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Anti-MitM TLSCAPTCHA (PoC)

Every time when you solve CAPTCHA, the CAPTCHA answer can be used as a common secret for a short time. Mainly, It can be used to prevent TLS certificate spoofing.

Since ordinary web pages (and their JavaScript) doesn't have access to TLS certificate data, I was have to make this extension. Actually it does the following:

let clientsideDigest = <Digest of TLS certificate that you get from website you're visiting>;
let yourAnswer = <Your CAPTCHA answer>;
let resultDigest = sha512(clientsideDigest + yourAnswer);
cookies["TLSCaptcha"] = representAsHexString(resultDigest);

To see it in action, you need to visit a website that have server-side implementation of this scheme.
At the moment of publishing this extension, there is no server-side implementations. If you want to make your own, please look into source code for details. It's very simple to understand.
See also: http://s01.geekpic.net/di-PKWLII.png

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