Dart

HOTP Algorithm: HMAC-Based One-Time Password Algorithm

See more Encryption Examples

Demonstrates how to generate an HMAC one-time password (HOTP) as specified in RFC 4226.

Note: This example requires Chilkat v9.5.0.77 or greater.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final crypt = CkCrypt2();

  // Duplicate the following results from RFC 4226

  // Appendix D - HOTP Algorithm: Test Values
  // 
  //   The following test data uses the ASCII string
  //   "12345678901234567890" for the secret:
  // 
  //   Secret = 0x3132333435363738393031323334353637383930
  // 
  //                     Truncated
  //   Count    Hexadecimal    Decimal        HOTP
  //   0        4c93cf18       1284755224     755224
  //   1        41397eea       1094287082     287082
  //   2         82fef30        137359152     359152
  //   3        66ef7655       1726969429     969429
  //   4        61c5938a       1640338314     338314
  //   5        33c083d4        868254676     254676
  //   6        7256c032       1918287922     287922
  //   7         4e5b397         82162583     162583
  //   8        2823443f        673399871     399871
  //   9        2679dc69        645520489     520489

  final secret = '12345678901234567890';
  for (var count = 0; count <= 9; count++) {
    final counterHex = crypt.encodeInt(count, 8, false, 'hex');
    final hotp = crypt.hotp(secret, 'ascii', counterHex, 6, -1, 'sha1');
    print('$count  HOTP = $hotp');
  }

  // Output is:
  // 0  HOTP = 755224
  // 1  HOTP = 287082
  // 2  HOTP = 359152
  // 3  HOTP = 969429
  // 4  HOTP = 338314
  // 5  HOTP = 254676
  // 6  HOTP = 287922
  // 7  HOTP = 162583
  // 8  HOTP = 399871
  // 9  HOTP = 520489
}