Password hashing moderno: argon2, bcrypt, peppers

import { hash, verify, argon2id } from '@node-rs/argon2'; // ou 'argon2' (native)

const PEPPER = process.env.PASSWORD_PEPPER!; // 32+ random bytes, nunca no git

async function hashPassword(plaintext: string): Promise<string> {
  // Pepper concatenado (convenção: antes do hash)
  const peppered = plaintext + PEPPER;
  return await hash(peppered, {
    algorithm: argon2id,
    timeCost: 2,       // t
    memoryCost: 19456, // m em KiB (19 MiB — OWASP 2024)
    parallelism: 1,    // p
  });
}

async function verifyPassword(plaintext: string, hashStr: string): Promise<boolean> {
  const peppered = plaintext + PEPPER;
  return await verify(hashStr, peppered);
}

import { timingSafeEqual } from 'node:crypto';

// ❌
if (userHash === storedHash) allow();  // timing leak

// ✅
const a = Buffer.from(userHash, 'hex');
const b = Buffer.from(storedHash, 'hex');
if (a.length === b.length && timingSafeEqual(a, b)) allow();

async function login(email: string, password: string) {
  const user = await db.user.findUnique({ where: { email } });
  if (!user) return null;

  const ok = await verifyPassword(password, user.passwordHash);
  if (!ok) return null;

  // Detecta hash desatualizado e rehash
  const currentParams = extractParams(user.passwordHash);
  if (needsRehash(currentParams, TARGET_PARAMS)) {
    const newHash = await hashPassword(password);
    await db.user.update({ where: { id: user.id }, data: { passwordHash: newHash } });
  }

  return user;
}