Disclaimer:
This document is a work in progress and subject to further refinements and updates. Please note that some details may change as new requirements emerge or as part of ongoing development. Feedback and suggestions for improvement are welcome.

This guide explains how to connect your issuer to an OpenID Federation (OIDF) trust framework. It includes details on configuring the authority_hints, trust_marks, federation info endpoint, and trust_anchors using specific values provided for the test environment.

Prerequisites

Before proceeding, ensure the following are in place:

• An understanding of your federation's structure and the required credential types.
• Access to the Trust Anchor (TA) with its entity ID and keys.
• HTTPS is properly set up for your issuer.

Key Configuration Points

Federation Entity Configuration Information

The configuration endpoint publishes the Entity Configuration document, detailing the issuer’s configuration information for federation participants.

1. Define the Endpoint:

   • The endpoint is defined under the following path: /.well-known/openid-federation

2. Implementation:

   • Ensure this endpoint serves the issuer’s Entity Configuration as specified in the OIDC Federation 1.0 document.

3. Example Entity Configuration: Here is an example of Entity Configuration that can be exposed at the endpoint: 

   { "sub": "https://my-issuer.example.com:8000", "metadata": { "federation_entity": { "organization_name": "The OP operator", "contacts": "operations@op.example.com" }, "oauth_authorization_server": { "jwks_uri": "https://my-issuer.example.com:8000/jwks/oauth_authorization_server", "token_endpoint_auth_methods_supported": [], "token_endpoint_auth_signing_alg_values_supported": [ "RS256", "RS384", "RS512", "ES256", "ES256K", "ES384", "ES512", "PS256", "PS384", "PS512", "HS256", "HS384", "HS512", "Ed25519", "Ed448", "EdDSA" ], "response_types_supported": [ "code" ], "response_modes_supported": [ "code" ], "acr_values_supported": [], "scopes_supported": [], "authorization_signing_alg_values_supported": [ "RS256", "RS384", "RS512", "ES256", "ES256K", "ES384", "ES512", "PS256", "PS384", "PS512", "HS256", "HS384", "HS512", "Ed25519", "Ed448", "EdDSA" ], "request_object_signing_alg_values_supported": [ "RS256", "RS384", "RS512", "ES256", "ES256K", "ES384", "ES512", "PS256", "PS384", "PS512", "HS256", "HS384", "HS512", "Ed25519", "Ed448", "EdDSA" ], "claims_parameter_supported": true, "request_parameter_supported": true, "request_object_encryption_alg_values_supported": [], "request_object_encryption_enc_values_supported": [], "code_challenge_methods_supported": [ "plain", "S256", "S384", "S512" ], "deny_unknown_scopes": false, "ui_locales_supported": [], "token_endpoint": "https://my-issuer.example.com:8000/token", "token_endpoint_auth_methods": [ "attest_jwt_client_auth" ], "authorization_endpoint": "https://my-issuer.example.com:8000/authorization", "authorization_endpoint_auth_methods": [ "pushed_authz" ], "pushed_authorization_request_endpoint": "https://my-issuer.example.com:8000/par", "pushed_authorization_request_endpoint_auth_methods": [ "attest_jwt_client_auth" ] }, "openid_credential_issuer": { "attribute_disclosure": { "": [ "given_name", "family_name", "name", "email", "nickname" ] }, "credential_configurations_supported": { "PDA1Credential": { "format": "vc+sd-jwt", "id": "eudiw.pda1.se", "cryptographic_binding_methods_supported": [ "jwk" ], "cryptographic_suites_supported": [ "RS256", "RS512", "ES256", "ES512" ], "display": { "name": "Swedish PDA1 Provider Example", "locale": "en-US" }, "vct": "PDA1Credential", "credential_definition": { "type": [ "PDA1Credential" ], "credentialSubject": { "family_name": { "display": [ { "locale": "en-US", "name": "Current Family Name" } ], "mandatory": true }, "given_name": { "display": [ { "locale": "en-US", "name": "Current First Name" } ], "mandatory": true }, "birth_date": { "display": [ { "locale": "en-US", "name": "Birth date" } ] } } } }, "EHICCredential": { "format": "vc+sd-jwt", "id": "eudiw.ehic.se", "cryptographic_binding_methods_supported": [ "jwk" ], "cryptographic_suites_supported": [ "RS256", "RS512", "ES256", "ES512" ], "display": { "name": "Swedish EHIC Provider Example", "locale": "en-US" }, "vct": "EHICCredential", "credential_definition": { "type": [ "EHICCredential" ], "credentialSubject": { "family_name": { "display": [ { "locale": "en-US", "name": "Current Family Name" } ], "mandatory": true }, "given_name": { "display": [ { "locale": "en-US", "name": "Current First Name" } ], "mandatory": true }, "birth_date": { "display": [ { "locale": "en-US", "name": "Birth date" } ] } } } } }, "jwks": { "keys": [ { "kty": "RSA", "use": "sig", "kid": "ODR1b1ZjUEpsRzVhVHBSaWxLR1hxQ2x3WTU2ZVFDcnVsMXBmdEF5WUM4UQ", "e": "AQAB", "n": "vqLXJgOHZn7YFqL78Kth6vP..." }, { "kty": "EC", "use": "sig", "kid": "YzIwZjJEaFJxU0NOLXJ5MS1mSXgyLUp5RWNZb3I4M1lRMDVhQWxMUjhsZw", "crv": "P-256", "x": "FdYslsTybViEudE4T-gyBrcKeZNleH9-QajFYVpOYW8", "y": "If-rr6KWEEnC_R8N93SrcQRn4E7lC4WXOqgANj-o0UE" }, { "kty": "EC", "kid": "default_signing_key_id", "crv": "P-256", "x": "-i8_UtCwdCic10eDuNwr68IEHWk4B1HSn119fdNT-pQ", "y": "UIMFXTj4kOWF2gZaKDTP3n3K-08TfkLHw8hIV6bOxqw" }, { "kty": "EC", "kid": "default_signing_key_id", "crv": "P-256", "x": "-i8_UtCwdCic10eDuNwr68IEHWk4B1HSn119fdNT-pQ", "y": "UIMFXTj4kOWF2gZaKDTP3n3K-08TfkLHw8hIV6bOxqw" } ] }, "credential_response_encryption_alg_values_supported": [ "RSA1_5", "RSA-OAEP", "RSA-OAEP-256", "A128KW", "A192KW", "A256KW", "ECDH-ES", "ECDH-ES+A128KW", "ECDH-ES+A192KW", "ECDH-ES+A256KW" ], "credential_response_encryption_enc_values_supported": [ "A128CBC-HS256", "A192CBC-HS384", "A256CBC-HS512", "A128GCM", "A192GCM", "A256GCM" ], "require_credential_response_encryption": false, "credentials_supported": [ "vp_token" ], "credential_endpoint": "https://my-issuer.example.com:8000/credential", "credential_endpoint_auth_methods": [ "dpop_client_auth" ] } }, "authority_hints": [ "https://trust-anchor.example.com:7001" ], "trust_marks": [ "eyJhbGciOiJSUzI1Ni...", "eyJhbGciOiJSUzI1N..." ], "jwks": { "keys": [ { "kty": "RSA", "use": "sig", "kid": "VmhPQndmVDNja09ZYTQ4UlM3eWl2Z3BxMlp1cVd1ZFB1YnhwdWUxa3p4Zw", "e": "AQAB", "n": "y68Zlt9DHIXHvH3HMFtY..." }, { "kty": "EC", "use": "sig", "kid": "dTlESU50RVVjVDA3eWFPV0dMQ2taMC0tbDlWclBjQTBUdkpyNlVhSVBfOA", "crv": "P-256", "x": "IqpTNpOAXTsQVVlO18zzAV1rHI36qBvZv7VbdtniV-c", "y": "JozJQWmYCkvxD4PtUnr6sKXRL8SOj7ggx6WHzQxHgaw" } ] }, "iss": "https://my-issuer.example.com:8000", "iat": 1732718163, "exp": 1732804563 }

   
   

Trust Anchors

The Trust Anchor (TA) is the root of the federation’s trust chain.

1. Trust Anchor URL:

   • For your setup, the Trust Anchor URL is: https://openidfed-test-1.sunet.se:7001

2. Trust Anchor Keys: Add the Trust Anchor’s  and public keys to your configuration: 

   trust_anchors: https://openidfed-test-1.sunet.se:7001: keys: - kty: RSA use: sig kid: UFpoajluZU42dTNUUXo5RnhBVEJnRk9JY2NtU1JKdlVYUk1RUFRyVkFFRQ n: p9S2whcSjmBdxerp80tIJreUUmZiGNGXIocJlNjx9pgD5_WD2l6mBNuEZMpP-QUB_TSV3VesNiqmOdydGp1wkfQ-NmVdoso29FjEdgrckLIwirAVmVQ6bGQQnXJrR56mRz0QqENi11vVpbDj6hsprxK1EZBQL-sQ2kem289B_BCNT-NvwVHrYJlaQA32z7cs1a7W8wt9eLxA10PeiYMgDVU_69wKBw4YrjjozOHKMRGchUQEjQhfSZfk49bip_5TNz4dmBmSCIbdE2yilFrfRSNrh7q2myuyDE3k2QZbSOXXGGT1LtHO74WIY58v-M3A7_zxp0f2Eo9ZD3N4h-InIw e: AQAB - kty: EC use: sig kid: Nm82cTJKMDkydXhxOUMtTm0teFpMWlZiR0ZVa2U3YVVtbkJTV3hBd3FqOA crv: P-256 x: 69XlQkKYfWJDXAv_Vbrqyfz9gfAhu1qQ4mtLde18-Cg y: ntBwdhy4_cS2PRBS-xdKkNwcO1yQP8TdoOHbHN9Yjv8

   
   

3. Purpose: Trust Anchors validate Trust Marks’ signatures and establish trust within the federation.

Registering the Issuer as a Subordinate Entity

In an OpenID Federation trust framework, the Issuer must be added as a Subordinate Entity under a Superior Entity (e.g., a Trust Anchor or an Intermediate Entity). This process ensures that the Issuer is recognized as part of the trust hierarchy.

Key Steps for the Issuer Operator

• Publish Metadata
  • Make the Issuer's metadata available at the following URL:
    https://<issuer-entity-id>/.well-known/openid-federation
• Share the Entity ID
  • Once the metadata is published, provide the `entity_id` to the Superior Entity.
  • The Superior Entity will retrieve the metadata from the `.well-known/openid-federation` endpoint and complete the registration process.
• Obtain Approval
  • The Superior Entity must approve the Issuer's inclusion in the federation.
  • If additional details are required, ensure they are provided as per the federation's guidelines.

Authority Hints

The authority_hints parameter specifies the URL of the Intermediate Entities or Trust Anchors that are Immediate Superiors of the Entity. This helps other federation participants understand upstream trust relationships.

1. Add to Configuration: Add authority_hints in your issuer’s metadata configuration: 

   authority_hints: - "https://openidfed-test-1.sunet.se:7001"

2. Purpose: This parameter establishes hierarchical trust relationships from your issuer to the Trust Anchor.

Trust Marks

Trust Marks are JWTs issued by a Trust Mark Issuer to validate compliance with federation policies.

Types of Trust Marks

The following Trust Marks are available for issuance:

• EHIC Credential:

  • ID: http://dc4eu.example.com/EHICCredential/se

• PDA1 Credential:

  • id: http://dc4eu.example.com/PDA1Credential/se

Issuing Trust Marks

1. Inputs to Trust Mark Issuer:

   • id: The identifier for the Trust Mark (e.g., http://dc4eu.example.com/EHICCredential/se).
   • sub: The entity's unique identifier (entity_id).

2. Steps:

   • Supply the id and sub to the Trust Mark Issuer.

   • Retrieve the issued Trust Mark as a signed JWT.

3. Validation:

   • Use a JWT library to verify the Trust Mark's signature using the Trust Mark Issuer's public key:
     • Retrieve public keys from the Trust Mark Issuer's .well-known/jwks.json endpoint.
     • Validate claims such as iss, sub, id, and iat for compliance.

4. Include in Metadata: Add issued Trust Marks to your issuer’s metadata:

   trust_marks: - "eyJhbGciOiJIUzI1NiIsInR..." - "eyJhbGciOiJIUzI1NiIsInR..."

   
   

Testing Trust Marks

1. Decode JWT: Use tools like jwt.io to inspect the Trust Mark's claims and ensure all required fields are present.

2. Verify Signature: Validate the JWT signature against the Trust Mark Issuer's public key.

3. Check Expiration: Ensure the exp claim (if present) has not expired.

4. Validate References: Follow the ref URL (if provided) to confirm compliance with human-readable policy documents.

Steps to Connect the Issuer

1. Configure the Issuer:

   • Update the issuer’s configuration to include authority_hints, trust_marks, federation info endpoint, and trust_anchors.

2. Register with the Federation:

   • Share your .well-known/openid-federation endpoint with the Trust Anchor or superior entity for registration.

3. Validate Configuration:

   • Test the issuer using federation testing tools or with the federation’s sandbox environment.

4. Monitor the Connection:

   • Regularly verify the federation status and ensure Trust Marks are up-to-date.

Testing the Trust Relationships

1. Validate Trust Marks: Use tools like jwt.io to decode and verify Trust Marks using the Trust Anchor's public keys.

2. Retrieve Metadata: Ensure the .well-known/openid-federation endpoint correctly serves the issuer’s metadata: 

   curl -X GET https://your-issuer.example.com/.well-known/openid-federation

3. Check Authority Hints: Verify that authority_hints points to the correct Trust Anchor: 

   authority_hints: - "https://openidfed-test-1.sunet.se:7001"

4. Validate Public Keys: Confirm that the Trust Anchor’s public keys match the ones provided in the configuration.