CDNI Working Group F.F. Fieau, Ed.
Internet-Draft E.S. Stephan
Intended status: Standards Track Orange
Expires: 14 March 2022 S.M. Mishra
Verizon
10 September 2021
CDNI extensions for HTTPS delegation
draft-ietf-cdni-interfaces-https-delegation-06
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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Known delegation methods . . . . . . . . . . . . . . . . . . 3
4. Extension to CDNI FCI . . . . . . . . . . . . . . . . . . . . 3
5. Extending the CDNI metadata model . . . . . . . . . . . . . . 4
5.1. Extension to HostMetadata object . . . . . . . . . . . . 4
5.2. Extension to PathMetadata object . . . . . . . . . . . . 5
6. AcmeStarDelegationMethod object . . . . . . . . . . . . . . . 6
7. Metadata Simple Data Type Descriptions . . . . . . . . . . . 8
7.1. Periodicity . . . . . . . . . . . . . . . . . . . . . . . 8
8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8
8.1. CDNI MI AcmeStarDelegationMethod Payload Type . . . . . . 9
9. Security considerations . . . . . . . . . . . . . . . . . . . 9
10. Comments and questions . . . . . . . . . . . . . . . . . . . 9
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
11.1. Normative References . . . . . . . . . . . . . . . . . . 9
11.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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.
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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 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. Extension to 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.
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{
"capabilities": [
{
"capability-type": "FCI.SupportedDelegationMethods",
"capability-value": {
"delegation-methods": [
"AcmeStarDelegationDelegationMethod",
"... Other delegation methods ..."
]
}
"footprints": [
<Footprint objects>
]
}
]
}
5. 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.
5.1. Extension to HostMetadata object
This extension reuses HostMetadata object, as defined in [RFC8006],
and adds new "Delegation methods" objects as specified in the
following sections.
The existence of the delegation methods in a HostMetaData Object
shall enable the use of one of this methods, chosen by the delegating
entity. The delegation method will be activated for the set of Host
defined in the HostMatch. See Section 6 for more details about
delegation methods metadata specification.
Example:
The HostMatch object can reference a host metadata that points at the
delegation information. Delegation metadata are added to
HostMetadata object.
Below shows both HostMatch and HostMetadata objects 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 HostMetadata can be modeled
for ACMEStarDelegationMethod as:
{
"hostmetadata": [
{
"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.
5.2. 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, and/or further delegation methods, implies
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.
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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 of 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 6 for more details about delegation
methods metadata specification.
6. AcmeStarDelegationMethod object
This section defines the AcmeStarDelegationMethod object which
describes metadata related to the use of ACME/STAR API presented in
[RFC8739]
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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.
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
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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 7.1.
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 [RFC8739] section 3. It should be included in
JSON/text format.
Type: JSON
Mandatory-to-Specify: Yes
7. Metadata Simple Data Type Descriptions
This section describes the simple data types that are used for
properties for objects in this document.
7.1. Periodicity
A time value expressed in seconds to indicate a periodicity.
Type: Integer
8. IANA considerations
This document requests the registration of the following entries
under the "CDNI Payload Types" registry hosted by IANA regarding
"CDNI delegation":
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+-------------------------------+---------------+
| Payload Type | Specification |
+-------------------------------+---------------+
| MI.AcmeStarDelegationMethod | RFCthis |
+-------------------------------+---------------+
[RFC Editor: Please replace RFCthis with the published RFC number for
this document.]
8.1. 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
9. Security considerations
Extensions proposed here do not alter nor change Security
Considerations as outlined in the CDNI Metadata and Footprint and
Capabilities RFCs [RFC8006].
10. 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.
11. References
11.1. 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>.
[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>.
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[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>.
11.2. 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
Sanjay Mishra
Verizon
13100 Columbia Pike
Silver Spring, MD 20904
United States of America
Email: sanjay.mishra@verizon.com
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