wdiff rfc7522.original rfc7522.txt

OAuth Working Group
Internet Engineering Task Force (IETF) B. Campbell
Internet-Draft
Request for Comments: 7522 Ping Identity
Intended status:
Category: Standards Track C. Mortimore
Expires: May 16, 2015
ISSN: 2070-1721 Salesforce
M. Jones
Microsoft
November 12, 2014

SAML
May 2015

Security Assertion Markup Language (SAML) 2.0 Profile
for OAuth 2.0 Client Authentication and Authorization Grants
draft-ietf-oauth-saml2-bearer-23

Abstract

This specification defines the use of a Security Assertion Markup
Language (SAML) 2.0 Bearer Assertion as a means for requesting an
OAuth 2.0 access token as well as for use as a means of client authentication.

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This Internet-Draft will expire on May 16, 2015.
http://www.rfc-editor.org/info/rfc7522.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. HTTP Parameter Bindings for Transporting Assertions . . . . . 4
2.1. Using SAML Assertions as Authorization Grants . . . . . . 4
2.2. Using SAML Assertions for Client Authentication . . . . . 5
3. Assertion Format and Processing Requirements . . . . . . . . 6
3.1. Authorization Grant Processing . . . . . . . . . . . . . 8
3.2. Client Authentication Processing . . . . . . . . . . . . 9
4. Authorization Grant Example . . . . . . . . . . . . . . . . . 9
5. Interoperability Considerations . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8.1. Sub-Namespace Registration of urn:ietf:params:oauth
:grant-type:saml2-bearer . . . . . . . . . .
urn:ietf:params:oauth:grant-type:saml2-bearer . . . . . . 12
8.2. Sub-Namespace Registration of urn:ietf:params:oauth
:client-assertion-type:saml2-bearer . . . . . . . . . . . 12
urn:ietf:params:oauth:client-assertion-type:saml2-bearer 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A.
Acknowledgements . . . . . . . . . . . . . . . . . . 14
Appendix B. Document History . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 15

1. Introduction

The Security Assertion Markup Language (SAML) 2.0
[OASIS.saml-core-2.0-os] is an XML-based framework that allows
identity and security information to be shared across security
domains. The SAML specification, while primarily targeted at
providing cross domain Web browser single sign-on, sign-on (SSO), was also
designed to be modular and extensible to facilitate use in other
contexts.

The Assertion, an XML security token, is a fundamental construct of
SAML that is often adopted for use in other protocols and
specifications. (Some examples include [OASIS.WSS-SAMLTokenProfile]
and [OASIS.WS-Fed].) An Assertion is generally issued by an identity
provider Identity
Provider and consumed by a service provider who Service Provider that relies on its
content to identify the Assertion's subject for security related security-related
purposes.

The OAuth 2.0 Authorization Framework [RFC6749] provides a method for
making authenticated HTTP requests to a resource using an access
token. Access tokens are issued to third-party clients by an
authorization server (AS) with the (sometimes implicit) approval of
the resource owner. In OAuth, an authorization grant is an abstract
term used to describe intermediate credentials that represent the
resource owner authorization. An authorization grant is used by the
client to obtain an access token. Several authorization grant types
are defined to support a wide range of client types and user
experiences. OAuth also allows for the definition of new extension
grant types to support additional clients or to provide a bridge
between OAuth and other trust frameworks. Finally, OAuth allows the
definition of additional authentication mechanisms to be used by
clients when interacting with the authorization server.

The Assertion

"Assertion Framework for OAuth 2.0 Client Authentication and
Authorization Grants [I-D.ietf-oauth-assertions] specification Grants" [RFC7521] is an abstract extension to OAuth 2.0
that provides a general framework for the use of Assertions assertions as client
credentials and/or authorization grants with OAuth 2.0. This
specification profiles the OAuth Assertion Framework for OAuth 2.0 Client Authentication and Authorization
Grants [I-D.ietf-oauth-assertions] specification [RFC7521] to
define an extension grant type that uses a SAML 2.0 Bearer Assertion
to request an OAuth 2.0 access token as well as for use as client
credentials. The format and processing rules for the SAML Assertion
defined in this specification are intentionally similar, though not
identical, to those in the Web Browser SSO Profile profile defined in the
SAML Profiles [OASIS.saml-profiles-2.0-os] specification. This
specification is reusing, to the extent reasonable, concepts and
patterns from that well-established Profile. profile.

This document defines how a SAML Assertion can be used to request an
access token when a client wishes to utilize an existing trust
relationship, expressed through the semantics of (and digital
signature or keyed message digest calculated over) the SAML Assertion,
without a direct user approval step at the authorization server. It
also defines how a SAML Assertion can be used as a client
authentication mechanism. The use of an Assertion for client
authentication is orthogonal to and separable from using an Assertion
as an authorization grant. They can be used either in combination or
separately. Client assertion authentication is nothing more than an
alternative way for a client to authenticate to the token endpoint endpoint,
and it must be used in conjunction with some grant type to form a
complete and meaningful protocol request. Assertion authorization
grants may be used with or without client authentication or
identification. Whether or not client authentication is needed in
conjunction with an assertion authorization grant, as well as the
supported types of client authentication, are policy decisions at the
discretion of the authorization server.

The process by which the client obtains the SAML Assertion, prior to
exchanging it with the authorization server or using it for client
authentication, is out of scope.

1.1. Notational 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].

Unless otherwise noted, all the protocol parameter names and values
are case sensitive.

1.2. Terminology

All terms are as defined in The the following specifications: "The OAuth
2.0 Authorization Framework Framework" [RFC6749], the OAuth Assertion Framework for OAuth 2.0 Client
Authentication
[RFC7521], and Authorization Grants [I-D.ietf-oauth-assertions], "Assertions and Protocols for the OASIS Security
Assertion Markup Language (SAML) 2.0
[OASIS.saml-core-2.0-os] specifications. V2.0" [OASIS.saml-core-2.0-os].

2. HTTP Parameter Bindings for Transporting Assertions

The OAuth Assertion Framework for OAuth 2.0 Client Authentication and
Authorization Grants [I-D.ietf-oauth-assertions] specification [RFC7521] defines generic HTTP
parameters for transporting Assertions assertions during interactions with a
token endpoint. This section defines specific parameters and
treatments of those parameters for use with SAML 2.0 Bearer
Assertions.

2.1. Using SAML Assertions as Authorization Grants

To use a SAML Bearer Assertion as an authorization grant, the client
uses an access token request as defined in Section 4 of the OAuth
Assertion Framework for OAuth 2.0 Client Authentication and Authorization
Grants [I-D.ietf-oauth-assertions] specification [RFC7521] with the following specific parameter
values and encodings.

The value of the "grant_type" parameter is
"urn:ietf:params:oauth:grant-type:saml2-bearer".

The value of the "assertion" parameter contains a single SAML 2.0
Assertion. It MUST NOT contain more than one SAML 2.0 assertion. Assertion.
The SAML Assertion XML data MUST be encoded using base64url, where
the encoding adheres to the definition in Section 5 of RFC 4648
[RFC4648] and where the padding bits are set to zero. To avoid the
need for subsequent encoding steps (by "application/x-www-form-
urlencoded" [W3C.REC-html401-19991224], for example), the base64url base64url-
encoded data MUST NOT be line wrapped and pad characters ("=") MUST
NOT be included.

The "scope" parameter may be used, as defined in the OAuth Assertion
Framework for OAuth 2.0 Client Authentication and Authorization
Grants [I-D.ietf-oauth-assertions] specification, [RFC7521], to indicate the requested scope.

Authentication of the client is optional, as described in
Section 3.2.1 of OAuth 2.0 [RFC6749] and consequently, the
"client_id" is only needed when a form of client authentication that
relies on the parameter is used.

The following example demonstrates an Access Token Request access token request with an
assertion
Assertion as an authorization grant (with extra line breaks for
display purposes only):

POST /token.oauth2 HTTP/1.1
Host: as.example.com
Content-Type: application/x-www-form-urlencoded

grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Asaml2-bearer&
assertion=PHNhbWxwOl...[omitted for brevity]...ZT4

2.2. Using SAML Assertions for Client Authentication

To use a SAML Bearer Assertion for client authentication, the client
uses the following parameter values and encodings.

The value of the "client_assertion_type" parameter is
"urn:ietf:params:oauth:client-assertion-type:saml2-bearer".

The value of the "client_assertion" parameter MUST contain a single
SAML 2.0 Assertion. The SAML Assertion XML data MUST be encoded
using base64url, where the encoding adheres to the definition in
Section 5 of RFC 4648 [RFC4648] and where the padding bits are set to
zero. To avoid the need for subsequent encoding steps (by
"application/x-www-form-urlencoded" [W3C.REC-html401-19991224], for
example), the base64url encoded base64url-encoded data SHOULD NOT be line wrapped and
pad characters ("=") SHOULD NOT be included.

The following example demonstrates a client authenticating using an
assertion
Assertion during the presentation of an authorization code grant in
an Access Token Request access token request (with extra line breaks for display purposes
only):

POST /token.oauth2 HTTP/1.1
Host: as.example.com
Content-Type: application/x-www-form-urlencoded

grant_type=authorization_code&
code=vAZEIHjQTHuGgaSvyW9hO0RpusLzkvTOww3trZBxZpo&
code=n0esc3NRze7LTCu7iYzS6a5acc3f0ogp4&
client_assertion_type=urn%3Aietf%3Aparams%3Aoauth
%3Aclient-assertion-type%3Asaml2-bearer&
client_assertion=PHNhbW...[omitted for brevity]...ZT

3. Assertion Format and Processing Requirements

In order to issue an access token response as described in OAuth 2.0
[RFC6749] or to rely on an Assertion for client authentication, the
authorization server MUST validate the Assertion according to the
criteria below. Application of additional restrictions and policy
are at the discretion of the authorization server.

1. The Assertion's <Issuer> element MUST contain a unique
identifier for the entity that issued the Assertion. In the
absence of an application profile specifying otherwise,
compliant applications MUST compare Issuer values using the
Simple String Comparison method defined in Section 6.2.1 of RFC
3986 [RFC3986].

2. The Assertion MUST contain a <Conditions> element with an
<AudienceRestriction> element with an <Audience> element that
identifies the authorization server as an intended audience.
Section 2.5.1.4 of Assertions "Assertions and Protocols for the OASIS
Security Assertion Markup Language (SAML) V2.0"
[OASIS.saml-core-2.0-os] defines the <AudienceRestriction> and
<Audience> elements and, in addition to the URI references
discussed there, the token endpoint URL of the authorization
server MAY be used as a URI that identifies the authorization
server as an intended audience. The Authorization Server authorization server MUST
reject any assertion Assertion that does not contain its own identity as
the intended audience. In the absence of an application profile
specifying otherwise, compliant applications MUST compare the audience
Audience values using the Simple String Comparison method
defined in Section 6.2.1 of RFC 3986 [RFC3986]. As noted in
Section 5, the precise strings to be used as the audience Audience for a
given Authorization Server authorization server must be configured out-of-band out of band by the Authorization Server
authorization server and the
Issuer issuer of the assertion. Assertion.

3. The Assertion MUST contain a <Subject> element identifying the
principal that is the subject of the Assertion. Additional
information identifying the subject/principal MAY be included in
an <AttributeStatement>.

A. For the authorization grant, the Subject typically
identifies an authorized accessor for which the access token
is being requested (i.e., the resource owner or an
authorized delegate), but in some cases, it may be a
pseudonymous identifier or other value denoting an anonymous
user.

B. For client authentication, the Subject MUST be the
"client_id" of the OAuth client.

4. The Assertion MUST have an expiry that limits the time window
during which it can be used. The expiry can be expressed either
as the NotOnOrAfter attribute of the <Conditions> element or as
the NotOnOrAfter attribute of a suitable
<SubjectConfirmationData> element.

5. The <Subject> element MUST contain at least one
<SubjectConfirmation> element that has a Method attribute with a
value of "urn:oasis:names:tc:SAML:2.0:cm:bearer". If the
Assertion does not have a suitable NonOnOrAfter NotOnOrAfter attribute on the
<Conditions> element, the <SubjectConfirmation> element MUST
contain a <SubjectConfirmationData> element. When present, the
<SubjectConfirmationData> element MUST have a Recipient
attribute with a value indicating the token endpoint URL of the
authorization server (or an acceptable alias). The
authorization server MUST verify that the value of the Recipient
attribute matches the token endpoint URL (or an acceptable
alias) to which the Assertion was delivered. The
<SubjectConfirmationData> element MUST have a NotOnOrAfter
attribute that limits the window during which the Assertion can
be confirmed. The <SubjectConfirmationData> element MAY also
contain an Address attribute limiting the client address from
which the Assertion can be delivered. Verification of the
Address is at the discretion of the authorization server.

6. The authorization server MUST reject the entire Assertion if the
NotOnOrAfter instant on the <Conditions> element has passed
(subject to allowable clock skew between systems). The
authorization server MUST reject the <SubjectConfirmation> (but
MAY still use the rest of the Assertion) if the NotOnOrAfter
instant on the <SubjectConfirmationData> has passed (subject to
allowable clock skew). Note that the authorization server may
reject Assertions with a NotOnOrAfter instant that is
unreasonably far in the future. The authorization server MAY
ensure that Bearer Assertions are not replayed, by maintaining
the set of used ID values for the length of time for which the
Assertion would be considered valid based on the applicable
NotOnOrAfter instant.

7. If the Assertion issuer directly authenticated the subject, the
Assertion SHOULD contain a single <AuthnStatement> representing
that authentication event. If the Assertion was issued with the
intention that the client act autonomously on behalf of the
subject, an <AuthnStatement> SHOULD NOT be included and the
client presenting the assertion Assertion SHOULD be identified in the
<NameID> or similar element in the <SubjectConfirmation>
element, or by other available means like SAML "SAML V2.0 Condition
for Delegation Restriction Restriction" [OASIS.saml-deleg-cs].

8. Other statements, in particular <AttributeStatement> elements,
MAY be included in the Assertion.

9. The Assertion MUST be digitally signed or have a Message
Authentication Code (MAC) applied by the issuer. The
authorization server MUST reject assertions Assertions with an invalid
signature or
Message Authentication Code. MAC.

10. Encrypted elements MAY appear in place of their plain text plaintext
counterparts as defined in [OASIS.saml-core-2.0-os].

11. The authorization server MUST reject an Assertion that is not
valid in all other respects per [OASIS.saml-core-2.0-os], such
as (but not limited to) all content within the Conditions
element including the NotOnOrAfter and NotBefore attributes,
unknown condition types, etc.

3.1. Authorization Grant Processing

Assertion authorization grants may be used with or without client
authentication or identification. Whether or not client
authentication is needed in conjunction with an assertion Assertion
authorization grant, as well as the supported types of client
authentication, are policy decisions at the discretion of the
authorization server. However, if client credentials are present in
the request, the authorization server MUST validate them.

If the Assertion is not valid (including if its subject confirmation
requirements cannot be met), the authorization server constructs an
error response as defined in OAuth 2.0 [RFC6749]. The value of the
"error" parameter MUST be the "invalid_grant" error code. The
authorization server MAY include additional information regarding the
reasons the Assertion was considered invalid using the
"error_description" or "error_uri" parameters.

For example:

HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store

{
"error":"invalid_grant",
"error_description":"Audience validation failed"
}

3.2. Client Authentication Processing

If the client Assertion is not valid (including if its subject
confirmation requirements cannot be met), the authorization server
constructs an error response as defined in OAuth 2.0 [RFC6749]. The
value of the "error" parameter MUST be the "invalid_client" error
code. The authorization server MAY include additional information
regarding the reasons the Assertion was considered invalid using the
"error_description" or "error_uri" parameters.

4. Authorization Grant Example

The following examples illustrate what a conforming Assertion and an
access token request would look like.

The example shows an assertion issued and signed by the SAML Identity
Provider identified as "https://saml-idp.example.com". The subject
of the assertion Assertion is identified by email address as
"brian@example.com", who authenticated to the Identity Provider by
means of a digital signature where the key was validated as part of
an X.509 Public Key Infrastructure. The intended audience of the
assertion
Assertion is "https://saml-sp.example.net", which is an identifier
for a SAML Service Provider with which the authorization server
identifies itself. The assertion Assertion is sent as part of an access token
request to the authorization server's token endpoint at
"https://authz.example.net/token.oauth2".

Below is an example SAML 2.0 Assertion (whitespace formatting is for
display purposes only):

<Assertion IssueInstant="2010-10-01T20:07:34.619Z"
ID="ef1xsbZxPV2oqjd7HTLRLIBlBb7"
Version="2.0"
xmlns="urn:oasis:names:tc:SAML:2.0:assertion">
<Issuer>https://saml-idp.example.com</Issuer>
<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
[...omitted for brevity...]
</ds:Signature>
<Subject>
<NameID
Format="urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress">
brian@example.com
</NameID>
<SubjectConfirmation
Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">
<SubjectConfirmationData
NotOnOrAfter="2010-10-01T20:12:34.619Z"
Recipient="https://authz.example.net/token.oauth2"/>
</SubjectConfirmation>
</Subject>
<Conditions>
<AudienceRestriction>
<Audience>https://saml-sp.example.net</Audience>
</AudienceRestriction>
</Conditions>
<AuthnStatement AuthnInstant="2010-10-01T20:07:34.371Z">
<AuthnContext>
<AuthnContextClassRef>
urn:oasis:names:tc:SAML:2.0:ac:classes:X509
</AuthnContextClassRef>
</AuthnContext>
</AuthnStatement>
</Assertion>

Figure 1: Example SAML 2.0 Assertion
To present the Assertion shown in the previous example as part of an
access token request, for example, the client might make the
following HTTPS request (with extra line breaks for display purposes
only):

POST /token.oauth2 HTTP/1.1
Host: authz.example.net
Content-Type: application/x-www-form-urlencoded

grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Asaml2-
bearer&assertion=PEFzc2VydGlvbiBJc3N1ZUluc3RhbnQ9IjIwMTEtMDU
[...omitted for brevity...]aG5TdGF0ZW1lbnQ-PC9Bc3NlcnRpb24-

Figure 2: Example Request

5. Interoperability Considerations

Agreement between system entities regarding identifiers, keys, and
endpoints is required in order to achieve interoperable deployments
of this profile. Specific items that require agreement are as
follows: values for the issuer Issuer and audience Audience identifiers, the location
of the token endpoint, the key used to apply and verify the digital
signature over the assertion, Assertion, one-time use restrictions on
assertions,
Assertions, maximum assertion Assertion lifetime allowed, and the specific
subject
Subject and attribute requirements of the assertion. Assertion. The exchange of
such information is explicitly out of scope for this specification specification,
and typical deployment of it will be done alongside existing SAML Web
SSO deployments that have already established a means of exchanging
such information. Metadata "Metadata for the OASIS Security Assertion Markup
Language (SAML) V2.0 V2.0" [OASIS.saml-metadata-2.0-os] is specifies one
common method of exchanging SAML related SAML-related information about system
entities.

The RSA-SHA256 algorithm, from [RFC6931], is a mandatory to implement mandatory-to-implement
XML signature algorithm for this profile.

6. Security Considerations

The security considerations described within the Assertion following
specifications are all applicable to this document: "Assertion
Framework for OAuth 2.0 Client Authentication and Authorization Grants
[I-D.ietf-oauth-assertions], The
Grants" [RFC7521], "The OAuth 2.0 Authorization Framework Framework" [RFC6749],
and the Security "Security and Privacy Considerations for the OASIS Security
Assertion Markup Language (SAML) V2.0
[OASIS.saml-sec-consider-2.0-os] specifications are all applicable to
this document. V2.0"
[OASIS.saml-sec-consider-2.0-os].

The specification does not mandate replay protection for the SAML
assertion
Assertion usage for either the authorization grant or for client
authentication. It is an optional feature, which implementations may
employ at their own discretion.

7. Privacy Considerations

A SAML Assertion may contain privacy-sensitive information and, to
prevent disclosure of such information to unintended parties, should
only be transmitted over encrypted channels, such as TLS. Transport Layer
Security (TLS). In cases where it is desirable to prevent disclosure
of certain information to the client, the Subject and/or individual
attributes of a SAML Assertion should be encrypted to the
authorization server.

Deployments should determine the minimum amount of information
necessary to complete the exchange and include only that information
in an Assertion (typically by limiting what information is included
in an <AttributeStatement> or by omitting it altogether). In some
cases, the Subject can be a value representing an anonymous or
pseudonymous user, as described in Section 6.3.1 of the OAuth
Assertion Framework for OAuth 2.0 Client Authentication and Authorization
Grants [I-D.ietf-oauth-assertions]. [RFC7521].

8. IANA Considerations

8.1. Sub-Namespace Registration of urn:ietf:params:oauth:grant-
type:saml2-bearer
urn:ietf:params:oauth:grant-type:saml2-bearer

This is a request to IANA to please register section registers the value "grant-
type:saml2-bearer" "grant-type:saml2-bearer" in the
IANA "OAuth URI" registry urn:ietf:params:oauth established
in An by "An IETF URN Sub-Namespace
for OAuth OAuth" [RFC6755].

o URN: urn:ietf:params:oauth:grant-type:saml2-bearer

o Common Name: SAML 2.0 Bearer Assertion Grant Type Profile for
OAuth 2.0

o Change controller: Controller: IESG

o Specification Document: [[this document]] RFC 7522

8.2. Sub-Namespace Registration of urn:ietf:params:oauth:client-
assertion-type:saml2-bearer
urn:ietf:params:oauth:client-assertion-type:saml2-bearer

This is a request to IANA to please register section registers the value "client-
assertion-type:saml2-bearer" "client-assertion-type:saml2-bearer"
in the IANA "OAuth URI" registry urn:ietf:params:oauth established in An by "An IETF URN Sub-Namespace Sub-
Namespace for OAuth OAuth" [RFC6755].

o URN: urn:ietf:params:oauth:client-assertion-type:saml2-bearer

o Common Name: SAML 2.0 Bearer Assertion Profile for OAuth 2.0
Client Authentication

o Change controller: Controller: IESG

o Specification Document: [[this document]] RFC 7522

9. References

9.1. Normative References

[I-D.ietf-oauth-assertions]
Campbell, B., Mortimore, C., Jones, M., and Y. Goland,
"Assertion Framework for OAuth 2.0 Client Authentication
and Authorization Grants", draft-ietf-oauth-assertions
(work in progress), October 2014.

[OASIS.saml-core-2.0-os]
Cantor, S., Kemp, J., Philpott, R., and E. Maler,
"Assertions and Protocol Protocols for the OASIS Security Assertion
Markup Language (SAML) V2.0", OASIS Standard saml-core-
2.0-os,
saml-core-2.0-os, March 2005, <http://docs.oasis-
open.org/security/saml/v2.0/saml-core-2.0-os.pdf>. <http://docs.oasis-open.org/
security/saml/v2.0/saml-core-2.0-os.pdf>.

[OASIS.saml-deleg-cs]
Cantor, S., Ed., "SAML V2.0 Condition for Delegation
Restriction", Nov 2009.
Restriction Version 1", Committee Specification 01,
November 2009, <http://docs.oasis-open.org/
security/saml/Post2.0/sstc-saml-delegation-cs-01.html>.

[OASIS.saml-sec-consider-2.0-os]
Hirsch, F., Philpott, R., and E. Maler, "Security and
Privacy Considerations for the OASIS Security Assertion
Markup Language (SAML) V2.0", OASIS Standard saml-sec-consider-
2.0-os,
saml-sec-consider-2.0-os, March 2005, <http://docs.oasis-
open.org/security/saml/v2.0/saml-sec-consider-2.0-os.pdf>.
<http://docs.oasis-open.org/security/saml/v2.0/
saml-sec-consider-2.0-os.pdf>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997. 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005. 2005,
<http://www.rfc-editor.org/info/rfc3986>.

[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006. 2006,
<http://www.rfc-editor.org/info/rfc4648>.

[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012. 2012,
<http://www.rfc-editor.org/info/rfc6749>.

[RFC6931] Eastlake, Eastlake 3rd, D., "Additional XML Security Uniform
Resource Identifiers (URIs)", RFC 6931,
DOI 10.17487/RFC6931, April 2013. 2013,
<http://www.rfc-editor.org/info/rfc6931>.

[RFC7521] Campbell, B., Mortimore, C., Jones, M., and Y. Goland,
"Assertion Framework for OAuth 2.0 Client Authentication
and Authorization Grants", RFC 7521, DOI 10.17487/RFC7521,
May 2015, <http://www.rfc-editor.org/info/rfc7521>.

9.2. Informative References

[OASIS.WS-Fed]
Goodner, M. and T. A. Nadalin, "Web Services Federation
Language (WS-Federation) Version 1.2", OASIS Standard, May
2009,
<http://docs.oasis-open.org/wsfed/federation/v1.2/os/
ws-federation-1.2-spec-os.html>. <http://docs.oasis-open.org/wsfed/
federation/v1.2/os/ws-federation-1.2-spec-os.html>.

[OASIS.WSS-SAMLTokenProfile]
Monzillo, R., Kaler, C., Nadalin, T., Hallam-Baker, P.,
and C. Milono, "Web Services Security SAML Token Profile
Version 1.1.1", OASIS Standard, May 2012, <http://docs.oasis-open.org/wss-
m/wss/v1.1.1/wss-SAMLTokenProfile-v1.1.1.html>.
<http://docs.oasis-open.org/wss-m/wss/v1.1.1/
wss-SAMLTokenProfile-v1.1.1.html>.

[OASIS.saml-metadata-2.0-os]
Cantor, S., Moreh, J., Philpott, R., and E. Maler,
"Metadata for the OASIS Security Assertion Markup Language
(SAML) V2.0", OASIS Standard saml-metadata-2.0-os, March
2005, <http://docs.oasis-open.org/security/saml/v2.0/
saml-metadata-2.0-os.pdf>.

[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,
<http://docs.oasis-open.org/security/saml/v2.0/
saml-profiles-2.0-os.pdf>.

[RFC6755] Campbell, B. and H. Tschofenig, "An IETF URN Sub-Namespace
for OAuth", RFC 6755, DOI 10.17487/RFC6755, October 2012. 2012,
<http://www.rfc-editor.org/info/rfc6755>.

[W3C.REC-html401-19991224]
Raggett, D., Hors, A., and I. Jacobs, "HTML 4.01
Specification", World Wide Web Consortium Recommendation
REC-html401-19991224, December 1999,
<http://www.w3.org/TR/1999/REC-html401-19991224>.

Appendix A.

Acknowledgements

The following people contributed wording and concepts to this
document: Paul Madsen, Patrick Harding, Peter Motykowski, Eran
Hammer, Peter Saint-Andre, Ian Barnett, Eric Fazendin, Torsten
Lodderstedt, Susan Harper, Scott Tomilson, Scott Cantor, Hannes
Tschofenig, David Waite, Phil Hunt, and Mukesh Bhatnagar.

Appendix B. Document History

[[ to be removed by RFC editor before publication as an RFC ]]

draft-ietf-oauth-saml2-bearer-23

o Fix typo per http://www.ietf.org/mail-archive/web/oauth/current/
msg13790.html

draft-ietf-oauth-saml2-bearer-22

o Changes/suggestions from IESG reviews.

draft-ietf-oauth-saml2-bearer-21

o Added Privacy Considerations section per AD review discussion
http://www.ietf.org/mail-archive/web/oauth/current/msg13148.html
and http://www.ietf.org/mail-archive/web/oauth/current/
msg13144.html

draft-ietf-oauth-saml2-bearer-20

o Clarified some text around the treatment of subject based on the
rough rough consensus from the thread staring at
http://www.ietf.org/mail-archive/web/oauth/current/msg12630.html

draft-ietf-oauth-saml2-bearer-19

o Updated references.

draft-ietf-oauth-saml2-bearer-18

o Clean up language around subject per http://www.ietf.org/mail-
archive/web/oauth/current/msg12254.html.

o As suggested in http://www.ietf.org/mail-
archive/web/oauth/current/msg12253.html stated that "In the
absence of an application profile specifying otherwise, compliant
applications MUST compare the audience/issuer values using the
Simple String Comparison method defined in Section 6.2.1 of RFC
3986."

o Clarify the potentially confusing language about the AS confirming
the assertion http://www.ietf.org/mail-archive/web/oauth/current/
msg12255.html.

o Combine the two items about AuthnStatement and drop the word
presenter as discussed in http://www.ietf.org/mail-
archive/web/oauth/current/msg12257.html.

o Added one-time use, maximum lifetime, and specific subject and
attribute requirements to Interoperability Considerations based on
http://www.ietf.org/mail-archive/web/oauth/current/msg12252.html.

o Reword security considerations and mention that replay protection
is not mandated based on http://www.ietf.org/mail-
archive/web/oauth/current/msg12259.html.

draft-ietf-oauth-saml2-bearer-17

o Stated that issuer and audience values SHOULD be compared using
the Simple String Comparison method defined in Section 6.2.1 of
RFC 3986 unless otherwise specified by the application.

draft-ietf-oauth-saml2-bearer-16

o Changed title from "SAML 2.0 Bearer Assertion Profiles for OAuth
2.0" to "SAML 2.0 Profile for OAuth 2.0 Client Authentication and
Authorization Grants" to be more explicit about the scope of the
document per http://www.ietf.org/mail-archive/web/oauth/current/
msg11063.html.

o Fixed typo in text identifying the presenter from "or similar
element, the" to "or similar element in the".

o Numbered the list of processing rules.

o Smallish editorial cleanups to try and improve readability and
comprehensibility.

o Cleaner split out of the processing rules in cases where they
differ for client authentication and authorization grants.

o Clarified the parameters that are used/available for authorization
grants.

o Added Interoperability Considerations section and info reference
to SAML Metadata.

o Added more explanatory context to the example in Section 4.

draft-ietf-oauth-saml2-bearer-15

o Reference RFC 6749 and RFC 6755.

o Update draft-ietf-oauth-assertions reference to -06.

o Remove extraneous word per http://www.ietf.org/mail-
archive/web/oauth/current/msg10055.html

draft-ietf-oauth-saml2-bearer-14

o Add more text to intro explaining that an assertion grant type can
be used with or without client authentication/identification and
that client assertion authentication is nothing more than an
alternative way for a client to authenticate to the token endpoint

o Add examples to Sections 2.1 and 2.2

o Update references

draft-ietf-oauth-saml2-bearer-13

o Update references: oauth-assertions-04, oauth-urn-sub-ns-05, oauth
-28

o Changed "Description" to "Specification Document" in both
registration requests in IANA Considerations per changes to the
template in ietf-oauth-urn-sub-ns(-03)

o Added "(or an acceptable alias)" so that it's in both sentences
about Recipient and the token endpoint URL so there's no ambiguity

o Update area and workgroup (now Security and OAuth was Internet and
nothing)

draft-ietf-oauth-saml2-bearer-12

o updated reference to draft-ietf-oauth-v2 from -25 to -26 and
draft-ietf-oauth-assertions from -02 to -03

draft-ietf-oauth-saml2-bearer-11

o Removed text about limited lifetime access tokens and the SHOULD
NOT on issuing refresh tokens. The text was moved to draft-ietf-
oauth-assertions-02 and somewhat modified per http://www.ietf.org/
mail-archive/web/oauth/current/msg08298.html.

o Fixed typo/missing word per http://www.ietf.org/mail-
archive/web/oauth/current/msg08733.html.

o Added Terminology section.

draft-ietf-oauth-saml2-bearer-10

o fix a spelling mistake

draft-ietf-oauth-saml2-bearer-09

o Attempt to address an ambiguity around validation requirements
when the Conditions element contain a NotOnOrAfter and
SubjectConfirmation/SubjectConfirmationData does too. Basically
it needs to have at least one bearer SubjectConfirmation element
but that element can omit SubjectConfirmationData, if Conditions
has an expiry on it. Otherwise, a valid SubjectConfirmation must
have a SubjectConfirmationData with Recipient and NotOnOrAfter.
And any SubjectConfirmationData that has those elements needs to
have them checked.

o clarified that AudienceRestriction is under Conditions (even
though it's implied by schema)

o fix a typo

draft-ietf-oauth-saml2-bearer-08

o fix some typos

draft-ietf-oauth-saml2-bearer-07

o update reference from draft-campbell-oauth-urn-sub-ns to draft-
ietf-oauth-urn-sub-ns

o Updated to reference draft-ietf-oauth-v2-20

draft-ietf-oauth-saml2-bearer-06

o Fix three typos NamseID->NameID and (2x) Namspace->Namespace

draft-ietf-oauth-saml2-bearer-05

o Allow for subject confirmation data to be optional when Conditions
contain audience and NotOnOrAfter

o Rework most of the spec to profile draft-ietf-oauth-assertions for
both authn and authz including (but not limited to):

* remove requirement for issuer to be
urn:oasis:names:tc:SAML:2.0:nameid-format:entity

* change wording on Subject requirements
o using a MAY, explicitly say that the Audience can be token
endpoint URL of the authorization server

o Change title to be more generic (allowing for client authn too)

o added client authentication to the abstract

o register and use urn:ietf:params:oauth:grant-type:saml2-bearer for
grant type rather than http://oauth.net/grant_type/saml/2.0/bearer

o register urn:ietf:params:oauth:client-assertion-type:saml2-bearer

o remove scope parameter as it is defined in
http://tools.ietf.org/html/draft-ietf-oauth-assertions

o remove assertion param registration because it [should] be in
http://tools.ietf.org/html/draft-ietf-oauth-assertions

o fix typo(s) and update/add references

draft-ietf-oauth-saml2-bearer-04

o Changed the grant_type URI from
"http://oauth.net/grant_type/assertion/saml/2.0/bearer" to
"http://oauth.net/grant_type/saml/2.0/bearer" - dropping the word
assertion from the path. Recent versions of draft-ietf-oauth-v2
no longer refer to extension grants using the word assertion so
this URI is more reflective of that. It also more closely aligns
with the grant type URI in draft-jones-oauth-jwt-bearer-00 which
is "http://oauth.net/grant_type/jwt/1.0/bearer".

o Added "case sensitive" to scope definition to align with draft-
ietf-oauth-v2-15/16.

o Updated to reference draft-ietf-oauth-v2-16

draft-ietf-oauth-saml2-bearer-03

o Cleanup of some editorial issues.

draft-ietf-oauth-saml2-bearer-02

o Added scope parameter with text copied from draft-ietf-oauth-v2-12
(the reorg of draft-ietf-oauth-v2-12 made it so scope wasn't
really inherited by this spec anymore)
o Change definition of the assertion parameter to be more generally
applicable per the suggestion near the end of http://www.ietf.org/
mail-archive/web/oauth/current/msg05253.html

o Editorial changes based on feedback

draft-ietf-oauth-saml2-bearer-01

o Update spec name when referencing draft-ietf-oauth-v2 (The OAuth
2.0 Protocol Framework -> The OAuth 2.0 Authorization Protocol)

o Update wording in Introduction to talk about extension grant types
rather than the assertion grant type which is a term no longer
used in OAuth 2.0

o Updated to reference draft-ietf-oauth-v2-12 and denote as work in
progress

o Update Parameter Registration Request to use similar terms as
draft-ietf-oauth-v2-12 and remove Related information part

o Add some text giving discretion to AS on rejecting assertions with
unreasonably long validity window.

draft-ietf-oauth-saml2-bearer-00

o Added Parameter Registration Request for "assertion" to IANA
Considerations.

o Changed document name to draft-ietf-oauth-saml2-bearer in
anticipation of becoming an OAUTH WG item.

o Attempt to move the entire definition of the 'assertion' parameter
into this draft (it will no longer be defined in OAuth 2 Protocol
Framework).

draft-campbell-oauth-saml-01

o Updated to reference draft-ietf-oauth-v2-11 and reflect changes
from -10 to -11.

o Updated examples.

o Relaxed processing rules to allow for more than one
SubjectConfirmation element.

o Removed the 'MUST NOT contain a NotBefore attribute' on
SubjectConfirmationData.

o Relaxed wording that ties the subject of the Assertion to the
resource owner.

o Added some wording about identifying the client when the subject
hasn't directly authenticated including an informative reference
to SAML V2.0 Condition for Delegation Restriction.

o Added a few examples to the language about verifying that the
Assertion is valid in all other respects.

o Added some wording to the introduction about the similarities to
Web SSO in the format and processing rules

o Changed the grant_type (was assertion_type) URI from
http://oauth.net/assertion_type/saml/2.0/bearer to
http://oauth.net/grant_type/assertion/saml/2.0/bearer

o Changed title to include "Grant Type" in it.

o Editorial updates based on feedback from the WG and others
(including capitalization of Assertion when referring to SAML).

draft-campbell-oauth-saml-00

o Initial I-D

Authors' Addresses

Brian Campbell
Ping Identity

Email:

EMail: brian.d.campbell@gmail.com

Chuck Mortimore
Salesforce.com

Email:

EMail: cmortimore@salesforce.com

Michael B. Jones
Microsoft

Email:

EMail: mbj@microsoft.com
URI: http://self-issued.info/