draft-ietf-krb-wg-ocsp-for-pkinit-06.txt   rfc4557.txt 
NETWORK WORKING GROUP L. Zhu Network Working Group L. Zhu
Internet-Draft K. Jaganathan Request for Comments: 4557 K. Jaganathan
Expires: January 20, 2006 Microsoft Corporation Category: Standards Track Microsoft Corporation
N. Williams N. Williams
Sun Microsystems Sun Microsystems
July 19, 2005 Online Certificate Status Protocol (OCSP) Support for
Public Key Cryptography for
OCSP Support for PKINIT Initial Authentication in Kerberos (PKINIT)
draft-ietf-krb-wg-ocsp-for-pkinit-06
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2006).
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
the validity of the certificates used in PKINIT - the Kerberos the validity of the certificates used in Public Key Cryptography for
Initial Authentication in Kerberos (PKINIT), which is the Kerberos
Version 5 extension that provides for the use of public key Version 5 extension that provides for the use of public key
cryptography. cryptography.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3 2. Conventions Used in This Document ...............................2
3. Message Definition . . . . . . . . . . . . . . . . . . . . . . 3 3. Message Definition ..............................................2
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations .........................................3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements ................................................4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 6. References ......................................................4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References .......................................4
7.1 Normative References . . . . . . . . . . . . . . . . . . . 5 6.2. Informative References .....................................4
7.2 Informative References . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 5
Intellectual Property and Copyright Statements . . . . . . . . 7
1. Introduction 1. Introduction
Online Certificate Status Protocol (OCSP) [RFC2560] enables Online Certificate Status Protocol (OCSP) [RFC2560] enables
applications to obtain timely information regarding the revocation applications to obtain timely information regarding the revocation
status of a certificate. Because OCSP responses are well-bounded and status of a certificate. Because OCSP responses are well bounded and
small in size, constrained clients may wish to use OCSP to check the small in size, constrained clients may wish to use OCSP to check the
validity of the certificates for Kerberos Key Distribution Center validity of the certificates for Kerberos Key Distribution Center
(KDC) in order to avoid transmission of large Certificate Revocation (KDC) in order to avoid transmission of large Certificate Revocation
Lists (CRLs) and therefore save bandwidth on constrained networks Lists (CRLs) and therefore save bandwidth on constrained networks
[OCSP-PROFILE]. [OCSP-PROFILE].
This document defines a pre-authentication type [RFC4120], where the This document defines a pre-authentication type [RFC4120], where the
client and the KDC MAY piggyback OCSP responses for certificates used client and the KDC MAY piggyback OCSP responses for certificates used
in authentication exchanges, as defined in [PKINIT]. in authentication exchanges, as defined in [RFC4556].
By using this OPTIONAL extension, PKINIT clients and the KDC can By using this OPTIONAL extension, PKINIT clients and the KDC can
maximize the reuse of cached OCSP responses. maximize the reuse of cached OCSP responses.
2. Conventions Used in This Document 2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
document are to be interpreted as described in [RFC2119]. and "OPTIONAL" 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 18 PA-PK-OCSP-RESPONSE 18
The corresponding padata-value field [RFC4120] contains the DER [X60] The corresponding padata-value field [RFC4120] contains the DER [X60]
encoding of the following ASN.1 type: encoding of the following ASN.1 type:
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-- MUST contain the OCSP response -- MUST contain the OCSP response
-- for the signer's certificate. -- for the signer's certificate.
-- The signer refers to the client for -- The signer refers to the client for
-- AS-REQ, and the KDC for the AS-REP, -- AS-REQ, and the KDC for the AS-REP,
-- respectively. -- respectively.
OcspResponse ::= OCTET STRING OcspResponse ::= OCTET STRING
-- Contains a complete OCSP response, -- Contains a complete OCSP response,
-- as defined in [RFC2560]. -- as defined in [RFC2560].
The client MAY send OCSP responses for certificates used in PA-PK-AS- The client MAY send OCSP responses for certificates used in PA-PK-
REQ [PKINIT] via a PA-PK-OCSP-RESPONSE. AS-REQ [RFC4556] via a PA-PK-OCSP-RESPONSE.
The KDC that receives a PA-PK-OCSP-RESPONSE then SHOULD send a PA-PK- The KDC that receives a PA-PK-OCSP-RESPONSE SHOULD send a PA-PK-
OCSP-RESPONSE containing OCSP responses for certificates used in the OCSP-RESPONSE containing OCSP responses for certificates used in the
KDC's PA-PK-AS-REP. The client can request a PA-PK-OCSP-RESPONSE by KDC's PA-PK-AS-REP. The client can request a PA-PK-OCSP-RESPONSE by
using a PKOcspData containing an empty sequence. using a PKOcspData containing an empty sequence.
The KDC MAY send a PA-PK-OCSP-RESPONSE when it does not receive a PA- The KDC MAY send a PA-PK-OCSP-RESPONSE when it does not receive a
PK-OCSP-RESPONSE from the client. PA-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 [RFC4556].
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
trusted by the receiver. Depending on local policy, further trusted by the receiver. Depending on local policy, further
verification of the validity of the OCSP servers may be needed verification of the validity of the OCSP servers may be needed
The client and the KDC SHOULD ignore invalid OCSP responses received The client and the KDC SHOULD ignore invalid OCSP responses received
via this mechanism, and they MAY implement CRL processing logic as a via this mechanism, and they MAY implement CRL processing logic as a
fall-back position, if the OCSP responses received via this mechanism fall-back position, if the OCSP responses received via this mechanism
alone are not sufficient for the verification of certificate alone are not sufficient for the verification of certificate
validity. The client and/or the KDC MAY ignore a valid OCSP response validity. The client and/or the KDC MAY ignore a valid OCSP response
and perform their own revocation status verification independently. and perform its 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 are 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 pre- response corresponding to a certificate used in a PKINIT 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 might have to download very
download very large CRLs in order to continue. Kerberos V does not large CRLs in order to continue. Kerberos V does not protect against
protect against denial-of-service attacks, therefore the denial-of- denial-of-service attacks; therefore, the denial-of-service aspect of
service aspect of these attacks are acceptable. these attacks is 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. Acknowledgements
No IANA actions are required for this document.
6. Acknowledgements
This document was based on conversations among the authors, Jeffrey This document was based on conversations among the authors, Jeffrey
Altman, Sam Hartman, Martin Rex and other members of the Kerberos Altman, Sam Hartman, Martin Rex, and other members of the Kerberos
working group. working group.
7. References 6. References
7.1 Normative References
[PKINIT] RFC-Editor: To be replaced by RFC number for draft-ietf- 6.1. Normative References
cat-kerberos-pk-init. Work in Progress.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2560] Myers, M., Ankney, R., Malpani, A., Galperin, S., and C. [RFC2560] Myers, M., Ankney, R., Malpani, A., Galperin, S., and
Adams, "X.509 Internet Public Key Infrastructure Online C. Adams, "X.509 Internet Public Key Infrastructure
Certificate Status Protocol - OCSP", RFC 2560, June 1999. Online Certificate Status Protocol - OCSP", RFC 2560,
June 1999.
[RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The [RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The
Kerberos Network Authentication Service (V5)", RFC 4120, Kerberos Network Authentication Service (V5)", RFC
July 2005. 4120, July 2005.
[RFC4556] Zhu, L. and B. Tung, "Public Key Cryptography for
Initial Authentication in Kerberos (PKINIT)", RFC
4556, June 2006.
[X690] ASN.1 encoding rules: Specification of Basic Encoding [X690] ASN.1 encoding rules: Specification of Basic Encoding
Rules (BER), Canonical Encoding Rules (CER) and Rules (BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER), ITU-T Recommendation Distinguished Encoding Rules (DER), ITU-T
X.690 (1997) | ISO/IEC International Standard 8825-1:1998. Recommendation X.690 (1997) | ISO/IEC International
Standard 8825-1:1998.
7.2 Informative References 6.2. Informative References
[OCSP-PROFILE] [OCSP-PROFILE] Deacon, A. and R. Hurst, "Lightweight OCSP Profile for
RFC-Editor: To be replaced by RFC number for draft-deacon- High Volume Environments", Work in Progress, May 2006.
lightweight-ocsp-profile. Work in Progress.
Authors' Addresses Authors' Addresses
Larry Zhu Larry Zhu
Microsoft Corporation Microsoft Corporation
One Microsoft Way One Microsoft Way
Redmond, WA 98052 Redmond, WA 98052
US US
Email: lzhu@microsoft.com EMail: lzhu@microsoft.com
Karthik Jaganathan Karthik Jaganathan
Microsoft Corporation Microsoft Corporation
One Microsoft Way One Microsoft Way
Redmond, WA 98052 Redmond, WA 98052
US US
Email: karthikj@microsoft.com EMail: karthikj@microsoft.com
Nicolas Williams Nicolas Williams
Sun Microsystems Sun Microsystems
5300 Riata Trace Ct 5300 Riata Trace Ct
Austin, TX 78727 Austin, TX 78727
US US
Email: Nicolas.Williams@sun.com EMail: Nicolas.Williams@sun.com
Intellectual Property Statement Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
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The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
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Disclaimer of Validity Acknowledgement
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
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