A discrete logarithm blob for noninteractive XOR gates

We present a bit commitment scheme based on discrete logarithms. Unlike earlier discrete log based schemes, our system allows non-interactive XORing and negation of bits contained in commitments. When used as a building block in zero-knowledge protocols, our scheme leads to protocols that are statistical (almost perfect) zero-knowledge, and where the prover is unable to break the system, unless he can find a secret discrete logarithm.