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@@ -0,0 +1,256 @@
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+<?php
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+namespace RobThree\Auth;
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+
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+use RobThree\Auth\Providers\Qr\IQRCodeProvider;
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+use RobThree\Auth\Providers\Rng\IRNGProvider;
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+use RobThree\Auth\Providers\Time\ITimeProvider;
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+
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+// Based on / inspired by: https://github.com/PHPGangsta/GoogleAuthenticator
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+// Algorithms, digits, period etc. explained: https://github.com/google/google-authenticator/wiki/Key-Uri-Format
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+class TwoFactorAuth
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+{
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+ private $algorithm;
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+ private $period;
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+ private $digits;
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+ private $issuer;
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+ private $qrcodeprovider = null;
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+ private $rngprovider = null;
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+ private $timeprovider = null;
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+ private static $_base32dict = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567=';
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+ private static $_base32;
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+ private static $_base32lookup = array();
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+ private static $_supportedalgos = array('sha1', 'sha256', 'sha512', 'md5');
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+
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+ function __construct($issuer = null, $digits = 6, $period = 30, $algorithm = 'sha1', IQRCodeProvider $qrcodeprovider = null, IRNGProvider $rngprovider = null, ITimeProvider $timeprovider = null)
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+ {
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+ $this->issuer = $issuer;
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+ if (!is_int($digits) || $digits <= 0)
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+ throw new TwoFactorAuthException('Digits must be int > 0');
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+ $this->digits = $digits;
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+
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+ if (!is_int($period) || $period <= 0)
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+ throw new TwoFactorAuthException('Period must be int > 0');
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+ $this->period = $period;
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+
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+ $algorithm = strtolower(trim($algorithm));
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+ if (!in_array($algorithm, self::$_supportedalgos))
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+ throw new TwoFactorAuthException('Unsupported algorithm: ' . $algorithm);
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+ $this->algorithm = $algorithm;
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+ $this->qrcodeprovider = $qrcodeprovider;
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+ $this->rngprovider = $rngprovider;
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+ $this->timeprovider = $timeprovider;
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+
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+ self::$_base32 = str_split(self::$_base32dict);
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+ self::$_base32lookup = array_flip(self::$_base32);
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+ }
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+
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+ /**
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+ * Create a new secret
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+ */
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+ public function createSecret($bits = 80, $requirecryptosecure = true)
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+ {
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+ $secret = '';
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+ $bytes = ceil($bits / 5); //We use 5 bits of each byte (since we have a 32-character 'alphabet' / BASE32)
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+ $rngprovider = $this->getRngprovider();
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+ if ($requirecryptosecure && !$rngprovider->isCryptographicallySecure())
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+ throw new TwoFactorAuthException('RNG provider is not cryptographically secure');
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+ $rnd = $rngprovider->getRandomBytes($bytes);
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+ for ($i = 0; $i < $bytes; $i++)
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+ $secret .= self::$_base32[ord($rnd[$i]) & 31]; //Mask out left 3 bits for 0-31 values
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+ return $secret;
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+ }
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+
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+ /**
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+ * Calculate the code with given secret and point in time
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+ */
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+ public function getCode($secret, $time = null)
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+ {
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+ $secretkey = $this->base32Decode($secret);
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+
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+ $timestamp = "\0\0\0\0" . pack('N*', $this->getTimeSlice($this->getTime($time))); // Pack time into binary string
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+ $hashhmac = hash_hmac($this->algorithm, $timestamp, $secretkey, true); // Hash it with users secret key
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+ $hashpart = substr($hashhmac, ord(substr($hashhmac, -1)) & 0x0F, 4); // Use last nibble of result as index/offset and grab 4 bytes of the result
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+ $value = unpack('N', $hashpart); // Unpack binary value
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+ $value = $value[1] & 0x7FFFFFFF; // Drop MSB, keep only 31 bits
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+
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+ return str_pad($value % pow(10, $this->digits), $this->digits, '0', STR_PAD_LEFT);
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+ }
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+
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+ /**
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+ * Check if the code is correct. This will accept codes starting from ($discrepancy * $period) sec ago to ($discrepancy * period) sec from now
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+ */
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+ public function verifyCode($secret, $code, $discrepancy = 1, $time = null, &$timeslice = 0)
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+ {
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+ $timetamp = $this->getTime($time);
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+
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+ $timeslice = 0;
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+
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+ // To keep safe from timing-attacks we iterate *all* possible codes even though we already may have
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+ // verified a code is correct. We use the timeslice variable to hold either 0 (no match) or the timeslice
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+ // of the match. Each iteration we either set the timeslice variable to the timeslice of the match
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+ // or set the value to itself. This is an effort to maintain constant execution time for the code.
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+ for ($i = -$discrepancy; $i <= $discrepancy; $i++) {
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+ $ts = $timetamp + ($i * $this->period);
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+ $slice = $this->getTimeSlice($ts);
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+ $timeslice = $this->codeEquals($this->getCode($secret, $ts), $code) ? $slice : $timeslice;
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+ }
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+
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+ return $timeslice > 0;
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+ }
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+
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+ /**
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+ * Timing-attack safe comparison of 2 codes (see http://blog.ircmaxell.com/2014/11/its-all-about-time.html)
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+ */
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+ private function codeEquals($safe, $user) {
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+ if (function_exists('hash_equals')) {
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+ return hash_equals($safe, $user);
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+ }
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+ // In general, it's not possible to prevent length leaks. So it's OK to leak the length. The important part is that
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+ // we don't leak information about the difference of the two strings.
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+ if (strlen($safe)===strlen($user)) {
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+ $result = 0;
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+ for ($i = 0; $i < strlen($safe); $i++)
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+ $result |= (ord($safe[$i]) ^ ord($user[$i]));
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+ return $result === 0;
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+ }
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+ return false;
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+ }
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+
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+ /**
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+ * Get data-uri of QRCode
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+ */
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+ public function getQRCodeImageAsDataUri($label, $secret, $size = 200)
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+ {
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+ if (!is_int($size) || $size <= 0)
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+ throw new TwoFactorAuthException('Size must be int > 0');
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+
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+ $qrcodeprovider = $this->getQrCodeProvider();
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+ return 'data:'
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+ . $qrcodeprovider->getMimeType()
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+ . ';base64,'
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+ . base64_encode($qrcodeprovider->getQRCodeImage($this->getQRText($label, $secret), $size));
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+ }
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+
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+ /**
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+ * Compare default timeprovider with specified timeproviders and ensure the time is within the specified number of seconds (leniency)
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+ */
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+ public function ensureCorrectTime(array $timeproviders = null, $leniency = 5)
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+ {
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+ if ($timeproviders != null && !is_array($timeproviders))
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+ throw new TwoFactorAuthException('No timeproviders specified');
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+
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+ if ($timeproviders == null)
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+ $timeproviders = array(
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+ new Providers\Time\NTPTimeProvider(),
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+ new Providers\Time\HttpTimeProvider()
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+ );
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+
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+ // Get default time provider
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+ $timeprovider = $this->getTimeProvider();
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+
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+ // Iterate specified time providers
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+ foreach ($timeproviders as $t) {
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+ if (!($t instanceof ITimeProvider))
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+ throw new TwoFactorAuthException('Object does not implement ITimeProvider');
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+
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+ // Get time from default time provider and compare to specific time provider and throw if time difference is more than specified number of seconds leniency
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+ if (abs($timeprovider->getTime() - $t->getTime()) > $leniency)
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+ throw new TwoFactorAuthException(sprintf('Time for timeprovider is off by more than %d seconds when compared to %s', $leniency, get_class($t)));
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+ }
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+ }
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+
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+ private function getTime($time)
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+ {
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+ return ($time === null) ? $this->getTimeProvider()->getTime() : $time;
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+ }
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+
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+ private function getTimeSlice($time = null, $offset = 0)
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+ {
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+ return (int)floor($time / $this->period) + ($offset * $this->period);
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+ }
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+
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+ /**
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+ * Builds a string to be encoded in a QR code
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+ */
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+ public function getQRText($label, $secret)
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+ {
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+ return 'otpauth://totp/' . rawurlencode($label)
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+ . '?secret=' . rawurlencode($secret)
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+ . '&issuer=' . rawurlencode($this->issuer)
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+ . '&period=' . intval($this->period)
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+ . '&algorithm=' . rawurlencode(strtoupper($this->algorithm))
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+ . '&digits=' . intval($this->digits);
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+ }
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+
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+ private function base32Decode($value)
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+ {
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+ if (strlen($value)==0) return '';
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+
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+ if (preg_match('/[^'.preg_quote(self::$_base32dict).']/', $value) !== 0)
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+ throw new TwoFactorAuthException('Invalid base32 string');
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+
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+ $buffer = '';
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+ foreach (str_split($value) as $char)
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+ {
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+ if ($char !== '=')
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+ $buffer .= str_pad(decbin(self::$_base32lookup[$char]), 5, 0, STR_PAD_LEFT);
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+ }
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+ $length = strlen($buffer);
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+ $blocks = trim(chunk_split(substr($buffer, 0, $length - ($length % 8)), 8, ' '));
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+
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+ $output = '';
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+ foreach (explode(' ', $blocks) as $block)
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+ $output .= chr(bindec(str_pad($block, 8, 0, STR_PAD_RIGHT)));
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+ return $output;
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+ }
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+
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+ /**
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+ * @return IQRCodeProvider
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+ * @throws TwoFactorAuthException
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+ */
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+ public function getQrCodeProvider()
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+ {
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+ // Set default QR Code provider if none was specified
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+ if (null === $this->qrcodeprovider) {
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+ return $this->qrcodeprovider = new Providers\Qr\GoogleQRCodeProvider();
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+ }
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+ return $this->qrcodeprovider;
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+ }
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+
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+ /**
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+ * @return IRNGProvider
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+ * @throws TwoFactorAuthException
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+ */
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+ public function getRngprovider()
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+ {
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+ if (null !== $this->rngprovider) {
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+ return $this->rngprovider;
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+ }
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+ if (function_exists('random_bytes')) {
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+ return $this->rngprovider = new Providers\Rng\CSRNGProvider();
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+ }
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+ if (function_exists('mcrypt_create_iv')) {
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+ return $this->rngprovider = new Providers\Rng\MCryptRNGProvider();
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+ }
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+ if (function_exists('openssl_random_pseudo_bytes')) {
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+ return $this->rngprovider = new Providers\Rng\OpenSSLRNGProvider();
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+ }
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+ if (function_exists('hash')) {
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+ return $this->rngprovider = new Providers\Rng\HashRNGProvider();
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+ }
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+ throw new TwoFactorAuthException('Unable to find a suited RNGProvider');
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+ }
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+
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+ /**
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+ * @return ITimeProvider
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+ * @throws TwoFactorAuthException
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+ */
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+ public function getTimeProvider()
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+ {
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+ // Set default time provider if none was specified
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+ if (null === $this->timeprovider) {
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+ return $this->timeprovider = new Providers\Time\LocalMachineTimeProvider();
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+ }
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+ return $this->timeprovider;
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+ }
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+}
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