auth-and-authorization-patterns

name	auth-and-authorization-patterns
description	Use this skill when implementing authentication (login, token issuance) or authorization (access control, permissions). Apply whenever the task involves login flows, JWT, OAuth2, session management, or RBAC.
category	security

Auth & Authorization Patterns

Authentication (who are you?):

• Use a battle-tested library — do not roll your own crypto.
• Hash passwords with bcrypt/argon2; never MD5/SHA1 for passwords.
• Use short-lived JWTs (15–60 min) with refresh tokens; store refresh tokens securely.
• Implement MFA for sensitive operations.

Authorization (what can you do?):

• Check authorization on every request, not just at login.
• Enforce RBAC or ABAC at the service layer, not the UI.
• Apply principle of least privilege: grant minimal permissions needed.

OAuth2 / OIDC:

• Use the Authorization Code flow with PKCE for user-facing apps.
• Validate iss, aud, exp, and nonce claims on every token.

Session management:

• Regenerate session ID after login (session fixation prevention).
• Set HttpOnly and Secure flags on session cookies.