xarSecGenAuthKey() in contact forms to limit spam?

Hi!

While developing a custom contact function and template and thinking about
an elegant way to fight spam, the idea to use the xarSecGenAuthKey() +
xarSecConfirmAuthKey() convenient pair srtoke me! 

Some spammers keep on posting data to the contact form action URL. Using the
above functions the visitor has to request the contact page before
submitting any
data.

What do you think? Is it safe to use this mechanism for non logged-in users?
Or is it going expose the system to dangers by revealing the hash
generation algorithm?


Thanks in advance!