GoogleAuthenticator.php in TFA Basic plugins 7

File

includes/googleauthenticator/GoogleAuthenticator.php

<?php

/**
 * PHP Class for handling Google Authenticator 2-factor authentication.
 *
 * @author Michael Kliewe
 * @copyright 2012 Michael Kliewe
 * @license http://www.opensource.org/licenses/bsd-license.php BSD License
 *
 * @link http://www.phpgangsta.de/
 */
class PHPGangsta_GoogleAuthenticator {
  protected $_codeLength = 6;

  /**
   * Create new secret.
   * 16 characters, randomly chosen from the allowed base32 characters.
   *
   * @param int $secretLength
   *
   * @return string
   */
  public function createSecret($secretLength = 16) {
    $validChars = $this
      ->_getBase32LookupTable();

    // Valid secret lengths are 80 to 640 bits
    if ($secretLength < 16 || $secretLength > 128) {
      throw new Exception('Bad secret length');
    }
    $secret = '';
    $rnd = false;
    if (function_exists('random_bytes')) {
      $rnd = random_bytes($secretLength);
    }
    elseif (function_exists('mcrypt_create_iv')) {
      $rnd = mcrypt_create_iv($secretLength, MCRYPT_DEV_URANDOM);
    }
    elseif (function_exists('openssl_random_pseudo_bytes')) {
      $rnd = openssl_random_pseudo_bytes($secretLength, $cryptoStrong);
      if (!$cryptoStrong) {
        $rnd = false;
      }
    }
    if ($rnd !== false) {
      for ($i = 0; $i < $secretLength; ++$i) {
        $secret .= $validChars[ord($rnd[$i]) & 31];
      }
    }
    else {
      throw new Exception('No source of secure random');
    }
    return $secret;
  }

  /**
   * Calculate the code, with given secret and point in time.
   *
   * @param string   $secret
   * @param int|null $timeSlice
   *
   * @return string
   */
  public function getCode($secret, $timeSlice = null) {
    if ($timeSlice === null) {
      $timeSlice = floor(time() / 30);
    }
    $secretkey = $this
      ->_base32Decode($secret);

    // Pack time into binary string
    $time = chr(0) . chr(0) . chr(0) . chr(0) . pack('N*', $timeSlice);

    // Hash it with users secret key
    $hm = hash_hmac('SHA1', $time, $secretkey, true);

    // Use last nipple of result as index/offset
    $offset = ord(substr($hm, -1)) & 0xf;

    // grab 4 bytes of the result
    $hashpart = substr($hm, $offset, 4);

    // Unpak binary value
    $value = unpack('N', $hashpart);
    $value = $value[1];

    // Only 32 bits
    $value = $value & 0x7fffffff;
    $modulo = pow(10, $this->_codeLength);
    return str_pad($value % $modulo, $this->_codeLength, '0', STR_PAD_LEFT);
  }

  /**
   * Get QR-Code URL for image, from google charts.
   *
   * @param string $name
   * @param string $secret
   * @param string $title
   * @param array  $params
   *
   * @return string
   */
  public function getQRCodeGoogleUrl($name, $secret, $title = null, $params = array()) {
    $width = !empty($params['width']) && (int) $params['width'] > 0 ? (int) $params['width'] : 200;
    $height = !empty($params['height']) && (int) $params['height'] > 0 ? (int) $params['height'] : 200;
    $level = !empty($params['level']) && array_search($params['level'], array(
      'L',
      'M',
      'Q',
      'H',
    )) !== false ? $params['level'] : 'M';
    $urlencoded = urlencode('otpauth://totp/' . $name . '?secret=' . $secret . '');
    if (isset($title)) {
      $urlencoded .= urlencode('&issuer=' . urlencode($title));
    }
    return 'https://chart.googleapis.com/chart?chs=' . $width . 'x' . $height . '&chld=' . $level . '|0&cht=qr&chl=' . $urlencoded . '';
  }

  /**
   * Check if the code is correct. This will accept codes starting from $discrepancy*30sec ago to $discrepancy*30sec from now.
   *
   * @param string   $secret
   * @param string   $code
   * @param int      $discrepancy      This is the allowed time drift in 30 second units (8 means 4 minutes before or after)
   * @param int|null $currentTimeSlice time slice if we want use other that time()
   *
   * @return bool
   */
  public function verifyCode($secret, $code, $discrepancy = 1, $currentTimeSlice = null) {
    if ($currentTimeSlice === null) {
      $currentTimeSlice = floor(time() / 30);
    }
    if (strlen($code) != 6) {
      return false;
    }
    for ($i = -$discrepancy; $i <= $discrepancy; ++$i) {
      $calculatedCode = $this
        ->getCode($secret, $currentTimeSlice + $i);
      if ($this
        ->timingSafeEquals($calculatedCode, $code)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Set the code length, should be >=6.
   *
   * @param int $length
   *
   * @return PHPGangsta_GoogleAuthenticator
   */
  public function setCodeLength($length) {
    $this->_codeLength = $length;
    return $this;
  }

  /**
   * Helper class to decode base32.
   *
   * @param $secret
   *
   * @return bool|string
   */
  protected function _base32Decode($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;
  }

  /**
   * Get array with all 32 characters for decoding from/encoding to base32.
   *
   * @return array
   */
  protected function _getBase32LookupTable() {
    return array(
      'A',
      'B',
      'C',
      'D',
      'E',
      'F',
      'G',
      'H',
      //  7
      'I',
      'J',
      'K',
      'L',
      'M',
      'N',
      'O',
      'P',
      // 15
      'Q',
      'R',
      'S',
      'T',
      'U',
      'V',
      'W',
      'X',
      // 23
      'Y',
      'Z',
      '2',
      '3',
      '4',
      '5',
      '6',
      '7',
      // 31
      '=',
    );
  }

  /**
   * A timing safe equals comparison
   * more info here: http://blog.ircmaxell.com/2014/11/its-all-about-time.html.
   *
   * @param string $safeString The internal (safe) value to be checked
   * @param string $userString The user submitted (unsafe) value
   *
   * @return bool True if the two strings are identical
   */
  private function timingSafeEquals($safeString, $userString) {
    if (function_exists('hash_equals')) {
      return hash_equals($safeString, $userString);
    }
    $safeLen = strlen($safeString);
    $userLen = strlen($userString);
    if ($userLen != $safeLen) {
      return false;
    }
    $result = 0;
    for ($i = 0; $i < $userLen; ++$i) {
      $result |= ord($safeString[$i]) ^ ord($userString[$i]);
    }

    // They are only identical strings if $result is exactly 0...
    return $result === 0;
  }

}

Classes

Name	Description
PHPGangsta_GoogleAuthenticator	PHP Class for handling Google Authenticator 2-factor authentication.