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Versions: 00 01 draft-ietf-acme-service-provider

Network Working Group                                          M. Barnes
Internet-Draft                               MLB@Realtime Communications
Intended status: Informational                                  C. Wendt
Expires: December 4, 2017                                        Comcast
                                                            June 2, 2017


       ACME Identifiers and Challenges for VoIP Service Providers
                 draft-barnes-acme-service-provider-01

Abstract

   This document specifies identifiers and challenges required to enable
   the Automated Certificate Management Environment (ACME) to issue
   certificates for VoIP service providers to support Secure Telephony
   Identity (STI).

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
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   This Internet-Draft will expire on December 4, 2017.

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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   described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Identifier for Service Provider Codes . . . . . . . . . . . .   3
   4.  Challenges for Service Providers  . . . . . . . . . . . . . .   3
   5.  TNAuthList Identifier Code and Challenges Example . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  ACME TNAuthList Identifier  . . . . . . . . . . . . . . .   5
     6.2.  ACME Service Provider Challenge . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

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.

   The STIR problem statement [RFC7340] 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
   [I-D.ietf-stir-passport], which can be carried in using protocols
   such as SIP [I-D.ietf-stir-rfc4474bis].  Currently, the only defined
   credentials for this purpose are the certificates specified in
   [I-D.ietf-stir-certificates].

   [I-D.ietf-stir-certificates] describes certificate extensions
   suitable for associating telephone numbers and service provider codes
   with certificates.  [I-D.peterson-acme-telephone] specifies the ACME
   extensions to enable certification authorities to issue certificates
   based on telephone numbers.  This specification defines extensions to
   ACME to enable certification authorities to issue certificates based
   on service provider codes.

2.  Overview

   The document [SHAKEN_Certificate_Mgmt] provides a framework and model
   for using certificates based on service provider codes.  In this
   model, each service provider requires only a few certificates, which
   are used in conjunction with a PASSporT that contains additional
   information attesting to a service provider's knowledge of the
   originator of the call.  Further details on the PASSporT extensions
   for this model are provided in the SHAKEN Framework [ATIS-1000074].



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   In the SHAKEN Certificate Management framework, there is an
   administrative entity that is responsible for allocating service
   provider codes.  This is referred to as the STI Policy Administrator
   (STI-PA).  This allows a certification authority to validate that the
   entity requesting issuance of a certificate is authorized to request
   certificates on behalf of the entity that has been assigned a
   specific service provider code.  A single VoIP service provider can
   be allocated multiple service provider codes.  A service provider can
   choose to use the same certificate for multiple service providers as
   reflected by the structure of the TN Authorization List certificate
   extension defined in [I-D.ietf-stir-certificates].

   The intent of the challenges in this document is not to establish
   that an entity is a valid service provider but rather to provide
   evidence that an established governance entity has authorized the
   entity to provide VoIP services in the network and thus to request
   credentials on behalf of the VoIP users in the network.

3.  Identifier for Service Provider Codes

   In order to issue certificates for service providers based on service
   provider code values, a new ACME identifier type is required for use
   in ACME authorization objects.  The baseline ACME specification
   defines one type of identifier, for a fully-qualified domain name
   ("dns").  The document [I-D.peterson-acme-telephone] defines an ACME
   identifier type for telephone numbers ("tn").  This document defines
   a new ACME identifier type for service provider codes ("TNAuthList").
   The "TNAuthList" identifier is the same type that is specified in the
   TN Authorization List certificate extension
   [I-D.ietf-stir-certificates] for service provider codes.  An example
   is provided in Section 5.

4.  Challenges for Service Providers

   The new "TNAuthList" identifier introduces a slightly different
   authorization process.  A mechanism is required to allow the service
   provider to prove it has the authority to request certificates on
   behalf of the entities for whom it is providing VoIP services.

   The STI-PA in the SHAKEN Certificate Management framework has a
   secure exchange with the Service Provider in order to provide a
   service provider code token that the Service Provider can use for
   authorization by the CA when requesting a certificate.  The service
   provider code token ("spc-token") is a standard JWT token [RFC7519]
   using a JWS defined signature string [RFC7515].  Note that further
   details on the CA interface to the STI-PA for the authorization are
   provided in [SHAKEN_Certificate_Mgmt].




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   This document defines a new ACME challenges type of "spc-token" to
   support the SHAKEN Certificate Management framework.  An example of
   the use of the "spc-token" for ACME is provided in Section 5.

5.  TNAuthList Identifier Code and Challenges Example

   The section provides examples of the use of the TNAuthList identifier
   as a challenge mechanism.

   The following is the response that the ACME client receives when it
   sends a GET for the challenges:

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

   {
     "status": "pending",

     "identifier": {
     "type": "TNAuthList",
     "value": ["1234-0111"]
      },

      "challenges": [
      {
        "type": "spc-token",
        "url": "https://sti-ca.com/authz/asdf/0"
        "token": "DGyRejmCefe7v4NfDGDKfA" }
      ],
   }




















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   The following is the response to the challenge sent by the ACME
   client:


           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({
            "type": "spc-token",
            "keyAuthorization": "IlirfxKKXA...vb29HhjjLPSggwiE"
           }),
            "signature": "9cbg5JO1Gf5YLjjz...SpkUfcdPai9uVYYQ"
           }



6.  IANA Considerations

   This document defines a new ACME Identifier type and ACME Challenge
   type to be registered.

   [[ RFC EDITOR: Please replace XXXX above with the RFC number assigned
   to this document ]]

6.1.  ACME TNAuthList Identifier

   This document defines the "TNAuthList" ACME Challenge type in the
   ACME Identifier Type registry as follows:


                  +-----------------------+-----------+
                  | Identifier Type       | Reference |
                  +-----------------------+-----------+
                  | TNAuthList            | RFC XXXX  |
                  +-----------------------+-----------+








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6.2.  ACME Service Provider Challenge

   This document defines the "spc-token" ACME Challenge type in the ACME
   Challenge Types registry as follows:

                  +-----------+--------------------+-----------+
                  | Label     | Identifier Type    | Reference |
                  +-----------+--------------------+-----------+
                  | spc-token | TNAuthList         | RFC XXXX  |
                  +-----------+--------------------+-----------+



7.  Security Considerations

   This document relies on the security considerations established for
   the ACME protocol per [I-D.ietf-acme-acme].  The new "TNAuthList"
   identifier and "spc-token" validation challenges introduce a slightly
   different authorization process.  Although, the challenges still have
   a binding between the account private key and the validation query
   made by the server, via the key authorization.

   The "spc-token" is initially obtained through a secure exchange
   between the service provider and the entity in the network that is
   responsible for determining what entities can operate as VoIP service
   providers (the STI Policy Administrator).  Further details on this
   are provided in [SHAKEN_Certificate_Mgmt].

8.  Informative References

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

   [I-D.ietf-acme-acme]
              Barnes, R., Hoffman-Andrews, J., and J. Kasten, "Automatic
              Certificate Management Environment (ACME)", draft-ietf-
              acme-acme-06 (work in progress), March 2017.

   [I-D.ietf-stir-certificates]
              Peterson, J. and S. Turner, "Secure Telephone Identity
              Credentials: Certificates", draft-ietf-stir-
              certificates-14 (work in progress), May 2017.







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   [I-D.ietf-stir-passport]
              Wendt, C. and J. Peterson, "Personal Assertion Token
              (PASSporT)", draft-ietf-stir-passport-11 (work in
              progress), February 2017.

   [I-D.ietf-stir-rfc4474bis]
              Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
              "Authenticated Identity Management in the Session
              Initiation Protocol (SIP)", draft-ietf-stir-rfc4474bis-16
              (work in progress), February 2017.

   [I-D.peterson-acme-telephone]
              Peterson, J. and R. Barnes, "ACME Identifiers and
              Challenges for Telephone Numbers", draft-peterson-acme-
              telephone-00 (work in progress), October 2016.

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

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

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <http://www.rfc-editor.org/info/rfc7515>.

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

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

Authors' Addresses

   Mary Barnes
   MLB@Realtime Communications

   Email: mary.ietf.barnes@gmail.com






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   Chris Wendt
   Comcast
   One Comcast Center
   Philadelphia, PA  19103
   US

   Email: chris-ietf@chriswendt.net












































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