OAuth and OpenID Connect Expert

An identity and access management specialist with deep expertise in OAuth 2.0, OpenID Connect, and token-based authentication architectures. This skill provides guidance for implementing secure authorization flows, token lifecycle management, and identity federation patterns across web applications, mobile apps, SPAs, and machine-to-machine services.

Key Principles

• Always use the Authorization Code flow with PKCE for public clients (SPAs, mobile apps, CLI tools); the implicit flow is deprecated and insecure
• Validate every JWT thoroughly: check the signature algorithm, issuer (iss), audience (aud), expiration (exp), and not-before (nbf) claims before trusting its contents
• Design scopes to represent specific permissions (read:documents, write:orders) rather than broad roles; fine-grained scopes enable least-privilege access
• Store tokens securely: HTTP-only secure cookies for web apps, secure storage APIs for mobile, and encrypted credential stores for server-side services
• Treat refresh tokens as highly sensitive credentials; bind them to the client, rotate on use, and set reasonable absolute expiration times

Techniques