Authentication Guide

Authentication verifies the identity of a user or system before granting access to protected resources. This guide covers common authentication strategies, security best practices, and practical implementation examples.

Authentication Types

Best Practices

• Store passwords using a strong adaptive hash (e.g., Argon2, bcrypt, scrypt).
• Enforce minimum password complexity and length.
• Implement rate limiting and account lockout after failed attempts.
• Prefer token‑based authentication (JWT) for stateless APIs.
• Use HTTPS everywhere to protect credentials in transit.
• Rotate secret keys regularly and store them securely (e.g., Vault).
• Adopt MFA for privileged accounts.
• Validate and sanitize all input to prevent injection attacks.

Implementation Steps

1. Choose an authentication strategy based on your threat model.
2. Set up a secure user store (database with hashed passwords).
3. Integrate a library/framework for handling auth flows (e.g., Passport.js, Spring Security).
4. Configure HTTPS and secure cookies (HttpOnly, Secure, SameSite).
5. Implement session management or token issuance.
6. Add MFA if required.
7. Test for common vulnerabilities (OWASP Top 10).

Code Samples

Node.js – Password Hashing with bcrypt

const bcrypt = require('bcrypt');
async function hashPassword(plain) {
  const salt = await bcrypt.genSalt(12);
  return await bcrypt.hash(plain, salt);
}
async function verifyPassword(plain, hash) {
  return await bcrypt.compare(plain, hash);
}

Express – JWT Generation & Verification

const jwt = require('jsonwebtoken');
const secret = process.env.JWT_SECRET;
function signToken(payload) {
  return jwt.sign(payload, secret, { expiresIn: '1h' });
}
function verifyToken(token) {
  try {
    return jwt.verify(token, secret);
  } catch (e) {
    return null;
  }
}

FAQ