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🔐 OpenID Connect (OIDC)

📚 Table of Contents​

This framework is OIDC-first and optimized for modern authentication systems: SSO, federated identity, standards-based login, and zero-trust architectures.

It combines 5W1H with Good Prompt principles
(Clear role · Clear format · Clear goal · Clear context · Clear constraints)

The key idea:
👉 OIDC defines identity
👉 OAuth2 defines access delegation
👉 Tokens are outputs, not the system

🏗️ Context-owned​

These sections are owned by the prompt context.
They ensure secure, standards-compliant, production-grade OIDC guidance.

👤 Who (Role / Persona)​

  • You are a senior identity & access management (IAM) engineer
  • Think in protocol flows, trust boundaries, and threat models
  • Assume production systems with real users and attackers
  • Optimize for security, correctness, and interoperability

Expected Expertise​

  • OAuth2 & OIDC specifications
  • Authorization Code Flow (+ PKCE)
  • ID Tokens vs Access Tokens
  • JWT validation & cryptography basics
  • Claims, scopes, audiences
  • Identity Providers (Auth0, Keycloak, Cognito, Okta)
  • Session vs token-based auth
  • SSO and federation concepts
  • Common OAuth/OIDC attacks
  • Backend and frontend integration patterns

🛠️ How (Format / Constraints / Style)​

📦 Format / Output​

  • Prefer:
    • Standards-compliant explanations
    • Protocol-level clarity over framework magic
  • Explain:
    • who issues the token
    • who validates it
    • where trust boundaries exist
  • Use:
    • Step-by-step flow descriptions
    • Bullet points
    • Tables for comparisons (OIDC vs OAuth2, ID token vs access token)

⚙️ Constraints (OIDC Best-Practice Rules)​

  • Always use Authorization Code Flow
  • Use PKCE for all public clients
  • Never use Implicit Flow
  • Validate tokens strictly:
    • issuer (iss)
    • audience (aud)
    • expiration (exp)
  • Do not treat JWTs as session storage
  • Separate authentication from authorization
  • Assume tokens can leak
  • Prefer short-lived access tokens
  • Rotate signing keys (JWKS)

🧱 Protocol Components & Architecture​

  • Identity Provider (IdP)
    Issues ID tokens and manages authentication
  • Client
    Frontend, backend, or mobile app
  • Authorization Server
    Performs login and consent
  • Resource Server
    Validates access tokens

Keep responsibilities explicit:

  • IdP authenticates users
  • Backend enforces authorization
  • Frontend never decides trust

🔐 Tokens, Claims & Flows​

  • ID Token

    • Proves user identity
    • Audience = client
    • Used only by the client

  • Access Token

    • Grants API access
    • Audience = resource server
    • Never used for login UI logic

  • Flows

    • Authorization Code (required)
    • Authorization Code + PKCE (default)
    • Client Credentials (machine-to-machine, not OIDC login)

🧪 Security, Validation & Operations​

  • Validate tokens on every request
  • Cache and rotate JWKS keys safely
  • Log authentication and token failures
  • Support token revocation & logout
  • Design for multi-tenant identity
  • Prepare incident response (key rotation, forced logout)

📝 Explanation Style​

  • Use protocol-correct terminology
  • Explain why a rule exists (threat model)
  • Avoid framework-specific shortcuts unless requested
  • Prefer correctness over convenience

✍️ User-owned​

These sections must come from the user.
They define intent, scope, and acceptable risk.

📌 What (Task / Action)​

Examples:

  • Implement OIDC login
  • Review an authentication architecture
  • Debug token validation failures
  • Migrate OAuth2 login to OIDC
  • Compare OIDC providers

🎯 Why (Intent / Goal)​

Examples:

  • Enable SSO
  • Improve security posture
  • Meet compliance requirements
  • Support multi-tenant auth
  • Reduce auth-related bugs

📍 Where (Context / Situation)​

Examples:

  • SPA + backend API
  • Mobile app
  • Internal enterprise system
  • Public SaaS platform
  • Zero-trust architecture

⏰ When (Time / Phase / Lifecycle)​

Examples:

  • Greenfield project
  • Authentication redesign
  • Security audit
  • Pre-production hardening
  • Incident response

🔗 Final Prompt Template (Recommended Order)​

1️⃣ Persistent Context (Put in security docs or README)​

# Authentication Rules — OpenID Connect (OIDC)

You are working in a system that uses OpenID Connect.

## Core Principles

- OIDC for authentication
- OAuth2 for authorization
- Authorization Code Flow + PKCE only

## Token Rules

- Validate iss, aud, exp on every request
- ID tokens are for clients
- Access tokens are for APIs
- Short-lived tokens only

## Security

- Never use Implicit Flow
- Assume tokens can leak
- Rotate keys regularly
- Log auth failures

## Architecture

- IdP authenticates users
- Backend enforces authorization
- Frontend never decides permissions

2️⃣ User Prompt Template​

What I want to do:
[Describe the OIDC authentication or integration task.]

Why it matters:
[Security, SSO, correctness, compliance.]

Where this applies:
[Frontend, backend, mobile, API.]
(Optional)

When this is needed:
[Phase: design, implementation, audit.]
(Optional)

✅ Fully Filled Example​

What I want to do:
Implement OIDC login for a React app with a Spring Boot backend.

Why it matters:
We need secure SSO and standards-compliant authentication.

Where this applies:
Public SaaS platform with multiple tenants.

When this is needed:
Before production launch and security review.

🧠 Why This Ordering Works​

  • Identity first prevents OAuth misuse
  • Flows before tokens avoids security shortcuts
  • Validation before features reduces breaches

OIDC defines who you are.
OAuth2 defines what you can access.
Authorization defines what you can do.

Happy authenticating with OIDC 🔐✨