Blockchain Papers

Joe Kilian, Charles Rackoff, Erez Petrank

No abstract is available for this record.

Hoeteck Wee

No abstract is available for this record.

Zhenfeng Zhang, Dengguo Feng, Jing Xu, Yongbin Zhou

No abstract is available for this record.

Kaoru Kurosawa, Swee‐Huay Heng

Abstract. In undeniable signature schemes, zero-knowledgeness and non-transferability have been identified so far. In this paper, by separating these two notions, we show the first 3-move confirmation and disavowal protocols for Chaum’s undeniable signature scheme which is secure against active and concurrent attacks. Our main observation is that while the signer has one public key and one secret key, there exist two witnesses in the confirmation and disavowal proofs of Chaum’s scheme.

A. Saxena

In this paper, we introduce the concept of additive zero knowledge. Essentially, an additive proof can be considered as a proof system involving many provers and one verifier such that the statements of all the provers are proved simultaneously. Our model of additive proofs is presented using constructions of blind group identification, aggregate signatures and chained signatures. The security of our protocols relies on the difficulty of the underlying Diffie-Hellman problem in bilinear maps. As applications, we present a novel method to prevent spam.

Fagen Li, Juntao Gao, Yupu Hu

No abstract is available for this record.

Giovanni Di Crescenzo

No abstract is available for this record.

Ivan Damgård, Yuval Ishai

We present a constant-round protocol for general secure multiparty computation which makes a black-box use of a pseudorandom generator. In particular, the protocol does not require expensive zero-knowledge proofs and its communication complexity does not depend on the computational complexity of the underlying cryptographic primitive. Our protocol withstands an active, adaptive adversary corrupting a minority of the parties. Previous constant-round protocols of this type were only known in the semi-honest model or for restricted classes of functionlities.

Shafi Goldwasser, Dmitriy Kharchenko

No abstract is available for this record.

Rafael Pass, Abhi Shelat

No abstract is available for this record.

Xavier Boyen, Brent Waters

No abstract is available for this record.

Matt Lepinski, Silvio Micali, Abhi Shelat

No abstract is available for this record.

Daniele Micciancio, Shien Jin Ong, Amit Sahai, Salil Vadhan

Abstract. We provide unconditional constructions of concurrent statistical zero-knowledge proofs for a variety of non-trivial problems (not known to have probabilistic polynomial-time algorithms). The problems include Graph Isomorphism, Graph Nonisomorphism, Quadratic Residuosity, Quadratic Nonresiduosity, a restricted version of Statistical Difference, and approximate versions of the (coNP forms of the) Shortest Vector Problem and Closest Vector Problem in lattices. For some of the problems, such as Graph Isomorphism and Quadratic Residuosity, the proof systems have provers that can be implemented in polynomial time (given an NP witness) and have ~O(log n) rounds, which is known to be essentially optimal for black-box simulation.

Tassos Dimitriou, Dimitris Foteinakis

No abstract is available for this record.

Hongda Li, Bao Li

No abstract is available for this record.

Marius-Cǎlin Silaghi

Mix-nets can be used to shuffle vectors of shared secrets. This operation can be an important building block for solving combinatorial problems where constraints depend on secrets of different participants. A main contribution of this paper is to show how participants in the mix-net can provide Zero-Knowledge proofs to convince each other that they do not tamper with the shuffled secrets, and that inverse permutations are correctly applied at unshu#ing. The approach is related to the proof of knowing an isomorphism between large graphs. We also make a detailed review and comparison with rationales and analysis of Chaum's and Merritt's mix-nets. Another

Jens Groth, Rafail Ostrovsky, Amit Sahai

No abstract is available for this record.

Salil Vadhan

We prove a number of general theorems about CZK, the class of problems possessing computational zero knowledge proofs. Our results are unconditional, in contrast to most previous works on CZK which rely on the assumption that one-way functions exist. We establish several new characterizations of CZK, and use these characterizations to prove results such as: 1) Honest-verifier CZK equals general CZK. 2) Public-coin CZK equals private-coin CZK. 3) CZK is closed under union (and more generally, "monotone formula closure"). 4) CZK with imperfect completeness equals CZK with perfect completeness. 5) Any problem in CZK /spl cap/ NP can be proven in computational zero knowledge by a BPP/sup NP/ prover. 6) CZK with black-box simulators equals CZK with general, non-black-box simulators. The above equalities refer to the resulting class of problems (and do not necessarily preserve other efficiency measures such as round complexity). Our approach is to combine the conditional techniques previously used in the study of CZK with the unconditional techniques developed in the study of SZK, the class of problems possessing statistical zero knowledge proofs. To enable this combination, we prove that every problem in CZK can be decomposed into a problem in SZK together with a set of instances from which a one-way function can be constructed.

Toru Nakanishi, Yuji Sugiyama

Efficient general secure multiparty computation (MPC) protocols were previously proposed, and the combination with the efficient auction circuits achieves the efficient sealed-bid auctions with the full privacy and correctness. However, the combination requires that each bidder submits ciphertexts of bits representing his bid, and their zero-knowledge proofs. This cost amounts to about 80.multi-exponentiations in usual case that the bid size is 20 bits (i.e. about 1,000,000 bid prices). This paper proposes sealed-bid auction protocols based on the efficient MPC protocols, where a bidder can submit only a single ciphertext. The bidder's cost is a few multi-exponentiations, and thus the proposed protocols are suitable for mobile bidders. A novel technique for the realization is a bit-slicing conversion by multiple servers, where a single ciphertext for a bid is securely converted into ciphertexts of bits representing the bid.

Silvio Micali, M. O. Rabin, Joe Kilian

We show how a polynomial-time prover can commit to an arbitrary finite set S of strings so that, later on, he can, for any string x, reveal with a proof whether x /spl isin/ S or x /spl notin/ S, without revealing any knowledge beyond the verity of these membership assertions. Our method is non interactive. Given a public random string, the prover commits to a set by simply posting a short and easily computable message. After that, each time it wants to prove whether a given element is in the set, it simply posts another short and easily computable proof, whose correctness can be verified by any one against the public random string. Our scheme is very efficient; no reasonable prior way to achieve our desiderata existed. Our new primitive immediately extends to providing zero-knowledge databases.

Chunming Tang, Dingyi Pei, Zhuojun Liu

A delegateable signature scheme is a signature scheme where the owner of the signing key(Alice) can securely delegate to another party(Bob) the ability to sign on Alice’s behalf on a restricted subset S of the message space. Barak first defined and constructed this signature scheme using non-interactive zero-knowledge proof of knowledge(NIZKPK)[1]. In his delegateable signature scheme, the function of NIZKPK is to prevent the signing verifier from tell which witness(i.e. restricted subset) is being used. Witness indistinguishable(WI) and witness hiding(WH) proof systems are weaker proof model than zero-knowledge proof and were proposed by Feige and Shamir in [2], however, the verifier cannot also distinguish the witness which is being used in these two protocols. In this paper, we construct delegateable signature scheme using WI and WH proof protocols.

Toru Nakanishi, Daisuke Yamamoto, Yuji Sugiyama

No abstract is available for this record.

Anderson C. A. Nascimento, Joern Mueller-Quade, Akira Otsuka, Goichiro Hanaoka · 5 authors

No abstract is available for this record.

Cynthia Dwork, Ronen Shaltiel, Adam Smith, Luca Trevisan

No abstract is available for this record.