Re: reCaptcha secret key - where is the point?

[Harry Strongburg <harry.fd () harry lu>]

On Sat, Sep 04, 2010 at 11:38:38PM +0200, BlackHawk wrote:
> Reading here & there i found lot of people scared about they "secret
> key" of reCaptcha coud be publically discovered;
> But, at this moment, is kind of useless for an attacker, right? or at
> least until we find out how the reCaptcha response is calculated..

It just adds more "trust" between the site running the CAPTCHA and 
Google. It's sent in plaintext to the reCAPTCHA server, anyways.

Quoting reCAPTCHA Supprt 
(http://groups.google.com/group/recaptcha/msg/bd79e6a0efadad51):
> The security of reCAPTCHA does not rely on the private key staying 
> private. We mostly do this to discourage the sharing of accounts. 
> Please note that we use the referrer to prevent people from hosting 
> your key on their site.

So as far as I can tell, Google/reCAPTCHA only require you get a private 
key to "lock you in" to it. According to that post, there's no major 
risk if someone else has your private key, but it should stay - as the 
name implies - "private".

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