Network Working Group E. Lear
Internet-Draft Cisco Systems GmbH
Intended status: Standards Track H. Tschofenig
Expires: February 14, 2011 Nokia Siemens Networks
H. Mauldin
Cisco Systems, Inc.
S. Josefsson
SJD AB
August 13, 2010
A SASL & GSS-API Mechanism for OpenID
draft-ietf-kitten-sasl-openid-00
Abstract
OpenID has found its usage on the Internet for Web Single Sign-On.
Simple Authentication and Security Layer (SASL) and the Generic
Security Service Application Program Interface (GSS-API) are
application frameworks to generalize authentication. This memo
specifies a SASL and GSS-API mechanism for OpenID that allows the
integration of existing OpenID Identity Providers with applications
using SASL and GSS-API.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on February 14, 2011.
Copyright Notice
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Copyright (c) 2010 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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described in the BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2. Applicability for non-HTTP Use Cases . . . . . . . . . . . . . 5
2.1. Binding SASL to OpenID in the Relying Party . . . . . . . 8
2.2. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 8
3. OpenID SASL Mechanism Specification . . . . . . . . . . . . . 10
3.1. Advertisement . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Initiation . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3. Authentication Request . . . . . . . . . . . . . . . . . . 10
3.4. Server Response . . . . . . . . . . . . . . . . . . . . . 11
4. OpenID GSS-API Mechanism Specification . . . . . . . . . . . . 12
4.1. GSS-API Principal Name Types for OpenID . . . . . . . . . 12
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6.1. Binding OpenIDs to Authorization Identities . . . . . . . 15
6.2. RP redirected by malicious URL to take an improper
action . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.3. Session Swapping (Cross-Site Request Forgery) . . . . . . 15
6.4. User Privacy . . . . . . . . . . . . . . . . . . . . . . . 16
6.5. Collusion between RPs . . . . . . . . . . . . . . . . . . 16
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
9. Normative References . . . . . . . . . . . . . . . . . . . . . 19
Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
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1. Introduction
OpenID [OpenID] is a three-party protocol that provides a means for a
user to offer identity assertions and other attributes to a web
server (Relying Party) via the help of an identity provider. The
purpose of this system is to provide a way to verify that an end user
controls an identifier.
Simple Authentication and Security Layer (SASL) [RFC4422] (SASL) is
used by application protocols such IMAP, POP and XMPP, with the goal
of modularizing authentication and security layers, so that newer
mechanisms can be added as needed. This memo specifies just such a
mechanism.
The Generic Security Service Application Program Interface (GSS-API)
[RFC2743] provides a framework for applications to support multiple
authentication mechanisms through a unified interface. This document
defines a pure SASL mechanism for OpenID, but it conforms to the new
bridge between SASL and the GSS-API called GS2 [I-D.ietf-sasl-gs2].
This means that this document defines both a SASL mechanism and a
GSS-API mechanism. We want to point out that the GSS-API interface
is optional for SASL implementers, and the GSS-API considerations can
be avoided in environments that uses SASL directly without GSS-API.
As currently envisioned, this mechanism is to allow the interworking
between SASL and OpenID in order to assert identity and other
attributes to relying parties. As such, while servers (as relying
parties) will advertise SASL mechanisms, clients will select the
OpenID mechanism.
The OpenID mechanism described in this memo aims to re-use the
available OpenID specification to a maximum extent and therefore does
not establish a separate authentication, integrity and
confidentiality mechanism. It is anticipated that existing security
layers, such as Transport Layer Security (TLS), will continued to be
used.
Figure 1 describes the interworking between OpenID and SASL. This
document requires enhancements to the Relying Party and to the Client
(as the two SASL communication end points) but no changes to the
OpenID Provider (OP) are necessary. To accomplish this goal indirect
messaging required by the OpenID specification is tunneled within
SASL.
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+-----------+
| |
>| Relying |
/ | Party |
// | |
// +-----------+
// ^
OpenID // +--|--+
// | O| |
/ S | p| |
// A | e| |
// S | n| |
// L | I| |
// | D| |
</ +--|--+
+------------+ v
| | +----------+
| OpenID | OpenID | |
| Provider |<--------------->| Client |
| | | |
+------------+ +----------+
Figure 1: Interworking Architecture
1.1. Terminology
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].
The reader is assumed to be familiar with the terms used in the
OpenID 2.0 specification.
1.2. Applicability
Because this mechanism transports information that should not be
controlled by an attacker, the OpenID mechanism MUST only be used
over channels protected by TLS [RFC5246], and the client MUST
successfully validate the server certificate, or similar integrity
protected and authenticated channels.
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2. Applicability for non-HTTP Use Cases
OpenID was originally envisioned for HTTP/HTML based communications,
and with the associated semantic, the idea being that the user would
be redirected by the Relying Party to an identity provider who
authenticates the user, and then sends identity information and other
attributes (either directly or indirectly) to the Relying Party. The
identity provider in the OpenID specifications is referred to as an
OpenID Provider (OP). The actual protocol flow, as copied from the
OpenID 2.0 specification, is as follows:
1. The end user initiates authentication by presenting a User-
Supplied Identifier to the Relying Party via their User-Agent
(e.g., http://user.example.com).
2. After normalizing the User-Supplied Identifier, the Relying Party
performs discovery on it and establishes the OP Endpoint URL that
the end user uses for authentication. It should be noted that
the User-Supplied Identifier may be an OP Identifier, which
allows selection of a Claimed Identifier at the OP or for the
protocol to proceed without a Claimed Identifier if something
else useful is being done via an extension.
3. The Relying Party and the OP optionally establish an association
-- a shared secret established using Diffie-Hellman Key Exchange.
The OP uses an association to sign subsequent messages and the
Relying Party to verify those messages; this removes the need for
subsequent direct requests to verify the signature after each
authentication request/response.
4. The Relying Party redirects the end user's User-Agent to the OP
with an OpenID Authentication request. This occurs as stated in
Section 10.3 of [RFC2616].
5. The OP authenticates the end user and establishes whether the end
user will authenticate to, and share specific attributes with,
the Relying Party. For instance, the OP often asks the user what
to do. The manner in which the end user authenticates to their
OP and any policies surrounding such authentication is out of
scope of OpenID.
6. The OP redirects the end user's User-Agent back to the Relying
Party with either an assertion that authentication is approved or
a message that authentication failed.
7. The Relying Party verifies the information received from the OP
including checking the Return URL, verifying the discovered
information, checking the nonce, and verifying the signature by
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using either the shared key established during the association or
by sending a direct request to the OP.
When considering this flow in the context of SASL, we note that while
the RP and the client both must change their code to implement this
SASL mechanism, it is a design constraint that the OP behavior remain
untouched, in order for implementations to interoperate with existing
IdPs. Hence, an analog flow that interfaces the three parties needs
to be created. In the analog, we note that unlike a web server, the
SASL server already has some sort of session (probably a TCP
connection) established with the client. However, it may be
necessary to redirect a SASL client to another application. This
will be discussed below. By doing so, we externalize much of the
authentiction from SASL.
The steps are shown from below:
1. The Relying Party or SASL server advertises support for the SASL
OpenID mechanism to the client.
2. The client initiates a SASL authentiation and transmits the
User-Supplied Identifier as well as an optional return_to
parameter.
3. After normalizing the User-Supplied Identifier, the Relying
Party performs discovery on it and establishes the OP Endpoint
URL that the end user uses for authentication.
4. The Relying Party and the OP optionally establish an association
-- a shared secret established using Diffie-Hellman Key
Exchange. The OP uses an association to sign subsequent
messages and the Relying Party to verify those messages; this
removes the need for subsequent direct requests to verify the
signature after each authentication request/response.
5. The Relying Party transmits an authentication request to the OP
to obtain an assertion in the form of an indirect request.
These messages are passed through the client rather than
directly between the RP and the OP. OpenID defines two methods
for indirect communication, namely HTTP redirects and HTML form
submission. Both mechanisms are not directly applicable for
usage with SASL. To ensure that a standard OpenID 2.0 capable
OP can be used a new method is defined in this document that
requires the OpenID message content to be encoded using a
Universal Resource Idenitifier (URI). [RFC3986]
6. The SASL client now sends an empty response, as authentication
continues via the normal OpenID flow.
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7. At this point the client application MUST construct a URL
containing the content received in the previous message from the
RP. This URL is transmitted to the OP either by the SASL client
application or an appropriate handler, such as a browser.
8. Next the client optionally authenticates to the OP and then
approves or disapproves authentication to the Relying Party.
The manner in which the end user is authenticated to their
respective OP and any policies surrounding such authentication
is out of scope of OpenID and and hence also out of scope for
this specification. This step happens out of band from SASL.
9. The OP will convey information about the success or failure of
the authentication phase back to the RP, again using an indirect
response via the client browser or handler. The client
transmits over HTTP the redirect of the OP result to the RP.
This step happens out of band from SASL.
10. The RP MAY send an OpenID check_authentication request directly
to the OP, if no association has been established, and the OP
should be expected to respond. Again this step happens out of
band from SASL.
11. The SASL server sends an appropriate SASL response to the
client, with optional Open Simple Registry (SREG) attributes.
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SASL Serv. Client OP
|>-----(1)----->| | Advertisement
| | |
|<-----(2)-----<| | Initiation
| | |
|> - - (3) - - - - - - - - - ->| Discovery
| |
|>- - -(4)- - - - - - - - - - >| Association
|<- - -(4)- - - - - - - - - - <|
| | |
|>-----(5)----->| | Indirect Auth Request
| | |
|<-----(6)-----<| | Client Empty Response
| | |
| |>- - (7)- - ->| Client GET to the OP (ext)
| | |
| |<- - (8)- - ->| Client / OP Auth. (ext.)
| | |
|<- - -(9)- - - + - - - - - - <| HTTP(s) Indirect id_res
| | |
|<- - -(10)- - - - - - - - - ->| Optional check_authenticate
| | |
|>-----(11)---->| | SASL completion with status
----- = SASL
- - - = HTTP or SSL
Note the directionality in SASL is such that the client MUST send an
empty response. Specifically, it processes the redirect and then
awaits a final SASL decision, while the rest of the OpenID
authentication process continues.
2.1. Binding SASL to OpenID in the Relying Party
To ensure that a specific request is bound, and in particular to ease
interprocess communication, it may be necessary for the relying party
to encode some sort of nonce in the URIs it transmits through the
client for success or failure. This can be done in any number of
ways. Examples would include making changes to the base URI or
otherwise including an additional fragment.
2.2. Discussion
As mentioned above OpenID is primarily designed to interact with web-
based applications. Portions of the authentication stream are only
defined in the crudest sense. That is, when one is prompted to
approve or disapprove an authentication, anything that one might find
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on a browser is allowed, including JavaScript, fancy style-sheets,
etc. Because of this lack of structure, implementations will need to
invoke a fairly rich browser in order to insure that the
authentication can be completed.
Once there is an outcome, the SASL server needs to know about it.
The astute will hopefully by now have noticed an empty client SASL
challenge. This is not to say that nothing is happening, but rather
that authentication flow has shifted from SASL to OpenID, and will
return when the server has an outcome to hand to the client. The
alternative to this flow is some signal from the HTML browser to the
SASL client of the results that is in turn passed to the SASL server.
The IPC issue this raises is substantial. Better, we conclude, to
externalize the authentication to the browser, and have an empty
client challenge.
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3. OpenID SASL Mechanism Specification
Based on the previous figure, the following operations are performed
with the OpenId SASL mechanism:
3.1. Advertisement
To advertise that a server supports OpenID, during application
session initiation, it displays the name "OPENID20" in the list of
supported SASL mechanisms.
3.2. Initiation
A client initiates an OpenID authentication with SASL by sending the
GS2 header followed by the XRI or URI, as specified in the OpenID
specification. The GS2 header carries the optional authorization
identity.
initial-response = gs2-header Auth-Identifier
Auth-Identifier = Identifier ; authentication identifier
Identifier = URI | XRI ; Identifer is specified in
; Sec. 7.2 of the OpenID 2.0 spec.
The "gs2-header" is specified in [I-D.ietf-sasl-gs2], and it is used
as follows. The "gs2-nonstd-flag" MUST NOT be present. The "gs2-cb-
flag" MUST be "n" because channel binding is not supported by this
mechanism. The "gs2-authzid" carries the optional authorization
identity.
The XRI syntax is defined in [XRI2.0]. URI is specified in
[RFC3986].
3.3. Authentication Request
The SASL Server sends an OpenID message that contains an openid.mode
of either "checkid_immediate" or "checkid_setup", as specified in
Section 9.1 of the OpenID 2.0 specification.
The client now sends that request via an HTTP GET to the OP, as if
redirected to do so from an HTTP server.
The client MUST handle both user authentication to the OP and
confirmation or rejection of the authentiation of the RP.
After all authentication has been completed by the OP, and after the
response has been sent to the client, the client will relay the
response to the Relying Party via HTTP or SSL.
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3.4. Server Response
The Relying Party now validates the response it received from the
client via HTTP or SSL, as specified in the OpenID specification.
The response by the Relying Party consists of an application specific
response code indicating success or failure of authentication. In
the additional data, the server MAY include OpenID Simple Registry
(SREG) attributes that are listed in Section 4 of [SREG1.0]. They
are encoded as follows:
1. Strip "openid.sreg." from each attribute name.
2. Treat the concatentation of results as URI parameters that are
separated by an ambersand (&) and encode as one would a URI,
absent the scheme, authority, and the question mark.
For example: email=lear@example.com&fullname=Eliot%20Lear
More formally:
outcome_data = [ sreg_avp *( "," sreg_avp ) ]
sreg_avp = sreg_attr "=" sreg_val
sreg_attr = sreg_word
sreg_val = sreg_word
sreg_word = 1* ( unreserved / pct-encoded )
; pct-encoded from Section 2.1 of RFC 3896
; unreserved from Section 2.3 of RFC 3896
If the application protocol allows, openid.error and
openid.error_code and any other useful diagnostic information SHOULD
be included in authentication failures.
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4. OpenID GSS-API Mechanism Specification
This section and its sub-sections and all normative references of it
not referenced elsewhere in this document are INFORMATIONAL for SASL
implementors, but they are NORMATIVE for GSS-API implementors.
The OpenID SASL mechanism is actually also a GSS-API mechanism. The
messages are the same, but a) the GS2 header on the client's first
message and channel binding data is excluded when OpenID is used as a
GSS-API mechanism, and b) the RFC2743 section 3.1 initial context
token header is prefixed to the client's first authentication message
(context token).
The GSS-API mechanism OID for OpenID is 1.3.6.1.4.1.11591.4.5.
OpenID security contexts always have the mutual_state flag
(GSS_C_MUTUAL_FLAG) set to TRUE. OpenID does not support credential
delegation, therefore OpenID security contexts alway have the
deleg_state flag (GSS_C_DELEG_FLAG) set to FALSE.
The OpenID mechanism does not support per-message tokens or
GSS_Pseudo_random.
4.1. GSS-API Principal Name Types for OpenID
OpenID supports standard generic name syntaxes for acceptors such as
GSS_C_NT_HOSTBASED_SERVICE (see [RFC2743], Section 4.1).
OpenID supports only a single name type for initiators:
GSS_C_NT_USER_NAME. GSS_C_NT_USER_NAME is the default name type for
OpenID.
OpenID name normalization is covered by the OpenID specification, see
[OpenID] section 7.2.
The query, display, and exported name syntaxes for OpenID principal
names are all the same. There are no OpenID-specific name syntaxes
-- applications should use generic GSS-API name types such as
GSS_C_NT_USER_NAME and GSS_C_NT_HOSTBASED_SERVICE (see [RFC2743],
Section 4). The exported name token does, of course, conform to
[RFC2743], Section 3.2, but the "NAME" part of the token should be
treated as a potential input string to the OpenID name normalization
rules.
GSS-API name attributes may be defined in the future to hold the
normalized OpenID Identifier.
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5. Example
Suppose one has an OpenID of http://openid.example, and wishes to
authenticate his IMAP connection to mail.example (where .example is
the top level domain specified in [RFC2606]). The user would input
his Openid into his mail user agent, when he configures the account.
In this case, no association is attempted between the OpenID Consumer
and the OP. The client will make use of the return_to attribute to
capture results of the authentication to be redirected to the server.
The authentication on the wire would then look something like the
following:
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(S = IMAP server; C = IMAP client)
C: < connects to IMAP port>
S: * OK
C: C1 CAPABILITY
S: * CAPABILITY IMAP4rev1 SASL-IR SORT [...] AUTH=OPENID20
S: C1 OK Capability Completed
C: C2 AUTHENTICATE OPENID biwsaHR0cDovL29wZW5pZC5leGFtcGxlLw==
[ This is the base64 encoding of "n,,http://openid.example/".
Server performs discovery on http://openid.example/ ]
S: + aHR0cDovL29wZW5pZC5leGFtcGxlL29wZW5pZC8/b3BlbmlkLm5z
PWh0dHA6Ly9zcGVjcy5vcGVuaWQubmV0L2F1dGgvMi4wJm9wZW5p
ZC5yZXR1cm5fdG89aHR0cHM6Ly9tYWlsLmV4YW1wbGUvY29uc3Vt
ZXIvMWVmODg4YyZvcGVuaWQuY2xhaW1lZF9pZD1odHRwczovL29w
ZW5pZC5leGFtcGxlLyZvcGVuaWQuaWRlbnRpdHk9aHR0cHM6Ly9v
cGVuaWQuZXhhbXBsZS8mb3BlbmlkLnJlYWxtPWltYXA6Ly9tYWls
LmV4YW1wbGUmb3BlbmlkLm1vZGU9Y2hlY2tpZF9zZXR1cA==
[ This is the base64 encoding of "http://openid.example/openid/
?openid.ns=http://specs.openid.net/auth/2.0
&openid.return_to=https://mail.example/consumer/1ef888c
&openid.claimed_id=https://openid.example/
&openid.identity=https://openid.example/
&openid.realm=imap://mail.example
&openid.mode=checkid_setup"
with line breaks and spaces added here for readibility.
]
C:
[ The client now sends the URL it received to a browser for
processing. The user logs into http://openid.example, and
agrees to authenticate imap://mail.example. A redirect is
passed back to the client browser who then connects to
https://imap.example/consumer via SSL with the results.
From an IMAP perspective, however, the client sends an empty
response, and awaits mail.example.
Server mail.example would now contact openid.example with an
openid.check_authenticate message. After that...
]
S: + ZW1haWw9bGVhckBtYWlsLmV4YW1wbGUsZnVsbG5hbWU9RWxp
b3QlMjBMZWFy
[ Here the IMAP server has returned an SREG attribute of
email=lear@mail.example,fullname=Eliot%20Lear.
Line break added in this example for clarity. ]
C:
[ In IMAP client must send a blank response to receive data
that is included in a success response. ]
S: C2 OK
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6. Security Considerations
This section will address only security considerations associated
with the use of OpenID with SASL applications. For considerations
relating to OpenID in general, the reader is referred to the OpenID
specification and to other literature. Similarly, for general SASL
Security Considerations, the reader is referred to that
specification.
6.1. Binding OpenIDs to Authorization Identities
As specified in [RFC4422], the server is responsible for binding
credentials to a specific authorization identity. It is therefore
necessary that either some sort of registration process takes place
to register specific OpenIDs, or that only specific trusted OpenID
Providers be allowed. Some out of band knowledge may help this
process along. For instance, users of a particular domain may
utilize a particular OP that enforces a mapping.
6.2. RP redirected by malicious URL to take an improper action
In the initial SASL client response a user or host can transmit a
malicious response to the RP for purposes of taking advantage of
weaknesses in the RP's OpenID implementation. It is possible to add
port numbers to the URL so that the outcome is the RP does a port
scan of the site. The URL could send the connection to an internal
host or even the local host, which the attacker would not normally
have access to. The URL could contain a protocol other than http or
https, such as file or ftp.
To mitigate this attack, implementations should carefully analyze
URLs received, eliminating any that would in some way be privileged.
A log of those sites that fail SHOULD be kept, and limitations on
queries from clients should be imposed, just as with any other
authentication attempt.
6.3. Session Swapping (Cross-Site Request Forgery)
There is no defined mechanism in the OpenID protocol to bind the
OpenID session to the user's browser. An attacker may forge a cross-
site request in the log-in form, which has the user logging into a
proper RP as the attacker. The user would not recognize they are
logged into the site as the attacker, and so may reveal information
at the RP. Cross-site request forgery is a widely exploited
vulnerability at web sites. This is only concern in the context SASL
in as much as the client is not configured with the Relying Party
(e.g., SASL server) in a safe manner.
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6.4. User Privacy
The OP is aware of each RP that a user logs into. There is nothing
in the protocol to hide this information from the OP. It is not a
requirement to track the visits, but there is nothing that prohibits
the collection of information. SASL servers should be aware that
OpenID Providers will be track - to some extent - user access to
their services and any additional information that OP provides.
6.5. Collusion between RPs
It is possible for RPs to link data that they have collected on you.
By using the same identifier to log into every RP, collusion between
RPs is possible. In OpenID 2.0, directed identity was introduced.
Directed identity allows the OP to transform the identifier the user
typed in to another identifier. This way the RP would never see the
actual user identifier, but a randomly generated identifier. This is
an option the user has to understand and decide to use if the OP is
supporting it.
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7. IANA Considerations
The IANA is requested to register the following SASL profile:
SASL mechanism profile: OPENID20
Security Considerations: See this document
Published Specification: See this document
For further information: Contact the authors of this document.
Owner/Change controller: the IETF
Note: None
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8. Acknowledgments
The authors would like to thank Alexey Melenkov, Joe Hildebrand, Mark
Crispin, Chris Newman, Leif Johansson, and Klaas Wierenga for their
review and contributions.
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9. Normative References
[I-D.ietf-sasl-gs2]
Josefsson, S. and N. Williams, "Using GSS-API Mechanisms
in SASL: The GS2 Mechanism Family", draft-ietf-sasl-gs2-20
(work in progress), January 2010.
[OpenID] OpenID Foundation, "OpenID Authentication 2.0 - Final",
December 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2606] Eastlake, D. and A. Panitz, "Reserved Top Level DNS
Names", BCP 32, RFC 2606, June 1999.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2743] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and
Security Layer (SASL)", RFC 4422, June 2006.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[SREG1.0] OpenID Foundation, "OpenID Simple Registration Extension
version 1.0", June 2006.
[XRI2.0] Reed, D. and D. McAlpin, "Extensible Resource Identifier
(XRI) Syntax V2.0", OASIS Standard xri-syntax-V2.0-cs,
September 2005.
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Appendix A. Changes
This section to be removed prior to publication.
o 00 WG -00 draft. Slight wording modifications abou design
constraints per Alexey.
o 02 Correct single (significant) error on mechanism name.
o 01 Add nonce discussion, add authorized identity, explain a
definition. Add gs2 support.
o 00 Initial Revision.
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Authors' Addresses
Eliot Lear
Cisco Systems GmbH
Richtistrasse 7
Wallisellen, ZH CH-8304
Switzerland
Phone: +41 44 878 9200
Email: lear@cisco.com
Hannes Tschofenig
Nokia Siemens Networks
Linnoitustie 6
Espoo 02600
Finland
Phone: +358 (50) 4871445
Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at
Henry Mauldin
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134
USA
Phone: +1 (800) 553-6387
Email: hmauldin@cisco.com
Simon Josefsson
SJD AB
Hagagatan 24
Stockholm 113 47
SE
Email: simon@josefsson.org
URI: http://josefsson.org/
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