Authentication System
The foundation of every web & app. Covers Register, Login, JWT Token, and Password Hashing.
Register System Flow
📋 Step-by-Step Flow
🧠 Key Concepts
JWT Token
JSON Web Token — stores user info in an encrypted string, decoded by the server without DB lookup. Contains: Header.Payload.Signature
bcrypt Hashing
One-way password hashing algorithm. Even if DB is leaked, attackers cannot reverse the hash. Use salt rounds ≥ 10.
Refresh Token
A long-lived token used to get a new Access Token. Stored securely (HttpOnly Cookie). Access Token expires in 15 min, Refresh Token in 30 days.
OAuth 2.0
Login with Google / Facebook / Apple. The provider authenticates the user and sends back a token. No need to store passwords.
MFA / 2FA
Multi-Factor Authentication. After password, verify with OTP (SMS / Google Authenticator). Greatly reduces account hijacking.
Session vs Token
Session stores state on server (DB/Redis), Token (JWT) is stateless. APIs and mobile apps prefer Token; traditional web prefers Session.
Need a secure authentication system? 🔑
We build secure Login systems with JWT, OAuth, and 2FA.