CDNI extensions for HTTPS delegation
draft-ietf-cdni-interfaces-https-delegation-07

CDNI Working Group                                         F. Fieau, Ed.
Internet-Draft                                                E. Stephan
Intended status: Standards Track                                  Orange
Expires: 28 April 2022                                         S. Mishra
                                                                 Verizon
                                                         25 October 2021

                  CDNI extensions for HTTPS delegation
             draft-ietf-cdni-interfaces-https-delegation-07

Abstract

   The delivery of content over HTTPS involving multiple CDNs raises
   credential management issues.  This document defines metadata in CDNI
   Control and Metadata interface to setup HTTPS delegation from an
   Upstream CDN (uCDN) to a Downstream CDN (dCDN).

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on 28 April 2022.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Known delegation methods  . . . . . . . . . . . . . . . . . .   3
   4.  Delegation metadata for CDNI FCI  . . . . . . . . . . . . . .   3
   5.  Delegation metadata for CDNI  . . . . . . . . . . . . . . . .   4
     5.1.  Usage example related to an HostMatch object  . . . . . .   4
     5.2.  AcmeStarDelegationMethod object . . . . . . . . . . . . .   5
   6.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  CDNI MI AcmeStarDelegationMethod Payload Type . . . . . .   8
     6.2.  CDNI FCI SupportedDelegationMethods Payload Type  . . . .   8
   7.  Security considerations . . . . . . . . . . . . . . . . . . .   8
   8.  Privacy considerations  . . . . . . . . . . . . . . . . . . .   8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Content delivery over HTTPS using one or more CDNs along the path
   requires credential management.  This specifically applies when an
   entity delegates delivery of encrypted content to another trusted
   entity.

   Several delegation methods are currently proposed within different
   IETF working groups.  They specify different methods for provisioning
   HTTPS delivery credentials.

   This document extends the CDNI Metadata interface to setup HTTPS
   delegation between an upstream CDN (uCDN) and downstream CDN (dCDN)
   using the Standardized delegation methods.  Furthermore, it includes
   a proposal of IANA registry to enable adding of new methods.

   Section 2 is about terminology used in this document.  Section 3
   presents delegation methods specified at the IETF.  Section 4
   addresses the extension for handling HTTPS delegation in CDNI.
   Section 5 describes simple data types.  Section 6 addresses IANA
   registry for delegation methods.  Section 7 covers the security
   issues.  Section 8 is about comments and questions.

2.  Terminology

   This document uses terminology from CDNI framework documents such as:
   CDNI framework document [RFC7336], CDNI requirements [RFC7337] and
   CDNI interface specifications documents: CDNI Metadata interface
   [RFC8006] and CDNI Control interface / Triggers [RFC8007].

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3.  Known delegation methods

   There are currently Internet drafts within the TLS and ACME working
   groups adopted to handle delegation of HTTPS delivery between
   entities.

   This Internet Draft (I-D) proposes standardizing HTTPS delegation
   between the CDN entities using CDNI interfaces.

   This document only considers the Short-term, Automatically-Renewed
   (STAR) certificates in Automated Certificate Management
   Environment(ACME) [RFC8739]

   This document allows the extension to other delegation methods.
   Those methods can easily be extended to any further methods in the
   future.

4.  Delegation metadata for CDNI FCI

   In order for CDNs to negotiate on which methods are supported, the
   Footprint and Capabilities interface as defined in RFC8008, allows a
   uCDN to send a FCI capability type objects, named
   FCI.SupportedDelegationMethods, to dCDN.

   The following example shows an exemple of the supported delegated
   methods capability object serialization for a CDN that supports STAR
   delegation method.

        {
        "capabilities": [
          {
            "capability-type": "FCI.SupportedDelegationMethods",
            "capability-value": {
              "delegation-methods": [
                       "AcmeStarDelegationDelegationMethod",
                       "... Other delegation methods ..."
              ]
            }
            "footprints": [
              <Footprint objects>
            ]
          }
        ]
      }

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5.  Delegation metadata for CDNI

   This section defines Delegation metadata using the current Metadata
   interface model.  This allows bootstrapping delegation methods
   between a uCDN and a delegate dCDN.

5.1.  Usage example related to an HostMatch object

   This section presents the use of CDNI Delegation metadata of an
   HostMatch object, as defined in [RFC8006] as specified in the
   following sections.

   The existence of the delegation methods in metadata in a CDNI Object
   shall enable the use of one of this methods, chosen by the delegating
   entity.  In the case of an HostMatch object, the delegation method
   will be activated for the set of Host defined in the HostMatch.  See
   Section 5.2 for more details about delegation methods metadata
   specification.

   The HostMatch object can reference a host metadata that points at the
   delegation information.  Delegation metadata are added to a Metadata
   object.

   Below shows both HostMatch its Metadata related to a host, for
   example, here is a HostMatch object referencing "video.example.com":

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   HostMatch:
      {
        "host": "video.example.com",
        "host-metadata": {
          "type": "MI.HostMetadata",
          "href": "https://metadata.ucdn.example/host1234"
        }
      }

   Following the example above, the metadata can be modeled
   for ACMEStarDelegationMethod as:

           {
       "metadata": [
               {
           "generic-metadata-type": "MI.AcmeStarDelegationMethod",
           "generic-metadata-value": {
              "star-proxy": "10.2.2.2",
              "acme-server" : "10.2.3.3",
              "credentials-location-uri": “www.ucdn.com/credentials",
              "periodicity": 36000,
              "CSR-template": Json/Text of the CSR template (see 4.2)
               }}]
           }

   This extension allows to explicitly indicate support for a given
   method.  Therefore, the presence (or lack thereof) of an
   AcmeStarDelegationMethod, and/or further delegation methods, implies
   support (or lack thereof) for the given method.

   Those metadata can apply to other MI objects such as PathMatch object
   metadata.

5.2.  AcmeStarDelegationMethod object

   This section defines the AcmeStarDelegationMethod object which
   describes metadata related to the use of ACME/STAR API presented in
   [RFC8739]

   As expressed in [RFC8739], when an origin has set a delegation to a
   specific domain (i.e. dCDN), the dCDN should present to the end-user
   client, a short-term certificate bound to the master certificate.

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dCDN                  uCDN             Content Provider           CA
 |              ACME/STAR proxy        ACME/STAR client    ACME/STAR srv
 |                     |                     |                     |
 | 1. GET Metadata incl. Delegation Method object with CSR template|
 +-------------------->|                     |                     |
 | 200 OK + Metadata incl. CSR template [CDNI]                     |
 |<--------------------+                     |                     |
 | 2. Request delegation: video.dcdn.example + dCDN public key     |
 +-------------------->|                     |                     |
 |                     | 3. Request STAR Cert + dCDN public key    |
 |                     +-------------------->| 4. Request STAR cert|
 |                     |                     |    + Pubkey         |
 |                     |                     |-------------------->|
 |                     |                     | 5. STAR certificate |
 |                     | 6. STAR certificate |<--------------------|
 | 7. STAR certificate |<--------------------+                     |
 +<--------------------|                     |                     |
 |                     |                     |                     |
 | 8. Retrieve STAR certificate (credential-location-uri)          |
 +---------------------------------------------------------------->|
 |                     |                     |         9. renew +--|
 |                     |                     |            cert  |  |
 | 10. Star certificate                      |                  +->|
 |<----------------------------------------------------------------+
 |  ...                |                     |                     |

Figure 1: Example call-flow of STAR delegation in CDNI showing 2 levels
of delegation

   Property: star-proxy

      Description: Used to advertise the STAR Proxy to the dCDN.
      Endpoint type defined in RFC8006, Section 4.3.3.

      Type: Endpoint

      Mandatory-to-Specify: Yes

   Property: acme-server

      Description: used to advertise the ACME server to the dCDN.
      Endpoint type is defined in RFC8006, Section 4.3.3.

      Type: Endpoint

      Mandatory-to-Specify: Yes

   Property: credentials-location-uri

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      Description: expresses the location of the credentials to be
      fetched by the dCDN.  Link type is as defined in RFC8006,
      Section 4.3.1.

      Type: Link

      Mandatory-to-Specify: Yes

   Property: periodicity

      Description: expresses the credentials renewal periodicity.

      Type: Integer

      Mandatory-to-Specify: Yes

   Property: CSR-template

      Description: The CSR template must be included in the metadata
      when dealing with AcmeStarDelegation Methods.  It shall follow the
      description in [RFC8739] section 3.  It should be included in
      JSON/text format.

      Type: JSON

      Mandatory-to-Specify: Yes

6.  IANA considerations

   This document requests the registration of the following entries
   under the "CDNI Payload Types" registry hosted by IANA regarding
   "CDNI delegation":

   +-------------------------------+---------------+
   | Payload Type                  | Specification |
   +-------------------------------+---------------+
   | MI.AcmeStarDelegationMethod   | RFCthis       |
   +-------------------------------+---------------+
   | FCI.SupportedDelegationMethods| RFCthis       |
   +-------------------------------+---------------+

   [RFC Editor: Please replace RFCthis with the published RFC number for
      this document.]

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6.1.  CDNI MI AcmeStarDelegationMethod Payload Type

   Purpose: The purpose of this Payload Type is to distinguish
   AcmeStarDelegationMethod MI objects (and any associated capability
   advertisement)

   Interface: MI

   Encoding: see Section 5

6.2.  CDNI FCI SupportedDelegationMethods Payload Type

   Purpose: The purpose of this Payload Type is to distinguish
   SupportedDelegationMethods FCI objects (and any associated capability
   advertisement)

   Interface: FCI

   Encoding: see Section 4

7.  Security considerations

   Extensions proposed here do not alter nor change Security
   Considerations as outlined in the CDNI Metadata and Footprint and
   Capabilities RFCs [RFC8006].

   However there are still some security questions that should be
   addressed such as: Are there concerns about using this incorrectly or
   limitations on how this can safely be used?

8.  Privacy considerations

   Some privacy questions are still pending: Are there any concerns with
   sharing the information that is in the metadata?  Is the metadata
   safe to redistribute, or is it something that is only valid between
   adjacent CDNs?

9.  References

9.1.  Normative References

   [RFC8006]  Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma,
              "Content Delivery Network Interconnection (CDNI)
              Metadata", RFC 8006, DOI 10.17487/RFC8006, December 2016,
              <https://www.rfc-editor.org/info/rfc8006>.

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   [RFC8007]  Murray, R. and B. Niven-Jenkins, "Content Delivery Network
              Interconnection (CDNI) Control Interface / Triggers",
              RFC 8007, DOI 10.17487/RFC8007, December 2016,
              <https://www.rfc-editor.org/info/rfc8007>.

   [RFC8739]  Sheffer, Y., Lopez, D., Gonzalez de Dios, O., Pastor
              Perales, A., and T. Fossati, "Support for Short-Term,
              Automatically Renewed (STAR) Certificates in the Automated
              Certificate Management Environment (ACME)", RFC 8739,
              DOI 10.17487/RFC8739, March 2020,
              <https://www.rfc-editor.org/info/rfc8739>.

9.2.  Informative References

   [RFC7336]  Peterson, L., Davie, B., and R. van Brandenburg, Ed.,
              "Framework for Content Distribution Network
              Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336,
              August 2014, <https://www.rfc-editor.org/info/rfc7336>.

   [RFC7337]  Leung, K., Ed. and Y. Lee, Ed., "Content Distribution
              Network Interconnection (CDNI) Requirements", RFC 7337,
              DOI 10.17487/RFC7337, August 2014,
              <https://www.rfc-editor.org/info/rfc7337>.

Authors' Addresses

   Frederic Fieau (editor)
   Orange
   40-48, avenue de la Republique
   92320 Chatillon
   France

   Email: frederic.fieau@orange.com

   Emile Stephan
   Orange
   2, avenue Pierre Marzin
   22300 Lannion
   France

   Email: emile.stephan@orange.com

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   Sanjay Mishra
   Verizon
   13100 Columbia Pike
   Silver Spring,  MD 20904
   United States of America

   Email: sanjay.mishra@verizon.com

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