MyCrypt.php

<?php

/**
 * User: AeolusAres
 * Date: 2015/9/25
 * Time: 19:30
 */
class MyCrypt {

    var $key = "pass";

    function __construct($key) {
        if($key!=""){
            $this->key = $key;
        }
    }

    function encrypt($data) {
        $key = md5($this->key);
        $x = 0;
        $len = strlen($data);
        $l = strlen($key);
        $char = "";
        $str = "";
        for ($i = 0; $i < $len; $i++) {
            if ($x == $l) {
                $x = 0;
            }
            $char .= $key{$x};
            $x++;
        }
        for ($i = 0; $i < $len; $i++) {
            $str .= chr(ord($data{$i}) + (ord($char{$i})) % 256);
        }
        return base64_encode($str);
    }

    function decrypt($data) {
        $char = "";
        $str = "";
        $key = md5($this->key);
        $x = 0;
        $data = base64_decode($data);
        $len = strlen($data);
        $l = strlen($key);
        for ($i = 0; $i < $len; $i++) {
            if ($x == $l) {
                $x = 0;
            }
            $char .= substr($key, $x, 1);
            $x++;
        }
        for ($i = 0; $i < $len; $i++) {
            if (ord(substr($data, $i, 1)) < ord(substr($char, $i, 1))) {
                $str .= chr((ord(substr($data, $i, 1)) + 256) - ord(substr($char, $i, 1)));
            } else {
                $str .= chr(ord(substr($data, $i, 1)) - ord(substr($char, $i, 1)));
            }
        }
        return $str;
    }


}