[franzus]

The price for human-solving 1000 captchas is $2. You get ~98% accuracy. There is no secure captcha library.

Captchas as a concept are flawed and should be replaced by something that $works. (Don't ask me what that could be - I have no idea.)

[ElliotH]

Oh, I agree. But I'd argue a working captcha is at least somewhat preferable to a broken poorly made one, even if they can both be trivially mechanically-turked.

Sadly the only solution I can see to the overall 'Captchas are broken' problem that's current available is forcing people to link to an established identity like a Google account or a Facebook account. This then of course recurses to how can you prevent automated Google/Facebook sign ups. I wonder whether Google/Facebook could use some kind of heuristic for detecting genuine users of the service? (maybe a Facebook account that plays games or uploads photos regularly, or has attended a few events could be a threshold?)

[blake8086]

I keep waiting to see them replaced with proofs-of-work.