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@@ -0,0 +1,167 @@
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+<?php
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+
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+class googleAuthenticator
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+{
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+ static protected $_codeLength = 6;
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+
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+ static public function createSecret($secretLength = 16)
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+ {
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+ $validChars = self::_getBase32LookupTable();
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+
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+ // Valid secret lengths are 80 to 640 bits
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+ if ($secretLength < 16 || $secretLength > 128) {
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+ throw new Exception('Bad secret length');
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+ }
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+ $secret = '';
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+ $rnd = false;
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+ if (function_exists('random_bytes')) {
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+ $rnd = random_bytes($secretLength);
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+ } elseif (function_exists('openssl_random_pseudo_bytes')) {
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+ $rnd = openssl_random_pseudo_bytes($secretLength, $cryptoStrong);
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+ if (!$cryptoStrong) {
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+ $rnd = false;
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+ }
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+ }
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+ if ($rnd !== false) {
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+ for ($i = 0; $i < $secretLength; ++$i) {
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+ $secret .= $validChars[ord($rnd[$i]) & 31];
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+ }
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+ } else {
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+ throw new Exception('No source of secure random');
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+ }
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+
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+ return $secret;
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+ }
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+
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+ static public function getCode($secret, $timeSlice = null)
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+ {
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+ if ($timeSlice === null) {
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+ $timeSlice = floor(time() / 30);
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+ }
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+
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+ $secretkey = self::_base32Decode($secret);
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+
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+ // Pack time into binary string
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+ $time = chr(0).chr(0).chr(0).chr(0).pack('N*', $timeSlice);
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+ // Hash it with users secret key
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+ $hm = hash_hmac('SHA1', $time, $secretkey, true);
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+ // Use last nipple of result as index/offset
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+ $offset = ord(substr($hm, -1)) & 0x0F;
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+ // grab 4 bytes of the result
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+ $hashpart = substr($hm, $offset, 4);
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+
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+ // Unpak binary value
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+ $value = unpack('N', $hashpart);
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+ $value = $value[1];
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+ // Only 32 bits
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+ $value = $value & 0x7FFFFFFF;
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+
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+ $modulo = pow(10, self::$_codeLength);
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+
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+ return str_pad($value % $modulo, self::$_codeLength, '0', STR_PAD_LEFT);
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+ }
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+
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+ static public function getGoogleUrl($name, $secret)
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+ {
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+ $urlencoded = 'otpauth://totp/'.$name.'?secret='.$secret;
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+ return $urlencoded;
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+ }
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+
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+ static public function verifyCode($secret, $code, $discrepancy = 1, $currentTimeSlice = null)
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+ {
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+ if ($currentTimeSlice === null) {
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+ $currentTimeSlice = floor(time() / 30);
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+ }
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+
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+ if (strlen($code) != 6) {
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+ return false;
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+ }
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+
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+ for ($i = -$discrepancy; $i <= $discrepancy; ++$i) {
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+ $calculatedCode = self::getCode($secret, $currentTimeSlice + $i);
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+ if (self::timingSafeEquals($calculatedCode, $code)) {
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+ return true;
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+ }
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+ }
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+
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+ return false;
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+ }
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+
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+ static public function setCodeLength($length)
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+ {
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+ return self::$_codeLength = $length;
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+ }
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+
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+ static protected function _base32Decode($secret)
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+ {
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+ if (empty($secret)) {
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+ return '';
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+ }
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+
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+ $base32chars = self::_getBase32LookupTable();
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+ $base32charsFlipped = array_flip($base32chars);
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+
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+ $paddingCharCount = substr_count($secret, $base32chars[32]);
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+ $allowedValues = array(6, 4, 3, 1, 0);
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+ if (!in_array($paddingCharCount, $allowedValues)) {
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+ return false;
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+ }
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+ for ($i = 0; $i < 4; ++$i) {
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+ if ($paddingCharCount == $allowedValues[$i] &&
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+ substr($secret, -($allowedValues[$i])) != str_repeat($base32chars[32], $allowedValues[$i])) {
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+ return false;
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+ }
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+ }
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+ $secret = str_replace('=', '', $secret);
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+ $secret = str_split($secret);
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+ $binaryString = '';
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+ for ($i = 0; $i < count($secret); $i = $i + 8) {
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+ $x = '';
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+ if (!in_array($secret[$i], $base32chars)) {
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+ return false;
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+ }
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+ for ($j = 0; $j < 8; ++$j) {
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+ $x .= str_pad(base_convert(@$base32charsFlipped[@$secret[$i + $j]], 10, 2), 5, '0', STR_PAD_LEFT);
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+ }
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+ $eightBits = str_split($x, 8);
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+ for ($z = 0; $z < count($eightBits); ++$z) {
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+ $binaryString .= (($y = chr(base_convert($eightBits[$z], 2, 10))) || ord($y) == 48) ? $y : '';
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+ }
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+ }
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+
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+ return $binaryString;
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+ }
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+
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+ static protected function _getBase32LookupTable()
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+ {
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+ return array(
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+ 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', // 7
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+ 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 15
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+ 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 23
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+ 'Y', 'Z', '2', '3', '4', '5', '6', '7', // 31
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+ '=', // padding char
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+ );
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+ }
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+
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+ static private function timingSafeEquals($safeString, $userString)
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+ {
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+ if (function_exists('hash_equals')) {
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+ return hash_equals($safeString, $userString);
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+ }
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+ $safeLen = strlen($safeString);
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+ $userLen = strlen($userString);
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+
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+ if ($userLen != $safeLen) {
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+ return false;
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+ }
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+
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+ $result = 0;
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+
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+ for ($i = 0; $i < $userLen; ++$i) {
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+ $result |= (ord($safeString[$i]) ^ ord($userString[$i]));
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+ }
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+
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+ // They are only identical strings if $result is exactly 0...
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+ return $result === 0;
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+ }
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+}
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stany.ferer