These files are part of the phpseclib distribution.
This is a PHP AES implementation. It also works if the PHP
mcrypt extension is not enabled on the server.

See: http://phpseclib.sourceforge.net/

We modified the files a little bit, to be able to distribute the code
with our Spam Hurdles module, without having to install the code globally
on the server and without having to modify the include path in PHP.
See the "// Phorum: ..." comment in the code for the required change.

We also renamed the files to lowercase only, which makes the files more
safe for file transfer (some file transfer agents break filename case).

