🔐 Authentication System – Project Summary (Part 1 + Part 2)

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📌 Tech Stack

Frontend

• React (Vite + TypeScript)
• Axios (interceptors)
• Chakra UI

Backend

• Node.js
• Express
• MongoDB

Security

• JWT (Access + Refresh Token split)
• bcrypt password hashing
• Rate limiting
• HttpOnly cookies

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✅ Part 1 – Core Authentication System

1️⃣ User Signup

• Validate user existence
• Hash password using bcrypt
• Store hashed password in MongoDB

2️⃣ User Login

• Compare password using bcrypt

• Generate:

  • Access Token (short-lived)
  • Refresh Token (long-lived)

3️⃣ Protected Route

• Middleware verifies access token
• Attaches req.userId
• Returns 401 if invalid or expired

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✅ Part 2 – Production-Level Security Upgrade

🔹 1. Rate Limiting

• Applied on login route
• Prevents brute-force attacks
• Returns 429 when exceeded

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🔹 2. Access + Refresh Token Architecture

Access Token

• Short expiry (e.g., 30s)
• Sent via Authorization header
• Stored in localStorage

Refresh Token

• Longer expiry (e.g., 5m)
• Stored in HttpOnly cookie
• Not accessible via JavaScript

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🔹 3. Axios Interceptors

Request Interceptor

• Automatically attaches access token to headers

Response Interceptor

• If 401:

  • Calls /auth/refresh
  • Gets new access token
  • Retries original request

• Prevents infinite refresh loops

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🔹 4. Secure Cookie Configuration

Backend:

• httpOnly: true
• sameSite: 'lax'
• secure: false (dev)
• withCredentials: true enabled

Frontend:

• Axios configured with withCredentials: true

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🔹 5. Session Persistence

On page refresh:

• Access token checked
• /profile verified
• Silent refresh triggered if expired
• User remains logged in

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🔹 6. Logout Flow (Production Style)

Frontend:

• Calls /auth/logout
• Removes access token

Backend:

• Clears refresh cookie

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🧠 What This Architecture Achieves

✔ Secure token lifecycle management ✔ Silent access token renewal ✔ HttpOnly refresh token security ✔ Brute-force protection ✔ Clean logout handling ✔ Stable session behavior ✔ No infinite refresh loops

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🏆 Current Level of System

This is:

• Beyond tutorial-level JWT auth
• Production-ready for small SaaS
• Interview-ready authentication architecture
• Mid-level backend engineering implementation

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🚀 Potential Next Upgrades (Part 3+)

• Refresh token rotation
• Store refresh tokens in database
• Logout all devices
• Session/device tracking
• Role-based access control (RBAC)
• CSRF protection
• Monitoring & suspicious login detection

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📈 Project Status

Part 1: Completed ✅ Part 2: Completed ✅

System is stable, secure, and production-aligned.