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There exist a variety of software libraries and solutions that implement the Client functionality defined by the OIDC specification. The following list provides a non-exhaustive list of requirements that they should address to include support federation as described in https://github.com/OpenIDC/fedoidc/blob/master/draft/oidcfed.hf.txt:
- A client library MUST include support (either by itself of by the use of third-party libraries) of JSON Web Tokens, as the federation spec heavily relies on them for its operation.
- A Client library MUST extend its discovery document retrieval functionality to support decoding, verification and flattening of compounded metadata statement (hereafter MS).
- A Client library MUST implement policies for determining whether the information in a compounded MS is valid (e.g. using federation specification's Appendix A rules).
- A Client library MAY implement a way of providing the application information on whether a particular claim is signed or not. As standard discovery documents are not signed, but might still contain valuable information a library might want to provide the application with:
- Both, the signed MS and the unsigned discovery document;
- Or a merged version of both the signed MS and the discovery document where the signed claims have prevalence.
- A Client library MUST provide a way for applications to specify their trusted keys for Federation Operators (FO)
- A Client library MUST provide a way for applications to specify which FO will be used for the authentication process. For instance:
- The application might provide an ordered list of FO where the first one available in the OP's MS is used;
- Or the application is fed with the list of supported FO's (according to the discovered MS) and let the end user to decide which one use.
- A Client library MAY provide means for automatically disabling federation support for specific OP's.
- A Client library MUST be able to use "signing_keys", "signing_keys_uri", and "signed_jwks_uri" to verify OP's "jwks_uri" claim (if present).
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