ABFAB J. Howlett
Internet-Draft JANET(UK)
Intended status: Informational S. Hartman
Expires: September 11, 2011 Painless Security
March 10, 2011
A RADIUS Attribute for SAML Messages
draft-ietf-abfab-aaa-saml-01
Abstract
This document defines the SAML-Message attribute for use with the
RADIUS protocol. This attribute is used for encapsulating Security
Assertion Mark-up Language (SAML) messages.
Status of This Memo
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This Internet-Draft will expire on September 11, 2011.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. SAML Message Attribute . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . . 5
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1. Introduction
The SAML-Message attribute has motivated by the requirements of the
ABFAB architecture [I-D.lear-abfab-arch]. In this architecture, the
attribute is used to convey Security Assertion Mark-up Language
(SAML) messages between a SAML requester and responder.
In the SAML model, the composition of such message exchanges with an
underlying transport protocol is known as a SAML binding. SAML
already defines [OASIS.saml-bindings-2.0-os] a number of mainly HTTP-
based bindings, principally (although by no means exclusively) for
use with the SAML Web Browser Single Sign-On Profile
[OASIS.saml-profiles-2.0-os].
In the ABFAB architecture, AAA-based transport protocols are used to
convey SAML messages. This document defines a RADIUS attribute
required for binding SAML to RADIUS [RFC2865] transport. A draft
document [1] exists that describes a proposed binding, but it has not
yet been submitted to the OASIS Security Services Technical
Committee. This is pending conclusions on the following aspects of
the ABFAB architecture:
o The use of the SAML attribute query at some arbitrary time after
the initial EAP authentication exchange.
o The use of the SAML attribute query to obtain attributes for a
principal from more than one attribute authority.
o Alignment with the Diameter ABFAB application
[I-D.jones-diameter-abfab].
This attribute is likely to be useful for other purposes besides
ABFAB; an example of a potential application is SAML-based
authorisation for network access.
2. Conventions
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. SAML Message Attribute
This attribute contains a SAML [OASIS.saml-core-2.0-os] message.
Where multiple SAML-Message attributes are included in a RADIUS
message, the Message fields of these attributes are to be
concatenated to form a single SAML message.
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A summary of the SAML-Message format is shown below. The fields are
transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | SAML Message...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
Type: TBD
Length: >=4
Message: The Message field is one or more octets containing a SAML
message. If larger than a single attribute, the SAML message data
MUST be split on 253-octet boundaries over as many attributes as
necessary. The SAML message is reconstructed by concatenating the
contents of all SAML-Message attributes.
4. Security Considerations
TODO
5. IANA Considerations
Assignments of additional enumerated values for the RADIUS attributes
defined in this document are to be processed as described in
[RFC3575], subject to the additional requirements of a published
specification.
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs
to Indicate Requirement Levels",
BCP 14, RFC 2119, March 1997.
[RFC2865] Rigney, C., Willens, S., Rubens, A.,
and W. Simpson, "Remote Authentication
Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[OASIS.saml-core-2.0-os] Cantor, S., Kemp, J., Philpott, R., and
E. Maler, "Assertions and Protocol for
the OASIS Security Assertion Markup
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Language (SAML) V2.0", OASIS
Standard saml-core-2.0-os, March 2005.
[RFC3575] Aboba, B., "IANA Considerations for
RADIUS (Remote Authentication Dial In
User Service)", RFC 3575, July 2003.
6.2. Informative References
[I-D.jones-diameter-abfab] Jones, M. and H. Tschofenig, "The
Diameter 'Application Bridging for
Federated Access Beyond Web (ABFAB)'
Application",
draft-jones-diameter-abfab-00 (work in
progress), March 2011.
[I-D.lear-abfab-arch] Howlett, J., Hartman, S., Tschofenig,
H., and E. Lear, "Application Bridging
for Federated Access Beyond Web (ABFAB)
Architecture", draft-lear-abfab-arch-02
(work in progress), March 2011.
[OASIS.saml-bindings-2.0-os] Cantor, S., Hirsch, F., Kemp, J.,
Philpott, R., and E. Maler, "Bindings
for the OASIS Security Assertion Markup
Language (SAML) V2.0", OASIS
Standard saml-bindings-2.0-os,
March 2005.
[OASIS.saml-profiles-2.0-os] Hughes, J., Cantor, S., Hodges, J.,
Hirsch, F., Mishra, P., Philpott, R.,
and E. Maler, "Profiles for the OASIS
Security Assertion Markup Language
(SAML) V2.0", OASIS
Standard OASIS.saml-profiles-2.0-os,
March 2005.
URIs
[1] <http://www.project-moonshot.org/sites/default/files/
sstc-saml-binding-aaa-draft-00.pdf>
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Authors' Addresses
Josh Howlett
JANET(UK)
Lumen House, Library Avenue, Harwell
Oxford OX11 0SG
UK
Phone: +44 1235 822363
EMail: Josh.Howlett@ja.net
Sam Hartman
Painless Security
Phone:
EMail: hartmans-ietf@mit.edu
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