draft-ietf-krb-wg-ocsp-for-pkinit-04.txt   draft-ietf-krb-wg-ocsp-for-pkinit-05.txt 
NETWORK WORKING GROUP L. Zhu NETWORK WORKING GROUP L. Zhu
Internet-Draft K. Jaganathan Internet-Draft K. Jaganathan
Expires: August 4, 2005 Microsoft Corporation Expires: November 21, 2005 Microsoft Corporation
N. Williams N. Williams
Sun Microsystems Sun Microsystems
January 31, 2005 May 20, 2005
OCSP Support for PKINIT OCSP Support for PKINIT
draft-ietf-krb-wg-ocsp-for-pkinit-04 draft-ietf-krb-wg-ocsp-for-pkinit-05
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of Section 3 of RFC 3667. By submitting this Internet-Draft, each of Section 3 of RFC 3667.
author represents that any applicable patent or other IPR claims of
which he or she is aware have been or will be disclosed, and any of By submitting this Internet-Draft, each author represents
which he or she become aware will be disclosed, in accordance with that any applicable patent or other IPR claims of which he
RFC 3668. or she is aware have been or will be disclosed, and any of
which he or she becomes aware will be disclosed, in
accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on August 4, 2005. This Internet-Draft will expire on November 21, 2005.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document defines a mechanism to enable in-band transmission of This document defines a mechanism to enable in-band transmission of
Online Certificate Status Protocol (OCSP) responses in the Kerberos Online Certificate Status Protocol (OCSP) responses in the Kerberos
network authentication protocol. These responses are used to verify network authentication protocol. These responses are used to verify
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2. Conventions Used in This Document 2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Message Definition 3. Message Definition
A pre-authentication type identifier is defined for this mechanism: A pre-authentication type identifier is defined for this mechanism:
PA-PK-OCSP-RESPONSE 16 PA-PK-OCSP-RESPONSE 18
The corresponding padata-value field [CLARIFICATIONS] contains the The corresponding padata-value field [CLARIFICATIONS] contains the
DER [X60] encoding of the following ASN.1 type: DER [X60] encoding of the following ASN.1 type:
PKOcspData ::= SEQUENCE OF OcspResponse PKOcspData ::= SEQUENCE OF OcspResponse
-- If more than one OcspResponse is
-- included, the first OcspResponse
-- MUST contain the OCSP response
-- for the signer's certificate.
OcspResponse ::= OCTET STRING OcspResponse ::= OCTET STRING
-- contains a complete OCSP response, -- Contains a complete OCSP response,
-- defined in [RFC2560] -- as defined in [RFC2560].
The client MAY send OCSP responses for certificates used in The client MAY send OCSP responses for certificates used in PA-PK-AS-
PA-PK-AS-REQ [PKINIT] via a PA-PK-OCSP-RESPONSE. REQ [PKINIT] via a PA-PK-OCSP-RESPONSE.
The KDC that receives a PA-PK-OCSP-RESPONSE then SHOULD send a The KDC that receives a PA-PK-OCSP-RESPONSE then SHOULD send a PA-PK-
PA-PK-OCSP-RESPONSE containing OCSP responses for certificates used OCSP-RESPONSE containing OCSP responses for certificates used in the
in the KDC's PA-PK-AS-REP. The client can request a KDC's PA-PK-AS-REP. The client can request a PA-PK-OCSP-RESPONSE by
PA-PK-OCSP-RESPONSE by using a PKOcspData containing an empty using a PKOcspData containing an empty sequence.
sequence.
The KDC MAY send a PA-PK-OCSP-RESPONSE when it does not receive a The KDC MAY send a PA-PK-OCSP-RESPONSE when it does not receive a PA-
PA-PK-OCSP-RESPONSE from the client. PK-OCSP-RESPONSE from the client.
The PA-PK-OCSP-RESPONSE sent by the KDC contains OCSP responses for The PA-PK-OCSP-RESPONSE sent by the KDC contains OCSP responses for
certificates used in PA-PK-AS-REP [PKINIT]. certificates used in PA-PK-AS-REP [PKINIT].
Note the lack of integrity protection for the empty or missing OCSP Note the lack of integrity protection for the empty or missing OCSP
response; lack of an expected OCSP response from the KDC for the response; lack of an expected OCSP response from the KDC for the
KDC's certificates SHOULD be treated as an error by the client, KDC's certificates SHOULD be treated as an error by the client,
unless it is configured otherwise. unless it is configured otherwise.
When using OCSP, the response is signed by the OCSP server, which is When using OCSP, the response is signed by the OCSP server, which is
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and perform their own revocation status verification independently. and perform their own revocation status verification independently.
4. Security Considerations 4. Security Considerations
The pre-authentication data in this document do not actually The pre-authentication data in this document do not actually
authenticate any principals, but is designed to be used in authenticate any principals, but is designed to be used in
conjunction with PKINIT. conjunction with PKINIT.
There is no binding between PA-PK-OCSP-RESPONSE pre-authentication There is no binding between PA-PK-OCSP-RESPONSE pre-authentication
data and PKINIT pre-authentication data other than a given OCSP data and PKINIT pre-authentication data other than a given OCSP
response corresponding to a certificate used in a PKINIT response corresponding to a certificate used in a PKINIT pre-
pre-authentication data element. Attacks involving removal or authentication data element. Attacks involving removal or
replacement of PA-PK-OCSP-RESPONSE pre-authentication data elements replacement of PA-PK-OCSP-RESPONSE pre-authentication data elements
are, at worst, downgrade attacks, where a PKINIT client or KDC would are, at worst, downgrade attacks, where a PKINIT client or KDC would
proceed without use of CRLs or OCSP for certificate validation, or proceed without use of CRLs or OCSP for certificate validation, or
denial of service attacks, where a PKINIT client or KDC that cannot denial of service attacks, where a PKINIT client or KDC that cannot
validate the other's certificate without an accompanying OCSP validate the other's certificate without an accompanying OCSP
response might reject the AS exchange or where they might have to response might reject the AS exchange or where they might have to
download very large CRLs in order to continue. Kerberos V does not download very large CRLs in order to continue. Kerberos V does not
protect against denial-of-service attacks, therefore the protect against denial-of-service attacks, therefore the denial-of-
denial-of-service aspect of these attacks are acceptable. service aspect of these attacks are acceptable.
If a PKINIT client or KDC cannot validate certificates without the If a PKINIT client or KDC cannot validate certificates without the
aid of a valid PA-PK-OCSP-RESPONSE then it SHOULD fail the AS aid of a valid PA-PK-OCSP-RESPONSE then it SHOULD fail the AS
exchange, possibly according to local configuration. exchange, possibly according to local configuration.
5. IANA Considerations 5. IANA Considerations
No IANA actions are required for this document. No IANA actions are required for this document.
6. Acknowledgements 6. Acknowledgements
 End of changes. 

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