New efficient timed commitment schemes

摘要

A timed commitment is an extension to the standard commitment scheme in which there is a forced-open phase for the verifier to open the committed value even without the help of the committer. The first notion of timed commitment was from Boneh and Naor, based on the hardness of the best-known algorithm for computing g{sup}(2{sup}n) mod N. We use a different approach to design two new schemes. These two schemes are based upon ElGamal encryption and Pubic Verifiable Secret Sharing (PVSS) respectively. Unlike the original scheme, our schemes can be timed precisely, thus easy to be applied in some short-term schemes. We also discuss the implementation of our schemes in contract-signing schemes.