Actually this isn't going to work, because rsa.pl relies on perl being executed with the -s switch, so if you execute the script like this perl never gets the -s switch. Either do

    % perl -s rsa.pl ...
[download]

Or make rsa.pl executable and run it like

    % ./rsa.pl ...
[download]

BTW, w/r/t to a "real" implementation of RSA: I think this'd be a great thing and I know that I've not really found much, so I think I'm going to do some work on this.