# Auth And Authorization Patterns

> 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.

- Skill: `gabrielmoreira/auth-and-authorization-patterns` (Agent Skill)
- Install (CLI): `npx skillmds@latest add gabrielmoreira/auth-and-authorization-patterns`
- Raw SKILL.md: https://api.skillmd.com/api/skills/gabrielmoreira/auth-and-authorization-patterns/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: gabrielmoreira (https://skillmd.com/u/gabrielmoreira)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/gabrielmoreira/auth-and-authorization-patterns

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# 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.