Blockchain Papers

Hoeteck Wee

No abstract is available for this record.

Sanjam Garg, Rafail Ostrovsky, Ivan Visconti, Akshay Wadia

Abstract Two central notions of Zero Knowledge that provide very strong, yet seemingly incomparable security guarantees against malicious verifiers are those of Statistical Zero Knowledge and Resettable Zero Knowledge. The current state of the art includes several feasibility and impossibility results about the two notions separately. However, the challenging question of achieving Resettable Statistical Zero Knowledge (i.e., Resettable Zero Knowledge and Statistical Zero Knowledge simultaneously) for non-trivial languages is still open. In this paper, we show:- Resettable Statistical Zero Knowledge with efficient provers: Efficient-prover Resettable Statistical Zero-Knowledge proof systems exist for all languages that admit hash proof systems (e.g., QNR, QR, DDH, DCR). Furthermore, for these languages, as an application of our technique, we also construct a two-round resettable statistical witness-indistinguishable argument system.- Resettable Statistical Zero Knowledge with unbounded provers: Under the assumption that sub-exponentially hard one-way functions exist, rSZK = SZK. In other words, every language that admits a Statistical Zero-Knowledge (SZK) proof system also admits a Resettable Statistical Zero-Knowledge (rSZK) proof system. (Further, the result can be re-stated unconditionally provided there exists a sub-exponentially hard language in SZK). Moreover, under the assumption that (standard) one-way functions exist, all languages L such that the complement of L is random self reducible, admit a rSZK, in other words: co-RSR ⊆ rSZK. The round complexity of all our proof systems is Õ(log κ), where κ is the security parameter, and all our simulators are black-box. 1

Amang Sudarsono, Toru Nakanishi, Nobuo Funabiki

No abstract is available for this record.

Oded Goldreich

No abstract is available for this record.

Jens Groth

No abstract is available for this record.

Jan Camenisch, Stephan Krenn, Victor Shoup

Abstract. Zero-knowledge proofs of knowledge (ZK-PoK) for discrete logarithms and related problems are indispensable for practical cryptographic protocols. At Eurocrypt 2009, Camenisch, Kiayias, and Yung provided a specification language (the CKY-language) for such protocols, which allows one to modularly design and analyze cryptographic protocols: protocol designers just need to specify the statement they want to prove in zero-knowledge and are ensured that an efficient proof protocol exists and indeed proves the specified statement, provided that the specification was in the CKY-language. However, as specifications in the CKY-language are realized by so-called Σ-protocols, the resulting protocols only satisfy the classical notion of zero-knowledge proofs of knowledge, which not retained if they are composed with themselves or with other protocols, e.g., when used as building blocks for higher-level applications. This problem can be tackled by moving to the Universal Composability (UC) framework, which guarantees retention of security when composing protocols and, in particular, when using them as building blocks in arbitrary contexts. While there exists generic transformations from Σ-protocols to protocols that are secure under this stronger security notion, these transformation are often not efficient enough for the design of practical protocols. In this paper we are aiming for practically efficient ZK-PoK in the UC-framework by introducing

Ning Ding, Dawu Gu

No abstract is available for this record.

Sanjam Garg, Abhishek Jain, Amit Sahai

No abstract is available for this record.

Jens Groth

No abstract is available for this record.

Jens Groth

A non-interactive zero-knowledge proof can be used to demonstrate the truth of a statement without revealing anything else. It has been shown under standard cryptographic assumptions that non-interactive zero-knowledge proofs of membership exist for all languages in NP. However, known non-interactive zero-knowledge proofs of membership of NP-languages yield proofs that are larger than the corresponding membership witnesses. We investigate the question of minimizing the communication overhead involved in making non-interactive zero-knowledge proofs and show that if fully homomorphic encryption exists then it is possible to minimize the size of non-interactive zero-knowledge proofs and get proofs that are of the same size as the witnesses. Our technique is applicable to many types of non-interactive zero-knowledge proofs. We apply it to both standard non-interactive zero-knowledge proofs and to universally composable non-interactive zero-knowledge proofs. The technique can also be applied outside the realm of non-interactive zero-knowledge proofs, for instance to get witness-size interactive zero-knowledge proofs in the plain model without any setup. Keywords: Non-interactive zero-knowledge proofs, fully homomorphic encryption. 1

Imad Fakhri Taha Alshaikhli, Rusydi Hasan Makarin, Siti Khairunnisa Mohd Bakri, Nur Dalilah More Yusoff · 5 authors

Much of the current innovation in advanced materials is occurring at the nanoscale, specifically in manufactured nanomaterials (MNs). MNs display unique attributes and behaviors, and may be biologically and physically unique, making them valuable across a wide range of applications. However, as the number, diversity and complexity of MNs coming to market continue to grow, assessing their health and environmental risks with traditional animal testing approaches is too time- and cost-intensive to be practical, and is undesirable for ethical reasons. New approaches are needed that meet current requirements for regulatory risk assessment while reducing reliance on animal testing and enabling safer-by-design product development strategies to be implemented. The adverse outcome pathway (AOP) framework presents a sound model for the advancement of MN decision making. Yet, there are currently gaps in technical and policy aspects of AOPs that hinder the adoption and use for MN risk assessment and regulatory decision making. This review outlines the current status and next steps for the development and use of the AOP framework in decision making regarding the safety of MNs. Opportunities and challenges are identified concerning the advancement and adoption of AOPs as part of an integrated approach to testing and assessing (IATA) MNs, as are specific actions proposed to advance the development, use and acceptance of the AOP framework and associated testing strategies for MN risk assessment and decision making. The intention of this review is to reflect the views of a diversity of stakeholders including experts, researchers, policymakers, regulators, risk assessors and industry representatives on the current status, needs and requirements to facilitate the future use of AOPs in MN risk assessment. It incorporates the views and feedback of experts that participated in two workshops hosted as part of an Organization for Economic Cooperation and Development (OECD) Working Party on Manufactured Nanomaterials (WPMN) project titled, "Advancing AOP Development for Nanomaterial Risk Assessment and Categorization", as well as input from several EU-funded nanosafety research consortia.

Zvika Brakerski, Jonathan Katz, Gil Segev, Arkady Yerukhimovich

No abstract is available for this record.

Xiaofeng Chen, Qianhong Wu, Fangguo Zhang, Haibo Tian · 8 authors

No abstract is available for this record.

Marek Jawurek, Martin Johns, Florian Kerschbaum

Traditional electricity meters are replaced by Smart Meters in customers' households. Smart Meters collects fine-grained utility consumption profiles from customers, which in turn enables the introduction of dynamic, time-of-use tariffs. However, the fine-grained usage data that is compiled in this process also allows to infer the inhabitant's personal schedules and habits. We propose a privacy-preserving protocol that enables billing with time-of-use tariffs without disclosing the actual consumption profile to the supplier. Our approach relies on a zero-knowledge proof based on Pedersen Commitments performed by a plug-in privacy component that is put into the communication link between Smart Meter and supplier's back-end system. We require no changes to the Smart Meter hardware and only small changes to the software of Smart Meter and back-end system. In this paper we describe the functional and privacy requirements, the specification and security proof of our solution and give a performance evaluation of a prototypical implementation.

Xiaolan Zhang, Hong-xiang Sun, Hua Zhang, Qiaoyan Wen · 5 authors

A coin-tossing protocol lets two parties decide on a string that should be a random (or at least pseudorandom) string. In this paper, we focus on taking advantage of the perfectly hiding commitment scheme, constant-round perfect zero-knowledge arguments and arguments of knowledge to construct a two-party constant-round perfect protocol for secure coin-tossing, where both of two parties can obtain the common resulting coins and the resulting coins are guaranteed to be statistically close to uniform. The security of our protocol is obtained against malicious non-uniform adversaries that may arbitrarily deviate from the protocol specification. Comparing with the Barak's protocol, we utilize the black-box reduction in the process of security proof and the rounds of our protocol decrease obviously.

Yan Xu, Hong Zhong, Xianping Yuan, Jia Yu

An identity-based threshold key management scheme without secure channel is proposed for ad hoc network. The master private key, which is shared among all nodes by the Shamir's secret sharing scheme, is produced by all nodes when network is formed. The nodes' public keys are derived from their identities. In order to get the private key, each node needs to prove their identity to distributed CAs using a zero-knowledge proof protocol to get the share of private key. Compared with former schemes, our scheme doesn't need any local registration authority(LRA), which is easy to be compromised by adversary. When a node leaves the network, shares of the master private key would be renewed. In the end, we prove our scheme is correct and secure.

Yanping Xiao, Chuang Lin, Yixin Jiang, Xiaowen Chu · 5 authors

Cloud computing provides a novel computing paradigm for enterprises to store programs and data in the Cloud in a transparent manner, which poses the challenge of security and privacy. In this paper, based on homomorphic cryptography and Zero-Knowledge Proof, we present a novel privacy-preserving scheme for Cloud publish/subscribe service, which achieve efficient privacy-preserving authentication, data integrity, and publish-subscribe confidentiality. The performance evaluation and security analysis demonstrate the practice and validity of the proposed scheme.

Héctor Pastén, Thanases Pheidas, Xavier Vidaux

No abstract is available for this record.

Sam Kerr, Michael S. Kirkpatrick, Elisa Bertino

As users have to manage an increasing number of accounts, they have to balance password security and password usability. As such, many users use insecure passwords resulting in their accounts and data being vulnerable to unauthorized accesses. In this paper, we present Physically Enhanced Authentication Ring, or PEAR, a system that alleviates this problem. We leverage Physically Unclonable Functions (PUF) to create unclonable hardware devices, which users use to authenticate. Using a hardware device, our system uses zero-knowledge proofs, which provide better security than traditional passwords, yet users must only enter a simple PIN. As such, our system is very usable and imposes little to no burden on end users and service providers. We present transaction levels on top of PEAR of as an extension and then discuss some other work that could be done in the future.

Giovanni Di Crescenzo, Javier Herranz, Germán Sáez

No abstract is available for this record.

Qinglei Hu, Bing Xiao

No abstract is available for this record.

Sukriti Bhattacharya, Agostino Cortesi

Abstract. This paper proposes a novel method for watermarking C source code by exploiting the programming language features.The key idea of our watermarking scheme is a semantics-preserving program transformation, based on a hidden permutation of local identifiers, followed by another hidden permutation of the functions defined in the source code. This last permutation allows to encrypt the prove of ownership, in the framework of interactive zero-knowledge proof system. The proposed watermarking scheme is invisible to compilers and does not reveal any information about the watermark, its nature and its location into the program, since the zero knowledge proof is independent of the encoding and of the embedding. Finally, we introduce a third party Trusted Time-Stamp Service into the system to prevent invertibility/ambiguity attacks.

Yiqi Gui, Hwang-Kyu Choi

The main idea is to protect the signer of a document against the document being digitally distributed without the cooperation of signer. This paper proposes a new scheme of undeniable signature, which is so effective and improved D. Chaum's scheme. And our scheme which is zero-knowledge proved by using one-way function and partition - selection method, shows that its communication(challenge-response) only needs much fewer times during the confirmation protocol and disavowal protocol respectively, being very useful for wireless network environment. In the meantime our scheme allows the verifier to verify that the signature is valid, while the signer doesn't know the original message and the signature, to preserve the privacy of the verifier.

Kun Peng, Ed Dawson, Feng Bao

No abstract is available for this record.