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@PHPGangsta @Sc00bz @LukaszPiechowiak @34x @leandro-lugaresi @yanniks @edwardmp @alexandregz
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<?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)) & 0x0F;
// 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://api.qrserver.com/v1/create-qr-code/?data=$urlencoded&size=${width}x${height}&ecc=$level";
}
/**
* 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
'=', // padding char
);
}
/**
* 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;
}
}
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