One document matched: draft-ietf-krb-wg-cammac-02.txt
Differences from draft-ietf-krb-wg-cammac-01.txt
Internet Engineering Task Force S. Sorce, Ed.
Internet-Draft Red Hat
Updates: 4120 (if approved) T. Yu, Ed.
Intended status: Standards Track T. Hardjono, Ed.
Expires: November 24, 2012 MIT Kerberos Consortium
May 23, 2012
Container Authenticated by Multiple MACs
draft-ietf-krb-wg-cammac-02
Abstract
Abstract: This document proposes a Kerberos Authorization Data
container that supersedes AD-KDC-ISSUED. It allows for multiple MACs
or signatures on the contained Authorization Data elements.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 24, 2012.
Copyright Notice
Copyright (c) 2012 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
3. Validation . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. AD-CAMMAC . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Assigned numbers . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . . 6
Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
This draft proposes a Authorization Data container for Kerberos that
identifies a base set of MAC and other elements necessary to
authenticate the authorization data being carried in such a way that
not only the KDC but also services can independently verify that the
data has been authenticated by the KDC and has not been tampered
with.
2. Requirements Language
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 RFC 2119 [RFC2119].
3. Validation
Authorization data is highly sensitive and must be validated to
insure no tampering has occured.
In order to validate any information the receiving application server
needs to be able to cryptographically verify the data. This is done
by introducing a new AuthorizationData element called AD-CAMMAC that
contains enough information to bind the contents to a principal in a
way that a receiving application server can verify autonomusly
without further contact with the KDC.
The following information is needed:
o The KDC MAC.
o The Service MAC.
o Optional Trusted Service Key MAC.
The KDC MAC is required to allow the KDC to validate the data
withouth requiring to recompute the contents at every TGS request.
The SVC MAC is required so that the Service can verify that the
authorization data has been validated by the KDC.
The Trusted Service MAC is useful to verify the authenticity of the
contents on the same host, when the data is received by a less
trusted service and passed to a more trusted service on the same host
without the need for additional roundtrips to the KDC.
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The ad-type for AD-CAMMAC is (TBD).
4. Encoding
The Kerberos protocol is defined in [RFC4120] using Abstract Syntax
Notation One (ASN.1) [X680]. As such, this specification also uses
the ASN.1 syntax for specifying both the abstract layout of the AD-
CAMMAC attributes, as well as its encoding.
4.1. AD-CAMMAC
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AD-CAMMAC ::= SEQUENCE {
elements [0] AuthorizationData,
kdc-verifier [1] Verifier-MAC,
svc-verifier [2] Verifier-MAC OPTIONAL,
other-verifiers [3] SEQUENCE OF Verifier
}
Verifier ::= CHOICE {
mac Verifier-MAC
}
Verifier-MAC ::= SEQUENCE {
identifier [0] PrincipalName OPTIONAL,
kvno [1] UInt32,
enctype [2] Int32,
mac [3] Checksum
}
elements
A sequence of authorization data elements issued by the KDC.
kdc-verifier
A container that includes a cryptographic checksum computed over
the encoding of the elements field, keyed with the krbtgt key.
Checksum type TBD.
svc-verifier
A container that includes a cryptographic checksum computed over
the encoding of the elements field, keyed with the service long
term key.
This field is marked OPTIONAL and can be omitted when the CAMMAC
is attached to a local TGT. It MUST be present in all other cases,
including cross-realm TGTs.
Checksum type TBD.
other-verifiers
A container including a principal name and a cryptographic
checksum computed over the encoding of the elements field, keyed
with the long term key of the principal name specified in the
identifier field. The PrincipalNAme MUST be present and a valid
principal in the REALM for additional verifiers.
KDCs MAY add one or more 'trusted service' verifiers. Unless
otherwise explicitly administratively configured, the 'trusted
service' SHOULD be found by substituting the service identifier
component of the principal name of the svc-verifier with 'host'.
Checksum type TBD.
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5. Assigned numbers
TBD
6. IANA Considerations
TBD.
7. Security Considerations
Although generally authorization data are conveyed within a ticket
and are thereby protected using the existing encryption methods on
the ticket, some authorization data requires the additional
protection provided by the CAMMAC.
8. Acknowledgements
TBD.
9. References
9.1. Normative References
[RFC3961] Raeburn, K., "Encryption and Checksum Specifications for
Kerberos 5", RFC 3961, February 2005.
[RFC3962] Raeburn, K., "Advanced Encryption Standard (AES)
Encryption for Kerberos 5", RFC 3962, February 2005.
[RFC4120] Neuman, C., Yu, T., Hartman, S., and K. Raeburn, "The
Kerberos Network Authentication Service (V5)", RFC 4120,
July 2005.
9.2. Informative References
[MIT-Athena]
Steiner, J., Neuman, B., and J. Schiller, "Kerberos: An
Authentication Service for Open Network Systems. In
Proceedings of the Winter 1988 Usenix Conference.
February.", 1988.
[RFC1510] Kohl, J. and B. Neuman, "The Kerberos Network
Authentication Service (V5)", RFC 1510, September 1993.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
[X.690] ISO, "ASN.1 encoding rules: Specification of Basic
Encoding Rules (BER), Canonical Encoding Rules (CER) and
Distinguished Encoding Rules (DER) - ITU-T Recommendation
X.690 (ISO/IEC International Standard 8825-1:1998)", 1997.
Appendix A. Additional Stuff
This becomes an Appendix.
Authors' Addresses
Simo Sorce (editor)
Red Hat
Email: ssorce@redhat.com
Tom Yu (editor)
MIT Kerberos Consortium
Email: tlyu@mit.edu
Thomas Hardjono (editor)
MIT Kerberos Consortium
Email: hardjono@mit.edu
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