next.js/examples/api-routes-apollo-server-and-client-auth/lib/user.ts

import crypto from "crypto";

/**
 * User methods. The example doesn't contain a DB, but for real applications you must use a
 * db here, such as MongoDB, Fauna, SQL, etc.
 */

const users = [];

export async function createUser({ email, password }) {
  // Here you should create the user and save the salt and hashed password (some dbs may have
  // authentication methods that will do it for you so you don't have to worry about it):
  const salt = crypto.randomBytes(16).toString("hex");
  const hash = crypto
    .pbkdf2Sync(password, salt, 1000, 64, "sha512")
    .toString("hex");
  const user = {
    id: crypto.randomUUID(),
    createdAt: Date.now(),
    email,
    hash,
    salt,
  };

  // This is an in memory store for users, there is no data persistence without a proper DB
  users.push(user);

  return user;
}

// Here you should lookup for the user in your DB
export async function findUser({ email }) {
  // This is an in memory store for users, there is no data persistence without a proper DB
  return users.find((user) => user.email === email);
}

// Compare the password of an already fetched user (using `findUser`) and compare the
// password for a potential match
export async function validatePassword(user, inputPassword) {
  const inputHash = crypto
    .pbkdf2Sync(inputPassword, user.salt, 1000, 64, "sha512")
    .toString("hex");
  const passwordsMatch = user.hash === inputHash;
  return passwordsMatch;
}