Re: zero-knowledge proof of elgamal

From: Alex Kronberg (alex_kronberg_nospam_at_web.de)
Date: 07/17/05 

Date: Sun, 17 Jul 2005 03:43:55 +0200

Alex Kronberg wrote:
> Hi group,
>
> I have a short question:
> Let p be a prime. Given the values: W=g^m mod p and c=(a,b)=(g^r,g^a*m)
> (so c is an elgamal encryption of m), then is it possible to proof
> efficiently in zero-knowledge:
> The exponent of g in W equals the plaintext of c?
>
> Thanks in advance,
> Alex
Hi,

it's a bit late ;) and I did a small mistake with the elgamal
encryption; c has to be:
c= (a,b)=(g^r,g^{kr}*m), where k is the secret key.

Bye,
Alex