>>16: Perhaps do not parse all lines that begin with a space (and display them in monospaced font as well)? I believe Wikipedia does something similar to that.

>>14: I hate you. :P Good work. Using "chr" never occurred to me. One anomaly that I'm finding with that method is that the base 64 string always ends with "==" for some reason, but that's not much of an issue since we're only using the first eight characters of it anyway. Thank you.

$stuff=explode("#",$_GET['tc']);

...

$s=$secret.$stuff[2];
$x = md5($s);
for($i=0;$i<32;$i+=2) {
$a = hexdec(substr($x,$i,2));
$bin .= chr($a);
}
$x = base64_encode($bin);

$y=exec('perl -e \'use Digest::MD5 qw(md5_base64);print md5_base64("'.$secret.$stuff[2].'");\'');

echo $x." ".$y;

x8B08Fuu76D3Edrp1uMPwQ== x8B08Fuu76D3Edrp1uMPwQ