How to simultaneously exchange secrets by general assumptions

摘要

The simultaneous secret exchange protocol is the key tool for contract signing protocols and certified mail protocols. This paper proposes efficient simultaneous secret exchange protocols (or gradual secret releasing protocols) that are based on general assumptions such as the existence of one-way permutations and one-way functions, while the existing efficient simultaneous secret exchange protocols are based on more constrained assumptions such as specific number theoretic problems and the existence of oblivious transfer primitives (or trap-door one-way permutations). Moreover, while the existing simultaneous secret exchange protocols have an additional requirement that the underlying commit (encryption) function is 'ideal', the above-mentioned 'general assumptions' are provably sufficient for our schemes. Therefore, our protocols are provably secure under the general assumptions. In addition, our protocols are at least as efficient as the existing practical protocols, when efficient one-way permutations and one-way functions are used.