https://wiki.refeds.org/display/ENT/Hide+From+Discovery
The research and education sector has over the past decades developed a global identity federation ecosystem which has simplified access to content, services and resources for their community. The eduGAIN interfederation comprises over 80 national federations connecting more than 8,000 Identity and Service Providers. On a national level even more services and institutions are connected. The sector has been able to achive this by creating a highly interoperable ecosystem, where both a high level of technical, as well as policy and trust interoperability has been accomplished, through the joined implementation of various specifications. The joined journey of establishing this ecosystem has enabled the emergance of a global research and education trust and identity comunity with strong bonds and decades of experience in deploying and operating identity federation at scale.
REFEDs, the Research and Education FEDerations group, has been instrumental in providing an open meeting place for articulating the mutual needs of research and education identity federations worldwide. Over the years, REFEDS has addressed issues and topics based on the interests and requirements of its participants. This includes mostly policy, but also some technical and outreach topics in areas such as interfederation, privacy, assurance, relationships with partner communities, marketing, and support of emerging federations.
While REFEDs as such has no bias towards a specific technical implementation, the fact that the SAML 2.0 specification is currently the dominant protocol in identity federation in R&E has had some impact on various specifications created by REFEDs. This ranges for protocol specific sections, to assumption on how a specification would be implemented operationally. The rise of protocols like OpenID Connect, OpenID Federation and the emergence of decentralized, wallet based ecosystems requires a revisit of the specifications. Not only should it be investigated in what way the specifications may be implemented in these protocols, in addition we must assume a multi-protocol ecosystem will emerge and exist for several years to come. This means the specifications may also need to take into account how to go between protocols as it may be required to translate between not just technical credentials, but also policy and trust frames.
This document provides a first assesment on how the current REFEDs specifications (Nov 2023) may be leveraged in an OpenID Federation (Draft 31) based federation and in a wallet ecosystem based on OpenID Federation and the OpenID4VC specifications. For the latter it should be noted that as this ecosystem and its standards are still being developed, the statments and assumptions on how REFEDs specification may be relevant should be considered speculative.
source: https://refeds.org/specifications (Nov 2023)
REFEDs identify 5 types of specifications:
OpenID Federation shares many concepts with the existing SAML based federations as currently deployed in R&E. The basic entities (OP, RP and trusted third parties like TA or IA) and the interactions between these can all be represented in OpenID Federation in a similar fashion as these exist in a SAML R&E federation.
Table 1 provides an overview of the specifications that were evaluated, and identifies the areas in the specification that would need modification to adopt OIDC and OpenID federation. Because of the commonalities in the structure of the Personalized Access, the Anonymous Access and the Pseudonymous Access Entity Category, only the first one was extensively evaluated, see Chapter 6. It was assumed similar modifications will be required for the Anonymous Access and Pseudonymous Access specification.
| specification name | type | Applies to entity | Asserted by | Level of Modification needed? | In scope for OpenIDFed | In scope for wallets | Attribute profile | SAML Specific Protocol requirements |
|---|---|---|---|---|---|---|---|---|
| Personalized Access v.2 | Entity Category | IdP/OP | Registrar |  |  (T) | | |
|
| Personalized Access v.2 | Entity Category | SP/RP | Registrar | | (T) | | | ^^^ |
| Anonymous Access v.2 | Entity Category | SP/RP | Registrar | | (T) | | |
|
| Anonymous Access v.2 | Entity Category | IdP/OP | IdP/OP | | (T) | | | ^^^ |
| Pseudonymous Access v.2 | Entity Category | SP/RP | Registrar | | (T) | | |
|
| Pseudonymous Access v.2 | Entity Category | IdP/OP | IdP/OP | | (T) | | | ^^^ |
| Research and Scholarship (R&S) v1.3 | Entity Category | SP/RP | Registrar | | (T) | | |
|
| Research and Scholarship (R&S) v1.3 | Entity Category | IdP/OP | IdP/OP | | (T) | | | ^^^ |
| Hide From Discovery v.1 | Entity Category | IdP/OP | IdP/OP |  | |
| ||
| Assurance v.1 | Framework | IdP/OP | IdP/OP |  | | | |
|
| MFA Profile v.1 | Profile | | | | |
| ||
| SFA Profile v.1 | Profile | | | | |
| ||
| Sirtfi v1 & v2 | Assurance Certification | SP/RP | Registrar | | (T) | | ||
| Sirtfi v1 & v2 | Assurance Certification | IdP/OP | IdP/OP | | (T) | | ||
| Security Contact | Metadata Extension | IdP/OP, SP/RP | IdP/OP, SP/RP | | | |
|
Legend for relevance column: Under investigation; 
Not relevant; Relevant; (T) Trustmark required
Indication of required changed: No changes required; Minor updates to wording required; Significant updates to wording required; Significant updates to wording and/or implementation required
Generally speaking, the information from the specifications is distributed in two ways:
When a specification defines specific metadata elements to be be present, if is often required to have a protocol specific section in the specification. Not only is the technical format different (XML vs JSON), but there is also a difference in the way certain capabilities are expressed, e.g. Entity Categories vs Trustmarks, see later). When the specification only deals with 'on the wire' information, which is transmitted as part of the transaction, like e.g. attribute assurance, it if often much easier to adopt the specification to use in OIDC and OpenID federation, as often it suffices to just use the equivalent OIDC claim to transport the same values that were defined in the SAML based specification.
REFEDs has defined a set of functionally similar specifications "Research and Scholarship", "Anonymous Access", "Pseudonoymous Access" and "Personalized Access". All of these specifications share the fact that they express the capabilities in entity metadata. To investigate the potential impact of introducing the use of OIDC and OpenID Federation, the Incubator has made an in depth analysis of the impact on "Personalized Access Entity Category". The document which was created is not intended as a proposal to replace the existing specification, but rather as a practical exercise to asses the impact. The document can be found here: https://github.com/surfnet-niels/REFEDs-specifications/blob/main/personalized.md
Generally speaking the following was noted:
The OIDC specification supports the concept of contact details, but only as a simple multivalued list of strings. In the SAML version of the specification a more fine grained methodology is used, where technical, administrative and support contact details are identifiable. To resolve this issue, the proposal in github suggests a new claim, "contacts_detailed", supports the same granularity as is used in the SAML implementation of the specification.
The use of entity labels, "Trustmarks" in OpenID Federation, is subject to specific rules as layed out in the OID Fed specification. As such it is not possible to have the same Trustmark exist both as a self-issued and at the same time as a trustmark issued by a trustmark issuer, which is what the current specification suggests (SPs and IdP may both publish support for the entity category, however the SP version is vetted by FedOps, whereas the IdP version is self issued). This might lead to the need to have different trustmark identifiers per protocol. This is probable not optimal as it may lead to ambiguity in the implementation of the same specification between protocols.
The assurance profile already has a provision (section 7) on how to use the specification with OIDC. All statements which are part of this specification are expressed as claim values.
The Multi- and Single Factor Authentication profile express all statements at transaction time. Both specifications already describe how to use these both in the SAML and in OIDC. For both SAML and OIDC the specification is relevant to the transaction at hand. In a wallet ecosystem, it might be relevant to transport this MFA or SFA information as part of the credentials statement made by a wallet, as such information refers to the LoA of the credentials stored in the wallet. To describe such information, it may require a specification similar to the existing RAF, or perhaps RAF may be extended to include this information.
The SIRTFI specification leverages metadata to signal compliance for both SPs/RP as well as IdP/OP. When discussing the SIRTFI specification the following was noted:
The OIDC specification supports the concept of contact details, but only as a simple multivalued list of strings. The SIRTFI specification mandates the presence of a security contact, as described in the Security Contact specification. To resolve this issue, a new claim, "contacts_detailed", could support the required granularity that is needed.
The use of entity labels, "Trustmarks" in OpenID Federation, is subject to specific rules as layed out in the OID Fed specification. As such it is not possible to have the same Trustmark exist both as a self-issued and at the same time as a trustmark issued by a trustmark issuer, which is what the current specification suggests (SPs and IdP may both publish support for the entity category, however the SP version is vetted by FedOps, whereas the IdP version is self issued). This might lead to the need to have different trustmark identifiers per protocol. This is probable not optimal as it may lead to ambiguity in the implementation of the same specification between protocols.