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5,430 results · page 220 of 227
Elli Androulaki, Binh Vo, Steven M. Bellovin
No abstract is available for this record.
Bogdan Cărbunar, Radu Sion
No abstract is available for this record.
Keita Emura, Atsuko Miyaji, Mohammad Shahriar Rahman
No abstract is available for this record.
Michael Backes, Stefan Lorenz, Matteo Maffei, Kim Pecina
No abstract is available for this record.
Ryan Henry, Kevin Henry, Ian Goldberg
No abstract is available for this record.
Ivan Damgård, Claudio Orlandi
Multiparty computation protocols have been known for more than twenty years now, but due to their lack of efficiency their use is still limited in real-world applications: the goal of this paper is the design of efficient two and multi party computation protocols aimed to fill the gap between theory and practice. We propose a new protocol to securely evaluate reactive arithmetic circuits, that offers security against an active adversary in the universally composable security framework. Instead of the “do-and-compile” approach (where the parties use zero-knowledge proofs to show that they are following the protocol) our key ingredient is an efficient version of the “cut-and-choose” technique, that allow us to achieve active security for just a (small) constant amount of work more than for passive security.
Sherman S. M. Chow, Changshe Ma, Jian Weng
No abstract is available for this record.
Steven Gordon, Hoeteck Wee, David Xiao, Arkady Yerukhimovich
No abstract is available for this record.
Benoît Libert, Moti Yung
No abstract is available for this record.
Joseph Y. Halpern, Rafael Pass, Vasumathi Raman
Halpern, Moses and Tuttle presented a definition of interactive proofs using a notion they called practical knowledge, but left open the question of finding an epistemic formula that completely characterizes zero knowledge; that is, a formula that holds iff a proof is zero knowledge. We present such a formula, and show that it does characterize zero knowledge. Moreover, we show that variants of the formula characterize variants of zero knowledge such as concurrent zero knowledge [Dwork, Naor, and Sahai 2004] and proofs of knowledge [Feige, Fiat, and Shamir 1987; Tompa and Woll 1987].
Iftach Haitner, Omer Reingold, Salil Vadhan, Hoeteck Wee
We put forth a new computational notion of entropy, which measures the (in)feasibility of sampling high entropy strings that are consistent with a given protocol. Specifically, we say that the i'th round of a protocol (A,B) has *accessible entropy* at most k, if no polynomial-time strategy A* can generate messages for A such that the entropy of its message in the i'th round has entropy greater than k when conditioned both on prior messages of the protocol and on prior coin tosses of A*. We say that the protocol has *inaccessible entropy* if the total accessible entropy (summed over the rounds) is noticeably smaller than the real entropy of A's messages, conditioned only on prior messages (but not the coin tosses of A). As applications of this notion, we -- Give a much simpler and more efficient construction of statistically hiding commitment schemes from arbitrary one-way functions. -- Prove that constant-round statistically hiding commitments are necessary for constructing constant-round zero-knowledge proof systems for NP that remain secure under parallel composition (assuming the existence of one-way functions).
Puwen Wei, Guoyan Zhang, Lijiang Zhang, Xiaoyun Wang
This paper shows that the protocol presented by Goyal et al. can be further simplified for a one-way function, with the simplified protocol being more practical for the decisional Diffie-Hellman assumption. Goyal et al. provided a general transformation from any honest verifier statistical zero-knowledge argument to a concurrent statistical zero-knowledge argument. Their transformation relies only on the existence of one-way functions. For the simplified transformation, the witness indistinguishable proof of knowledge protocols in “parallel” not only plays the role of preamble but also removes some computational zero-knowledge proofs, which Goyal et al. used to prove the existence of the valid openings to the commitments. Therefore, although some computational zero-knowledge proofs are replaced with a weaker notion, the witness indistinguishable protocol, the proof of soundness can still go through.
Jianwei Ye, Xu-lu Jiao, Yuge Zhang
Based on the verifiable encryption and zero-knowledge proof protocols of Jarecki and Shmatikov and Pedersen’s verifiable threshold secret sharing scheme, this paper proposes a new full fair secure two-party computation protocols. For getting full fair, the new protocol employs a group of third-party servers. We prove that when more than two-thirds of the third-party servers are honest, the new protocol guarantees that two parties can get their correct outputs full fairly. In the new protocol, the computation is performed in the form of garbled circuit, and only two added interaction rounds are needed for full fairness.
Yingpeng Sang, Hong Shen, Hui Tian
We address the problems of privacy-preserving duplicate tuple matching (PPDTM) and privacy-preserving threshold attributes matching (PPTAM) in the scenario of a horizontally partitioned database among N parties, where each party holds a private share of the database's tuples and all tuples have the same set of attributes. In PPDTM, each party determines whether its tuples have any duplicate on other parties' private databases. In PPTAM, each party determines whether all attribute values of each tuple appear at least a threshold number of times in the attribute unions. We propose protocols for the two problems using additive homomorphic cryptosystem based on the subgroup membership assumption, e.g., Paillier's and ElGamal's schemes. By analysis on the total numbers of modular exponentiations, modular multiplications and communication bits, with a reduced computation cost which dominates the total cost, by trading off communication cost, our PPDTM protocol for the semihonest model is superior to the solution derivable from existing techniques in total cost. Our PPTAM protocol is superior in both computation and communication costs. The efficiency improvements are achieved mainly by using random numbers instead of random polynomials as existing techniques for perturbation, without causing successful attacks by polynomial interpolations. We also give detailed constructions on the required zero-knowledge proofs and extend our two protocols to the malicious model, which were previously unknown.
Guifang Huang, Dongdai Lin, Yanshuo Zhang
No abstract is available for this record.
Huafei Zhu, Feng Bao
No abstract is available for this record.
Zongyang Zhang, Zhenfu Cao, Rong Ma
No abstract is available for this record.
Shlomi Dolev, Marina Kopeetsky
No abstract is available for this record.
Matt Smart, Eike Ritter
No abstract is available for this record.
Man Ho Au
Digital signatures are fundamental cryptographic primitives. They are useful as a stand-alone application and building blocks of complex cryptographic systems. Accumulators are another useful cryptographic primitive which provide a way to combine a set of values into one short value. They are useful in improving efficiency of cryptographic systems. In particular, these two primitives are key components in privacy-preserving cryptographic systems. In this thesis, we study the use of digital signatures and accumulators in cryptographic applications. We design digital signature schemes and accumulators with different features that are suitable for a wide range of applications. We are interested in privacy-preserving cryptographic applications including anonymous electronic cash systems, anonymous authentication schemes and anonymous credential systems. We construct three different digital signature schemes, each with distinctive features. We also propose two novel constructions of accumulators. Based on our signature schemes and accumulators, we design two compact electronic cash schemes and a divisible electronic cash scheme. All our schemes are truly anonymous, meaning that privacy of the users is well-protected. We also explore other applications of our newly proposed signatures and accumulators. Specifically, we give a construction of k-times anonymous authentication schemes and attribute-based anonymous credential systems. During the course of the development of the thesis, we generalise existing techniques of zero-knowledge proof-of-knowledge protocol of double-discrete logarithms into zero-knowledge proof-of-knowledge protocol of representation of a committed value. Our protocol is compatible with existing zero-knowledge proof-of-knowledge protocols that demonstrate relationship amongst discrete logarithms. We believe that this protocol, together with the newly introduced primitives, are of independent interest.
Iftach Haitner, Alon Rosen, Ronen Shaltiel
No abstract is available for this record.
Ying Qiu, Huafei Zhu
This paper studies mobile devices mediated electronic voting system based on the distributed Pailler's encryptions; We apply the standard cut-of-the-choose technique to avoid the computational zero-knowledge proofs and show that the proposed scheme is efficient yet somewhat provably secure in the simulation-based paradigm.
Rafael Dowsley, Jörn Müller‐Quade, Akira Otsuka, Goichiro Hanaoka · 6 authors
Abstract. This paper presents a non-interactive verifiable secret sharing scheme (VSS) tolerating a dishonest majority based on data predistributed by a trusted authority. As an application of this VSS scheme we present very efficient unconditionally secure multiparty protocols based on pre-distributed data which generalize two-party computations based on linear pre-distributed bit commitments. The main results of this paper are a non-interactive VSS where the amount of data which needs to be pre-distributed to each player depends on the number of tolerable cheaters only, a simplified multiplication protocol for shared values based on pre-distributed random products, and non-interactive zero knowledge proofs for arbitrary polynomial relations. The security of the schemes are proved using the UC framework.
Chunming Tang, Zheng‐an Yao
Multi-prover zero-knowledge proof is an interesting proof in which a few provers synchronously prove validity of a statement to an verifier, however, the verifier will learn nothing beyond the fact that the statement is correct. We call multi-prover zero-knowledge proof as multi-prover zero-knowledge arguments if all provers are probabilistic polynomial-time participants. In this paper, we give the formal definition of multi-prover zero-knowledge argument and construct it based on discrete logarithm problem (DLP).