how to randomize human verfication text

Now, human verfication in advance guestbook,it's good but it's will be better if the human verfication using random text.So, it's will be more secure.
Can't all of you update this?

Somebody did mod my mod to make it randomised. If you do a search of the forum you should find the relevant post although most people have reported a 99% drop in spam just using it as it is.

Or you could use the mod posted there : http://proxy2.de/forum/viewtopic.php?t=5057&postdays=0&postorder=asc&start=0

It also protects comments from beeing spamed.