the billing entity and reject the session if
   there is none.  This check may be performed only for certain sessions
   based on origination and/or destination identity for the call.

7.  Acknowledgements

8.  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>.

   [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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   [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>.

Author's Address

   Tolga Asveren
   Ribbon Communications
   Freehold, NJ  07728
   USA

   Email: tasveren@rbbn.com







































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