How should you store passwords securely?

Passwords need a one-way function that is expensive to brute force. A general-purpose hash such as SHA-256 is too fast; attackers can test billions of candidates per second. Password hashing algorithms add a salt and a configurable work factor.

import { hash, verify } from "@node-rs/argon2";

const digest = await hash(password, {
  memoryCost: 19456,
  timeCost: 2,
  parallelism: 1,
});

const valid = await verify(digest, password);

The rules

• Use a unique random salt per password, generated by the library
• Use Argon2id, scrypt or bcrypt; never MD5, SHA-1 or plain SHA-256
• Tune cost against your hardware and measure login latency
• Compare with a constant-time verify function from the library
• Rehash on successful login when you raise the cost parameters
• Rate limit login attempts and add breached-password checks

bcrypt has a 72-byte input limit and truncates longer passwords silently or throws depending on the implementation. Argon2id is the modern default and lets you tune memory separately from CPU. A pepper, stored outside the database, adds defense in depth but complicates rotation.