byte[] key = fillByteArray(16, 0xaa);
    byte[] data = fillByteArray(50, 0xdd);

    checkMd5("56be34521d144c88dbb8c733f0e8b3f6", key, data);
  }

  public void testRfc2202_hmacMd5_case4() {
    byte[] key = base16().lowerCase().decode("0102030405060708090a0b0c0d0e0f10111213141516171819");
    byte[] data = fillByteArray(50, 0xcd);

    checkMd5("697eaf0aca3a3aea3a75164746ffaa79", key, data);