...
$md5->add('mypass');
...

This doesn't seem to work quite right. The results are:

a029d0df84eb5549c641e04a9ef389e5
977f6d9e19594bd58e68030e029cbb3c

##</code><code>##

perl -e 'print "mypass"' | /sbin/md5

##</code><code>##

a029d0df84eb5549c641e04a9ef389e5