International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Bernardo David

Affiliation: Tokyo Institute of Technology, Japan

Publications

Year
Venue
Title
2019
ASIACRYPT
Efficient UC Commitment Extension with Homomorphism for Free (and Applications)
Homomorphic universally composable (UC) commitments allow for the sender to reveal the result of additions and multiplications of values contained in commitments without revealing the values themselves while assuring the receiver of the correctness of such computation on committed values. In this work, we construct essentially optimal additively homomorphic UC commitments from any (not necessarily UC or homomorphic) extractable commitment, while the previous best constructions require oblivious transfer. We obtain amortized linear computational complexity in the length of the input messages and rate 1. Next, we show how to extend our scheme to also obtain multiplicative homomorphism at the cost of asymptotic optimality but retaining low concrete complexity for practical parameters. Moreover, our techniques yield public coin protocols, which are compatible with the Fiat-Shamir heuristic. These results come at the cost of realizing a restricted version of the homomorphic commitment functionality where the sender is allowed to perform any number of commitments and operations on committed messages but is only allowed to perform a single batch opening of a number of commitments. Although this functionality seems restrictive, we show that it can be used as a building block for more efficient instantiations of recent protocols for secure multiparty computation and zero knowledge non-interactive arguments of knowledge.
2018
EUROCRYPT
2017
CRYPTO
2016
CRYPTO
2016
JOFC
2015
EPRINT
2015
EPRINT
2014
EPRINT
2013
PKC
2012
ASIACRYPT

Program Committees

PKC 2018
Asiacrypt 2018