

CAPTCHA Arbitrage - xel02
http://bit-player.org/2010/captcha-arbitrage?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+bit-player+(Bit-Player)

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bartman
"In an attempt to learn where the solvers live, Savage et al. sent out
specially fabricated CAPTCHAs with images of words in various languages. [..]
But one organization showed exceptional linguistic versatility, even solving
challenges in Klingon."

This is a rather surprising finding.

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dkarl
I came here to post the same. Has someone written an algorithm than can
recognize an alphabet and solve any CAPTCHA based on an alphabet it knows
(maybe all of Unicode)? Good god....

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trotsky
They were trying to measure the worker's native language by assuming error
rates would go down. One provider had low error rates across the board - the
easiest explanation for this is a different incentive system that promoted low
error rates, likely at the expense of speed. I'd guess this was one of the
expensive service providers, and is how they try to differentiate themselves
in the market.

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dkarl
Wouldn't they throw aside a Klingon sample rather than spend time trying to
decipher it? CAPTCHAs are supposed to expire after a minute or two.

I'm assuming the Klingon was written in the Klingon alphabet, though, which
(as I realized after reading Tycho's post) could be wrong. If it was written
in the Latin alphabet, then a person could easily have solved it letter-by-
letter in a few seconds.

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trotsky
Yeah. I was assuming it was in a latin alphabet but I was wrong. I just read
the paper, it was in a klingon alphabet, so essentially arbitrary symbols. So
my guess was wrong, it's difficult to see an explanation here that makes any
financial sense. Apparently they concluded that they were other researchers? I
suppose you could imagine the results in some sort of auction system that
ended up paying a lot (more than they were making) for problems no one else
was willing to solve. But that doesn't seem too likely.

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Xuzz

        This last caveat leads to an interesting economic question. As noted above, retail prices for CAPTCHA-
        solving vary over a wide range, from about $1 per thousand to $20 per thousand. This price spread, and 
        the fact that it’s technically feasible to route a CAPTCHA through the system more than once, suggests a
        major arbitrage opportunity. We can set up a high-price CAPTCHA service and farm out all the actual work to
        low-price competitors. In a free economy—and what economy could be freer of regulation than a criminal
        one?—that situation is not supposed to endure.
    

Well, at least until they add CAPTCHAs.

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adamtmca
"This last caveat leads to an interesting economic question. As noted above,
retail prices for CAPTCHA-solving vary over a wide range, from about $1 per
thousand to $20 per thousand. This price spread, and the fact that it’s
technically feasible to route a CAPTCHA through the system more than once,
suggests a major arbitrage opportunity. We can set up a high-price CAPTCHA
service and farm out all the actual work to low-price competitors. In a free
economy—and what economy could be freer of regulation than a criminal
one?—that situation is not supposed to endure."

Finack's comment on the original post was worth noting here: Arbitrage has far
more to do with information transparency than the free-ness of the economy, as
such arbitrage is pretty common in criminal economies where prices aren't
public information.

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willscott
I went to a speech by savage earlier this fall. The point that I took away
from it is that what captchas do is filter out the bad guys who haven't
figured out a business model.

On the klingon point: They theorized that the particular organization was a
bunch of PHDs rather than farmed labor - and that it had learned from previous
'example answers' they had submitted. That particular organization, it was
noted, was also an order of magnitude more expensive than the others.

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gwern
But... why is an organization of PhDs solving CAPTCHAs? Even if they are the
most expensive service, it still seems to offer terrible hourly returns. That
only raises the mystery.

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aristus
An organization of PhDs writing software that solves captchas.

