It's called captcha.

Yes, you can do it in Perl. As for how they know which captcha they sent you, they probably set a cookie with a session ID, and then keep track of which captcha goes with which session. Sending the data about the captcha with the form would be a very bad idea. It would defeat the whole purpose.

Look at CGI::Session to see how to do session management without sending all the data to the client's browser.

In reply to Re: Adding Imagewords for security by matija
in thread Adding Imagewords for security by ukndoit

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