Authentication Patterns
Implement secure authentication with OAuth 2.1, Passkeys, and modern security standards.
Overview
- Login/signup flows
- JWT token management
- Session security
- OAuth 2.1 with PKCE
- Passkeys/WebAuthn
- Multi-factor authentication
- Role-based access control
Quick Reference
Password Hashing (Argon2id)
from argon2 import PasswordHasher
ph = PasswordHasher()
password_hash = ph.hash(password)
ph.verify(password_hash, password)JWT Access Token
import jwt
from datetime import datetime, timedelta, timezone
payload = {
'user_id': user_id,
'type': 'access',
'exp': datetime.now(timezone.utc) + timedelta(minutes=15),
}
token = jwt.encode(payload, SECRET_KEY, algorithm='HS256')OAuth 2.1 with PKCE (Required)
import hashlib, base64, secrets
code_verifier = secrets.token_urlsafe(64)
digest = hashlib.sha256(code_verifier.encode()).digest()
code_challenge = base64.urlsafe_b64encode(digest).rstrip(b'=').decode()Session Security
app.config['SESSION_COOKIE_SECURE'] = True # HTTPS only
app.config['SESSION_COOKIE_HTTPONLY'] = True # No JS access
app.config['SESSION_COOKIE_SAMESITE'] = 'Strict'Token Expiry (Guidelines)
| Token Type | Expiry | Storage |
|---|---|---|
| Access | 15 min - 1 hour | Memory only |
| Refresh | 7-30 days | HTTPOnly cookie |
Anti-Patterns (FORBIDDEN)
# ❌ NEVER store passwords in plaintext
user.password = request.form['password']
# ❌ NEVER use implicit OAuth grant
response_type=token # Deprecated in OAuth 2.1
# ❌ NEVER skip rate limiting on login
@app.route('/login') # No rate limit!
# ❌ NEVER reveal if email exists
return "Email not found" # Information disclosure
# ✅ ALWAYS use Argon2id or bcrypt
password_hash = ph.hash(password)
# ✅ ALWAYS use PKCE
code_challenge=challenge&code_challenge_method=S256
# ✅ ALWAYS rate limit auth endpoints
@limiter.limit("5 per minute")
# ✅ ALWAYS use generic error messages
return "Invalid credentials"Key Decisions
| Decision | Recommendation |
|---|---|
| Password hash | Argon2id > bcrypt |
| Access token expiry | 15 min - 1 hour |
| Refresh token expiry | 7-30 days with rotation |
| Session cookie | HTTPOnly, Secure, SameSite=Strict |
| Rate limit | 5 attempts per minute |
| MFA | Passkeys > TOTP > SMS |
| OAuth | 2.1 with PKCE (no implicit) |
Detailed Documentation
| Resource | Description |
|---|---|
| references/oauth-2.1-passkeys.md | OAuth 2.1, PKCE, Passkeys/WebAuthn |
| examples/auth-implementations.md | Complete implementation examples |
| checklists/auth-checklist.md | Security checklist |
| scripts/auth-middleware-template.py | Flask/FastAPI middleware |
Related Skills
owasp-top-10- Security fundamentalsinput-validation- Data validationapi-design-framework- API security
Capability Details
password-hashing
Keywords: password, hashing, bcrypt, argon2, hash Solves:
- Securely hash passwords with modern algorithms
- Configure appropriate cost factors
- Migrate legacy password hashes
jwt-tokens
Keywords: JWT, token, access token, claims, jsonwebtoken Solves:
- Generate and validate JWT access tokens
- Implement proper token expiration
- Handle token refresh securely
oauth2-pkce
Keywords: OAuth, PKCE, OAuth 2.1, authorization code, code verifier Solves:
- Implement OAuth 2.1 with PKCE flow
- Secure authorization for SPAs and mobile apps
- Handle OAuth provider integration
passkeys-webauthn
Keywords: passkey, WebAuthn, FIDO2, passwordless, biometric Solves:
- Implement passwordless authentication
- Configure WebAuthn registration and login
- Support cross-device passkeys
session-management
Keywords: session, cookie, session storage, logout, invalidate Solves:
- Manage user sessions securely
- Implement session invalidation on logout
- Handle concurrent sessions
role-based-access
Keywords: RBAC, role, permission, authorization, access control Solves:
- Implement role-based access control
- Define permission hierarchies
- Check authorization in routes