Password Hashing Done Right: bcrypt, Argon2 & Security

Password Hashing

Regular hash functions (SHA-256, etc.) are NOT suitable for passwords. Here's why and what to use instead.

Why SHA-256 is Wrong for Passwords

// ❌ WRONG: Raw SHA-256
const hash = crypto.createHash('sha256')
  .update(password)
  .digest('hex');
// Problems:
// 1. Too fast - attackers can try billions/second
// 2. No salt - rainbow table attacks
// 3. Identical passwords have identical hashes

The Right Way: bcrypt

import bcrypt from 'bcrypt';
// Hashing a password
const saltRounds = 12;
const hash = await bcrypt.hash(password, saltRounds);
// $2b$12$LQv3c1yqBWVHxkd0LHAkCOYz6TtxMQJqhN8/X4.aAfnvKY5P8m3K.
// Verifying a password
const isMatch = await bcrypt.compare(password, hash);

Even Better: Argon2

import argon2 from 'argon2';
// Hashing
const hash = await argon2.hash(password, {
  type: argon2.argon2id,  // Recommended variant
  memoryCost: 65536,      // 64 MB
  timeCost: 3,            // Iterations
  parallelism: 4          // Threads
});
// Verifying
const isMatch = await argon2.verify(hash, password);

Comparison

Best Practices

• Never store plaintext passwords
• Use Argon2id or bcrypt
• Use a work factor that takes ~250ms
• Increase work factor over time
• Re-hash on login when upgrading
• Implement rate limiting
• Use secure password requirements