Spam problem - ensure human makes comment?

[FretNoMore]

Hi!

I have just been attacked by spammers making what must be automated comments.
For the time being I've disabled comments for the guest group but I'd like to allow
that again if possible.

Has someone implemented something like having to read and enter a random generated
confirmation code to at least ensure a human is making the comment? (At least I would
then not have to deal with huge numbers of computer-entered spam).

Thanks,
Anders

[Nibbler]

http://coppermine-gallery.com/forum/index.php?topic=29564.0

[FretNoMore]

Thanks!!!