5 min read

Password hashing — Argon2id is the answer, here is how

If you still store passwords, you must hash them with a memory-hard function. Here is how to configure Argon2id correctly in a Node.js or Python backend.

The single most common password-hashing mistake is picking the wrong algorithm. Argon2id is the current OWASP recommendation. Bcrypt is still acceptable but should be migrated. Everything else (MD5, SHA-256, PBKDF2 with too few iterations) is unsafe.

What it is

A password hash converts a password into a verifiable value that cannot be reversed. Memory-hard functions (Argon2id, scrypt, bcrypt) are resistant to GPU + ASIC cracking.

Vulnerable example

// Vulnerable: fast hash + no salt
import { createHash } from "crypto";
const stored = createHash("sha256").update(password).digest("hex");
// An attacker with a GPU rainbow-tables this in hours.

Fixed example

// Fixed: Argon2id
import argon2 from "argon2";

// On signup
const hash = await argon2.hash(password, {
  type: argon2.argon2id,
  memoryCost: 19456,  // 19 MiB
  timeCost: 2,
  parallelism: 1,
});

// On login
const valid = await argon2.verify(hash, passwordInput);

How Securie catches it

Securie findingmedium
apps/web/app/api/route.ts:22

Password hashing

Securie's crypto specialist flags any password-hashing call-site using MD5, SHA-1, SHA-256/512 (without PBKDF2), or PBKDF2 with too few iterations.

Suggested fix — ready as a PR
// Fixed: Argon2id
import argon2 from "argon2";

// On signup
const hash = await argon2.hash(password, {
  type: argon2.argon2id,
  memoryCost: 19456,  // 19 MiB
  timeCost: 2,
  parallelism: 1,
});

// On login
const valid = await argon2.verify(hash, passwordInput);
Catch this in my repo →Securie reviews every PR · proves the issue · ships a verified fix PR

Checklist

  • Argon2id with OWASP-recommended parameters
  • Salt is random + unique per password (handled by argon2 library)
  • Old bcrypt hashes are re-hashed on next login
  • No MD5, SHA-1, SHA-256, or plain-sha without PBKDF2
  • Password verification is constant-time (handled by library)

FAQ

Should I migrate existing bcrypt hashes?

Yes, but not immediately. On next successful login with the old bcrypt hash, re-hash with Argon2id. Over 6-12 months your entire user table migrates without a lockout event.

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