in reply to Image encryption?
I'd specifically recommend the Captcha::reCAPTCHA module which would give you the captcha functionality you're seeking as well as supporting a worthy project.
Therapy is expensive. Popping bubble wrap is cheap. You choose.
Throwing nuclear weapons into the sun
Making everybody on Earth disappear
A threat from an alien with a mighty robot
A new technology or communications medium
Providing a magic fish to a Miss Universe
Establishing a Group mind
Results (195 votes). Check out past polls.