bug in hextToString

It looks like there is a problem in the hexToString function in AES. Replace it with this, and it should be fixed (at least for all the strings I tested):

public function hexToString($hex) {
$str="";
for($i=0; $i<strlen($hex); $i=$i+2 ) {
$str .= chr(hexdec($hex[$i].$hex[$i+1]));
}
return $str;
}

or if you're using php>5.4, just use bin2hex/hex2bin.

Also, in order for decrypted strings to match, sometimes you need to trim the decrypted string; some extra "white" characters get added upon decryption. I've noticed this with other encryption libraries as well.

Last fix. If the last chunk is less than 16 bytes, you need to right pad it with zeros; otherwise you get an unpredictable shift in the hex. Replace the encrypt function with the following to get it to work in AESCipher:

public function encrypt($content, $password) {
$key = $this->_generateKey($password);
$input = str_split($this->_cipher->stringToHex($content), self::BYTE_LIMIT*2);
$output = '';
foreach ($input as $chunk)
{
if(strlen($chunk) < self::BYTE_LIMIT*2)
{
// Pad it on the right with zeros if it's short.
$chunk = str_pad($chunk,self::BYTE_LIMIT*2,'0',STR_PAD_RIGHT);
}
$output .= $this->_cipher->encrypt($chunk, $key);
}
return $this->_cipher->hexToString($output);
}