Php session finger print

Session.php

<?php



class ProtectPage {


    public $check_browser = true;


    public $check_ip_blocks = 0;


    public $secure_word = 'a39ccdef11305d5999dbccddcf4';


    public $regenerate_id = true;

 
 
    public function Open() {
        $_SESSION['fingerPrint'] = $this->_Fingerprint();
        $this->_RegenerateId();
    }


    public function Check() {
        $this->_RegenerateId();
        return (isset($_SESSION['fingerPrint']) && $_SESSION['fingerPrint'] == $this->_Fingerprint());
    }


    public function _Fingerprint() {
        $fingerprint = $this->secure_word;
        if ($this->check_browser) {
            $fingerprint .= $_SERVER['HTTP_USER_AGENT'];
        }
        if ($this->check_ip_blocks) {
            $num_blocks = abs(intval($this->check_ip_blocks));
            if ($num_blocks > 4) {
                $num_blocks = 4;
            }
            list($blocks) = explode('.', $_SERVER['REMOTE_ADDR']);
            for ($i = 0; $i < $num_blocks; $i++) {
                $fingerprint .= $blocks[$i] . '.';
            }
        }
        return md5($fingerprint);
    }


    private function _RegenerateId() {
        if ($this->regenerate_id && function_exists('session_regenerate_id')) {
            if (version_compare(phpversion(), '5.1.0', '>=')) {
                session_regenerate_id(true);
            } else {
                session_regenerate_id();
            }
        }
    }
}