protected function PHPGangsta_GoogleAuthenticator::_base32Decode in TFA Basic plugins 7

Helper class to decode base32.

Parameters

$secret:

Return value

bool|string

1 call to PHPGangsta_GoogleAuthenticator::_base32Decode()

PHPGangsta_GoogleAuthenticator::getCode in includes/googleauthenticator/GoogleAuthenticator.php

Calculate the code, with given secret and point in time.

File

includes/googleauthenticator/GoogleAuthenticator.php, line 166

Class

PHPGangsta_GoogleAuthenticator

PHP Class for handling Google Authenticator 2-factor authentication.

Code

protected function _base32Decode($secret) {
  if (empty($secret)) {
    return '';
  }
  $base32chars = $this
    ->_getBase32LookupTable();
  $base32charsFlipped = array_flip($base32chars);
  $paddingCharCount = substr_count($secret, $base32chars[32]);
  $allowedValues = array(
    6,
    4,
    3,
    1,
    0,
  );
  if (!in_array($paddingCharCount, $allowedValues)) {
    return false;
  }
  for ($i = 0; $i < 4; ++$i) {
    if ($paddingCharCount == $allowedValues[$i] && substr($secret, -$allowedValues[$i]) != str_repeat($base32chars[32], $allowedValues[$i])) {
      return false;
    }
  }
  $secret = str_replace('=', '', $secret);
  $secret = str_split($secret);
  $binaryString = '';
  for ($i = 0; $i < count($secret); $i = $i + 8) {
    $x = '';
    if (!in_array($secret[$i], $base32chars)) {
      return false;
    }
    for ($j = 0; $j < 8; ++$j) {
      $x .= str_pad(base_convert(@$base32charsFlipped[@$secret[$i + $j]], 10, 2), 5, '0', STR_PAD_LEFT);
    }
    $eightBits = str_split($x, 8);
    for ($z = 0; $z < count($eightBits); ++$z) {
      $binaryString .= ($y = chr(base_convert($eightBits[$z], 2, 10))) || ord($y) == 48 ? $y : '';
    }
  }
  return $binaryString;
}