International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Susumu Kiyoshima

Affiliation: NTT

Publications

Year
Venue
Title
2020
CRYPTO
Round-optimal Black-box Commit-and-prove with Succinct Communication 📺
Susumu Kiyoshima
We give a four-round black-box construction of a commit-and-prove protocol with succinct communication. Our construction is WI and has constant soundness error, and it can be upgraded into a one that is ZK and has negligible soundness error by relying on a round-preserving transformation of Khurana et al. (TCC 2018). Our construction is obtained by combining the MPC-in-the-head technique of Ishai et al. (SICOMP 2009) with the two-round succinct argument of Kalai et al. (STOC 2014), and the main technical novelty lies in the analysis of the soundness---we show that, although the succinct argument of Kalai et al. does not necessarily provide soundness for NP statements, it can be used in the MPC-in-the-head technique for proving the consistency of committed MPC views. Our construction is based on sub-exponentially hard collision-resistant hash functions, two-round PIRs, and two-round OTs.
2019
JOFC
Non-black-box Simulation in the Fully Concurrent Setting, Revisited
Susumu Kiyoshima
We give a new proof of the existence of $$O(n^{\epsilon })$$ O ( n ϵ ) -round public-coin concurrent zero-knowledge arguments for $$\mathcal {NP}$$ NP , where $$\epsilon >0$$ ϵ > 0 is an arbitrary constant. The security is proven in the plain model under the assumption that collision-resistant hash functions exist. The existence of such concurrent zero-knowledge arguments was previously proven by Goyal (STOC’13) in the plain model under the same assumption. In the proof, we use a new variant of the non-black-box simulation technique of Barak (FOCS’01). An important property of our simulation technique is that the simulator runs in a “straight-line” manner in the fully concurrent setting. Compared with the simulation technique of Goyal, which also has such a property, the analysis of our simulation technique is (arguably) simpler.
2019
JOFC
Round-Efficient Black-Box Construction of Composable Multi-Party Computation
Susumu Kiyoshima
We present a round-efficient black-box construction of a general multi-party computation (MPC) protocol that satisfies composability in the plain model. The security of our protocol is proven in the angel-based UC framework [Prabhakaran and Sahai, STOC’04] under the minimal assumption of the existence of semi-honest oblivious transfer protocols. The round complexity of our protocol is $$\max (\widetilde{O}(\log ^2n), O(R_{{{{\mathsf {O}}}{{\mathsf {T}}}}}))$$ max ( O ~ ( log 2 n ) , O ( R O T ) ) when the round complexity of the underlying oblivious transfer protocol is $$R_{{{{\mathsf {O}}}{{\mathsf {T}}}}}$$ R O T . Since constant-round semi-honest oblivious transfer protocols can be constructed under standard assumptions (such as the existence of enhanced trapdoor permutations), our result gives a $$\widetilde{O}(\log ^2n)$$ O ~ ( log 2 n ) -round protocol under these assumptions. Previously, only an $$O(\max (n^{\epsilon }, R_{{{{\mathsf {O}}}{{\mathsf {T}}}}}))$$ O ( max ( n ϵ , R O T ) ) -round protocol was shown, where $$\epsilon >0$$ ϵ > 0 is an arbitrary constant. We obtain our MPC protocol by constructing a $$\widetilde{O}(\log ^2n)$$ O ~ ( log 2 n ) -round CCA-secure commitment scheme in a black-box way under the assumption of the existence of one-way functions.
2018
EUROCRYPT
2018
TCC
No-signaling Linear PCPs
Susumu Kiyoshima
In this paper, we give a no-signaling linear probabilistically checkable proof (PCP) system for polynomial-time deterministic computation, i.e., a PCP system for $${\mathcal {P}}$$P such that (1) the PCP oracle is a linear function and (2) the soundness holds against any (computational) no-signaling cheating prover, who is allowed to answer each query according to a distribution that depends on the entire query set in a certain way. To the best of our knowledge, our construction is the first PCP system that satisfies these two properties simultaneously.As an application of our PCP system, we obtain a 2-message scheme for delegating computation by using a known transformation. Compared with existing 2-message delegation schemes based on standard cryptographic assumptions, our scheme requires preprocessing but has a simpler structure and makes use of different (possibly cheaper) standard cryptographic primitives, namely additive/multiplicative homomorphic encryption schemes.
2017
EUROCRYPT
2017
TCC
2016
EUROCRYPT
2015
EPRINT
2015
EPRINT
2015
TCC
2015
CRYPTO
2015
ASIACRYPT
2014
CRYPTO
2014
TCC
2014
EPRINT

Program Committees

Eurocrypt 2020
TCC 2019