PUBLIC-RANDOMNESS IN PUBLIC-KEY CRYPTOGRAPHY

In this work we investigate the power of Public Randomness in the context of Public-key cryptosystems. We consider the Diffie-Hellman Public-key model in which an additional short random string is shared by all users. This, which we call Public-Key Public-Randomness (PKPR) model, is very powerful as we show that it supports simple non-interactive implementations of important cryptographic primitives. We give the first completely non-interactive implementation of Oblivious Transfer. Our implementation is also secure against receivers with unlimited computational power. We propose the first implementation of non-interactive nature for Perfect Zero-Knowledge in the dual model of Brassard, Crepeau, and Chaum for all NP-languages.