Network Working Group F. Fieau, Ed.
Internet-Draft E. Stephan
Intended status: Standards Track Orange
Expires: January 4, 2018 S. Mishra
Verizon
July 03, 2017
CDNI interfaces update for HTTPS delegation
draft-fieau-cdni-interfaces-https-delegation-01
Abstract
The delivery of content over HTTPS involving multiple CDNs raises
credential management issues. This document recalls the methods
under study at the IETF. Then it specifies the updates needed in
CDNI Control and Metadata interfaces to setup HTTPS delegation
between an uCDN and dCDN.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Known delegation methods . . . . . . . . . . . . . . . . . . 3
4. SecuredDelegation object definition . . . . . . . . . . . . . 3
5. Delegation methods . . . . . . . . . . . . . . . . . . . . . 5
5.1. AcmeStarDelegationMethod object . . . . . . . . . . . . . 6
5.2. SubcertsDelegationMethod object . . . . . . . . . . . . . 7
6. Metadata Simple Data Type Descriptions . . . . . . . . . . . 7
6.1. Periodicity . . . . . . . . . . . . . . . . . . . . . . . 7
7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 7
7.1. CDNI MI AcmeStarDelegationMethod Payload Type . . . . . . 7
7.2. CDNI MI SubCertsDelegationMethod Payload Type . . . . . . 8
8. Security considerations . . . . . . . . . . . . . . . . . . . 8
9. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
When content is delivered over HTTPS using one or more CDNs along the
path, credential management is required. This is specifically
required when an entity delegates delivery of encrypted content to
another trusted entity. This document presents updates needed in
CDNI Control and Metadata interfaces to setup HTTPS delegation
between an uCDN and dCDN.
Several delegation methods are currently proposed within several IETF
working groups (refer to [I-D.fieau-cdni-https-delegation] for an
overview of delegation works ongoing at the IETF). They specify
separately the provisioning of their credentials.
This document specifies an update to the CDNI control / Triggers and
Metadata interfaces to support these methods. Furthermore, it
includes a proposal of registry to enable the adding of new methods
in the future.
Section 2 is about terminology used in this document. Section 3
presents delegation methods specified at the IETF. Section 4
introduces a secured delegation object for CDNI. Section 5 addresses
the delegation methods objects. Section 6 describes simple data
types. Section 7 is about an IANA registry for delegation methods.
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Section 8 raises the security issues. Section 9 opens the
discussion.
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], CDNI Control interface / Triggers [RFC8007] and Logging
interface [RFC7937].
3. Known delegation methods
A few methods are currently being proposed at the IETF to handle
delegation of HTTPS delivery between entities respecting those
constraints (refer to [I-D.fieau-cdni-https-delegation]). Note that
many of these methods are still an ongoing work at the IETF within
specific WGs.
We however anticipate the need to handle delegation in interconnected
CDNs and a need to address within the CDNI WG. Despite the types of
delegation methods, we need a common framework in CDNI that would
provide new requirements on the CDNI interfaces.
This document considers the following methods supporting HTTPS
delegation and may be used between two or more CDNs with applicable
interface support following the CDNI framework, such as the CI/
Triggers and Metadata Interface:
- Sub-certificates [I-D.rescorla-tls-subcerts] likely to be a TLS WG
draft.
- Short-term certificates in ACME using STAR API [I-D.ietf-acme-star]
4. SecuredDelegation object definition
As expressed in [I-D.rescorla-tls-subcerts], when HTTPS origin
delivery is requested for a specific domain, the delegate, i.e. a
dCDN, presents the Origin, or uCDN certificate or even,
"delegated_credential" instead of its own certificate at the TLS
handshake to the end.
When HTTPS delegation has been set for a specific domain, the dCDN
should present the Origin or uCDN certificate or
"delegated_credential" instead of its own certificate when content
delivery is requested.
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The SecuredDelegation object metadata aims at describing a secured
delegation between an uCDN and dCDN by indicating the delegated
domain, the start and end of a delegation, and the delegation method
used.
property: delegateddomain
type: HostMatch
Description: It describes the delegated hostname, restricted to
Hostname. HostMatch is defined in RFC8006 section 4.3.3. This
value should match the SAN value in certificates.
property: pathpattern
type: PathPattern
Description: a PathPattern object contains a PathPattern object
with a path to match against a resource's URI path in order to
trigger the delegation. It is described in RFC8006, 4.1.4.
property: timewindow
type: TimeWindow
Description: Describes delegation start and end times. Timewindow
is defined in RFC8006 section 4.2.
Property: delegationmethod
type: DelegationMethod
Description: the delegation method(s) used between a uCDN and a
dCDN (ex. Subcerts, short term cert, etc.), as defined in the
next section.
As an example: a SecuredDelegation object (which contains a
TimeWindow object, DelegationMethod and a HostMatch) that only allows
the dCDN to deliver content to clients between 09:00 01/01/2000 UTC
and 17:00 01/01/2000 UTC:
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SecuredDelegation object:
{
"generic-metadata-type": "MI.SecuredDelegation",
"generic-metadata-value":
{
"timewindow": {start: 946717200, end: 946746000},
"delegationMethod": AcmeStarDelegationMethod,
"pathpattern": {
"pattern": "/movies/*",
"case-sensitive": true
},
"delegatedDomain": "www.origin.com",
}
}
Such as object shall be conveyed over the CDNI metadata interface.
5. Delegation methods
This section defines the delegation methods objects metadata used by
a securedDelegation. Each method consists of 4 phases:
o Bootstrapping: bootstrapping a secured delegation consists in
providing the dCDN with enough parameters to set it up, e.g. ACME
servers, Key Servers, etc..
o Credential renewal: In case of certificates based approaches,
[I-D.rescorla-tls-subcerts] and [I-D.ietf-acme-star], there is a
need in CDNI to periodically provision and update credentials
(certificates or private keys) on the dCDNs for a given delegated
domain.
o Expiration/Revocation: expiration of delegation can occur for
multiple reasons: changes in delegation rights, delegation
validity is over. In [I-D.rescorla-tls-subcerts] or
[I-D.ietf-acme-star] approaches, the uCDN may implicitly enforce
revocation and will prevent any dCDN to renew certificates, or
access credentials, when delegation is expired.
o Logging: Regarding logging aspects, we consider to log usages and
errors related to a delegated domain. As an example, CDNI logs
include: supported delegation method(s), credentials renewal
requests, credential revocation notice, mutual agreement for
selected credential method to use, credentials download status for
a specific domain, as well as errors, related to credentials
transfer, or crypto aspects such as bad cypher suite supports,
revoked delegations, etc.
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5.1. 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]
Property: starproxy
Type: Endpoint
Description: Used to advertise the STAR Proxy to the dCDN.
Endpoint type defined in RFC8006, section 4.3.3
Property: acmeserver
Type: Endpoint
Description: used to advertise the ACME server to the dCDN.
Endpoint type is defined in RFC8006, section 4.3.3
Property: credentialslocationuri
Type: Link
Description: expresses the location of the credentials to be
fetched by the dCDN. Link type is as defined in RFC8006, section
4.3.1
Property: periodicity
Type: Periodicity
description: expresses the credentials renewal periodicity. See
next section on simple meta data type.
As an example, AcmeStarDelegationMethod object could express the
Acme-Star-delegation as the following:
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AcmeStarDelegationMethod: {
"generic-metadata-type": "MI.AcmeStarDelegationMethod",
"generic-metadata-value": {
"starproxy": "10.2.2.2",
"acmeserver": "10.2.3.3",
"credentialslocationuri": "www.ucdn.com/credentials",
"periodicity": 36000
}
}
5.2. SubcertsDelegationMethod object
TBD
6. Metadata Simple Data Type Descriptions
This section describes the simple data types that are used for
properties for objects in this document.
6.1. Periodicity
A time value expressed in seconds.
Type: Integer
7. 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| TBD |
| MI.SubCertDelegationMethod | TBD |
| ... | |
+----------------------------+---------------+
7.1. CDNI MI AcmeStarDelegationMethod Payload Type
Purpose: The purpose of this Payload Type is to distinguish
AcmeStarDelegationMethod MI objects (and any associated capability
advertisement)
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Interface: MI/FCI
Encoding: see Section 5.1
7.2. 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 5.2
8. Security considerations
The CI/T interface and Metadata interface need only to specify
mechanisms for delegation between uCDN and dCDN without the use of
actual transfer of encrypting keys within the interface messages.
The uCDN actions must be limited to in specifying its support for
methods it prefers for delegation, actual delegation and revocation
of any delegation. The dCDN similarly, must indicate delegation
methods it supports. Any subsequent communications enabling
delegation must be limited to the agreed delegation method.
Additionally, the HTTPS delegation framework must comply with
security considerations as specified within RFC 8007 [CDNI Control
Interfaces].
9. Discussion
More prospective works include:
- Keyless SSL / LURK [I-D.mglt-lurk-tls]: No WG is currently
addressing Lurk.
- Out-of-Band encoding redirection [I-D.reschke-http-oob-encoding]
Should they be considered as delegation methods for CDNI?
10. References
10.1. Normative References
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
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[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<http://www.rfc-editor.org/info/rfc5280>.
[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, <http://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,
<http://www.rfc-editor.org/info/rfc7337>.
[RFC7937] Le Faucheur, F., Ed., Bertrand, G., Ed., Oprescu, I., Ed.,
and R. Peterkofsky, "Content Distribution Network
Interconnection (CDNI) Logging Interface", RFC 7937,
DOI 10.17487/RFC7937, August 2016,
<http://www.rfc-editor.org/info/rfc7937>.
[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,
<http://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,
<http://www.rfc-editor.org/info/rfc8007>.
10.2. Informative References
[I-D.fieau-cdni-https-delegation]
Fieau, F., Emile, S., and S. Mishra, "HTTPS delegation in
CDNI", draft-fieau-cdni-https-delegation-01 (work in
progress), March 2017.
[I-D.ietf-acme-star]
Sheffer, Y., Lopez, D., Dios, O., Pastor, A., and T.
Fossati, "Use of Short-Term, Automatically-Renewed (STAR)
Certificates to Delegate Authority over Web Sites", draft-
ietf-acme-star-00 (work in progress), June 2017.
[I-D.mglt-lurk-tls]
Migault, D., "LURK Protocol for TLS/DTLS1.2 version 1.0",
draft-mglt-lurk-tls-01 (work in progress), March 2017.
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[I-D.reschke-http-oob-encoding]
Reschke, J. and S. Loreto, "'Out-Of-Band' Content Coding
for HTTP", draft-reschke-http-oob-encoding-12 (work in
progress), June 2017.
[I-D.rescorla-tls-subcerts]
Barnes, R., Iyengar, S., Sullivan, N., and E. Rescorla,
"Delegated Credentials for TLS", draft-rescorla-tls-
subcerts-01 (work in progress), March 2017.
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
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