Verschlüsselungsalgorithmus

<form action="<? $_SERVER['PHP_SELF'];?>" method="post">
	<input type="radio" name="crypt" value="caesar" id="caesar" checked="checked"/><label for="caesar">C&auml;sar</label>
	<input type="radio" name="crypt" value="rot13" id="rot13"/><label for="rot13">ROT-13</label>



	<input type="text" name="text" />
	<input type="submit" name="submit" value="Verschl&uuml;sseln" />
</form>
<?
function caesar($string)
	{
	$string = str_replace(" ", "", $string);
	$string = strtolower($string);
	$key = 3;
	$array = array();
	$i = 0;
	for ($i; $i<strlen($string); $i++)
		$array[] = substr($string, $i, 1);
	foreach ($array as $char) 
		{
		$ordchar = ord($char);
		$ordchar += $key;
		if ($ordchar >= 122)
			$ordchar -= 26;		
		$char = chr($ordchar);
		echo $char;
		}
	}
function rot13($string)
	{
	$string = str_replace(" ", "", $string);
	$string = strtolower($string);
	$key = 13;
	$i = 0;
	$array = array();
	for ($i; $i<strlen($string); $i++)
		$array[] = substr($string, $i, 1);
	foreach ($array as $char) 
		{
		$ordchar = ord($char);
		$ordchar += $key;
		if ($ordchar >= 122)
			$ordchar -= 26;		
		$char = chr($ordchar);
		echo $char;
		}
	}


if (isset($_POST['submit']))
	echo $_POST['crypt']($_POST['text']);
?>