passlib

Storing passwords securely, simplified

Usage

const passlib = require("passlib");

async function createUser(name, password) {
  const wrapped = await passlib.create(password);
  await db.store(name, wrapped); // or something like that
}

async function checkCredentials(name, password) {
  const expected = await db.get(name); // or something like that

  /* The actual check!
   * Make sure to always call this function (with a dummy password if needed),
   * even if you didn't find an account in your db, unless you're OK with an
   * attacker finding out all valid user names in your system.
   * If you do not call this function, the attacker may try user names and see
   * when something responds real quick, meaning no password check performed,
   * ergo not a valid user, or somewhat slower, account valid as it tried to
   * verify the password.
   * This is not a concern if you user directory is public anyway.
   */
  if (!(await passlib.verify(expected, password))) {
    throw new Error("Incorrect credentials");
  }

  // Upgrade when needed, so we always use the most current version
  if (passlib.needsUpgrade(expected)) {
    const wrapped = await passlib.create(password);
    await db.store(name, wrapped); // or something like that
  }
}

Word of advise

Do not mess with the wrapped values, ever. Just consider them opaque.

API

/**
 * Checks whether a stored value needs updating to a new version.
 * Important: this does *NOT* check the integrity of a stored value.
 * @param {string|Buffer} value Value to check
 * @returns {boolean} True if update is needed
 */
export function needsUpgrade(value: string | Buffer): boolean;
/**
 * Creates a value from a password that is suitable for storing
 * in a peristent store. If the store ever gets compromised,
 * the returned value is supposed to be secure enough so that
 * the password cannot be computed from it.
 *
 * @async
 * @param {string} password Password to wrap
 * @param {object} [options]
 * @param {integer} [options.version] Create with this specific version
 *   instead of the most current one
 * @param {boolean} [options.asBuffer] Return a node buffer instead of a string
 * @returns {Promise<string|Buffer>} Wrapped password value
 */
export function create(password: string, options?: {
    version?: any;
    asBuffer?: boolean;
}): Promise<string | Buffer>;
/**
 * Verifies a stored value created by this library matches
 * a user provided password.
 *
 * @async
 * @param {string|Buffer} value Previously stored value
 * @param {string} password Password to wrap
 * @returns {Promise<boolean>} True if password matches
 *   (e.g. login can proceed)
 */
export function verify(value: string | Buffer, password: string): Promise<boolean>;

Algorithms

v2 (current)

This algorithm just uses argon2 (via node-argon2), type argoon2id in version 1.3, with a memory cost of 20 MiB and a time cost of 5.

v1

This algorithm derives a key k using crypto.pbkdf2(password, salt, iterations, salt, 64, "sha512") where salt is a per-call generated crypto-random buffer of 32-bytes, and iterations is a value of minimum 20000 but adjusted to take approximately at least 100 milliseconds on the runtime computer.

A check = SHA224(VERSION(1) | iterations | salt) is computed, acting as a checksum around the parameters.

Finally, using mac = HMAC-SHA512(k, VERSION(1) | iterations | salt | check) (the important bit), the concatenation of VERSION(1) | iterations | salt | check | mac is returned, acting as the wrapped password value that can be securely stored.

This construction is analog to what scrypt (and node-scrypt) are using, except for the different KDF of course. Using PBKDF2 has the drawback that it is better "crackable" than e.g. scrypt. The decision to use it instead of scrypt in this version stems from PBKDF2 being part of the node standard library. It still is believed to be secure enough (given enough iterations)[citation needed] today.

v0

Do NOT Use: The password is just put plain text into a buffer, aka zero security. This version exists mainly for testing purposes. Did I mention you should NOT EVER use this?