Versions Compared

Old Version 1

changes.mady.by.user Scott Cantor

Saved on

compared with

New Version Current

changes.mady.by.user Scott Cantor

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

This document is an attempt to clarify the R&S specification to address issues that have arisen in its initial deployment by federations, particularly confusion over its relationship to other, unrelated mechanisms and regimes for attribute release faciliationfacilitation. It also attempts to clarify what an SP and IdP are obligated or assumed to be doing, and moves some "implicit" guidance into formally suggested behavior.

Note
While it represents a perception of some mild consensus on the REFEDS list and reflects wider discussion on one phone conference, it currently should be viewed as the author's opinion, pending further review.

...

Example Service Providers may include (but are not limited to) collaborative tools and services such as wikis, blogs, project and grant management tools that require some personal information about users to work effectively. This Entity Category should not be used for access to licensed content such as e-journals.

Identity Providers may indicate support for Service Providers in this category (typically through self-assertion, though this is not required) to facilitate discovery and improve the user experience at Service Providers.

The following sections detail the requirements for both Service Providers and Identity Providers, in category membership and support respectively.

2. Syntax

The following URI is used as the attribute value for the Entity Category and Entity Category Support attribute:

http://refeds.org/category/research-and-scholarship

Refer to Section 7 for usage examples.

3. Semantics

By asserting a Service Provider to be a member of an Entity Category, a registrar claims that:

...

In possessing the Entity Category Support Attribute with the above value, an Identity Provider claims that it will release attributes to R&S Service Providers as outlined in the “Attribute “Identity Provider Attribute Release” section below.

4. Registration Criteria

...

  • 4.1 The service enhances the research and scholarship activities of some subset of the registrar’s user community.
  • 4.2 Service metadata has been submitted to the registrar and published in the registrar’s public metadata aggregate for publication.
  • 4.3 The service meets the following technical requirements:
    • 4.3.1 The Service Provider is a production SAML deployment that supports SAML V2.0 HTTP-POST binding.
    • 4.3.2 The Service Provider claims to refresh federation metadata at least daily.
    • 4.3.3 The Service Provider provides an mdui:DisplayName and mdui:InformationURL in metadata.
    • 4.3.4 The Service Provider provides one or more technical contacts in metadata.
    • 4.3.5 The Service Provider provides requested attributes in metadata.

...

The mechanism by which this entity category provides for consistent attribute release is through the definition of a set of commonly supported and consumed attributes typically required for effective use of R&S services. The attributes chosen represent a privacy baseline such that further minimization achieves no particular benefit to a user. Thus, the minimal disclosure principle is already designed into the category.

This approach is orthogonal to the practice of attempting to enumerate the specific attributes needed by a service, debate over whether those attributes are actually required or not, and the complexity inherent in attempting to curate and communicate them. Specifically, the The use of the <md:RequestedAttribute> mechanism supported by SAML metadata is outside the scope of this category, and may co-exist with it in deployments as desired, subject to this specification's requirements being met.

The R&S attribute bundle consists (abstractly) of the following required data elements:

  • shared user identifier
  • person name
  • email address

and one optional data element:

  • affiliation

where shared user identifier is a persistent, non-reassigned, non-targeted identifier defined to be any one either of the following:

  1. eduPersonPrincipalName (if non-reassigned)
  2. eduPersonPrincipalName + eduPersonTargetedID

...

and where affiliation is defined to be the eduPersonScopedAffiliation attribute.

All of the above attributes are defined or referenced in the [eduPerson] specification. The specific naming and format of these attributes is guided by the protocol in use. In the case of SAML 2.0 the [SAMLAttr] profile MUST be used. This specification may be extended to reference other protocol-specific formulations as circumstances warrant.

6. Service Provider

...

Requirements

Service Providers SHOULD request a subset of R&S Category Attributes that represent only those attributes that the Service Provider requires to operate its service.

Service Providers SHOULD limit their data requirements to the bundle of attributes defined in Section 5, but MAY negotiate for additional data as required via mechanisms that are outside the scope of this specification.

7. Identity Provider Attribute Release

Identity Service Providers are strongly encouraged to release the bundle defined support all of the specified alternatives for the shared user identifier and person name attributes described in Section 5 to R&S category Service Providers.

If multiple attributes satisfying a required data element are supported (e.g., all of displayName, givenName, and sn), Identity Providers SHOULD make all of them available if they make any of them available.

An Identity Provider is said to "support" the R&S Category if, for a significant subset of the Identity Provider’s user population, the Identity Provider releases the minimal subset of the R&S attribute bundle (described below) to R&S Service Providers without administrative involvement by any party, either automatically or subject to user consent.

The following attributes constitute the  minimal subset of the R&S attribute bundle for the purposes of the "supports R&S" designation:

  • eduPersonPrincipalName
  • mail
  • displayName OR (givenName AND sn)

For the purposes of effective access control, A non-reassigned persistent identifier is required. If the deployment of eduPersonPrincipalName is non-reassigned, it will suffice. Otherwise the IdP MUST release eduPersonTargetedID (which is non-reassigned by definition) in addition to eduPersonPrincipalName. In any case, release of both identifiers is RECOMMENDED.

8. Examples

maximize interoperability. Failure to do so will result in problems even when working exclusively with Identity Providers that claim support for the category. In the case of the eduPersonTargetedID attribute, this recommendation includes the ability to support SAML 2.0's "persistent" Name Identifier format, which is the recommended modern expression of the eduPersonTargetedID attribute in SAML 2.0.

In accordance with the requirements in Section 7, if an Identity Provider exhibits the R&S entity attribute in its metadata and no accompanying eduPersonTargetedID attribute is recieved, then Service Providers can rely on the non-reassignment of eduPersonPrincipalName values it receives from that Identity Provider.

Alternatively, Service Providers can obtain a non-reassigned shared user identifier by combining (e.g., concatenating) the eduPersonPrincipalName and eduPersonTargetedID values. If a given combination of the two values ever changes, Service Providers can assume that the eduPersonPrincipalName has been reassigned and now represents a different subject.

A Service Provider that conforms to R&S would exhibit the following EntityAttribute entity attribute in SAML metadata:

Code Block
titleAn entity attribute for SPs that conform to R&S
<mdattr:EntityAttributes xmlns:mdattr="urn:oasis:names:tc:SAML:metadata:attribute">
  <!-- entity attribute for SPs that conform to R&amp;S -->
  <saml:Attribute
      xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
      NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"
      Name="http://macedir.org/entity-category-support">
    <!-- the refeds.org R&amp;S entity attribute value -->
    <saml:AttributeValue>
      http<saml:AttributeValue>http://refeds.org/category/research-and-scholarship
    <scholarship</saml:AttributeValue>
  </saml:Attribute>
</mdattr:EntityAttributes>

7. Identity Provider Requirements

An Identity Provider indicates support for the R&S Category by exhibiting the R&S entity attribute in its metadata. Such an Identity Provider MUST, for a significant subset of its user population, release all required attributes in the bundle defined in Section 5 to all R&S Service Providers without administrative involvement by any party, either automatically or subject to user consent.

An Identity Provider that does not release all of the required elements of the R&S attribute bundle (shared user identifier, person name, email address), for any reason, SHALL NOT exhibit the R&S entity attribute in its metadata. Exceptions, limiting the release of attributes to specific R&S Service Providers, may be permitted in the event of a security incident or other isolated circumstances.

For the purposes of effective access control, A persistent, non-reassigned, non-targeted identifier is REQUIRED. If the Identity Provider’s deployment of eduPersonPrincipalName is non-reassigned, and the organization believes in good faith that it will remain so, it will suffice. Otherwise the Identity Provider MUST release eduPersonTargetedID (which is non-reassigned by definition) in addition to eduPersonPrincipalName. In any case, release of both identifiers is RECOMMENDED. Likewise the release of all three person name attributes (displayName, givenName, sn) is also RECOMMENDED.

Identity Providers are strongly encouraged to release the entire attribute bundle (both required and optional attributes) defined in Section 5 to R&S category Service Providers, both to maximize interoperability and the scope of supported services. The only optional data element is affiliation, which while different in nature to the rest of the bundle, is important to many R&S services and is a particular differentiator for academic organizations.

An Identity Provider that supports R&S would exhibit the following EntityAttribute entity attribute in SAML metadata:

Code Block
titleAn entity attribute for IdPs that support R&S
<mdattr:EntityAttributes xmlns:mdattr="urn:oasis:names:tc:SAML:metadata:attribute">
  <!-- entity attribute for IdPs that support R&amp;S -->
  <saml:Attribute
      xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
      NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri"
      Name="http://macedir.org/entity-category-support">
    <!-- the refeds.org R&amp;S entity attribute value -->
    <saml:AttributeValue>
      http<saml:AttributeValue>http://refeds.org/category/research-and-scholarship
    <scholarship</saml:AttributeValue>
  </saml:Attribute>
</mdattr:EntityAttributes>

 

References

[EntityCatTypes] Young, I, Johansson, L, and Cantor, S Ed., “The Entity Category SAML Attribute Types”, July 2014.

[R&SFAQ] Harris, N., “Research and Scholarship FAQ”, November 2014.

[RFC2119] Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, BCP 14, RFC 2119, March 1997.

[eduPerson] Internet2 MACE Directory Working Group, "eduPerson Object Class Specification (201602)", February 2016.

[SAMLAttr] Internet2 MACE Directory Working Group, "MACE-Dir SAML Attribute Profiles", April 2008.