Re: My solution to chess grandmaster problem in zero knowledge proofs of identity.

From: Vladimir Shabanov (virl_at_mail.ru)
Date: 02/27/05 

Date: 27 Feb 2005 11:26:57 -0800

Maybe I don't understanded grandmaster problem.
My protocol is intended to be against "mafia fraud" attacks.

> Step 2 is useless from the standpoint of authentication

No, I think it doesn't.

> Bob does not "restore" the unsigned message--he verifies
> that the signature could only have been
> computed by someone holding Alice's private key(s).

Yes, of course.

> When he decrypts Q using his private key, of course
> it's going to be what he sent since it was encrypted
> with his own public key.
> In other words, anyone could have encrypted it.

But Bob, thanks to this protocol, in result gets knowledge of two
things:
1) That other side knows private key that corresponds to public key
this side sended to Bob.
2) That other side is not mafiosi (who just redirects Alice's answers).

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