php的一个简单加密解密代码

class SysCrypt{
private $crypt_key='//www.52php.cn';//密钥
public function __construct($crypt_key){
$this->crypt_key=$crypt_key;
}
public function encrypt($txt){
srand((double)microtime()*1000000);
$encrypt_key=md5(rand(0,32000));
$ctr=0;
$tmp='';
for($i=0;$i$ctr=$ctr==strlen($encrypt_key)?0:$ctr;
$tmp.=$encrypt_key[$ctr].($txt[$i]^$encrypt_key[$ctr++]);
}
return base64_encode(self::__key($tmp,$this->crypt_key));
}
public function decrypt($txt){
$txt=self::__key(base64_decode($txt),$this->crypt_key);
$tmp='';
for($i=0;$i$md5=$txt[$i];
$tmp.=$txt[++$i]^$md5;
}
return $tmp;
}
private function __key($txt,$encrypt_key){
$encrypt_key=md5($encrypt_key);
$ctr=0;
$tmp='';
for($i=0;$i$ctr=$ctr==strlen($encrypt_key)?0:$ctr;
$tmp.=$txt[$i]^$encrypt_key[$ctr++];
}
return $tmp;
}
public function __destruct(){
$this->crypt_key=NULL;
}
}

$sc=new SysCrypt('//www.52php.cn');
$text='yhm.1234@163.com';
$test1=$sc->encrypt($text);
echo '原文：',$text;
echo '
';
echo '密文：',$test1;
echo "
";
echo '解密：',$sc->decrypt($test1);