
Metadata: An Invisible CAPTCHA - nreece
http://www.forbes.com/security/2008/11/25/captcha-pramana-bots-tech-identity08-cx_ag_1125captcha.html
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pedalpete
Though it's an interesting concept, I think they would need to recreate their
algorithms too quickly to stop spammers, plus recaptcha has a dual
purpose/benefit of helping computers when they fail with OCR. I don't hate
captcha as long as it is done well.

