what can be used instead if captcha is insecure?

Question

As far as I read from here, the fact that captchas are not 100% secure.what can be used instead of captcha? As a programmer what do you think? how to solve this issue?

Edit: thanks for all answers.

Answer 1

This is an unsolved problem, and will become more unsolved as time passes. The better the OCR tools get, the smaller the gap between humans and computers, and the harder it will be to tell them apart. Eventually, computers will be indistinguishable from humans, and then the game will be up.

If your server wants to make sure that a human is at the other end of a TCP pipe, there isn't a turing-test in existence that won't eventually be defeated (and there probably never will be one). CAPTCHA is doomed, it's just a matter of how soon.

Of course, that doesn't mean it's all over as far as human authentication is concerned. It just means that automated turing tests, as convenient as they are, won't be an effective way to achieve this for very much longer.

Answer 2

• Captcha involving human reflexion (like calculation, really simple question, and the like).
• Session tokens
• randomly generated hidden input which requires to be null, on the server side generate a random identifier, keep it in a session for a while. If the input is filled and not null, then it might have been filled by a robot, do your users will fill an hidden input ?

I think it really depends on what you are trying to control over the use of captcha.