git.squeep.com Git - squeep-totp/blob - lib/totp.js

   1 'use strict';
   2
   3 const HOTP = require('./hotp');
   4
   5 class TimeBasedOneTimePassword extends HOTP {
   6   /**
   7    *
   8    * @param {Object} options
   9    * @param {Number} options.codeLength
  10    * @param {Buffer|String} options.key
  11    * @param {String} options.keyEncoding
  12    * @param {String} options.algorithm
  13    * @param {Number} options.timeStepSeconds
  14    * @param {Number} options.timeStepStartSeconds
  15    * @param {Number} options.driftForward
  16    * @param {Number} options.driftBackward
  17    */
  18   constructor(options) {
  19     const _options = { ...options };
  20     super(_options);
  21     this.driftOffsets = [
  22       0n, // check now first
  23       ...Array.from({ length: this.driftBackward }, (v, k) => BigInt(-(k + 1))),
  24       ...Array.from({ length: this.driftForward }, (v, k) => BigInt(k + 1)),
  25     ];
  26   }
  27
  28   get _algorithmKeyLengths() {
  29     return {
  30       ...super._algorithmKeyLengths,
  31       'sha256': 32,
  32       'sha512': 64,
  33     };
  34   }
  35
  36   get counter() {
  37     const epoch = Math.floor(Date.now() / 1000);
  38     return BigInt(Math.floor((epoch - this.timeStepStartSeconds) / this.timeStepSeconds));
  39   }
  40
  41   set counter(_) { /* */ }
  42
  43   get _defaultOptions() {
  44     const options = Object.assign(super._defaultOptions, {
  45       timeStepSeconds: 30,
  46       timeStepStartSeconds: 0,
  47       driftForward: 1,
  48       driftBackward: 1,
  49     });
  50     delete options.counter;
  51     return options;
  52   }
  53
  54   generate(count = this.counter) {
  55     return super.generate(count);
  56   }
  57
  58   /**
  59    *
  60    * @param {String} hotp
  61    * @param {BigInt=} count
  62    * @returns {Boolean}
  63    */
  64   validate(hotp, count) {
  65     const counter = count ?? this.counter;
  66     for (const offset of this.driftOffsets) {
  67       const codeString = this.generate(counter + offset);
  68       if (codeString === hotp.trim()) {
  69         return true;
  70       }
  71     }
  72     return false;
  73   }
  74
  75 }
  76
  77 module.exports = TimeBasedOneTimePassword;