Simpele PHP Scrambler

[code]
<?php
echo '<form method="post">
<textarea cols="100" rows="25" name="txt">';
if(empty($_POST['txt'])){
    echo '<?php echo \'hello world\'; ?>';
}else{
    echo $_POST['txt'];
}
echo '</textarea><br>
<input type="submit" value="Scramble">
</form>';
if($_POST['txt']){
    echo '<br><br><br>';
    echo '<textarea cols="100" rows="25">';
    $input = $_POST['txt'];
    function createrand(){
        $alp = array('48', '49', '50', '51', '52', '53', '54', '55', '56', '57', '65', '66', '67', '68', '69', '70', '71', '72', '73', '74', '75', '76', '77', '78', '79', '80', '81', '82', '83', '84', '85', '86', '87', '88', '89', '90', '97', '98', '99', '100', '101', '102', '103', '104', '105', '106', '107', '108', '109', '110', '111', '112', '113', '114', '115', '116', '117', '118', '119', '120', '121', '122');
        shuffle($alp);
        $encd = '';
        foreach($alp as $value){
            $encd .= chr($value);
        }
        return $encd;
    }
    $input1 = createrand();
    $input2 = createrand();

    echo '<?php
$_F=__FILE__;
$_X=\''.base64_encode('?>'.strtr($input, $input1, $input2).'<?php').'\';
eval(base64_decode(\''.base64_encode('$_X=base64_decode($_X);$_X=strtr($_X,\''.$input2.'\',\''.$input1.'\');$_R=ereg_replace(\'__FILE__\',"\'".$_F."\'",$_X);eval($_R);$_R=0;$_X=0;').'\'));
?>';
    echo '</textarea>';
}
?>[/code]