21st Annual IEEE Conference on Computational Complexity (CCC'06)
Parallel Repetition of Zero-Knowledge Proofs and the Possibility of Basing Cryptography on NP-Hardness
Prague, Czech Republic
July 16-July 20
ISBN: 0-7695-2596-2
Two long-standing open problems exist on the fringe of Complexity Theory and Cryptography: 1. Does there exist a reduction from an NP-Complete Problem to a one-way function? 2. Do parallelized versions of classical constant-round zero-knowledge proofs for NP conceal every "hard" bit of the witness to the statement proved? We show that, unless the Polynomial-Hierarchy collapses, black-box reductions cannot be used to provide positive answers to both questions.