MFKDF

setup/factors/hmacsha1.js

  1. /**
  2.  * @file MFKDF HMAC-SHA1 Factor Setup
  3.  * @copyright Multifactor 2022 All Rights Reserved
  4.  *
  5.  * @description
  6.  * Setup an HMAC-SHA1 challenge-response factor for multi-factor key derivation
  7.  *
  8.  * @author Vivek Nair (https://nair.me) <vivek@nair.me>
  9.  */
  10. const defaults = require('../../defaults')
  11. const crypto = require('crypto')
  12. const xor = require('buffer-xor')
  14. /**
  15.  * Setup a YubiKey-compatible MFKDF HMAC-SHA1 challenge-response factor
  16.  *
  17.  * @example
  18.  * // setup key with hmacsha1 factor
  19.  * const setup = await mfkdf.setup.key([
  20.  *   await mfkdf.setup.factors.hmacsha1()
  21.  * ], {size: 8})
  22.  *
  23.  * // calculate response; could be done using hardware device
  24.  * const secret = setup.outputs.hmacsha1.secret
  25.  * const challenge = Buffer.from(setup.policy.factors[0].params.challenge, 'hex')
  26.  * const response = crypto.createHmac('sha1', secret).update(challenge).digest()
  27.  *
  28.  * // derive key with hmacsha1 factor
  29.  * const derive = await mfkdf.derive.key(setup.policy, {
  30.  *   hmacsha1: mfkdf.derive.factors.hmacsha1(response)
  31.  * })
  32.  *
  33.  * setup.key.toString('hex') // -> 01d0c7236adf2516
  34.  * derive.key.toString('hex') // -> 01d0c7236adf2516
  35.  *
  36.  * @param {Object} [options] - Configuration options
  37.  * @param {string} [options.id='hmacsha1'] - Unique identifier for this factor
  38.  * @param {Buffer} [options.secret] - HMAC secret to use; randomly generated by default
  39.  * @returns {MFKDFFactor} MFKDF factor information
  40.  * @author Vivek Nair (https://nair.me) <vivek@nair.me>
  41.  * @since 0.21.0
  42.  * @async
  43.  * @memberof setup.factors
  44.  */
  45. async function hmacsha1 (options) {
  46.   options = Object.assign(Object.assign({}, defaults.hmacsha1), options)
  48.   if (typeof options.id !== 'string') throw new TypeError('id must be a string')
  49.   if (options.id.length === 0) throw new RangeError('id cannot be empty')
  51.   if (typeof options.secret === 'undefined') options.secret = crypto.randomBytes(20)
  52.   if (!Buffer.isBuffer(options.secret)) throw new TypeError('secret must be a buffer')
  53.   if (Buffer.byteLength(options.secret) !== 20) throw new RangeError('secret must be 20 bytes')
  55.   return {
  56.     type: 'hmacsha1',
  57.     id: options.id,
  58.     data: options.secret,
  59.     entropy: 160,
  60.     params: async ({ key }) => {
  61.       const challenge = crypto.randomBytes(64)
  62.       const response = crypto.createHmac('sha1', options.secret).update(challenge).digest()
  63.       const pad = xor(response.subarray(0, 20), options.secret)
  64.       return {
  65.         challenge: challenge.toString('hex'),
  66.         pad: pad.toString('hex')
  67.       }
  68.     },
  69.     output: async () => {
  70.       return { secret: options.secret }
  71.     }
  72.   }
  73. }
  74. module.exports.hmacsha1 = hmacsha1