Internet DRAFT - draft-ietf-cdni-delegation-acme
draft-ietf-cdni-delegation-acme
Content Delivery Networks Interconnection F. Fieau, Ed.
Internet-Draft E. Stephan
Intended status: Standards Track Orange
Expires: 2 August 2024 S. Mishra
Verizon
30 January 2024
CDNI delegation using Automated Certificate Management Environment
draft-ietf-cdni-delegation-acme-05
Abstract
This document defines metadata to support delegating the delivery of
HTTPS content between two or more interconnected Content Delivery
Networks (CDNs). Specifically, this document defines a Content
Delivery Network Interconnection (CDNI) Metadata interface object to
enable delegation of X.509 certificates leveraging delegation schemes
defined in RFC9115. Per RFC 9115, delegating entities can remain in
full control of the delegation and can revoke it at any time. This
avoids the need to share private cryptographic key material between
the involved entities.
About This Document
This note is to be removed before publishing as an RFC.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-ietf-cdni-delegation-acme/.
Discussion of this document takes place on the Content Delivery
Networks Interconnection Working Group mailing list
(mailto:cdni@ietf.org), which is archived at
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https://www.ietf.org/mailman/listinfo/cdni/.
Source for this draft and an issue tracker can be found at
https://github.com/FredericFi/cdni-wg.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Advertising Delegation Metadata for CDNI through FCI . . . . 3
3. ACME Delegation Metadata for CDNI . . . . . . . . . . . . . 4
3.1. ACMEDelegationMethod Object . . . . . . . . . . . . . . . 6
3.1.1. Examples . . . . . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . 8
4.1. CDNI MI ACMEDelegationMethod Payload Type . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1. Normative References . . . . . . . . . . . . . . . . . . 9
6.2. Informative References . . . . . . . . . . . . . . . . . 10
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Content delivery over HTTPS using two or more cooperating CDNs along
the path requires credential management, specifically when DNS-based
redirection is used. In such cases, an upstream CDN (uCDN) needs to
delegate its credentials to a downstream (dCDN) for content delivery.
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[RFC9115] defines delegation methods that allow a uCDN on behalf of
the content provider, the holder of the domain, to generate on-demand
an X.509 certificate that binds the designated domain name with a
key-pair owned by the dCDN. For further details, please refer to
Section 1 of [RFC9115] and Section 5.1.2.1 of [RFC9115].
This document defines CDNI Metadata to make use of HTTPS delegation
between a uCDN and a dCDN based on the mechanism specified in
[RFC9115]. Furthermore, it adds a delegation method to the "CDNI
Payload Types" IANA registry.
Section 2 presents delegation metadata for the Footprint &
Capabilities Advertisement interface (FCI). Section 3 addresses the
metadata for handling HTTPS delegation with the Metadata Interface.
1.1. Terminology
This document uses terminology from CDNI framework documents such as:
CDNI framework document [RFC7336] and CDNI interface specifications
documents: CDNI Metadata interface [RFC8006] and CDNI Footprint and
Capabilities Advertisement interface [RFC8008]. It also uses
terminology from Section 1.2 of [RFC8739] and Section 1.1 of
[RFC9115], including Short-Term, Automatically Renewed (STAR), as
applied to X.509 certificates.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Advertising Delegation Metadata for CDNI through FCI
The Footprint and Capabilities Advertisement interface (FCI) defined
in [RFC8008] allows a dCDN to send a FCI capability type object to a
uCDN.
This document uses the CDNI Metadata capability object serialization
from [RFC8008] for a CDN that supports delegation methods.
The following is an example of the supported delegated methods
capability object for a dCDN implementing the ACME delegation method.
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{
"capabilities": [
{
"capability-type": "FCI.Metadata",
"capability-value": {
"metadata": [
// list of supported delegation methods
"ACMEDelegationMethod"
]
},
"footprints": [
"Footprint objects"
]
}
]
}
3. ACME Delegation Metadata for CDNI
When a uCDN delegates the delivery of HTTPS traffic to a dCDN using
DNS Redirection [RFC7336], the dCDN must use a certificate bound to
the origin's name to successfully authenticate to the end-user (see
also Section 5.1.2.1 of [RFC9115]).
To that end, this section defines the AcmeDelegationMethod object
which describes metadata for using the ACME delegation interface
[RFC9115].
The ACMEDelegationMethod applies to both ACME STAR delegation, which
provides a delegation model based on short-term certificates with
automatic renewal (Section 2.3.2 of [RFC9115]), and non-STAR
delegation, which allows delegation between CDNs using long-term
certificates (Section 2.3.3 of [RFC9115]).
Figure 1 provides a high-level view of the combined CDNI and ACME
delegation message flows to obtain STAR certificate from the
Certificate Authority (CA) bound to the Content Provider's (CP) name.
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.----. .----. .----. .----.
|dCDN| |uCDN| | CP | | CA |
'-+--' '-+--' '--+-' '--+-'
| GET metadata | | |
+--------[CDNI]------>| | |
| 200 OK, metadata | | |
| (inc. dele config) | | |
|<-------[CDNI]-------+ | |
| | | |
| GET delegation | | |
+-----[ACME dele]---->| | |
| 200 OK, delegation | | |
| (inc. CSR template) | | |
|<----[ACME dele]-----+ | |
| | | |
+----. | | |
| | | | |
| create key pair and| | |
| CSR w/ delegated | | |
| name | | |
| | | | |
|<---' | | |
| | | |
| POST Order1 | | |
+-----[ACME dele]---->| | |
| | forward Order1 | |
| +-----[ACME dele]---->| |
| | | POST Order2 |
| | +-----[ACME STAR]----->|
| | | |
| | |<---authorizations--->|
| | | |
|<---wait issuance--->|<---wait issuance--->|<---wait issuance---->|
| |
| (unauthenticated) GET star-certificate |
+----------------------------------------------------------------->|
| certificate #1 |
|<-----------------------------------------------------------------+
| ... |
Figure 1: Example call-flow of STAR delegation in CDNI showing 2
levels of delegation
| Note: The delegation object defined in Section 2.3.1.3 of
| [RFC9115] only allows DNS mappings to be specified using CNAME
| RRs. A future document updating [RFC9115] could expand the
| delegation object to also include SVCB/HTTPS-based [RFC9460]
| mappings.
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Section 3.1 defines the objects used for bootstrapping the ACME
delegation method between a uCDN and a delegate dCDN.
3.1. ACMEDelegationMethod Object
The ACMEDelegationMethod object allows a uCDN to define both STAR and
non-STAR delegation. The dCDN, the consumer of the delegation, can
determine the type of delegation by the presence (or absence) of the
"lifetime" property. That is, the presence of the "lifetime"
property explicitly means a short-term delegation with lifetime of
the certificate based on that property (and the optional "lifetime-
adjust" attribute). A non-STAR delegation will not have the
"lifetime" property in the delegation. See also the examples in
Section 3.1.1.
The ACMEDelegationMethod object is defined with the properties shown
below.
* Property: acme-delegation
- Description: a URL pointing at an ACME delegation object,
either STAR or non-STAR, associated with the dCDN account on
the uCDN ACME server (see Section 2.3.1.3 of [RFC9115] for the
details). The URL MUST use the https scheme.
- Type: String
- Mandatory-to-Specify: Yes
* Property: time-window
- Description: Validity period of the certificate. According to
Section 4.3.4 of [RFC8006], a TimeWindow object is defined by a
window "start" time, and a window "end" time. In case of STAR
method, the "start" and "end" properties of the window MUST be
understood respectively as the start-date and end-date of the
certificate validity. In the case of the non-STAR method, the
"start" and "end" properties of the window MUST be understood
respectively as the notBefore and notAfter fields of the
certificate.
- Type: TimeWindow
- Mandatory-to-Specify: Yes
* Property: lifetime
- Description: See lifetime in Section 3.1.1 of [RFC8739]
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- Type: Integer
- Mandatory-to-Specify: Yes, only if a STAR delegation method is
specified
* Property: lifetime-adjust
- Description: See lifetime-adjust in Section 3.1.1 of [RFC8739]
- Type: Integer
- Mandatory-to-Specify: No
3.1.1. Examples
The following example shows an ACMEDelegationMethod object for a
STAR-based ACME delegation.
{
"generic-metadata-type": "MI.ACMEDelegationMethod",
"generic-metadata-value": {
"acme-delegation": "https://acme.ucdn.example/delegation/ogfr",
"time-window": {
"start": 1665417434,
"end": 1665676634
},
"lifetime": 345600,
"lifetime-adjust": 259200
}
}
The example below shows an ACMEDelegationMethod object for a non-STAR
ACME delegation. The delegation object is defined as per Section 4.3
of [RFC8006].
{
"generic-metadata-type": "MI.ACMEDelegationMethod",
"generic-metadata-value": {
"acme-delegation": "https://acme.ucdn.example/delegation/wSi5",
"time-window": {
"start": 1570982234,
"end": 1665417434
}
}
}
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4. IANA Considerations
This document requests the registration of the following entry under
the "CDNI Payload Types" registry:
+=========================+===============+
| Payload Type | Specification |
+=========================+===============+
| MI.ACMEDelegationMethod | RFCthis |
+-------------------------+---------------+
Table 1
// RFC Editor: please replace RFCthis with the RFC number of this RFC
// and remove this note.
4.1. CDNI MI ACMEDelegationMethod Payload Type
Purpose: The purpose of this Payload Type is to distinguish
AcmeDelegationMethod MI objects (and any associated capability
advertisement)
Interface: MI/FCI
Encoding: See Section 3.1
5. Security Considerations
The metadata object defined in this document does not introduce any
new security or privacy concerns over those already discussed in
[RFC9115], [RFC8006] and [RFC8008].
The reader is expected to understand the ACME delegation trust model
(Section 7.1 of [RFC9115]) and security goal (Section 7.2 of
[RFC9115]).]). In particular, the reader is expected to understand
the criticality of the protection of the user account associated with
the delegation; this account authorizes all the security-relevant
operations between a dCDN and a uCDN over the ACME channel.
The dCDN's ACME account is also relevant to the privacy of the entire
scheme; for example, the acme-delegation resource in the Metadata
object is only accessible to the holder of the account key, who is
allowed to fetch its content exclusively via POST-as-GET
(Section 2.3.1.2 of [RFC9115]).
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In addition, the Metadata interface authentication and
confidentiality requirements defined in Section 8 of [RFC8006] MUST
be followed.
Implementers MUST adhere to the security considerations defined in
the CDNI Request Routing: Footprint and Capabilities Semantics,
Section 7 of [RFC8008].
When TLS is used to achieve the above security objectives, the
general TLS usage guidance in [RFC9325] MUST be followed.
6. References
6.1. Normative References
[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/rfc/rfc2119>.
[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/rfc/rfc8006>.
[RFC8008] Seedorf, J., Peterson, J., Previdi, S., van Brandenburg,
R., and K. Ma, "Content Delivery Network Interconnection
(CDNI) Request Routing: Footprint and Capabilities
Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016,
<https://www.rfc-editor.org/rfc/rfc8008>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[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/rfc/rfc8739>.
[RFC9115] Sheffer, Y., López, D., Pastor Perales, A., and T.
Fossati, "An Automatic Certificate Management Environment
(ACME) Profile for Generating Delegated Certificates",
RFC 9115, DOI 10.17487/RFC9115, September 2021,
<https://www.rfc-editor.org/rfc/rfc9115>.
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[RFC9325] Sheffer, Y., Saint-Andre, P., and T. Fossati,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November
2022, <https://www.rfc-editor.org/rfc/rfc9325>.
6.2. 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/rfc/rfc7336>.
[RFC9460] Schwartz, B., Bishop, M., and E. Nygren, "Service Binding
and Parameter Specification via the DNS (SVCB and HTTPS
Resource Records)", RFC 9460, DOI 10.17487/RFC9460,
November 2023, <https://www.rfc-editor.org/rfc/rfc9460>.
Acknowledgments
We would like to thank authors of the [RFC9115], Antonio Augustin
Pastor Perales, Diego Lopez, Thomas Fossati and Yaron Sheffer.
Additionally, our gratitude to Thomas Fossati who participated in the
drafting, reviewing and giving his feedback in finalizing this
document. We also thank CDNI co-chair Kevin Ma for his continual
review and feedback during the development of this document.
Authors' Addresses
Frédéric 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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