Clarification of Enrollment over Secure Transport (EST): transfer encodings and ASN.1
draft-richardson-lamps-rfc7030est-clarify-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
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|---|---|---|---|
| Authors | Michael Richardson , Thomas Werner | ||
| Last updated | 2019-06-17 | ||
| Replaced by | draft-ietf-lamps-rfc7030est-clarify, RFC 8951 | ||
| RFC stream | (None) | ||
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| Consensus boilerplate | Unknown | ||
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| IESG | IESG state | I-D Exists | |
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draft-richardson-lamps-rfc7030est-clarify-00
LAMPS Working Group M. Richardson
Internet-Draft Sandelman Software Works
Intended status: Standards Track T. Werner
Expires: December 19, 2019 Siemens
June 17, 2019
Clarification of Enrollment over Secure Transport (EST): transfer
encodings and ASN.1
draft-richardson-lamps-rfc7030est-clarify-00
Abstract
This document updates RFC7030: Enrollment over Secure Transport (EST)
to resolve some errata that was reported, and which has proven to
have interoperability when RFC7030 has been extended.
This document deprecates the specification of "Content-Transfer-
Encoding" headers for EST endpoints, providing a way to do this in an
upward compatible way. This document additional defines a GRASP
discovery mechanism for EST endpoints, and specifies requirements for
them.
Finally, this document fixes some syntactical errors in ASN.1 that
was presented.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 19, 2019.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
4. Changes to EST endpoint processing . . . . . . . . . . . . . 3
4.1. Client configuration . . . . . . . . . . . . . . . . . . 4
4.2. Retrieval of certificate attributes . . . . . . . . . . . 4
5. Clarification of ASN.1 for Certificate Attribute set. . . . . 5
6. Clarification of error messages for certificate enrollment
operations . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Definition of GRASP discovery for updated EST servers . . . . 5
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . 5
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
12.1. Normative References . . . . . . . . . . . . . . . . . . 5
12.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
{[RFC7030}} defines the Enrollment over Secure Transport, or EST
protocol.
This specification defines a number of HTTP end points for
certificate enrollment and management. The details of the
transaction were defined in terms of MIME headers as defined in
[RFC2045], rather than in terms of the HTTP protocol as defined in
[RFC2616] and [RFC7230].
[RFC2616] has text specifically deprecating Content-Transfer-
Encoding. [RFC7030] calls it out this header incorrectly.
[I-D.ietf-anima-bootstrapping-keyinfra] extends [RFC7030], adding new
functionality, and interop testing of the protocol has revealed that
unusual processing called out in [RFC7030] causes confusion.
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Changes to [RFC7030] to bring it inline with typical HTTP processing
would change the on-wire protocol in a way that is not backwards
compatible. This document provides a compromise that moves towards
the correct behaviour without breaking existing deployments.
This document deals with errata numbers [errata4384], [errata5107],
and [errata5108].
2. Terminology
This document uses the term "amended server" to refer to an EST
server that complies with the changes in this document. The term
"legacy EST server" refers to servers that do not support the changes
in this document.
The term "BRSKI EST server" refers to an EST server that also
supports the mechanisms described in
[I-D.ietf-anima-bootstrapping-keyinfra].
The abbreviation "CTE" is used to denote the Content-Transfer-
Encoding header, and the abbreviation "CTE-base64" is used to denote
a request or response whose Content-Transfer-Encoding header contains
the value "base64".
3. Requirements Language
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
[RFC2119] and indicate requirement levels for compliant STuPiD
implementations.
4. Changes to EST endpoint processing
[RFC7030] sections 4.1.3 (CA Certificates Response, /cacerts),
4.3.1/4.3.2 (Full CMC, /fullcmc), 4.4.2 (Server-Side Key Generation,
/serverkeygen), and 4.5.2 (CSR Attributes, /csrattrs) specify the use
of base64 encoding with a Content-Transsfer-Encoding for requests and
response.
Both section 4.1.3 (CA certificate response), and Section 4.5.2,
/csrattrs is a GET operation, and will be dealt with below.
For the other three methods, when the client is aware that this is an
amended server then it SHOULD send the POST request in binary form
(DER-encoded), and omit the Content-Transfer-Encoding header. How
the client knows what kind of server it is dealing with is
communicating with is detailed in the next section.
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An amended server, when it receives a request that has no Content-
Transfer-Encoding header, or has a Content-Transfer-Encoding header
with the "binary" attribute, MUST respond in the same binary format.
When an amended server receives a request in CTE-base64 form, then it
MAY respond in kind. It is reasonable for a server to be configured
to ignore or fail requests of this form, either via run-time
configuration, or via a compile-time option. A main reason to do
this is to avoid a permutation that requires testing in the future
when no legacy EST clients are expected to connect.
4.1. Client configuration
[RFC7030] has some significant deployment. The protocol has no
version numbers or other ways to indicate that the format of the
operations has changed, and as the protocol is driven by a client
state machine, the client has to know whether it has to operate in
legacy EST server mode.
In certain market verticals it may be well known to client system
designers whether or not this is the case. In those cases, the out-
of-band configuration mechanism is appropriate.
Clients that start their process using
[I-D.ietf-anima-bootstrapping-keyinfra] SHOULD assume that the server
supports this amended specification.
Clients that discover an EST server in an ANIMA ACP via GRASP, using
the mechanism detailed in Section 7 SHOULD also assume that these
servers support this amended specification.
Other users or extensions for [RFC7030] should specify if clients are
to assume this amended specification or not.
4.2. Retrieval of certificate attributes
The 4.5.2 (CSR Attributes, /csrattrs) is a GET operation. It occurs
at the beginning of a transaction.
TBD how can the client indicate it is willing to accept an un-encoded
response?
The 4.1.3 (CA Certificates Response, /cacerts) is also a GET
operation, but it occurs after enrollment. The server SHOULD assume
that a client that wanted a binary response also wants a binary
response here.
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5. Clarification of ASN.1 for Certificate Attribute set.
errata 4384.
6. Clarification of error messages for certificate enrollment
operations
errata 5108.
7. Definition of GRASP discovery for updated EST servers
An ANIMA ACP device can discover the location of the nearest EST
server using a [I-D.ietf-anima-grasp-api] M_DISCOVERY mechanism.
objective = ["AN_EST", F_DISC, 255 ]
EST servers discovered in this way MUST support the amended server
mechanism described in this document. The response will include a
hostname and port number for a nearby EST server that can be used to
renew an ACP credential.
8. Privacy Considerations
This document does not disclose any additional identifies to either
active or passive observer would see with [RFC7030].
9. Security Considerations
This document clarifies an existing security mechanism. An option is
introduced to the security mechanism using an implicit negotiation.
10. IANA Considerations
Allocate the name AN_EST from the [I-D.ietf-anima-grasp-api] "GRASP
Objective Names Table".
11. Acknowledgements
This work was supported by the Huawei Technologies.
12. References
12.1. Normative References
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[I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Behringer, M., Bjarnason,
S., and K. Watsen, "Bootstrapping Remote Secure Key
Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
keyinfra-21 (work in progress), June 2019.
[I-D.ietf-anima-grasp-api]
Carpenter, B., Liu, B., Wang, W., and X. Gong, "Generic
Autonomic Signaling Protocol Application Program Interface
(GRASP API)", draft-ietf-anima-grasp-api-03 (work in
progress), January 2019.
[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>.
[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>.
12.2. Informative References
[errata4384]
"EST errata 4384: ASN.1 encoding error", n.d.,
<https://www.rfc-editor.org/errata/eid4384>.
[errata5107]
"EST errata 5107: use Content-Transfer-Encoding", n.d.,
<https://www.rfc-editor.org/errata/eid5107>.
[errata5108]
"EST errata 5108: use of Content-Type for error message",
n.d., <https://www.rfc-editor.org/errata/eid5108>.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
<https://www.rfc-editor.org/info/rfc2045>.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616,
DOI 10.17487/RFC2616, June 1999,
<https://www.rfc-editor.org/info/rfc2616>.
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[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
Authors' Addresses
Michael Richardson
Sandelman Software Works
Email: mcr+ietf@sandelman.ca
Thomas Werner
Siemens
Email: thomas.werner@siemens.com
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