Zamana ve Anahtara Göre Değişken Şifreleme Sınıfı

<?php
class Sifreleyici{
    var $anahtar;
    function Sifreleyici($anahtar){
        $this->anahtar = $anahtar;
        }
    function anahtardegistir($anahtar){
        $this->anahtar = $anahtar;
    }
    function anahtarED($metin) { 
        $sifrele_anahtar = md5($this->anahtar); 
        $ctr=0; 
        $topla = ""; 
        for ($i=0;$i<strlen($metin);$i++) { 
            if ($ctr==strlen($sifrele_anahtar)) $ctr=0; 
            $topla.= substr($metin,$i,1) ^ substr($sifrele_anahtar,$ctr,1); 
            $ctr++; 
        } 
        return $topla; 
    } 
    function sifrele($metin){ 
        srand((double)microtime()*1000000); 
        $sifrele_anahtar = md5(rand(0,32000)); 
        $ctr=0; 
        $topla = ""; 
        for ($i=0;$i<strlen($metin);$i++){ 
            if ($ctr==strlen($sifrele_anahtar)) $ctr=0; 
            $topla.= substr($sifrele_anahtar,$ctr,1) . 
            (substr($metin,$i,1) ^ substr($sifrele_anahtar,$ctr,1)); 
            $ctr++; 
        } 
        return base64_encode($this->anahtarED($topla)); 
    } 
    function coz($metin) { 
        $metin = $this->anahtarED(base64_decode($metin)); 
        $topla = ""; 
        for ($i=0;$i<strlen($metin);$i++){ 
            $md5 = substr($metin,$i,1); 
            $i++; 
            $topla.= (substr($metin,$i,1) ^ $md5); 
        } 
        return $topla; 
    } 
}
$c=new Sifreleyici("asd");
echo $c->sifrele("12345678");
echo $c->coz("VGoJPwM/B2ACNl8+BWhSOQ==");
?>
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

VGoJPwM/B2ACNl8+BWhSOQ==
12345678
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX