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.