OAuth 2.1 Government Content Access Control

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Table of Contents

1. Introduction

Governments increasingly require online services to restrict access to certain categories of content based on the age or legal status of users. Existing approaches frequently rely on disclosure of personal data, third-party identity providers, or proprietary mechanisms that enable tracking across services.¶

This document specifies OAuth 2.1 Government Content Access Control (GCAC), an OAuth 2.1 [I-D.ietf-oauth-v2-1] profile in which a government-operated authorization server evaluates user eligibility for regulated content categories and issues privacy-preserving attestations to relying parties. GCAC is designed to answer narrowly scoped regulatory questions (e.g., whether a user may access a category of content) while minimizing data disclosure and preventing correlation across services.¶

GCAC is not an identity system and MUST NOT be used for authentication, user login, or personalization.¶

2. Definitions

The following terms are used:¶

• Government Content Control Authority (GCCA):¶

  • A government-operated OAuth Authorization Server responsible for identity verification, age evaluation, and policy enforcement.¶

• Relying Party (RP):¶

  • An OAuth client requesting eligibility decisions for regulated content.¶

• Scope:¶

  • A government-defined content access category (e.g., pornography, social_media, gambling, alcohol, firearms, vpn, proxy).¶

• Person Key:¶

  • A government-internal, pseudonymous identifier derived from a national identity record and never exposed outside the GCCA.¶

• Site Token:¶

  • An RP-scoped, non-reversible token representing a government eligibility attestation.¶

3. Goals and Non-Goals

4. Architecture Overview

GCCA uses the OAuth 2.1 Authorization Code flow with mandatory security extensions and additional semantic constraints.¶

    User → Relying Party → Government Content Control Authority
    ↑                      ↓
    └──── OAuth 2.1 ───────┘

The GCCA operates as a constrained OAuth Authorization Server, and the RP operates as a confidential OAuth client.¶

5. Scope Model

6. Client Registration

Relying parties MUST register with the GCCA prior to using GCAC.¶

During registration, the RP MUST provide:¶

• Legal entity identification¶

• Intended use and justification for requested scopes¶

• One or more redirect URIs¶

• A client authentication method (mutual TLS [RFC8705] or private_key_jwt)¶

The GCCA MAY restrict which scopes an RP is authorized to request.¶

7. Protocol Flow

GET /authorize
?response_type=code
&client_id=client_id
&redirect_uri=registered_uri
&scope=pornography+social_media
&state=random_nonce
&code_challenge=pkce_value

HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store

{
  "access_token": "opaque_site_token_string",
  "token_type": "Bearer",
  "expires_in": 3600,
  "scope_results": {
    "pornography": true,
    "social_media": false
  }
}

8. Token Derivation

The GCCA MUST derive an internal person key using HMAC-SHA256 with a globally unique master secret key (master_secret_key) and a stable, unique national identifier for the person (national_person_id):¶

person_key = HMAC_SHA256(master_secret_key, national_person_id)

The site token MUST be derived deterministically using HMAC-SHA256 from the person key (person_key) and the client identifier (client_id):¶

site_token = HMAC_SHA256(person_key, client_id)

The person key and national identifiers MUST NOT be exposed outside the GCCA.¶

9. Re-Verification

Relying parties MUST provide a user-accessible mechanism to re- initiate the GCAC flow. Re-verification MUST follow the same protocol as the initial authorization.¶

10. Security Considerations

GCAC relies on OAuth 2.1 security best practices, including authorization code flow, PKCE [RFC7636], redirect URI allowlists, and strong client authentication. General security considerations for OAuth 2.0 [RFC6819] also apply. To further protect the integrity and confidentiality of authorization requests, RPs SHOULD use JWT-Secured Authorization Request (JAR) [RFC9101]. Leaked client identifiers alone do not enable token issuance. Tokens are RP-scoped and non-transferable, preventing cross-service correlation and replay attacks.¶

11. IANA Considerations

This document has no IANA actions.¶

Acknowledgments

The author would like to acknowledge ongoing discussions within the OAuth and digital privacy communities that informed the design principles of this specification.¶

Author's Address