SAML V2.0 Protocol Extension for Requesting Attributes per Request Version 1.0
Committee Specification 01
23 August 2017
Specification URIs
This version:
http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/cs01/saml-protoc-req-attr-req-v1.0-cs01.odt (Authoritative)
Previous version:
http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/csprd01/saml-protoc-req-attr-req-v1.0-csprd01.odt (Authoritative)
Latest version:
http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/saml-protoc-req-attr-req-v1.0.odt (Authoritative)
http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/saml-protoc-req-attr-req-v1.0.html
http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/saml-protoc-req-attr-req-v1.0.pdf
Technical Committee:
OASIS Security Services (SAML) TC
Chairs:
Thomas Hardjono (hardjono@mit.edu), MIT
Nate Klingenstein (ndk@internet2.edu), Internet2
Editors:
Madalina Sultan (madalina.sultan@connectis.nl), Connectis
Mert Aybat (mert.aybat@connectis.nl), Connectis
Robert van Herk (robert.van.herk@connectis.nl), Connectis
Martijn Kaag (martijn.kaag@connectis.nl), Connectis
This prose specification is one component of a Work Product that also includes:
Related work:
This specification is related to:
Abstract:
This specification defines an extension to the SAML V2.0 protocol specification [SAML2Core]. The extension allows Service Providers to specify ad-hoc sets of attributes per request. This brings more flexibility than existing mechanisms, which are based on signaling pre-defined sets of requested attributes.
Status:
This document was last revised or approved by the OASIS Security Services (SAML) TC on the above date. The level of approval is also listed above. Check the “Latest version” location noted above for possible later revisions of this document. Any other numbered Versions and other technical work produced by the Technical Committee (TC) are listed at https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=security#technical.
TC members should send comments on this specification to the TC’s email list. Others should send comments to the TC's public comment list, after subscribing to it by following the instructions at the "Send A Comment" button on the Technical Committee’s web page at https://www.oasis-open.org/committees/security/.
This Committee Specification is provided under the RF on RAND Terms Mode of the OASIS IPR Policy, the mode chosen when the Technical Committee was established. For information on whether any patents have been disclosed that may be essential to implementing this Work Product, and any offers of patent licensing terms, please refer to the Intellectual Property Rights section of the TC's web page (https://www.oasis-open.org/committees/security/ipr.php).
Note that any machine-readable content (Computer Language Definitions) declared Normative for this Work Product is provided in separate plain text files. In the event of a discrepancy between any such plain text file and display content in the Work Product's prose narrative document(s), the content in the separate plain text file prevails.
Citation format:
When referencing this Work Product the following citation format should be used:
[SAML-ReqAttrExt-v1.0]
SAML V2.0 Protocol Extension for Requesting Attributes per Request Version 1.0. Edited by Madalina Sultan, Mert Aybat, Robert van Herk, and Martijn Kaag. 23 August 2017. OASIS Committee Specification 01. http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/cs01/saml-protoc-req-attr-req-v1.0-cs01.html. Latest version: http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/saml-protoc-req-attr-req-v1.0.html.
Notices
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Table of Contents
1.1 IPR Policy
This Committee Specification is provided under the RF on RAND Terms Mode of the OASIS IPR Policy, the mode chosen when the Technical Committee was established.
For information on whether any patents have been disclosed that may be essential to implementing this specification, and any offers of patent licensing terms, please refer to the Intellectual Property Rights section of the TC’s web page (https://www.oasis-open.org/committees/security/ipr.php).
1.2 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 [RFC2119].
1.3 Normative References
[RFC2119] Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, BCP 14, RFC 2119, March 1997. http://www.ietf.org/rfc/rfc2119.txt.
[SAML2Core] OASIS Standard, Assertions and Protocols for the OASIS Security Assertion Markup Language (SAML) V2.0. March 2005. http://docs.oasis-open.org/security/saml/v2.0/saml-core-2.0-os.pdf.
[SAML2Meta] S. Cantor et al. Metadata for the OASIS Security Assertion Markup Language (SAML) V2.0. OASIS Standard, March 2005. Document ID saml-metadata-2.0- os. http://docs.oasis-open.org/security/saml/v2.0/saml-metadata-2.0-os.pdf.
[Schema1] H. S. Thompson et al. XML Schema Part 1: Structures. World Wide Web Consortium Recommendation, May 2001. https://www.w3.org/TR/2001/REC-xmlschema-1-20010502/
1.4 Non-Normative References
[ReqAttrExt-xsd] See schema file linked from Additional artifacts.
This specification defines an extension to the SAML V2.0 protocol specification [SAML2Core], specifically to the Authentication Request protocol. The extension allows Service Providers to specify ad-hoc sets of attributes per-request.
The existing mechanism for specifying requested attributes is based on signaling predefined sets of attributes via SAML metadata in conjunction with the AttributeConsumingServiceIndex attribute. This approach has two limitations. First, all possible combinations of attributes must be known and exchanged beforehand. Second, the number of possible combination of attributes is limited because AttributeConsumingServiceIndex is of type short. In federations with many different attributes and where data minimization is required, the number of possible combinations easily exceeds the maximum number of 32767. Enumerating that number of combinations is impractical in any event.
Unless specifically noted, nothing in this document should be taken to conflict with the SAML V2.0 protocol specification [SAML2Core]. Readers are advised to familiarize themselves with that specification first.
2.1 Element <req-attr:RequestedAttributes>
The element <req-attr:RequestedAttributes>, of complex type req-attr:RequestedAttributesType, contains a list of one or more <md:RequestedAttribute> elements. In this way, the Service Provider specifies its desire that the resultant assertion contains a list of AttributeStatements expressing the values of the queried attribute.
The following schema fragment defines the <req-attr:RequestedAttribute> element:
<element name="RequestedAttributes" type="req-attr:RequestedAttributesType"/>
<complexType name="RequestedAttributeType">
<sequence>
<element ref="md:RequestedAttribute" minOccurs="1" maxOccurs="unbounded"/>
</sequence>
</complexType>
2.2 Example
The following is an example of a <samlp:Extensions> element (in an <samlp:AuthnRequest>, not shown) where the SP is expressing that it desires the resultant assertions to contain a <saml:AttributeStatement> that contains the LDAP-derived sn and givenName attributes, optionally includes mail, and includes a custom role attribute where its values match 'User' or 'Administrator'.
<samlp:Extensions>
<req-attr:RequestedAttributes>
<md:RequestedAttribute isRequired="true" Name="urn:oid:2.5.4.4"
NameFormat=”urn:oasis:names:tc:SAML:2.0:attrname-format:uri” />
<md:RequestedAttribute isRequired="true" Name="urn:oid:2.5.4.42"
NameFormat=”urn:oasis:names:tc:SAML:2.0:attrname-format:uri” />
<md:RequestedAttribute Name="urn:oid:0.9.2342.19200300.100.1.3"
NameFormat=”urn:oasis:names:tc:SAML:2.0:attrname-format:uri” />
<md:RequestedAttribute Name="https://example.org/attributes/role"
NameFormat=”urn:oasis:names:tc:SAML:2.0:attrname-format:uri”>
<saml:AttributeValue>User</saml:AttributeValue>
<saml:AttributeValue>Administrator</saml:AttributeValue>
</md:RequestedAttribute>
</req-attr:RequestedAttributes>
</samlp:Extensions>
2.3 Processing Rules
A <req-attr:RequestedAttributes> element is included in a <samlp:AuthnRequest> message by placing it in the optional <samlp:Extensions> element. All extensions are explicitly deemed optional; therefore, senders SHOULD only include this extension when they can be reasonably confident that the extension will be understood by the recipient. The metadata extension defined in section 2.4 MAY be used for this purpose.
Each <md:RequestedAttribute> describes a SAML attribute the requester desires or requires to be supplied by the identity provider in the response. The identity provider MAY use this information to populate one or more <saml:AttributeStatement> elements in the assertion(s) it returns.
The isRequired attribute, expressing that an attribute is mandatory, remains advisory. The Identity Provider MAY choose to ignore this flag and omit these attributes in the response, if it cannot or will not provide them.
If a Service Provider includes the <req-attr:RequestedAttributes> extension, then it MUST NOT include an AttributeConsumingServiceIndex attribute in the same message. In the event that both are present, an Identity Provider SHOULD ignore the extension and process the request based on the AttributeConsumingServiceIndex attribute.
2.4 Metadata Considerations
SAML V2.0 metadata [SAML2Meta] MAY be used to indicate support for this protocol extension at particular protocol endpoints, using the extensions capabilities of the metadata schema.
Support for this extension is expressed in metadata by adding a boolean-typed XML attribute to an element derived from md:EndpointType complex type, indicating that SAML request messages sent to that endpoint MAY include this extension.
The following schema fragment defines the req-attr:suppportsRequestedAttributes attribute:
<attribute name="supportsRequestedAttributes" type="boolean"/>
2.4.1 Metadata Example
The example below shows a fragment of an <md:SingleSignOnService> element that advertises support for this extension. The namespace declaration must be in scope, but the prefix is arbitrary.
<md:SingleSignOnService xmlns:req-attr="urn:oasis:names:tc:SAML:protcol:ext:req-attr"
req-attr:supportsRequestedAttributes="true" .../>
2.4.2 Metadata Processing Rules
If the Identity Provider’s metadata contains the req-attr:suppportsRequestedAttributes attribute set to “true”, then the Service Provider MAY send the <req-attr:RequestedAttributes> element in its messages to the corresponding endpoint(s).
If the Identity Provider metadata contains both the req-attr:suppportsRequestedAttributes attribute (set to “true”) and also contains one or more <md:AttributeConsumingService> elements with sets of associated attributes, then the Service Provider SHOULD use the AttributeConsumingServiceIndex attribute if it can find a predefined set of attributes matching its needs.
2.5 Security Considerations
The Identity Provider is always free to ignore this extension and populate its response with more or fewer attributes than requested, as well as ignore the isRequired attribute. A Service Provider must therefore always inspect the response and cannot assume the contents will match its requirements.
3.1 Conformance as a Service Provider
A Service Provider implementation conforms to this specification if it supports the extension defined in section 2.1 and the processing rules defined in section 2.3 .
3.2 Conformance as an Identity Provider
An Identity Provider implementation conforms to this specification if it supports the extension defined in section 2.1 and the processing rules defined in section 2.3 .
The following individuals have participated in the creation of this specification and are gratefully acknowledged:
Mert Aybat – Connectis
Scott Cantor -- Internet2
Thomas Hardjono – MIT
Robert van Herk – Connectis
Mohammad Jafari -- Veterans Health Administration
Martijn Kaag – Connectis
Hal Lockhart -- Oracle
Madalina Sultan -- Connectis
|
Revision |
Date |
Editor |
Changes Made |
|
1 |
01-09-2015 |
Mert Aybat |
First Draft |
|
2 |
19-01-2016 |
Mert Aybat |
Adding in xsd and wrapping RequestedAttribute elements with RequestedAttributes element. |
|
3 |
13-10-2016 |
Madalina Sultan |
Defined a new namespace for RequestedAttribute Added supportsRequestedAttributes metadata flag |
|
4 |
21-10-2016 |
Madalina Sultan |
Added the req:RequestedAttributes element, as a wrapper for a list of md:RequestedAttribute elementss |
|
5 |
21-11-2016 |
Madalina Sultan |
Cosmetic changes |
|
6 |
02-12-2016 |
Madalina Sultan |
Added Conformance section and other changes based on feeback received during SSTC meeting |
|
7 |
09-12-2016 |
Scott Cantor |
Editorial pass for formatting, references, and some language cleanup. |
|
8 |
15-08-2017 |
Madalina Sultan |
Non-material changes suggested during public review |
<?xml version="1.0" encoding="UTF-8"?>
<!--
SAML v2.0 Protocol Extension for Requesting Attributes per Request Version 1.0
Committee Specification Draft 01 / Public Review Draft 01
09 May 2017
Copyright (c) OASIS Open 2017. All Rights Reserved.
Source: http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/csprd01/schema/
Latest version of the specification: http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/saml-protoc-req-attr-req-v1.0.html
TC IPR Statement: https://www.oasis-open.org/committees/security/ipr.php
-->
<schema xmlns:req-attr="urn:oasis:names:tc:SAML:protocol:ext:req-attr"
targetNamespace="urn:oasis:names:tc:SAML:protocol:ext:req-attr"
xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata"
xmlns="http://www.w3.org/2001/XMLSchema"
elementFormDefault="unqualified"
attributeFormDefault="unqualified"
blockDefault="substitution"
version="1.0">
<import namespace="urn:oasis:names:tc:SAML:2.0:metadata"
schemaLocation="saml-schema-metadata-2.0.xsd"/>
<annotation>
<documentation>
Document title: SAML V2.0 Protocol Extension For Requesting Attributes Per Request
Document identifier: sstc-req-attr-ext
Location: http://docs.oasis-open.org/security/saml-protoc-req-attr-req/v1.0/csprd01/schema/
Revision history: WD-03
</documentation>
</annotation>
<element name="RequestedAttributes" type="req-attr:RequestedAttributesType"/>
<complexType name="RequestedAttributesType">
<sequence>
<element ref="md:RequestedAttribute" minOccurs="1" maxOccurs="unbounded"/>
</sequence>
</complexType>
<attribute name="supportsRequestedAttributes" type="boolean"/>
</schema>