Hash

class Bcrypt {
        private $rounds;
        public function __construct($rounds = 12) {
            if(CRYPT_BLOWFISH != 1) {
                throw new Exception("bcrypt not supported in this installation. See http://php.net/crypt");
            }

            $this->rounds = $rounds;
        }

        public function hash($input) {
            $hash = crypt($input, $this->getSalt());

            if(strlen($hash) > 13)
                return $hash;

            return false;
        }

        public function verify($input, $existingHash) {
            $hash = crypt($input, $existingHash);

            return $hash === $existingHash;
        }

        private function getSalt() {
            $salt = sprintf('$2a$%02d$', $this->rounds);

            $bytes = $this->getRandomBytes(16);

            $salt .= $this->encodeBytes($bytes);

            return $salt;
        }

        private $randomState;
        private function getRandomBytes($count) {
            $bytes = '';

            if(function_exists('openssl_random_pseudo_bytes') &&
                (strtoupper(substr(PHP_OS, 0, 3)) !== 'WIN')) { // OpenSSL slow on Win
                $bytes = openssl_random_pseudo_bytes($count);
            }

            if($bytes === '' && is_readable('/dev/urandom') &&
                ($hRand = @fopen('/dev/urandom', 'rb')) !== FALSE) {
                $bytes = fread($hRand, $count);
                fclose($hRand);
            }

            if(strlen($bytes) < $count) {
                $bytes = '';

                if($this->randomState === null) {
                    $this->randomState = microtime();
                    if(function_exists('getmypid')) {
                        $this->randomState .= getmypid();
                    }
                }

                for($i = 0; $i < $count; $i += 16) {
                    $this->randomState = md5(microtime() . $this->randomState);

                    if (PHP_VERSION >= '5') {
                        $bytes .= md5($this->randomState, true);
                    } else {
                        $bytes .= pack('H*', md5($this->randomState));
                    }
                }

                $bytes = substr($bytes, 0, $count);
            }

            return $bytes;
        }

        private function encodeBytes($input) {
            // The following is code from the PHP Password Hashing Framework
            $itoa64 = './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';

            $output = '';
            $i = 0;
            do {
                $c1 = ord($input[$i++]);
                $output .= $itoa64[$c1 >> 2];
                $c1 = ($c1 & 0x03) << 4;
                if ($i >= 16) {
                    $output .= $itoa64[$c1];
                    break;
                }

                $c2 = ord($input[$i++]);
                $c1 |= $c2 >> 4;
                $output .= $itoa64[$c1];
                $c1 = ($c2 & 0x0f) << 2;

                $c2 = ord($input[$i++]);
                $c1 |= $c2 >> 6;
                $output .= $itoa64[$c1];
                $output .= $itoa64[$c2 & 0x3f];
            } while (1);

            return $output;
        }


    }