CDNI Working Group F. Fieau, Ed. Internet-Draft E. Stephan Intended status: Standards Track Orange Expires: September 10, 2020 S. Mishra Verizon March 09, 2020 CDNI extensions for HTTPS delegation draft-ietf-cdni-interfaces-https-delegation-03 Abstract The delivery of content over HTTPS involving multiple CDNs raises credential management issues. This document proposes extensions in CDNI Control and Metadata interfaces 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 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/. 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Expires September 10, 2020 [Page 1] Internet-Draft CDNI extensions for HTTPS delegation March 2020 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. Known delegation methods . . . . . . . . . . . . . . . . . . 3 4. Extending the CDNI metadata model . . . . . . . . . . . . . . 3 4.1. Extension to PathMetadata object . . . . . . . . . . . . 3 4.2. Delegation methods . . . . . . . . . . . . . . . . . . . 4 4.2.1. AcmeStarDelegationMethod object . . . . . . . . . . . 5 4.2.2. SubcertsDelegationMethod object . . . . . . . . . . . 6 5. Metadata Simple Data Type Descriptions . . . . . . . . . . . 8 5.1. Periodicity . . . . . . . . . . . . . . . . . . . . . . . 8 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8 6.1. CDNI MI AcmeStarDelegationMethod Payload Type . . . . . . 9 6.2. CDNI MI SubCertsDelegationMethod Payload Type . . . . . . 9 7. Security considerations . . . . . . . . . . . . . . . . . . . 9 8. Comments and questions . . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . 10 9.2. Informative References . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 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. Fieau, et al. Expires September 10, 2020 [Page 2] Internet-Draft CDNI extensions for HTTPS delegation March 2020 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]. 3. Known delegation methods There are currently two 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 entities using CDNI interfaces. This document considers the following two I-Ds that deals with HTTPS delegation: - Sub-certificates [I-D.ietf-tls-subcerts] in the TLS Working Group. - Short-term, Automatically-Renewed (STAR) certificates in Automated Certificate Management Environment(ACME) [I-D.ietf-acme-star] 4. Extending the CDNI metadata model This section defines a CDNI extension to the current Metadata interface model that allows bootstrapping delegation methods between a uCDN and a delegate dCDN. 4.1. Extension to PathMetadata object This extension reuses PathMetadata object, as defined in [RFC8006], and adds new "Delegation methods" objects as specified in the following sections. This allows to explicitly indicate support for a given method. Therefore, the presence (or lack thereof) of an AcmeStarDelegationMethod, SubcertsDelegationMethod, and/or further delegation methods, imply support (or lack thereof) for the given method. Example: The PathMatch object can reference a path-metadata that points at the delegation information. Delegation metadata are added to PathMetaData object. Fieau, et al. Expires September 10, 2020 [Page 3] Internet-Draft CDNI extensions for HTTPS delegation March 2020 Below shows both PathMatch and PathMetaData objects related to a path, for example, here /movies/* located at https://metadata.ucdn.example/video.example.com/movies PathMatch: { "path-pattern": { "pattern": "/movies/*", "case-sensitive": true }, "path-metadata": { "type": "MI.PathMetadata", "href": "https://metadata.ucdn.example/video.example.com/movies" } } Following the example above, the PathMetadata can be modeled for ACMEStarDelegationMethod as: PathMetadata: { "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 representing the CSR template (see section 4.2) }}] } The existence of the "MI.AcmeStarDelegationMethod" object in a PathMetaData Object shall enable the use of one of the AcmeStarDelegation Methods, chosen by the delegating entity. The delegation method will be activated for the set of Path defined in the PathMatch. See Section 4.2 for more details about delegation methods metadata specification. 4.2. Delegation methods This section defines the delegation methods objects metadata. Those metadata allows bootstrapping a secured delegation by providing the dCDN with the needed parameters to set it up. Fieau, et al. Expires September 10, 2020 [Page 4] Internet-Draft CDNI extensions for HTTPS delegation March 2020 4.2.1. AcmeStarDelegationMethod object This section defines the AcmeStarDelegationMethod object which describes metadata related to the use of ACME/STAR API presented in [I-D.ietf-acme-star] As expressed in [I-D.ietf-acme-star], 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. dCDN uCDN Content Provider CA | ACME/STAR proxy ACME/STAR client ACME/STAR Server | | | | | 1. GET Metadata incl. Delegation Method object with CSR template [CDNI] +-------------------->| | | | 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 Fieau, et al. Expires September 10, 2020 [Page 5] Internet-Draft CDNI extensions for HTTPS delegation March 2020 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 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. See Section 5.1. Type: Periodicity 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 [I-D.ietf-acme-star-delegation] section 3. It should be included in JSON/text format. Type: JSON Mandatory-to-Specify: Yes 4.2.2. SubcertsDelegationMethod object This section defines the SubcertsDelegationMethod object which describes metadata related to the use of Subcerts as presented in [I-D.ietf-tls-subcerts] Fieau, et al. Expires September 10, 2020 [Page 6] Internet-Draft CDNI extensions for HTTPS delegation March 2020 Client dCDN uCDN Content | | | Provider | | | | | | | Certificate | | | |<--------------------| | | GET Metadata incl. Subcerts method obj | | +-------------------->| | | | 200 OK + Metadata | | | |<--------------------+ | | | Get Subcert | | | +-------------------->| | | | Subcert | | | |<--------------------+ | | Client Hello + Subcert support | | +-------------------->| | | | Server Hello + Subcert | | |<--------------------| | | | Certificate | | | |<--------------------| | | | TLS ServerKeyExchange | | |<--------------------| | | | TLS ClientKeyExchange | | |<--------------------| | | | TLS Finished | | | |<--------------------| | | | | | | Figure 2: Example call-flow of SubCert delegation in CDNI As expressed in [I-D.ietf-tls-subcerts], when an origin has set a delegation to a downstream entity such as a downstream CDN (i.e. dCDN), the dCDN should present the Origin or uCDN certificate or "delegated_credential" during the TLS handshake [RFC8446] to the end- user client application, instead of its own certificate. Property: credentials-delegating-entity Description: Endpoint ID (IP) of the delegating Entity (uCDN). Endpoint type defined in RFC8006, Section 4.3.3. Type: Endpoint Mandatory-to-Specify: Yes Property: credential-recipient-entity Fieau, et al. Expires September 10, 2020 [Page 7] Internet-Draft CDNI extensions for HTTPS delegation March 2020 Description: Endpoint ID (IP) of the delegated entity (dCDN). Endpoint type is defined in RFC8006, Section 4.3.3. Type: Endpoint Mandatory-to-Specify: Yes Property: credentials-location-uri 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. See Section 5.1. Type: Periodicity Mandatory-to-Specify: Yes 5. Metadata Simple Data Type Descriptions This section describes the simple data types that are used for properties for objects in this document. 5.1. Periodicity A time value expressed in seconds to indicate a periodicity. Type: Integer 6. IANA considerations This document requests the registration of the following entries under the "CDNI Payload Types" registry hosted by IANA regarding "CDNI delegation": Fieau, et al. Expires September 10, 2020 [Page 8] Internet-Draft CDNI extensions for HTTPS delegation March 2020 +----------------------------+---------------+ | Payload Type | Specification | +----------------------------+---------------+ | MI.AcmeStarDelegationMethod| RFCthis | | MI.SubCertDelegationMethod | RFCthis | +----------------------------+---------------+ [RFC Editor: Please replace RFCthis with the published RFC number for this document.] 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/FCI Encoding: see Section 4.2.1 6.2. CDNI MI SubCertsDelegationMethod Payload Type Purpose: The purpose of this Payload Type is to distinguish SubcertsDelegationMethod MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.2 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]. 8. Comments and questions Should dCDN be visible from the Content Provider or not? This would lead to different solutions to handle delegation towards the CP. In most cases, the dCDNs should never be visible to the CP, in order to reduce the burden of certificates generation for dCDN. Fieau, et al. Expires September 10, 2020 [Page 9] Internet-Draft CDNI extensions for HTTPS delegation March 2020 9. References 9.1. Normative References [I-D.ietf-acme-star] Sheffer, Y., Lopez, D., Dios, O., Pastor, A., and T. Fossati, "Support for Short-Term, Automatically-Renewed (STAR) Certificates in Automated Certificate Management Environment (ACME)", draft-ietf-acme-star-11 (work in progress), October 2019. [I-D.ietf-acme-star-delegation] Sheffer, Y., Lopez, D., Pastor, A., and T. Fossati, "An ACME Profile for Generating Delegated STAR Certificates", draft-ietf-acme-star-delegation-03 (work in progress), March 2020. [I-D.ietf-tls-subcerts] Barnes, R., Iyengar, S., Sullivan, N., and E. Rescorla, "Delegated Credentials for TLS", draft-ietf-tls- subcerts-06 (work in progress), February 2020. [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, . [RFC8007] Murray, R. and B. Niven-Jenkins, "Content Delivery Network Interconnection (CDNI) Control Interface / Triggers", RFC 8007, DOI 10.17487/RFC8007, December 2016, . 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, . [RFC7337] Leung, K., Ed. and Y. Lee, Ed., "Content Distribution Network Interconnection (CDNI) Requirements", RFC 7337, DOI 10.17487/RFC7337, August 2014, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . Fieau, et al. Expires September 10, 2020 [Page 10] Internet-Draft CDNI extensions for HTTPS delegation March 2020 Authors' Addresses Frederic Fieau (editor) Orange 40-48, avenue de la Republique Chatillon 92320 France Email: frederic.fieau@orange.com Emile Stephan Orange 2, avenue Pierre Marzin Lannion 22300 France Email: emile.stephan@orange.com Sanjay Mishra Verizon 13100 Columbia Pike Silver Spring MD 20904 USA Email: sanjay.mishra@verizon.com Fieau, et al. Expires September 10, 2020 [Page 11]