<?
// H.Yeend, puremango.co.uk.
// thanks to Simon Singh for authoring 'the code book',
// which inspired me to write this little app.
$_POST = $HTTP_POST_VARS;
$_SERVER = $HTTP_SERVER_VARS;

// using a randomised square, otherwise, capitals tend to become capitals, numbers to numbers, etc.
$square['a'] = "i$?LOHuhC !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-P";
$square['b'] = "$?LOHuhC !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi";
$square['c'] = "?LOHuhC !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$";
$square['d'] = "LOHuhC !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?";
$square['e'] = "OHuhC !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?L";
$square['f'] = "HuhC !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LO";
$square['g'] = "uhC !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOH";
$square['h'] = "hC !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHu";
$square['i'] = "C !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuh";
$square['j'] = " !ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC";
$square['k'] = "!ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC ";
$square['l'] = "ŁDQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !";
$square['m'] = "DQlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !Ł";
$square['n'] = "Qlsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁD";
$square['o'] = "lsjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQ";
$square['p'] = "sjzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQl";
$square['q'] = "jzt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQls";
$square['r'] = "zt3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsj";
$square['s'] = "t3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsjz";
$square['t'] = "3qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsjzt";
$square['u'] = "qS9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsjzt3";
$square['v'] = "S9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsjzt3q";
$square['w'] = "9,T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsjzt3qS";
$square['x'] = ",T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsjzt3qS9";
$square['y'] = "T74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsjzt3qS9,";
$square['z'] = "74r}v]{MGak>A0V1nBwEmY_[ZN)y%(+ogR=6bc<X2U8eJ.xFpdW5KfI-Pi$?LOHuhC !ŁDQlsjzt3qS9,T";


$result = "";

$_POST['key'] = empty($_POST['key']) ? "Enter Key Here" : $_POST['key'];

if(!empty($_POST['input']))
{
	$text = $_POST['input'];

	// lowercase alphabetic keys only - if anyone feels like modifying it to accept more keys, you know who to send the code to!
	$key = ereg_replace("[^:a-z:]","",strtolower($_POST['key']));

	// encode or decode
	$type = $_POST['type'];

	// how much?
	$len = strlen($text);

	$j=0;
	for($i=0 ; $i<$len ; $i++)
	{
		// grab the next letter of the text
		$key_part = substr($text,$i,1);

		if($j==strlen($key))
		{
			// end of key - start at beginning again
			$j=0;
		}
		if($type=="encode")
		{
			// if the letter is a valid encipherable character
			if(strpos($square['a'],$key_part)!==false)
			{
				// then add the enciphered character to the result
				$result .= substr($square[$key{$j}],strpos($square['a'],$key_part),1);
			} else {
				// else leave as-is.
				$result .= $key_part;
			}
		} else {
			// for decoding, we simply do the opposite of encoding
			if(strpos($square['a'],$key_part)!==false)
			{
				$result .= substr($square['a'],strpos($square[$key{$j}],$key_part),1);
			} else {
				$result .= $key_part;
			}
		}
		$j++;
	}
} else {
	$_POST['input'] = "Enter Text Here";
}
?>
<html>
<head>
	<title>Vigenere Cipher</title>
	<style>
		body{
			background: white;
			color: black;
			font-family: verdana;
			font-size: 10px;
		}
		b{
			font-size: 12px;
		}
	</style>
</head>
<body>
	<form action="<?=$_SERVER['PHP_SELF']?>" method="post">
	<b>Howard's Vignere Cipherer.</b><br />
	<small>Anything other than [abcdefghijklmnopqrstuvwxyz (space)!?$Ł%()-=+_[]{}&lt;&gt;,.ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789] will not be enciphered.</small>
	<table align="center">
	<tr>
		<td align="center">
			Key: <input type="text" name="key" value="<?=$_POST['key']?>">
		</td>
	</tr>
	<tr>
		<td align="center">
			<textarea name="input" cols="50" rows="6" wrap="physical"><?=stripslashes($_POST['input'])?></textarea><br />
		</td>
	</tr>
	<tr>
		<td align="center">
			<input type="submit" name="type" value="encode">&nbsp;<input type="submit" name="type" value="decode">
		</td>
	</tr>
	<tr>
		<td align="center">
			<textarea name="output" cols="50" rows="6" wrap="physical"><?=stripslashes($result)?></textarea>
		</td>
	</tr>
	</table>
	</form>
</body>
</html>