- substr: documentation ( source)
- chr: documentation ( source)
- utf8_encode: documentation ( source)
- ord: documentation ( source)
<?php
$str = '4556494730120644';
$sKey = '8519293193919192153';
$s = '';
$j = 0;
for($i=0;$i < strlen($str);$i++)
{
$s .= chr( ord(substr($str,$i,1)) + ord(substr($sKey,$j++,1)));
if($j==strlen($sKey))
$j=0;
}
;
echo $s;
echo "\n";
echo utf8_encode($s);