The round complexity of commitment schemes secure against man-in-the-middle attacks has been the focus of extensive research for about 25 years. The recent breakthrough of Goyal et al.  showed that 3 rounds are sufficient for (one-left, one-right) non-malleable commitments. This result matches a lower bound of . The state of affairs leaves still open the intriguing problem of constructing 3-round concurrent non-malleable commitment schemes. In this paper we solve the above open problem by showing how to transform any 3-round (one-left one-right) non-malleable commitment scheme (with some extractability property) in a 3-round concurrent nonmalleable commitment scheme. Our transform makes use of complexity leveraging and when instantiated with the construction of  gives a 3-round concurrent non-malleable commitment scheme from one-way permutations secure w.r.t. subexponential-time adversaries. We also show a 3-round arguments of knowledge and a 3-round identification scheme secure against concurrent man-in-the-middle attacks.
|Titolo:||Concurrent non-malleable commitments (and more) in 3 rounds|
|Data di pubblicazione:||2016|
|Appare nelle tipologie:||4.1.2 Proceedings con ISBN|