Internet DRAFT - draft-richardson-lamps-rfc7030-csrattrs
draft-richardson-lamps-rfc7030-csrattrs
LAMPS Working Group M. Richardson, Ed.
Internet-Draft Sandelman Software Works
Intended status: Standards Track O. Friel
Expires: 25 January 2023 Cisco
D. von Oheimb
Siemens
D. Harkins
The Industrial Lounge
24 July 2022
Clarification of RFC7030 CSR Attributes definition
draft-richardson-lamps-rfc7030-csrattrs-04
Abstract
The Enrollment over Secure Transport (EST, RFC7030) is ambiguous in
its specification of the CSR Attributes Response. This has resulted
in implementation challenges and implementor confusion.
This document updates RFC7030 (EST) and clarifies how the CSR
Attributes Response can be used by an EST server to specify both CSR
attribute OIDs and also CSR attribute values that the server expects
the client to include in subsequent CSR request.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 25 January 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. CSR Attributes Handling . . . . . . . . . . . . . . . . . . . 3
3.1. Current EST CSR Attributes Specification . . . . . . . . 3
3.2. Revised/Simplified EST CSR Attributes Specification . . . 3
4. Co-existence with existing implementations . . . . . . . . . 4
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. RFC8994/ACP subjectAltName with specific otherName
included . . . . . . . . . . . . . . . . . . . . . . . . 4
5.2. EST server requires public keys of a specific size . . . 5
5.3. EST server requires a public key of a specific algorithm/
curve . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.4. EST server requires a specific extension to be present . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6.1. Identity and Privacy Considerations . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Enrollment over Secure Transport [RFC7030] (EST) has been used in a
wide variety of applications. In particular, [RFC8994] and [RFC8995]
describe a way to use it in order to build out an autonomic control
plane (ACP) [RFC8368].
The ACP requires that each node be given a very specific
SubjectAltName. In the ACP specification, the solution was for the
EST server to use section 2.6 of [RFC7030] to convey to the EST
client the actual SubjectAltName that will end up in its certificate.
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As a result of some implementation challenges, it came to light that
this particular way of using the CSR attributes was not universally
agreed upon, and it was suggested that it went contrary to section
2.6.
Section 2.6 says that the CSR attributes "provide additional
descriptive information that the EST server cannot access itself".
After significant discussion, it has been determined that Section 4.5
of [RFC7030] specification is sufficiently difficult to read that
clarification is needed.
This document motivates the different use cases, and provides
additional worked out examples.
This document also updates section 4.5 to include revised ASN.1 that
covers all uses and is backward compatible with the existing use.
2. Terminology
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.
3. CSR Attributes Handling
3.1. Current EST CSR Attributes Specification
The ASN.1 for CSR Attributes as defined in EST section 4.5.2 is:
CsrAttrs ::= SEQUENCE SIZE (0..MAX) OF AttrOrOID
AttrOrOID ::= CHOICE (oid OBJECT IDENTIFIER, attribute Attribute }
Attribute { ATTRIBUTE:IOSet } ::= SEQUENCE {
type ATTRIBUTE.&id({IOSet}),
values SET SIZE(1..MAX) OF ATTRIBUTE.&Type({IOSet}{@type}) }
3.2. Revised/Simplified EST CSR Attributes Specification
(XXX: This isn't really simpler, is it?)
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CsrAttrs ::= SEQUENCE SIZE (0..MAX) OF AttrOrOID
AttrOrOID ::= CHOICE (oid OBJECT IDENTIFIER,
attribute Attribute }
Attribute { ATTRIBUTE:IOSet } ::= SEQUENCE {
extType ATTRIBUTE.&id({IOSet}),
extAttr SET SIZE(1..MAX) OF ATTRIBUTE.&Type({IOSet}{@type})
}
A key part that was unclear is that extAttr above could be an entire
Extension, as per Section 4.2 of [RFC5280]. This structure naturally
includes both the extention ID, a critical bit, and the extension
value.
The extType for such an extension would be "ExtensionRequest"
(extReq), which is OID 1.2.840.113549.1.9.14.
Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension
Extension ::= SEQUENCE {
extnID OBJECT IDENTIFIER,
critical BOOLEAN DEFAULT FALSE,
extnValue OCTET STRING
-- contains the DER encoding of an ASN.1 value
-- corresponding to the extension type identified
-- by extnID
}
With this understand, the needs of [RFC8994] and [RFC8995] are
satisfied, however with a change to the bits on the wire.
4. Co-existence with existing implementations
5. Examples
5.1. RFC8994/ACP subjectAltName with specific otherName included
This is a dump in "dumpasn1" format of a CSR Attributes object which
a specific otherName included.
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0 90: SEQUENCE {
2 88: SEQUENCE {
4 9: OBJECT IDENTIFIER extensionRequest (1 2 840 113549 1 9 14)
15 75: SET {
17 73: SEQUENCE {
19 3: OBJECT IDENTIFIER subjectAltName (2 5 29 17)
24 3: [0] {
26 1: BOOLEAN TRUE
: }
29 61: SEQUENCE {
31 59: [0] {
33 57: UTF8String
: 'rfc8994+fd739fc23c3440112233445500000000+@acp.ex'
: 'ample.com'
: }
: }
: }
: }
: }
: }
5.2. EST server requires public keys of a specific size
TBD
5.3. EST server requires a public key of a specific algorithm/curve
TBD
5.4. EST server requires a specific extension to be present
TBD
6. Security Considerations
All security considertions from EST [RFC7030] section 6 are
applicable.
6.1. Identity and Privacy Considerations
An EST server may use this mechanism to instruct the EST client about
the identities it should include in the CSR it sends as part of
enrollment. The client may only be aware of its IDevID Subject,
which includes a manufacturer serial number. The EST server can use
this mechanism to tell the client to include a specific fully
qualified domain name in the CSR in order to complete domain
ownership proofs required by the CA. Additionally, the EST server
may deem the manufacturer serial number in an IDevID as personally
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identifiable information, and may want to specify a new random opaque
identifier that the pledge should use in its CSR. This may be
desirable if the CA and EST server have different operators.
7. IANA Considerations
No requests are made to IANA.
8. Acknowledgements
TODO
9. Changelog
10. References
10.1. 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/info/rfc2119>.
[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,
<https://www.rfc-editor.org/info/rfc5280>.
[RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
"Enrollment over Secure Transport", RFC 7030,
DOI 10.17487/RFC7030, October 2013,
<https://www.rfc-editor.org/info/rfc7030>.
[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/info/rfc8174>.
[RFC8994] Eckert, T., Ed., Behringer, M., Ed., and S. Bjarnason, "An
Autonomic Control Plane (ACP)", RFC 8994,
DOI 10.17487/RFC8994, May 2021,
<https://www.rfc-editor.org/info/rfc8994>.
[RFC8995] Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructure (BRSKI)", RFC 8995, DOI 10.17487/RFC8995,
May 2021, <https://www.rfc-editor.org/info/rfc8995>.
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10.2. Informative References
[RFC8368] Eckert, T., Ed. and M. Behringer, "Using an Autonomic
Control Plane for Stable Connectivity of Network
Operations, Administration, and Maintenance (OAM)",
RFC 8368, DOI 10.17487/RFC8368, May 2018,
<https://www.rfc-editor.org/info/rfc8368>.
Authors' Addresses
Michael Richardson (editor)
Sandelman Software Works
Email: mcr+ietf@sandelman.ca
Owen Friel
Cisco
Email: ofriel@cisco.com
Dr. David von Oheimb
Siemens
Email: dev@ddvo.net
Dan Harkins
The Industrial Lounge
Email: dharkins@lounge.org
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