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name: auth-implementation-patterns description: "Implement or review authentication and authorization with explicit token, session and resource-access boundaries." risk: critical source: community date_added: "2026-02-27"

Authentication & Authorization Implementation Patterns

Build secure, scalable authentication and authorization systems using industry-standard patterns and modern best practices.

Use this skill when

• Implementing user authentication systems
• Securing REST or GraphQL APIs
• Adding OAuth2/social login or SSO
• Designing session management or RBAC
• Debugging authentication or authorization issues

Do not use this skill when

• You only need UI copy or login page styling
• The task is infrastructure-only without identity concerns
• You cannot change auth policies or credential storage

Instructions

• Define users, tenants, flows, and threat model constraints.
• Choose auth strategy (session, JWT, OIDC) and token lifecycle.
• Design authorization model and policy enforcement points.
• Plan secrets storage, rotation, logging, and audit requirements.
• If detailed examples are required, open resources/implementation-playbook.md.

Safety

• Never log secrets, tokens, or credentials.
• Enforce least privilege and secure storage for keys.

Resources

• resources/implementation-playbook.md for detailed patterns and examples.

Worked example

Input: an Express application accepts a user's login and keeps the pre-login session ID. Read the bundled playbook, regenerate the session after credential verification, save only required identity fields, and verify that the old cookie cannot access /api/profile. Also test failed login, logout and store failure. Expected: successful login changes the session ID; failed login grants no access.

Inputs and prerequisites

Record the installed framework/SDK versions, identity provider, tenant model, credential store and test environment. Supply project-specific database adapters and request schemas; examples are integration sketches, not a runnable identity service.

Limitations

• JWT validation does not establish resource ownership; enforce tenant and object policy on reads and writes.
• Refresh rotation requires atomic persistence and concurrency tests; the issuance example alone does not provide it.
• Cookie flags do not replace CSRF protection, and secure-cookie behavior needs the actual HTTPS/proxy configuration tested.
• Provider integrations and password policies must be checked against current primary documentation and the application's threat model.