draft-ietf-kitten-gssapi-channel-bindings-07.txt   rfc5554.txt 
KITTEN WG N. Williams Network Working Group N. Williams
Internet-Draft Sun Request for Comments: 5554 Sun
Updates: rfc2743 April 6, 2009
(if approved)
Intended status: Standards Track
Expires: October 8, 2009
Clarifications and Extensions to the GSS-API for the Use of Channel
Bindings
draft-ietf-kitten-gssapi-channel-bindings-07.txt
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http://www.ietf.org/ietf/1id-abstracts.txt. the Generic Security Service Application Program Interface (GSS-API)
for the Use of Channel Bindings
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Abstract Abstract
This document clarifies and generalizes the Generic Security Services This document clarifies and generalizes the Generic Security Service
Application Programming Interface (GSS-API) "channel bindings" Application Programming Interface (GSS-API) "channel bindings"
facility, and imposes requirements on future GSS-API mechanisms and facility, and imposes requirements on future GSS-API mechanisms and
programming language bindings of the GSS-API. programming language bindings of the GSS-API.
Table of Contents Table of Contents
1. Conventions used in this document . . . . . . . . . . . . . . 3 1. Introduction ....................................................2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions Used in This Document ...............................2
3. New Requirements for GSS-API Mechanisms . . . . . . . . . . . 5 3. New Requirements for GSS-API Mechanisms .........................2
4. Generic Structure for GSS-API Channel Bindings . . . . . . . . 6 4. Generic Structure for GSS-API Channel Bindings ..................2
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations .........................................3
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. References ......................................................4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.1. Normative References .......................................4
7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 6.2. Informative References .....................................4
7.2. Informative References . . . . . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Conventions used in this document
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 [RFC2119].
2. Introduction 1. Introduction
The base GSS-API v2, update 1 specification [RFC2743] provides a The base GSS-API version 2, update 1 specification [RFC2743] provides
facility for channel binding (see also [RFC5056]), but its treatment a facility for channel binding (see also [RFC5056]), but its
was incomplete. The C-bindings of the GSS-API [RFC2744] expanded a treatment is incomplete. The GSS-API C-bindings specification
little on this facility in what should have been a generic way, but [RFC2744] expands somewhat on this facility in what should be a
was a C-specific way, and still, the treatment of this facility was generic way, but is instead a C-specific way, thus leaving the
incomplete. treatment of this facility incomplete.
This document clarifies the GSS-API's channel binding facility and This document clarifies the GSS-API's channel binding facility and
generalizes the parts of it that are specified in the C-bindings generalizes the parts of it that are specified in the C-bindings
document but which should have been generic from the first. document but that should have been generic from the start.
2. Conventions Used in This Document
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 [RFC2119].
3. New Requirements for GSS-API Mechanisms 3. New Requirements for GSS-API Mechanisms
Given the publication of RFC5056 we now assert that all new GSS-API Given the publication of RFC 5056, we now assert that all new GSS-API
mechanisms that support channel binding MUST conform to [RFC5056]. mechanisms that support channel binding MUST conform to [RFC5056].
4. Generic Structure for GSS-API Channel Bindings 4. Generic Structure for GSS-API Channel Bindings
The base GSS-API v2, update 1 specification [RFC2743] provides a The base GSS-API version 2, update 1 specification [RFC2743] provides
facility for channel binding. It models channel bindings as an OCTET a facility for channel binding. It models channel bindings as an
STRING and leaves it to the GSS-API v2, update 1 C-Bindings OCTET STRING and leaves it to the GSS-API version 2, update 1
specification to specify the structure of the contents of the channel C-bindings specification to specify the structure of the contents of
bindings OCTET STRINGs. The C-Bindings specification [RFC2744] then the channel bindings OCTET STRINGs. The C-bindings specification
defines, in terms of C, what should have been a generic structure for [RFC2744] then defines, in terms of C, what should have been a
channel bindings. The Kerberos V GSS mechanism [RFC4121] also generic structure for channel bindings. The Kerberos V GSS mechanism
defines a method for encoding GSS channel bindings in a way that is [RFC4121] also defines a method for encoding GSS channel bindings in
independent of the C-Bindings -- otherwise the mechanism's channel a way that is independent of the C-bindings -- otherwise, the
binding facility would not be useable with other language bindings. mechanism's channel binding facility would not be useable with other
language bindings.
In other words, the structure of GSS channel bindings given in In other words, the structure of GSS channel bindings given in
[RFC2744] is actually generic, rather than specific to the C [RFC2744] is actually generic in spite of being specified in terms of
programming language. C concepts and syntax.
We generalize it as shown below, using the same pseudo-ASN.1 as is We generalize it as shown below, using the same pseudo-ASN.1 as is
used in RFC2743. Although the figure below is, indeed, a valid ASN.1 used in RFC 2743. Although the figure below is, indeed, a valid
[CCITT.X680.2002] type, we do not provide a full ASN.1 module as none ASN.1 [CCITT.X680] type, we do not provide a full ASN.1 module as
is needed because no standard encoding of this structure is needed -- none is needed because no standard encoding of this structure is
the definition below is part of an abstract API, not part of a needed -- the definition below is part of an abstract API, not part
protocol defining bits on the wire. GSS-API mechanisms do need to of a protocol defining bits on the wire. GSS-API mechanisms do need
encode the contents of this structure, but that encoding will be to encode the contents of this structure, but that encoding will be
mechanism specific (see below). mechanism specific (see below).
GSS-CHANNEL-BINDINGS ::= SEQUENCE { GSS-CHANNEL-BINDINGS ::= SEQUENCE {
initiator-address-type INTEGER, -- See RFC2744 initiator-address-type INTEGER, -- See RFC2744
initiator-address OCTET STRING, -- See RFC2744 initiator-address OCTET STRING, -- See RFC2744
acceptor-address-type INTEGER, -- See RFC2744 acceptor-address-type INTEGER, -- See RFC2744
acceptor-address OCTET STRING, -- See RFC2744 acceptor-address OCTET STRING, -- See RFC2744
application-data OCTET STRING -- See RFC5056 application-data OCTET STRING -- See RFC5056
} }
Abstract GSS-API channel bindings structure Abstract GSS-API Channel Bindings Structure
The values for the address fields are described in [RFC2744]. The values for the address fields are described in [RFC2744].
New language-specific bindings of the GSS-API SHOULD specify a New language-specific bindings of the GSS-API SHOULD specify a
language-specific formulation of this structure. language-specific formulation of this structure.
Where a language binding of the GSS-API models channel bindings as Where a language binding of the GSS-API models channel bindings as
OCTET STRINGs (or the language's equivalent), then the implementation OCTET STRINGs (or the language's equivalent), then the implementation
MUST assume that the given bindings correspond only to the MUST assume that the given bindings correspond only to the
application-data field of GSS-CHANNEL-BINDINGS as shown above, rather application-data field of GSS-CHANNEL-BINDINGS as shown above, rather
than some encoding of GSS-CHANNEL-BINDINGS. than some encoding of GSS-CHANNEL-BINDINGS.
As mentioned above, [RFC4121] describes an encoding of the above GSS- As mentioned above, [RFC4121] describes an encoding of the above GSS-
CHANNEL-BINDINGS structure, and then hashes that encoding. Other CHANNEL-BINDINGS structure and then hashes that encoding. Other GSS-
GSS-API mechanisms are free to use that encoding. API mechanisms are free to use that encoding.
5. IANA Considerations
There are no IANA considerations in this document.
6. Security Considerations 5. Security Considerations
For general security considerations relating to channel bindings see For general security considerations relating to channel bindings, see
[RFC5056]. [RFC5056].
Language bindings that use OCTET STRING (or equivalent) for channel Language bindings that use OCTET STRING (or equivalent) for channel
bindings will not support the use of network addresses as channel bindings will not support the use of network addresses as channel
bindings. This should not cause any security problems, as the use of bindings. This should not cause any security problems, as the use of
network addresses as channel bindings is not generally secure. network addresses as channel bindings is not generally secure.
However, it is important that "end-point channel bindings" not be However, it is important that "end-point channel bindings" not be
modelled as network addresses, otherwise such channel bindings may modeled as network addresses; otherwise, such channel bindings may
not be useable with all language bindings of the GSS-API. not be useable with all language bindings of the GSS-API.
7. References 6. References
7.1. Normative References 6.1. Normative References
[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.
[RFC2743] Linn, J., "Generic Security Service Application Program [RFC2743] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000. Interface Version 2, Update 1", RFC 2743, January 2000.
[RFC2744] Wray, J., "Generic Security Service API Version 2 : [RFC2744] Wray, J., "Generic Security Service API Version 2 :
C-bindings", RFC 2744, January 2000. C-bindings", RFC 2744, January 2000.
[RFC4121] Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos [RFC4121] Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos
Version 5 Generic Security Service Application Program Version 5 Generic Security Service Application Program
Interface (GSS-API) Mechanism: Version 2", RFC 4121, Interface (GSS-API) Mechanism: Version 2", RFC 4121,
July 2005. July 2005.
[RFC5056] Williams, N., "On the Use of Channel Bindings to Secure [RFC5056] Williams, N., "On the Use of Channel Bindings to Secure
Channels", RFC 5056, November 2007. Channels", RFC 5056, November 2007.
7.2. Informative References 6.2. Informative References
[CCITT.X680.2002] [CCITT.X680] International Telephone and Telegraph Consultative
International International Telephone and Telegraph Committee, "Abstract Syntax Notation One (ASN.1):
Consultative Committee, "Abstract Syntax Notation One Specification of basic notation", CCITT Recommendation
(ASN.1): Specification of basic notation", X.680, July 2002.
CCITT Recommendation X.680, July 2002.
Author's Address Author's Address
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
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