Implementing Authentication

Learn how to implement secure authentication systems with ClaudeKit - from basic JWT authentication to OAuth2, 2FA, and passwordless login.

Overview

Goal: Implement secure, production-ready authentication Time: 20-40 minutes (vs 4-8 hours manually) Agents Used: planner, researcher, tester, code-reviewer Commands: /ck

, /ck

update

Prerequisites

Existing API or web application
Database configured (PostgreSQL, MongoDB, etc.)
Email service for verification (optional)
OAuth provider accounts (optional: Google, GitHub, etc.)

Authentication Methods

Method	Use Case	Security	Complexity	Time
JWT	API authentication	High	Low	15-20 min
Session-based	Traditional web apps	High	Medium	20-25 min
OAuth2	Social login	Very High	Medium	25-35 min
Passwordless	Magic links, OTP	High	Medium	20-30 min
2FA	Additional security	Very High	Medium	15-20 min
Biometric	Mobile apps	Very High	High	30-40 min

Step-by-Step Workflow

Step 1: Plan Authentication Strategy

Choose authentication method and plan implementation:

/ck:plan [implement JWT authentication with email/password and password reset]

Generated plan:

# JWT Authentication Implementation Plan

## Components

### 1. User Model
- id (UUID)
- email (unique, indexed)
- password (hashed with bcrypt)
- emailVerified (boolean)
- resetToken (nullable)
- resetTokenExpiry (nullable)
- createdAt, updatedAt

### 2. Endpoints
- POST /api/auth/register - User registration
- POST /api/auth/login - User login
- POST /api/auth/logout - User logout
- GET /api/auth/me - Get current user
- POST /api/auth/verify-email - Email verification
- POST /api/auth/forgot-password - Request password reset
- POST /api/auth/reset-password - Reset password
- POST /api/auth/refresh-token - Refresh JWT token

### 3. Middleware
- authenticateJWT - Verify JWT token
- requireAuth - Protect routes
- checkEmailVerified - Require verified email

### 4. Security Features
- Password hashing (bcrypt, 12 rounds)
- JWT token (access + refresh)
- Token expiry (15 min access, 7 day refresh)
- Rate limiting on auth endpoints
- Email verification
- Password strength validation
- Account lockout after failed attempts

### 5. Testing
- Unit tests for auth service
- Integration tests for endpoints
- Security tests (brute force, token theft)
- E2E authentication flows

Step 2: Implement Basic JWT Authentication

/ck:cook [implement JWT authentication with registration and login]

Implementation:

[1/6] Setting up user model...
  ✓ Created User schema/model
  ✓ Added password hashing hooks
  ✓ Created database migration

[2/6] Implementing JWT service...
  ✓ Token generation (access + refresh)
  ✓ Token verification
  ✓ Token refresh logic
  ✓ Secure token storage

[3/6] Creating auth endpoints...
  ✓ POST /api/auth/register
  ✓ POST /api/auth/login
  ✓ POST /api/auth/logout
  ✓ GET /api/auth/me
  ✓ POST /api/auth/refresh-token

[4/6] Adding middleware...
  ✓ JWT authentication middleware
  ✓ Route protection
  ✓ Error handling

[5/6] Implementing validation...
  ✓ Email format validation
  ✓ Password strength (min 8 chars, uppercase, number, symbol)
  ✓ Input sanitization

[6/6] Testing...
  ✓ 32 tests generated
  ✓ All tests pass
  ✓ Coverage: 93%

✅ JWT authentication implemented

Files created:
- src/models/User.js
- src/services/auth.service.js
- src/middleware/auth.middleware.js
- src/routes/auth.routes.js
- src/utils/jwt.js
- tests/auth/auth.test.js

Step 3: Add Email Verification

/ck:cook [add email verification to registration process]

Implementation:

[1/4] Email verification setup...
  ✓ Add verificationToken to User model
  ✓ Generate verification tokens
  ✓ Create verification endpoint

[2/4] Email service integration...
  ✓ Email template for verification
  ✓ Send verification email on registration
  ✓ Resend verification email endpoint

[3/4] Middleware...
  ✓ requireEmailVerified middleware
  ✓ Apply to protected routes

[4/4] Testing...
  ✓ Verification flow tests (8 tests)
  ✓ Email sending mocked

✅ Email verification added

Usage:
1. User registers → receives verification email
2. User clicks link → account verified
3. Only verified users access protected routes

Step 4: Implement Password Reset

/ck:cook [implement password reset with email verification]

Implementation:

[1/5] Database changes...
  ✓ Add resetToken field
  ✓ Add resetTokenExpiry field
  ✓ Migration created

[2/5] Reset flow endpoints...
  ✓ POST /api/auth/forgot-password
  ✓ POST /api/auth/reset-password
  ✓ Token validation logic

[3/5] Email templates...
  ✓ Password reset email
  ✓ Password changed confirmation

[4/5] Security measures...
  ✓ Token expiry (15 minutes)
  ✓ Single-use tokens
  ✓ Rate limiting (5 requests/hour)

[5/5] Testing...
  ✓ Reset flow tests (12 tests)
  ✓ Security tests (token expiry, reuse)

✅ Password reset implemented

/ck:cook [add OAuth2 login with Google and GitHub]

Implementation:

[1/6] OAuth setup...
  ✓ Installed passport.js
  ✓ Configured Google strategy
  ✓ Configured GitHub strategy

[2/6] OAuth endpoints...
  ✓ GET /api/auth/google
  ✓ GET /api/auth/google/callback
  ✓ GET /api/auth/github
  ✓ GET /api/auth/github/callback

[3/6] User model updates...
  ✓ Add oauthProvider field
  ✓ Add oauthId field
  ✓ Link OAuth accounts to existing users

[4/6] Account linking...
  ✓ Link OAuth to email if exists
  ✓ Create new user if doesn't exist
  ✓ Merge accounts logic

[5/6] Frontend integration...
  ✓ OAuth buttons
  ✓ Redirect handling
  ✓ Token extraction

[6/6] Testing...
  ✓ OAuth flow tests (16 tests)
  ✓ Account linking tests

✅ OAuth2 implemented

Configuration needed (.env):
GOOGLE_CLIENT_ID=your-client-id
GOOGLE_CLIENT_SECRET=your-secret
GITHUB_CLIENT_ID=your-client-id
GITHUB_CLIENT_SECRET=your-secret

Step 6: Add Two-Factor Authentication (2FA)

/ck:cook [implement TOTP-based 2FA with QR code setup]

Implementation:

[1/5] 2FA setup...
  ✓ Installed speakeasy (TOTP library)
  ✓ Installed qrcode (QR generation)
  ✓ Add twoFactorSecret to User model
  ✓ Add twoFactorEnabled field

[2/5] 2FA endpoints...
  ✓ POST /api/auth/2fa/setup - Generate QR code
  ✓ POST /api/auth/2fa/verify - Verify and enable
  ✓ POST /api/auth/2fa/disable - Disable 2FA
  ✓ POST /api/auth/login/2fa - Login with 2FA code

[3/5] Modified login flow...
  ✓ Check if 2FA enabled
  ✓ Require 2FA code
  ✓ Validate TOTP token

[4/5] Backup codes...
  ✓ Generate 10 backup codes
  ✓ Store hashed backup codes
  ✓ Use backup code endpoint

[5/5] Testing...
  ✓ 2FA flow tests (14 tests)
  ✓ Backup code tests

✅ 2FA implemented

Flow:
1. User enables 2FA → scans QR code
2. User enters 6-digit code → 2FA activated
3. Future logins require 2FA code
4. Backup codes for emergencies

Step 7: Add Passwordless Authentication

/ck:cook [implement passwordless login with magic links]

Implementation:

[1/4] Magic link setup...
  ✓ Generate secure login tokens
  ✓ Store tokens with expiry (10 min)
  ✓ Email template for magic link

[2/4] Endpoints...
  ✓ POST /api/auth/magic-link/request
  ✓ GET /api/auth/magic-link/verify
  ✓ Token validation and cleanup

[3/4] Security...
  ✓ Single-use tokens
  ✓ Short expiry (10 minutes)
  ✓ Rate limiting

[4/4] Testing...
  ✓ Magic link flow tests (10 tests)

✅ Passwordless authentication added

Usage:
1. User enters email
2. Receives magic link email
3. Clicks link → automatically logged in

Step 8: Add Security Features

Account Lockout

/ck:cook [add account lockout after 5 failed login attempts]

Session Management

/ck:cook [implement session management with active session tracking]

IP Whitelisting

/ck:cook [add IP whitelisting option for high-security accounts]

Step 9: Testing Authentication

/ck:test

Test results:

✓ Unit Tests (48 tests)
  ✓ Password hashing (8 tests)
  ✓ JWT generation/verification (12 tests)
  ✓ Token refresh (6 tests)
  ✓ 2FA TOTP (10 tests)
  ✓ Magic link generation (6 tests)
  ✓ OAuth account linking (6 tests)

✓ Integration Tests (56 tests)
  ✓ Registration (10 tests)
  ✓ Login (12 tests)
  ✓ Password reset (12 tests)
  ✓ OAuth flows (14 tests)
  ✓ 2FA flows (8 tests)

✓ Security Tests (24 tests)
  ✓ Brute force protection (6 tests)
  ✓ Token theft scenarios (8 tests)
  ✓ SQL injection attempts (4 tests)
  ✓ XSS attempts (6 tests)

Test Suites: 3 passed, 3 total
Tests:       128 passed, 128 total
Coverage:    94.7%

✅ All tests passed

Step 10: Security Review

/review

Security checklist:

✓ Passwords hashed with bcrypt (12 rounds)
✓ JWT tokens properly signed
✓ Refresh tokens securely stored
✓ Rate limiting on auth endpoints
✓ SQL injection protection
✓ XSS protection
✓ CSRF protection
✓ Secure password requirements
✓ Email verification implemented
✓ Account lockout after failed attempts
✓ 2FA option available
✓ Session timeout configured
✓ Secure token storage
✓ HTTPS enforcement
✓ Audit logging enabled

Security Score: 9.4/10 (Excellent)

Step 11: Documentation

/ck:docs update

Generated documentation:

✓ Authentication guide
✓ API endpoint documentation
✓ Security best practices
✓ OAuth setup guide
✓ 2FA setup guide
✓ Testing guide
✓ Troubleshooting guide

Complete Example: E-Commerce Authentication

Requirements

Implement authentication for e-commerce site with:
- User registration/login
- Email verification
- Password reset
- Social login (Google, Facebook)
- Guest checkout
- Remember me option
- Account deletion
- GDPR compliance

Implementation

# Plan authentication
/ck:plan [design authentication system for e-commerce with all requirements]

# Implement base auth
/ck:cook [implement JWT authentication with email verification]

# Add OAuth
/ck:cook [add Google and Facebook OAuth login]

# Guest checkout
/ck:cook [implement guest checkout with optional account creation]

# Remember me
/ck:cook [add remember me functionality with long-lived tokens]

# Account management
/ck:cook [implement account deletion with data export (GDPR)]

# Test everything
/ck:test

# Document
/ck:docs update

Time Comparison

Manual implementation: 6-10 hours

JWT setup: 1-2 hours
Email verification: 1 hour
Password reset: 1 hour
OAuth setup: 2-3 hours
Testing: 1-2 hours
Security review: 1-2 hours

With ClaudeKit: 38 minutes

Planning: 5 minutes
JWT + email: 10 minutes
Password reset: 5 minutes
OAuth: 12 minutes
Testing: 6 minutes

Time saved: 5.5-9.5 hours (88% faster)

Authentication Patterns

Pattern 1: API-First Authentication

/ck:cook [implement JWT authentication optimized for mobile apps]

Pattern 2: SSO (Single Sign-On)

/ck:cook [implement SSO with SAML for enterprise integration]

Pattern 3: Multi-Tenant Authentication

/ck:cook [implement multi-tenant authentication with organization isolation]

Pattern 4: Role-Based Access Control (RBAC)

/ck:cook [add role-based permissions with admin, user, and guest roles]

Best Practices

1. Secure Password Storage

✅ Good:
- bcrypt with 12+ rounds
- Async password hashing
- Never store plain text

❌ Bad:
- MD5/SHA1 hashing
- No salt
- Plain text passwords

2. JWT Token Security

✅ Good:
- Short access token expiry (15 min)
- Refresh token rotation
- Secure token storage (httpOnly cookies)
- Token blacklisting on logout

❌ Bad:
- Long-lived tokens
- Tokens in localStorage
- No token refresh
- No logout mechanism

3. Input Validation

/ck:cook [add comprehensive input validation to all auth endpoints]

4. Rate Limiting

Auth endpoints rate limits:
- Login: 5 attempts per 15 minutes
- Registration: 3 per hour
- Password reset: 3 per hour
- Email verification: 5 per hour

5. Audit Logging

/ck:cook [add audit logging for all authentication events]

Troubleshooting

Issue: Tokens Expiring Too Fast

Solution:

/ck:cook [increase JWT access token expiry to 30 minutes]

Issue: OAuth Callback Failing

Solution:

/ck:fix --quick [OAuth callback returning 400 error]

Issue: Password Reset Not Working

Solution:

/ck:fix --quick [password reset emails not being sent]

Issue: 2FA QR Code Not Displaying

Solution:

/ck:fix [2FA QR code not rendering in mobile view]

Security Checklist

Before production deployment:

✓ All passwords hashed with bcrypt
✓ JWT tokens use strong secret
✓ Refresh token rotation enabled
✓ Rate limiting configured
✓ HTTPS enforced
✓ CORS properly configured
✓ Input validation on all endpoints
✓ SQL injection protection
✓ XSS protection
✓ CSRF protection
✓ Email verification working
✓ Password reset tested
✓ OAuth redirect URIs whitelisted
✓ 2FA tested with multiple apps
✓ Account lockout working
✓ Audit logging enabled
✓ Error messages don't leak info
✓ Session timeout configured
✓ Secure cookies (httpOnly, secure)
✓ Token blacklist on logout

Next Steps

Building a REST API - Create APIs
Integrating Payments - Add payments
Adding a New Feature - Build features

/ck
- Implement features
/ck
- Test suite
/ck
—quick - Quick fixes

Integration Guides

/integrate
- Polar payments
Better Auth Skill - Better Auth framework