PHP & JS mcrypt decryption not working

Question

I have the following code in Javascript to encrypt a string using a key:

des.js is this: http://www.tero.co.uk/des/code.php

<script src="/js/des.js"></script>
<script>
var key = '12345678';
var message = 'hello world';

var ciph = des(key, message, 1, 0);
ciph = stringToHex(ciph);
console.log("Encrypted Result: " + ciph);
</script> 

Then I send it server side and attempt to decrypt with this PHP code:

$key = '12345678';
$hexa = '0x28dba02eb5f6dd476042daebfa59687a'; /This is the output from Javascript
$string = '';
for ($i=0; $i < strlen($hexa)-1; $i+=2) {
$string .= chr(hexdec($hexa[$i].$hexa[$i+1])); }
echo mcrypt_decrypt(MCRYPT_DES, $key, $string, MCRYPT_MODE_ECB);

Ive tried converting it to utf8, changing encoding, changing the hex decoding, etc, but it always comes out gibberish, sometimes as nonreadable characters, other times as readable but nonsense.

Answer 1

The way to decrypt the string is not working properly, try this:

$key = '12345678';
$hexa = '0x28dba02eb5f6dd476042daebfa59687a'; 

function hexToString ($h) {
  $r = "";
 for ($i= (substr($h, 0, 2)=="0x")?2:0; $i<strlen($h); $i+=2) {$r .= chr (base_convert (substr ($h, $i, 2), 16, 10));}
return $r;
}

echo mcrypt_decrypt(MCRYPT_DES, $key,hexToString('0x28dba02eb5f6dd476042daebfa59687a'), MCRYPT_MODE_ECB);

The output will be: hello world

This way work properly, however, you should search another method to encrypt your data, in your script the key (12345678) and your encrypt method is visible to everyone.