function GoogleAuthenticator::oath_hotp in Google Authenticator login 6

3 calls to GoogleAuthenticator::oath_hotp()

ga_loginGA::authenticateUser in ./ga_login.class.php

GoogleAuthenticator::authenticateUser in ./ga4php.php

GoogleAuthenticator::resyncCode in ./ga4php.php

File

./ga4php.php, line 379

Class

GoogleAuthenticator

Code

function oath_hotp($key, $counter) {
  $key = pack("H*", $key);
  $cur_counter = array(
    0,
    0,
    0,
    0,
    0,
    0,
    0,
    0,
  );
  for ($i = 7; $i >= 0; $i--) {
    $cur_counter[$i] = pack('C*', $counter);
    $counter = $counter >> 8;
  }
  $bin_counter = implode($cur_counter);

  // Pad to 8 chars
  if (strlen($bin_counter) < 8) {
    $bin_counter = str_repeat(chr(0), 8 - strlen($bin_counter)) . $bin_counter;
  }

  // HMAC
  $hash = hash_hmac('sha1', $bin_counter, $key);
  return str_pad($this
    ->oath_truncate($hash), 6, "0", STR_PAD_LEFT);
}