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

From: Vladimir Shabanov (virl_at_mail.ru)
Date: 02/28/05 

Date: 28 Feb 2005 07:43:14 -0800

> Would you please
> explain how encrypting a public token with a public key
> conveys any authenticating information about the entity
> doing the encrypting?

In my protocol it prevents Bob from just relaying Alice's answers
to Dave (because Dave will see that challenge response is encrypted not
to him).

> We do not agree Bob knows that Alice
> signed the encrypted token.

Then I see no way how this problem can be solved,
because Alice's private key is Alice _itself_.

Anyway, I'm newbie to cryptography. So, can you
recommend any literature (in electronic form)
on subject?

> Think about this more elaborate protocol

Yes, it is better, but using symmetric cipher
for perfomance is just implementation detail.

It is good idea to place "for Alice" mark on
Bob's challenge, but I think it is not neccessary: if
Alice know Bob's real public key (as so in
internet shops protected by SSL), her challenge
response is no use for eavesdropper.

> This doesn't guarantee that fifteen minutes later, the mafia
> doesn't kidnap Alice and grab the keys.

I see no way preventing this by cryptography.

P.S. Sorry for my English.

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