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Versions: 00 draft-ietf-acme-authority-token-tnauthlist

Network Working Group                                           C. Wendt
Internet-Draft                                                D. Hancock
Intended status: Informational                                   Comcast
Expires: September 6, 2018                                     M. Barnes
                                                               iconectiv
                                                             J. Peterson
                                                            Neustar Inc.
                                                          March 05, 2018


               TNAuthList profile of ACME Authority Token
             draft-wendt-acme-authority-token-tnauthlist-00

Abstract

   This document defines a profile of the Automated Certificate
   Management Environment (ACME) Authority Token for the automated and
   authorized creation of certificates for VoIP Telephone Providers to
   support Secure Telephony Identity (STI) using the TNAuthList defined
   by STI certificates.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   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 September 6, 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
   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



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   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 . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  ACME new-order identifiers for TNAuthList . . . . . . . . . .   3
   4.  TNAuthList Identifier Authorization . . . . . . . . . . . . .   4
   5.  TNAuthList Authority Token  . . . . . . . . . . . . . . . . .   6
     5.1.  "iss" claim . . . . . . . . . . . . . . . . . . . . . . .   6
     5.2.  "exp" claim . . . . . . . . . . . . . . . . . . . . . . .   7
     5.3.  "jti" claim . . . . . . . . . . . . . . . . . . . . . . .   7
     5.4.  "atc" claim . . . . . . . . . . . . . . . . . . . . . . .   7
     5.5.  Acquiring the token from the Authority  . . . . . . . . .   7
   6.  Validating the TNAuthList Authority Token . . . . . . . . . .   7
   7.  Example TNAuthList Tokens . . . . . . . . . . . . . . . . . .   8
     7.1.  Example-1 . . . . . . . . . . . . . . . . . . . . . . . .   8
     7.2.  Example-2 . . . . . . . . . . . . . . . . . . . . . . . .   8
     7.3.  Example-3 . . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Large number of Non-contiguous TNAuthList values  . . . . . .   9
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     11.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   [I-D.ietf-acme-acme] is a mechanism for automating certificate
   management on the Internet.  It enables administrative entities to
   prove effective control over resources like domain names, and
   automates the process of generating and issuing certificates.
   [I-D.peterson-acme-authority-token] extends ACME to provide a general
   method of extending the Authority and authorization of entities to
   control a resource via a third party Authority beyond the
   Certification Authority.

   This document addresses the STIR problem statement [RFC7340] which
   identifies the need for Internet credentials that can attest
   authority for the originator of VoIP calls in order to detect
   impersonation, which is currently an enabler for common attacks
   associated with illegal robocalling, voicemail hacking, and swatting.
   These credentials are used to sign PASSporTs [RFC8225], which can be
   carried in using protocols such as SIP [RFC8224].  Currently, the



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   only defined credentials for this purpose are the certificates
   specified in [RFC8226].

   [RFC8226] describes certificate extensions suitable for associating
   telephone numbers and service provider codes with certificates.
   Specifically, the TN Authorization List defined in [RFC8226]
   Section 9, defines the ability to associate a STI certificate with a
   specific set of Service Provider Codes (SPC), Telephone Numbers
   (TNs), or Telephone Number ranges (TN ranges).  Typically, these
   identifiers have been associated to a Communications Service Provider
   (CSP) that is authorized to use a set of telephone numbers or
   telephone number ranges in association with a Service Provider Code
   as defined in [RFC8226].  The SPC is a unique code or string managed
   by a national regulatory body that has the authority over those code
   associations.

2.  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].

3.  ACME new-order identifiers for TNAuthList

   In [I-D.ietf-acme-acme], Section 7.4 defines the procedure that an
   ACME client uses to order a new certificate from a Certificate
   Authority.  The new-order request contains an identifier object that
   specifies the identifiers the order corresponds to.  For the
   TNAuthList identifier, the new-order request MUST include a type set
   to the string "TNAuthList".  The value of the identifier MUST be set
   to the details of the TNAuthList requested.

   The format of the string that represents the TNAuthList MUST be
   constructed as follows.  The TNAuthList as defined in [RFC8226] can
   include three types of identifiers.

   1.  Service Provider Code (SPC) identified as "spc"

   2.  Telephone Number (TN) identified as "tn"

   3.  Telephone Number Range (TNRange) identified as "tnrange"

   The above types of identifiers and the corresponding strings should
   be used as a JSON key part of an array of JSON key and value pairs.
   The JSON value would be the string representing the corresponding
   SPC, TN, or TNRange values.





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   For example, a request for a TNAuthList certificate with a SPC value
   of "1234" and a TN value of "2155551212" would look as follows,

    "identifiers": [{"type":"TNAuthList","value":"["spc":"1234",
       "tn","2155551212"]"}]

   A full new-order request would look as follows,

   POST /acme/new-order HTTP/1.1
   Host: example.com
   Content-Type: application/jose+json

   {
     "protected": base64url({
       "alg": "ES256",
       "kid": "https://example.com/acme/acct/1",
       "nonce": "5XJ1L3lEkMG7tR6pA00clA",
       "url": "https://example.com/acme/new-order"
     }),
     "payload": base64url({
       "identifiers": [{"type:"TNAuthList","value":"["spc":"1234",
         "tn":"2155551212"]"}],
       "notBefore": "2016-01-01T00:00:00Z",
       "notAfter": "2016-01-08T00:00:00Z"
     }),
     "signature": "H6ZXtGjTZyUnPeKn...wEA4TklBdh3e454g"
   }

4.  TNAuthList Identifier Authorization

   On receiving a valid new-order request, the CA creates an
   authorization challenge and can be queried by the following example
   request and response.

   GET /acme/authz/1234 HTTP/1.1
   Host: example.com















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   HTTP/1.1 200 OK
   Content-Type: application/json
   Link: <https://example.com/acme/some-directory>;rel="index"

   {
     "status": "pending",
     "expires": "2018-03-03T14:09:00Z",

     "identifier": {
       "type:"TNAuthList",
       "value":"["spc":"1234","tn":"2155551212"]"
     },

     "challenges": [
       {
         "type": "tkauth-01",
         "tkauth-type": "ATC",
         "token-authority": "https://authority.example.org/authz",
         "url": "https://boulder.example.com/authz/asdf/0"
         "token": "IlirfxKKXAsHtmzK29Pj8A"
       }
     ]
   }

   This follows [I-D.peterson-acme-authority-token] with a specific
   identifier corresponding to the specific challenge as defined
   previously in this document.

   When processing a certificate order containing an identifier of type
   "TNAuthList", a CA MUST use the Authority Token challenge mechanism
   defined in [I-D.peterson-acme-authority-token] to verify that the
   requesting ACME client has control over the requested "TNAuthList"
   value.

   The challenge "token-authority" parameter is optional and only used
   in cases where the VoIP telephone network requires a CA to determine
   the authority.  This is currently not the case for the SHAKEN
   [ATIS-1000080] certificate framework governance, but may be used by
   other frameworks.  If a "token-authority" parameter is present, then
   the ACME client MAY use the "token-authority" value to identify the
   URL representing the authority that will provide the TNAuthList
   Authority Token response to the challenge.  If the "token-authority"
   parameter is not present, then the ACME client MUST identify the
   Authority based on locally configured information or local policies.

   A client responds to this challenge by providing an TNAuthList
   Authority Token to the CA.  The ACME client MUST respond to the
   challenge by posting the TNAuthList Authority Token to the URL



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   identified in the ACME challenge with a request, an example of which
   follows.

        POST /acme/authz/asdf/0 HTTP/1.1
        Host: sti-ca.com
        Content-Type: application/jose+json

        {
         "protected": base64url({
         "alg": "ES256",
         "kid": "https://sti-ca.com/acme/reg/asdf",
         "nonce": "Q_s3MWoqT05TrdkM2MTDcw",
         "url": "https://sti-ca.com/acme/authz/asdf/0"
        }),
         "payload": base64url({
         "ATC": "DGyRejmCefe7v4N...vb29HhjjLPSggwiE"
        }),
         "signature": "9cbg5JO1Gf5YLjjz...SpkUfcdPai9uVYYQ"
        }

   The specifics of the construction of the "ATC" token is defined in
   the next section.

5.  TNAuthList Authority Token

   The Telephone Number Authority List Authority Token (TNAuthList
   Authority Token) is an extension of the ACME Authority Token defined
   in [I-D.peterson-acme-authority-token].

   The TNAuthList Authority Token Protected header MUST comply with the
   Authority Token Protected header as defined in
   [I-D.peterson-acme-authority-token].

   The TNAuthList Authority Token Payload MUST include the claims
   defined for the Authority Token.  These are detailed in the next
   subsections.

5.1.  "iss" claim

   The "iss" claim is an optional claim.  It can be used as a URL
   identifying the Authority that issued the TNAuthList Authority Token
   beyond the "x5u" Header claim that identifies the location of the
   certificate of the Authority used to validate the Authority Token.








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5.2.  "exp" claim

   The "exp" claim contains the DateTime value of the ending time and
   date that the TNAuthList Authority Token expires.

5.3.  "jti" claim

   The "jti" claim contains a unique identifier for the TNAuthList
   Authority Token transaction.

5.4.  "atc" claim

   The "atc" claim is the only claim specifically defined in this
   document.  It contains an array of three elements; a string set to
   "TNAuthList", an identifier value which is an array of the
   identifiers to be included in the TNAuthList of the requesting SP,
   and a nonce.

   An example of the TNAuthList Authority Token is as follows,

      { "typ":"JWT",
        "alg":"ES256",
        "x5u":https://authority.example.org/cert
      }

      {
       "iss":"https://authority.example.org/authz",
       "exp":1300819380,
       "jti":"id6098364921",
       "atc":["TnAuthList","["spc":"1234","tn":"2155551212"]",
         "Q_s3MWoqT05TrdkM2MTDcw"]
      }

   Similar to how the TNAuthList identifier value is defined, the
   identifier value in the "atc" should also include the same JSON array
   of TNAuthList values with key/value pairs representing each part of
   the TNAuthList.

5.5.  Acquiring the token from the Authority

   The specifics of how the token is acquired from the authority is out
   of the scope of this document.

6.  Validating the TNAuthList Authority Token

   Upon receiving a response to the challenge, the ACME server MUST
   perform the following steps to determine the validity of the
   response.



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   o  Verify that the token contained in the Payload "ATC" field is an
      TNAuthList Authority Token.

   o  Verify the TNAuthList Authority Token signature using the public
      key of the certificate referenced by the token's "x5u" parameter.

   o  Verify that "atc" claim contains an identifier type of
      "TNAuthList",

   o  Verify that the "atc" claim contains keys and values that matches
      the keys and values of the Identifier specified in the original
      challenge.

   o  Verify that the remaining claims are valid (e.g., verify that
      token has not expired)

   If all steps in the token validation process pass, then the CA MUST
   set the challenge object "status" to "valid".  If any step of the
   validation process fails, the "status" in the challenge object MUST
   be set to "invalid".

7.  Example TNAuthList Tokens

   This section provides some TNAuthList Authority Token examples.

7.1.  Example-1

   TNAuthList Authority Token authorizing a TNAuthList containing a
   single SPC value

   {
     "typ":"JWT",
     "alg":"ES256",
     "x5u":https://authority.example.org/cert
   }

   {
     "iss":"https://authority.example.org/authz",
     "exp":1300819380,
     "jti":"id6098364921",
     "atc":["TnAuthList","["spc":"1234"]","Q_s3MWoqT05TrdkM2MTDcw"]
   }

7.2.  Example-2

   TNAuthList Authority Token authorizing a TNAuthList identifier
   containing an SPC value plus a range of TNs




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  {
    "typ":"JWT",
    "alg":"ES256",
    "x5u":https://authority.example.org/cert
  }

  {
    "iss":"https://authority.example.org/authz",
    "exp":1300819380,
    "jti":"id6098364921",
    "atc":["TnAuthList",
         ["spc":"1234","tn-range":{"start":"12155551212","count":"50"}],
         "Q_s3MWoqT05TrdkM2MTDcw"]
  }

7.3.  Example-3

   TNAuthList Authority Token authorizing a TNAuthList identifier
   containing a single TN

   {
     "typ":"JWT",
     "alg":"ES256",
     "x5u":https://authority.example.org/cert
   }

   {
     "iss":"https://authority.example.org/authz",
     "exp":1300819380,
     "jti":"id6098364921",
     "atc":["TnAuthList",
          ["tn":"12155551212"],
          "Q_s3MWoqT05TrdkM2MTDcw"]
   }

8.  Large number of Non-contiguous TNAuthList values

   There are many scenarios and reasons to have various combinations of
   SPCs, TNs, and TN Ranges.  [RFC8226] has provided a somewhat
   unbounded set of combinations.  It's possible that a complex non-
   contiguous set of telephone numbers are being managed by a CSP.  Best
   practice may be simply to split a set of non-contiguous numbers under
   management into multiple STI certificates to represent the various
   contiguous parts of the greater non-contiguous set of TNs,
   particularly if length of the set of values in identifier object
   grows to be too large.





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9.  Security Considerations

   TBD

10.  Acknowledgements

   We would like to thank you for your review of this document.

11.  References

11.1.  Normative References

   [I-D.ietf-acme-acme]
              Barnes, R., Hoffman-Andrews, J., McCarney, D., and J.
              Kasten, "Automatic Certificate Management Environment
              (ACME)", draft-ietf-acme-acme-09 (work in progress),
              December 2017.

   [I-D.peterson-acme-authority-token]
              Peterson, J., "ACME Challenges Using an Authority Token",
              draft-peterson-acme-authority-token-00 (work in progress),
              October 2017.

   [RFC7340]  Peterson, J., Schulzrinne, H., and H. Tschofenig, "Secure
              Telephone Identity Problem Statement and Requirements",
              RFC 7340, DOI 10.17487/RFC7340, September 2014,
              <https://www.rfc-editor.org/info/rfc7340>.

   [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







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

   [ATIS-1000080]
              ATIS/SIP Forum NNI Task Group, "Signature-based Handling
              of Asserted information using toKENs (SHAKEN) Governance
              Model and Certificate Management", July 2017.

   [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>.

Authors' Addresses

   Chris Wendt
   Comcast
   One Comcast Center
   Philadelphia, PA  19103
   USA

   Email: chris-ietf@chriswendt.net


   David Hancock
   Comcast

   Email: davidhancock.ietf@gmail.com


   Mary Barnes
   iconectiv

   Email: mary.ietf.barnes@gmail.com


   Jon Peterson
   Neustar Inc.
   1800 Sutter St Suite 570
   Concord, CA  94520
   US

   Email: jon.peterson@neustar.biz






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