Upgrading from bcrypt to Argon2id

Argon2id is the winner of the 2015 Password Hashing Competition and is recommended by OWASP for password storage. It’s more resistant to GPU and ASIC-based brute-force attacks than bcrypt because it’s memory-hard — it requires a large amount of RAM to compute, not just CPU time.

1. Install argon2

npm install argon2

Note: Unlike bcryptjs, the argon2 package requires native compilation. This works fine in Codespaces but may need build tools (Python, make, g++) on other systems.

2. Update server.js

Replace the require:

// Before
const bcrypt = require('bcryptjs');

// After
const argon2 = require('argon2');

Replace the hash in the registration route:

// Before
const hashedPassword = await bcrypt.hash(password, 10);

// After
const hashedPassword = await argon2.hash(password, { type: argon2.argon2id });

Replace the compare in the login route:

// Before
const validPassword = await bcrypt.compare(password, user.password);

// After
const validPassword = await argon2.verify(user.password, password);

That’s it — three lines changed. The API behavior and all 8 autograder tests remain identical.

Why Argon2id over bcrypt?

	bcrypt	Argon2id
Attack resistance	CPU-hard only	CPU-hard + memory-hard
GPU cracking	Partially resistant	Highly resistant
Tunability	Cost factor only	Time, memory, and parallelism
Max password length	72 bytes	No practical limit
Recommended by	Still acceptable	OWASP, NIST (2024+)