Using a Turing test (CAPTCHA) for example.
http://en.wikipedia.org/wiki/Captcha
There are many well known ways to defeat CAPTCHAs, unfortunately.
It depends on the CAPTCHA you are using and your application.
You may want to take a look at the following talk?
http://www.youtube.com/watch?v=dtFroEJN1nI
I've seen it. Without getting into more details that the IETF list wants
to see, let me just say that having been thinking about the introduction
problem for the better part of a decade, I'm pretty sure I'm not the only
one who thinks that approaches that depend on something like a CAPTCHA to
work don't have much of a long term future.
Regards,
John Levine, johnl@xxxxxxxx, Primary Perpetrator of "The Internet for Dummies",
Information Superhighwayman wanna-be, http://www.johnlevine.com, ex-Mayor
"More Wiener schnitzel, please", said Tom, revealingly.
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