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8,503 results · page 267 of 355
Fabrice Benhamouda, Houda Ferradi, RĂ©mi GĂ©raud, David Naccache
No abstract is available for this record.
Wided Boubakri, Walid Abdallah, Noureddine Boudriga
No abstract is available for this record.
Olivier Blazy, CĂ©line Chevalier, Paul Germouty
No abstract is available for this record.
Magnus Gausdal Find, Daniel Smith Tone, Meltem Sönmez Turan
Multiplicative complexity is a complexity measure defined as the minimum number of AND gates required to implement a given primitive by a circuit over the basis (AND, XOR, NOT). Implementations of cyphers with a small number of AND gates are preferred in protocols for fully homomorphic encryption, multiparty computation and zero-knowledge proofs. Fischer and Peralta (2002) computed the number of n-variable Boolean functions with multiplicative complexity 1. In this paper, we study Boolean functions that can be constructed with two AND gates. By characterising the structure of these functions in terms of affine equivalence relations, we provide a closed-form formula for the number of Boolean functions with multiplicative complexity 2.
Meilof Veeningen
Pinocchio is a practical zk-SNARK that allows a prover to perform cryptographically verifiable computations with verification effort potentially less than performing the computation itself. A recent proposal showed how to make Pinocchio adaptive (or âhash-and-proveâ), i.e., to enable proofs with respect to computation-independent commitments. This enables computations to be chosen after the commitments have been produced, and for data to be shared between different computations in a flexible way. Unfortunately, this proposal is not zero-knowledge. In particular, it cannot be combined with Trinocchio, a system in which Pinocchio is outsourced to three workers that do not learn the inputs thanks to multi-party computation (MPC). In this paper, we show how to make Pinocchio adaptive in a zero-knowledge way; apply this to make Trinocchio work on computation-independent commitments; present tooling to easily program flexible verifiable computations (with or without MPC); and use it to build a prototype in a medical research case study.
Xuechao Yang, Xun Yi, Caspar Ryan, Ron van Schyndel · 7 authors
No abstract is available for this record.
Nazmul Islam, Kazi Md. Rokibul Alam, Shinsuke Tamura, Yasuhiko Morimoto
This paper proposes a new electronic voting (e-voting) scheme that exploits confirmation numbers (CNs) and revised simplified verifiable re-encryption mixnet (R-SVRM). R-SVRM is a recently introduced mechanism of mixnet also used to develop an e-voting scheme where a vote is decomposed to protect its voter from being coerced to cast a particular vote. Though the scheme avoids complicated zero knowledge proof (ZKP), the verification procedures of its cryptographic operations are still cumbersome. Again, another e-voting scheme based on CNs comes with benefits of vote verifiability and unlinkability between the vote and its voter, lags behind in adopting public keys for encryption and signature verification. Also its exploited mixnet is not verifiable; therefore requires a pair of signatures on each encrypted vote to ensure the verifiability of mixnet. Hence, the computation and communication overhead of the scheme becomes weighty, though ZKP is avoided. In contrast, the proposed scheme deploys both CNs and R-SVRM to eliminate these limitations. Hence, any coercer cannot force the voter to cast a specific vote as well as cryptographic operations and their verifications become simpler. Also the computation and communication overheads for involved entities get decreased. Finally, the security requirements of e-voting are achieved more elegantly.
Daniel Genkin, Yuval Ishai, Mor Weiss
No abstract is available for this record.
Claude Crépeau, Nan Yang
Several Multi-Prover Interactive Proofs (MIPs) found in the literature contain proofs of soundness that are lacking. This was first observed [1] in which a notion of Prover isolation is defined to partly address the issue. Furthermore, some existing Zero-Knowledge MIPs suffer from a catastrophic flaw: they outright allow the Provers to communicate via the Verifier. Consequently, their soundness claims are now seriously in doubt, if not plain wrong. This paper outlines the lack of isolation and numerous other issues found in the (ZK)MIP literature. A follow-up paper will resolve most of these issues in detail.
Denise Demirel, Lucas SchabhĂŒser, Johannes Buchmann
No abstract is available for this record.
Prabhanjan Ananth, Aloni Cohen, Abhishek Jain
No abstract is available for this record.
Robert K. Cunningham, Benjamin Fuller, Sophia Yakoubov
No abstract is available for this record.
Gorjan Alagic, Yfke Dulek, Christian Schaffner, Florian Speelman
Fully-homomorphic encryption (FHE) enables computation on encrypted data while maintaining secrecy. Recent research has shown that such schemes exist even for quantum computation. Given the numerous applications of classical FHE (zero-knowledge proofs, secure two-party computation, obfuscation, etc.) it is reasonable to hope that quantum FHE (or QFHE) will lead to many new results in the quantum setting. However, a crucial ingredient in almost all applications of FHE is circuit verification. Classically, verification is performed by checking a transcript of the homomorphic computation. Quantumly, this strategy is impossible due to no-cloning. This leads to an important open question: can quantum computations be delegated and verified in a non-interactive manner? In this work, we answer this question in the affirmative, by constructing a scheme for QFHE with verification (vQFHE). Our scheme provides authenticated encryption, and enables arbitrary polynomial-time quantum computations without the need of interaction between client and server. Verification is almost entirely classical; for computations that start and end with classical states, it is completely classical. As a first application, we show how to construct quantum one-time programs from classical one-time programs and vQFHE.
Yashvanth Kondi, Arpita Patra
No abstract is available for this record.
Rishab Goyal, Vipul Goyal
Blockchain technology has the potential to disrupt how cryptography is done. In this work, we propose to view blockchains as an âenablerâ, much like indistinguishability obfuscation [5, 23, 46] or one-way functions, for building a variety of cryptographic systems. Our contributions in this work are as follows: 1. A Framework for Proof-of-Stake based Blockchains: We provide an abstract framework for formally analyzing and defining useful security properties for Proof-of-Stake (POS) based blockchain protocols. Interestingly, for some of our applications, POS based protocols are more suitable. We believe our framework and assumptions would be useful in building applications on top of POS based blockchain protocols even in the future. 2. Blockchains as an Alternative to Trusted Setup Assumptions in Cryptography: A trusted setup, such as a common reference string (CRS) has been used to realize numerous systems in cryptography. The paragon example of a primitive requiring trusted setup is a non-interactive zero-knowledge (NIZK) system. We show that already existing blockchains systems including Bitcoin, Ethereum etc. can be used as a foundation (instead of a CRS) to realize NIZK systems. The novel aspect of our work is that it allows for utilizing an already existing (and widely trusted) setup rather than proposing a new one. Our construction does not require any additional functionality from the miners over the already existing ones, nor do we need to modify the underlying blockchain protocol. If an adversary can violate the security of our NIZK, it could potentially also take over billions of dollars worth of coins in the Bitcoin, Ethereum or any such cryptocurrency! We believe that such a âtrusted setupâ represents significant progress over using CRS published by a central trusted party. Indeed, NIZKs could further serve as a foundation for a variety of other cryptographic applications such as round efficient secure computation [33, 36]. 3. One-time programs and pay-per use programs: Goldwasser et al. [29] introduced the notion of one time program and presented a construction using tamper-proof hardware. As noted by Goldwasser et al. [29], clearly a one-time program cannot be solely software based, as software can always be copied and run again. While there have been a number of follow up works [4, 6, 30], there are indeed no known constructions of one-time programs which do not rely on self destructing tamper-proof hardware (even if one uses trusted setup or random oracles). Somewhat surprisingly, we show that it is possible to base one-time programs on POS based blockchain systems without relying on trusted hardware. Our ideas do not seem to translate over to Proof-of-Work (POW) based blockchains. We also introduce the notion of pay-per-use programs which is simply a contract between two parties â service provider and customer. A service provider supplies a program such that if the customer transfers a specific amount of coins to the provider, it can evaluate the program on any input of its choice once, even if the provider is offline. This is naturally useful in a subscription based model where your payment is based on your usage.
Wentao Zhang, Qianhong Wu, Bo Qin, Tianxu Han · 7 authors
No abstract is available for this record.
Sanjam Garg, Akshayaram Srinivasan
In this paper, we initiate the study of garbled protocols — a generalization of Yaos garbled circuits construction to distributed protocols. More specifically, in a garbled protocol construction, each party can independently generate a garbled protocol component along with pairs of input labels. Additionally, it generates an encoding of its input. The evaluation procedure takes as input the set of all garbled protocol components and the labels corresponding to the input encodings of all parties and outputs the entire transcript of the distributed protocol.We provide constructions for garbling arbitrary protocols based on standard computational assumptions on bilinear maps (in the common random string model). Next, using garbled protocols we obtain a general compiler that compresses any arbitrary round multiparty secure computation protocol into a two-round UC secure protocol. Previously, two-round multiparty secure computation protocols were only known assuming witness encryption or learning-with errors. Benefiting from our generic approach we also obtain protocols (i) for the setting of random access machines (RAM programs) while keeping communication and computational costs proportional to running times, while (ii) making only a black-box use of the underlying group, eliminating the need for any expensive non-black-box group operations. Our results are obtained by a simple but powerful extension of the non-interactive zero-knowledge proof system of Groth, Ostrovsky and Sahai [Journal of ACM, 2012].
ASIACRYPT 2017 Hongkong, Tsuyoshi Takagi, Thomas Peyrin
No abstract is available for this record.
Roberto Metere, Changyu Dong
Aiming for strong security assurance, recently there has been an increasing interest in formal verification of cryptographic constructions. This paper presents a mechanised formal verification of the popular Pedersen commitment protocol, proving its security properties of correctness, perfect hiding, and computational binding. To formally verify the protocol, we extended the theory of EasyCrypt, a framework which allows for reasoning in the computational model, to support the discrete logarithm and an abstraction of commitment protocols. Commitments are building blocks of many cryptographic constructions, for example, verifiable secret sharing, zero-knowledge proofs, and e-voting. Our work paves the way for the verification of those more complex constructions.
Kevin M. Clermont
The law speaks clearly on the standards of proof, but listeners often misunderstand its words. This article tries, with some common sense, to explain how the law expects its standards to be applied, and then to show how the law thereby avoids such complications as the conjunction paradox. First, in accordance with belief function theory, the factfinder should start at zero belief. Given imperfect evidence, the factfinder will end up retaining a fair amount of uncommitted belief. As evidence comes in, though, the factfinder will form a belief in the truth of the disputed fact but also form a disbelief, or a belief in the factâs falsity. At the close of evidence, the standard of proof requires only comparing belief and disbelief. For example, the civil standard, rather than asking whether a fact more likely than not happened according to traditional probability theory, asks whether the factfinder believes the fact more than the factfinder believes that the fact did not happen. The burdened party need not push proof above 50% by dispelling the phantoms of every possibility, while the opponent need not generate a competing version of truth but can instead rely on denial to demand that the burdened party generate a belief.Second, belief and disbelief being nonadditive partial truths, the mathematical result is that one cannot combine beliefs by traditional probability theory, as by using the product rule designed for conjunction of betting odds. Instead, one must use multivalent logic, including its rule that conjoined likelihood equals the likelihood of the least likely element. Linking the elements in a chain tells a story that is as likely as its weakest link. Consequently, if each element of a claim or defense passes the standard of proof, the conjunction of elements will pass the standard of proof. The conjunction paradox thus vaporizes for factfinding, just as the law has always maintained. The law has found the way to decide in accord with our best knowledge of the facts.
Yunsen Wang
No abstract is available for this record.
Areej M. Abduldaim
Innovative idea using ring theory is raised to build a new algorithm for zero knowledge (ZK) cryptosystem. In this paper we introduce an algorithm for zero knowledge protocol based on a specific kind of rings named weak Armendariz. On the other hand, the aim of this paper focuses on the category of noncommutative algebraic structures to describe a new algebraic scheme of zero knowledge proof using weak Armendariz rings. As a result, we employ for the first time weak Armendariz rings in the science of cryptographic which regards as a new application of this class of rings. Finally, we present a novel idea combining between abstract algebra and cryptography.
Jorge Bernal Bernabé, José L. Hernåndez-Ramos, Antonio Skårmeta
Security and privacy concerns are becoming an important barrier for large scale adoption and deployment of the Internet of Things. To address this issue, the identity management system defined herein provides a novel holistic and privacy-preserving solution aiming to cope with heterogeneous scenarios that requires both traditional online access control and authentication, along with claim-based approach for M2M (machine to machine) interactions required in IoT. It combines a cryptographic approach for claim-based authentication using the Idemix anonymous credential system, together with classic IdM mechanisms by relying on the FIWARE IdM (Keyrock). This symbiosis endows the IdM system with advanced features such as privacy-preserving, minimal disclosure, zero-knowledge proofs, unlikability, confidentiality, pseudonymity, strong authentication, user consent, and offline M2M transactions. The IdM system has been specially tailored for the Internet of Things bearing in mind the management of both usersâ and smart objectsâ identity. Moreover, the IdM system has been successfully implemented, deployed, and tested in the scope of SocIoTal European research project.
Shachar Lovett, Jiapeng Zhang
No abstract is available for this record.