Internet Engineering Task Force (IETF) S. Turner
Request for Comments: 5940 IECA
Category: Standards Track R. Housley
ISSN: 2070-1721 Vigil Security
August 2010
Additional Cryptographic Message Syntax (CMS)
Revocation Information Choices
Abstract
The Cryptographic Message Syntax (CMS) allows revocation information
to be conveyed as part of the SignedData, EnvelopedData,
AuthenticatedData, and AuthEnvelopedData content types. The
preferred format for revocation information is the Certificate
Revocation List (CRL), but an extension mechanism supports other
revocation information formats. This document defines two additional
revocation information formats for Online Certificate Status Protocol
(OCSP) responses and Server-Based Certificate Validation Protocol
(SCVP) requests and responses.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc5940.
Turner & Housley Standards Track [Page 1]
RFC 5940 Additional CMS Revocation Information Choices August 2010
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
1. Introduction
The RevocationInfoChoices type defined in [CMS] provides a set of
revocation status information alternatives, which allows revocation
information to be conveyed as part of the SignedData, EnvelopedData,
AuthenticatedData, and AuthEnvelopedData content types. The intent
is to provide information sufficient to determine whether the
certificates and attribute certificates carried elsewhere in the CMS-
protected content have been revoked. There may be more revocation
status information than necessary or there may be less revocation
status information than necessary.
X.509 Certificate Revocation Lists (CRLs) [PROFILE] are the primary
source of revocation status information, but any other revocation
information format can be supported. This document specifies two
other formats: Online Certificate Status Protocol (OCSP) responses
[OCSP] and Server-Based Certificate Validation Protocol (SCVP)
requests and responses [SCVP].
Section 2 discusses the RevocationInformation structure. Section 3
defines a mechanism to carry OCSP responses. Section 4 defines a
mechanism to carry SCVP requests and responses. Appendix A provides
the normative ASN.1 syntax for the two mechanisms.
1.1. Requirements Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [WORDS].
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RFC 5940 Additional CMS Revocation Information Choices August 2010
2. Revocation Information
For convenience, the ASN.1 definition of the RevocationInfoChoices
type from [CMS] is repeated here:
RevocationInfoChoices ::= SET OF RevocationInfoChoice
RevocationInfoChoice ::= CHOICE {
crl CertificateList,
other [1] IMPLICIT OtherRevocationInfoFormat }
OtherRevocationInfoFormat ::= SEQUENCE {
otherRevInfoFormat OBJECT IDENTIFIER,
otherRevInfo ANY DEFINED BY otherRevInfoFormat }
The other CHOICE MUST be used to convey OCSP responses, SCVP
requests, and SCVP responses.
This document defines the id-ri arc under which the revocation
information formats are defined. The id-ri object identifier is:
id-ri OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7) ri(16) }
NOTE: Numbers 1 and 3 were assigned to CRL and Delta CRL. These two
numbers are not used because these formats use the
RevocationInfoChoice crl CHOICE when included in CMS [CMS].
3. OCSP Response
To carry an OCSP response, the otherRevInfoFormat is set to
id-ri-ocsp-response, which has the following ASN.1 definition:
id-ri-ocsp-response OBJECT IDENTIFIER ::= { id-ri 2 }
In this case, otherRevInfo MUST carry the OCSP response using the
OCSPResponse type defined in [OCSP]. The responseStatus field MUST
be successful and the responseBytes field MUST be present.
4. SCVP Request and Response
Unlike OSCP, SCVP permits unprotected and protected responses, where
protected responses can be digitally signed or include message
authentication codes. While this provides more flexibility, it
complicates implementations when an SCVP response can be validated by
entities other than the entity that generated the SCVP request. If a
lower layer provides authentication and integrity for the client-
server interaction and the response is not protected, then a third
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RFC 5940 Additional CMS Revocation Information Choices August 2010
party cannot validate the response because there is no way to know
that the response was returned over a protected connection. If a
message authentication code is used, then the third party will be
unable to validate the message authentication code because it does
not possess the necessary private key. For these reasons, SCVP
responses sent to a third party MUST be signed by the SCVP server so
that the third party can validate them.
SCVP response validation requires matching it to the SCVP request.
This means that the SCVP request MUST always be included with the
response. SCVP permits the client to retain the response, and SCVP
permits the request to be returned in the response (in the requestReq
field). The request need not be protected for matching to be
performed; nonces and certIds can be checked.
To carry the SCVP request and response, the otherRevInfoFormat is set
to id-ri-scvp, which has the following ASN.1 definition:
id-ri-scvp OBJECT IDENTIFIER ::= { id-ri 4 }
In this case, the otherRevInfo MUST carry both the SCVP request and
response with the following structure:
SCVPReqRes ::= SEQUENCE {
request [0] EXPLICIT ContentInfo OPTIONAL,
response ContentInfo }
The SCVPReqRes has the following fields:
o request contains the SCVP request. It contains the unprotected
request, authenticated request, or the signed request. The request
MUST be present if the response does not include the requestRef
fullRequest field.
o response contains the SCVP response. It MUST contain the signed
response. Additionally, the responseStatus MUST be okay.
Unprotected and authenticated responses MUST NOT be included.
5. Security Considerations
The security considerations of [CMS], [CMS-ASN], [OCSP], [SCVP], and
[PROFILE-ASN] apply.
To locally store unprotected or authenticated SCVP responses, a
client can encapsulate the unprotected or authenticated SCVP response
in a SignedData. It is a matter of local policy whether these SCVP
responses that are encapsulated and signed by the client are
considered valid by another entity.
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RFC 5940 Additional CMS Revocation Information Choices August 2010
6. IANA Considerations
This document makes use of object identifiers. These object
identifiers are defined in an arc delegated by IANA to the PKIX
Working Group. When the PKIX Working Group closes, this arc and its
registration procedures will be transferred to IANA. No further
action by IANA is necessary for this document or any anticipated
updates.
7. References
7.1. Normative References
[CMS] Housley, R., "Cryptographic Message Syntax (CMS)", RFC
5652, September 2009.
[CMS-ASN] Hoffman, P. and J. Schaad, "New ASN.1 Modules for
Cryptographic Message Syntax (CMS) and S/MIME", RFC 5911,
June 2010.
[OCSP] Myers, M., Ankney, R., Malpani, A., Galperin, S., and C.
Adams, "X.509 Internet Public Key Infrastructure Online
Certificate Status Protocol - OCSP", RFC 2560, June 1999.
[PROFILE-ASN]
Hoffman, P. and J. Schaad, "New ASN.1 Modules for the
Public Key Infrastructure Using X.509 (PKIX)", RFC 5912,
June 2010.
[SCVP] Freeman, T., Housley, R., Malpani, A., Cooper, D., and W.
Polk, "Server-Based Certificate Validation Protocol
(SCVP)", RFC 5055, December 2007.
[WORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[X.680] ITU-T Recommendation X.680 (2002) | ISO/IEC 8824- 1:2002.
Information Technology - Abstract Syntax Notation One.
[X.681] ITU-T Recommendation X.681 (2002) | ISO/IEC 8824- 2:2002.
Information Technology - Abstract Syntax Notation One:
Information Object Specification.
[X.682] ITU-T Recommendation X.682 (2002) | ISO/IEC 8824- 3:2002.
Information Technology - Abstract Syntax Notation One:
Constraint Specification.
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RFC 5940 Additional CMS Revocation Information Choices August 2010
[X.683] ITU-T Recommendation X.683 (2002) | ISO/IEC 8824- 4:2002.
Information Technology - Abstract Syntax Notation One:
Parameterization of ASN.1 Specifications, 2002.
7.2. Informative References
[PROFILE] 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, May 2008.
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RFC 5940 Additional CMS Revocation Information Choices August 2010
Appendix A. ASN.1 Modules
Appendix A.1 provides the normative ASN.1 definitions for the
structures described in this specification using ASN.1 as defined in
[X.680] for compilers that support the 1988 ASN.1.
Appendix A.2 provides informative ASN.1 definitions for the
structures described in this specification using ASN.1 as defined in
[X.680], [X.681], [X.682], and [X.683] for compilers that support the
2002 ASN.1. This appendix contains the same information as Appendix
A.1 in a more recent (and precise) ASN.1 notation, however Appendix
A.1 takes precedence in case of conflict.
A.1. 1988 ASN.1 Module
CMS-Other-RIs-2009-88
{ iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0) id-mod-cms-otherRIs-2009-88(63)
}
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL
IMPORTS
-- FROM CMS [CMS]
ContentInfo
FROM CryptographicMessageSyntax2004
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
smime(16) modules(0) cms-2004(24) }
;
id-ri OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7) ri(16) }
-- RevocationInfoChoice for OCSP response
-- OID included in otherRevInfoFormat
-- signed OCSP response included in otherRevInfo
id-ri-ocsp-response OBJECT IDENTIFIER ::= { id-ri 2 }
-- RevocationInfoChoice for SCVP response
-- OID included in otherRevInfoFormat
-- SCVPReqRes included in otherRevInfo
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RFC 5940 Additional CMS Revocation Information Choices August 2010
id-ri-scvp OBJECT IDENTIFIER ::= { id-ri 4 }
SCVPReqRes ::= SEQUENCE {
request [0] EXPLICIT ContentInfo OPTIONAL,
response ContentInfo }
END
A.2. 2002 ASN.1 Module
CMS-Other-RIs-2009-02
{ iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0) id-mod-cms-otherRIs-2009-93(64)
}
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- EXPORT ALL
IMPORTS
-- FROM [PROFILE-ASN]
OCSPResponse
FROM OCSP-2009
{ iso(1) identified-organization(3) dod(6) internet(1) security(5)
mechanisms(5) pkix(7) id-mod(0) id-mod-ocsp-02(48) }
-- FROM [CMS-ASN]
ContentInfo, OTHER-REVOK-INFO
FROM CryptographicMessageSyntax-2009
{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-9(9)
smime(16) modules(0) id-mod-cms-2004-02(41) }
;
-- Defines OCSP and SCVP formats for RevocationInfoChoice
SupportedOtherRevokInfo OTHER-REVOK-INFO ::= {
ri-ocsp-response |
ri-scvp,
... }
ri-ocsp-response OTHER-REVOK-INFO ::= {
OCSPResponse IDENTIFIED BY id-ri-ocsp-response }
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RFC 5940 Additional CMS Revocation Information Choices August 2010
id-ri OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7) ri(16) }
id-ri-ocsp-response OBJECT IDENTIFIER ::= { id-ri 2 }
ri-scvp OTHER-REVOK-INFO ::= {
SCVPReqRes IDENTIFIED BY id-ri-scvp }
id-ri-scvp OBJECT IDENTIFIER ::= { id-ri 4 }
SCVPReqRes ::= SEQUENCE {
request [0] EXPLICIT ContentInfo OPTIONAL,
response ContentInfo }
END
Authors' Addresses
Sean Turner
IECA, Inc.
3057 Nutley Street, Suite 106
Fairfax, VA 22031
USA
EMail: turners@ieca.com
Russ Housley
Vigil Security, LLC
918 Spring Knoll Drive
Herndon, VA 20170
USA
EMail: housley@vigilsec.com
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RFC, FYI, BCP