Ancient crypto in php

**Gravecorp** · 01-13-2010

A lot of people might find it useless but its something i made when i first started learning php.
Yes i know the code isn't that good. But i was learning back then.

Its a simple php implementation of a text cipher crypto that was from the time of the romans.

Hence the name of the cipher: Ceasar

How the cipher works is you have the standard alphabet and a number you call the key. For instance you take the number 3 to use that key for the cipher you move every character up the number of spaces in the alphabet table.
a -> d, b -> e, c -> f
And so on.
Its extremely simple source and simple form provided.
A lot of cryptology is based on this simple concept. And with that i don't mean the advanced cryptology(its moved beyond this). But for example the cipher text crypto's and things like base64 encoding.

Code:

<?php
$word = '';
$result = '';
$mod = 0;

if (isset($_POST['word'])) 
{
	$word = $_POST['word'];
	$savedWord = 'value=\''.$_POST['word'].'\'';
}

if (isset($_POST['mod'])) 
{
	$mod = $_POST['mod'];
}

if (isset($_POST['action']) && $_POST['action'] == 'cipher')
{
	$length = strlen($word);
	while($mod > 26)
	{
		$mod = $mod-26;
	}
	for($i=0;$i<$length;$i++) {
		$cclass = ord($word[$i]);
		if($cclass > 64&& $cclass < 91) {
			$cclass = $cclass + $mod;
			if($cclass > 90) {
				$cclass = $cclass-26;
			}
		}elseif($cclass > 96 && $cclass < 123) {
			$cclass = $cclass + $mod;
			if($cclass > 122) {
				$cclass = $cclass-26;
			}
		}elseif($cclass == 32) {
			$cclass = 32;
		}else{
			$cclass = 0;
		}
		$result .= chr($cclass);
	}
}
elseif ($_POST['action'] == 'showall') 
{
	$length = strlen($word);
	while($mod > 26) 
	{
		$mod = $mod-26;
	}
	for($mod=0;$mod<26;$mod++){
		if($mod < 10) {
			$result .= 'Option 0'.$mod.': ';
		}else{
			$result .= 'Option '.$mod.': ';
		}
		for($i=0;$i<$length;$i++) {
			$cclass = ord($word[$i]);
			if($cclass > 64&& $cclass < 91) {
				$cclass = $cclass + $mod;
				if($cclass > 90) {
					$cclass = $cclass-26;
				}
			}elseif($cclass > 96 && $cclass < 123) {
				$cclass = $cclass + $mod;
				if($cclass > 122) {
					$cclass = $cclass-26;
				}
			}elseif($cclass == 32) {
				$cclass = 32;
			}else{
				$cclass = 0;
			}
			$result .= chr($cclass);
		}
		$result .= '<br />';
	}
}
?>

<html>
	<head>
		<title>Simple Ceasar script example</title>
	</head>
	<body>
		<form action='<?PHP echo $PHP_SELF;?>' method='post'>
			<input type='text' name='word' id='word' <?php echo $savedWord; ?> />Text<br />
			<input type='text' name='mod' id='mod' maxlength='3' value='<?php echo $mod; ?>' />Mod = 1-26(+)<br />
			<select name='action' id='action'>
				<option value='cipher'>Ciphertext it!</option>
				<option value='showall'>Show all ciphers possible</option>
			</select>
			<input type='submit' value='ciphertext it!' />
		</form>
		
		<p><?php echo $result; ?></p>
	</body>
</html>

Its that easy. Only supports characters a-z both capital and non capital.