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8,503 results · page 228 of 355
Aarushi Goel, Matthew Green, Mathias Hall-Andersen, Gabriel Kaptchuk
No abstract is available for this record.
David Chaum, Mario Larangeira, Mario Yaksetig, William Carter
No abstract is available for this record.
Xianrui Qin, Cailing Cai, Tsz Hon Yuen
No abstract is available for this record.
Thomas Attema, Ronald Cramer, Lisa Kohl
We show a lattice-based solution for commit-and-prove transparent circuit zero-knowledge (ZK) with polylog-communication, the first not depending on PCPs. We start from compressed Σ-protocol theory (CRYPTO 2020), which is built around basic Σ-protocols for opening an arbitrary linear form on a long secret vector that is compactly committed to. These protocols are first compressed using a recursive “folding-technique” adapted from Bulletproofs, at the expense of logarithmic rounds. Proving in ZK that the secret vector satisfies a given constraint – captured by a circuit – is then by (blackbox) reduction to the linear case, via arithmetic secret-sharing techniques adapted from MPC. Commit-and-prove is also facilitated, i.e., when commitment(s) to the secret vector are created ahead of any circuit-ZK proof. On several platforms (incl. DL) this leads to logarithmic communication. Non-interactive versions follow from Fiat-Shamir. This abstract modular theory strongly suggests that it should somehow be supported by a lattice platform as well. However, when going through the motions and trying to establish low communication (on an SIS-platform), a certain significant lack in current understanding of multi-round protocols is exposed. Namely, as opposed to the DL-case, the basic Σ-protocol in question typically has poly-small challenge space. Taking into account the compression-step – which yields non-constant rounds – and the necessity for parallelization to reduce error, there is no known tight result that the compound protocol admits an efficient knowledge extractor. We resolve the state of affairs here by a combination of two novel results which are fully general and of independent interest. The first gives a tight analysis of efficient knowledge extraction in case of non-constant rounds combined with poly-small challenge space, whereas the second shows that parallel repetition indeed forces rapid decrease of knowledge error. Moreover, in our present context, arithmetic secret sharing is not defined over a large finite field but over a quotient of a number ring and this forces our careful adaptation of how the linearization techniques are deployed. We develop our protocols in an abstract framework that is conceptually simple and can be flexibly instantiated. In particular, the framework applies to arbitrary rings and norms.
Weiqi Dai, Yan Lv, Kim‐Kwang Raymond Choo, Zhongze Liu · 6 authors
As cryptocurrency and blockchain-related assets become more common in our digital society, there is a corresponding need to secure our digital assets, including the private keys used to secure access to such assets (e.g., due to loss or corruption of the data storage medium). However, there are limitations in existing blockchain-related asset management and recovery methods. Therefore, we use zero-knowledge proof to design a cryptocurrency recovery scheme based on hidden assisting relationships (hereafter referred to as the CRSA scheme) to facilitate the recovery of blockchain assets. Specifically, when the user's private key is lost, and access to the assets cannot be obtained, the user leverages information such as the pre-defined list of assistants to authenticate himself/herself on the blockchain. Once the assistants have confirmed the legitimacy of the user's authentication request, the asset will be transferred from the old address to the new address. During the (identity) proof process, the zero-knowledge proof is used to ensure that the identification of assistants is not leaked to other nodes, assistants, and the adversary. We provide the formal definition of the above scheme and the security proof of the construction. We also implement a prototype of the system and evaluate its performance. Evaluations indicate that the time required for the zero-knowledge proof is less than 10s, and the block verification time is less than 100ms.
Alexander R. Block, Justin Holmgren, Alon Rosen, Ron D. Rothblum · 5 authors
No abstract is available for this record.
Teik Guan Tan, Jianying Zhou
No abstract is available for this record.
Jung Hee Cheon, Dongwoo Kim, Keewoo Lee
We propose a multi-party computation (MPC) protocol over \(\mathbb {Z}_{2^k}\) secure against actively corrupted majority from somewhat homomorphic encryption. The main technical contributions are: (i) a new efficient packing method for \(\mathbb {Z}_{2^k}\)-messages in lattice-based somewhat homomorphic encryption schemes, (ii) a simpler reshare protocol for level-dependent packings, (iii) a more efficient zero-knowledge proof of plaintext knowledge on cyclotomic rings \({\mathbb Z}[X]/\varPhi _M(X)\) with M being a prime. Integrating them, our protocol shows from 2.2x upto 4.8x improvements in amortized communication costs compared to the previous best results. Our techniques not only improve the efficiency of MPC over \(\mathbb {Z}_{2^k}\) considerably, but also provide a toolkit that can be leveraged when designing other cryptographic primitives over \(\mathbb {Z}_{2^k}\).
Efe Seyitoglu, Attila A. Yavuz, Thang Hoang
Proof-of-Work (PoW) is one of the fundamental and widely-used consensus algorithms in blockchains. In PoW, nodes compete to receive the mining reward by trying to be the first to solve a puzzle. Despite its fairness and wide-availability, traditional PoW incurs extreme computational and energy waste over the blockchain. This waste is considered to be one of the biggest problems in PoW-based blockchains and cryptocurrencies. In this work, we propose a new useful PoW called Proof-of-Useful-Randomness (PoUR) that mitigates the energy waste by incorporating pre-computed (disclosable) randomness into the PoW. The key idea is to inject special randomness into puzzles via algebraic commitments that can be stored and later disclosed. Unlike the traditional wasteful PoWs, our approach enables pre-computed commitments to be utilized by a vast array of public-key cryptography methods that require offline-online processing (e.g., digital signature, key exchange, zero-knowledge protocol). Moreover, our PoW preserves the desirable properties of the traditional PoW and therefore does not require a substantial alteration in the underlying protocol. We showed the security of our PoW, and then fully implemented it to validate its significant energy-saving capabilities.
Amit Sahai, Brent Waters
We introduce a new technique, that we call punctured programs, to apply indistinguishability obfuscation towards cryptographic problems. We use this technique to carry out a systematic study of the applicability of indistinguishability obfuscation to a variety of cryptographic goals. Along the way, we resolve the 16-year-old open question of Deniable Encryption, posed by Canetti, Dwork, Naor, and Ostrovsky in 1997: In deniable encryption, a sender who is forced to reveal to an adversary both her message and the randomness she used for encrypting it should be able to convincingly provide “fake” randomness that can explain any alternative message that she would like to pretend that she sent. We resolve this question by giving the first construction of deniable encryption that does not require any pre-planning by the party that must later issue a denial. In addition, we show the generality of our punctured programs technique by also constructing a variety of core cryptographic objects from indistinguishability obfuscation and one-way functions (or close variants). In particular we obtain: public key encryption, short “hash-and-sign” selectively secure signatures, chosen-ciphertext secure public key encryption, non-interactive zero knowledge proofs (NIZKs), injective trapdoor functions, and oblivious transfer. These results suggest the possibility of indistinguishability obfuscation becoming a “central hub” for cryptography. Amit Sahai is supported for this research effort in part from NSF grants 1228984, 1136174, 1118096, 1065276, 0916574 and 0830803, a Xerox Faculty Research Award, a Google Faculty Research Award, an equipment grant from Intel, and an Okawa Foundation Research Grant. The views expressed are those of the author and do not reflect the official policy or position of the National Science Foundation, or the U.S. Government. Brent Waters is supported by NSF CNS-0915361 and CNS-0952692, CNS-1228599 DARPA through the U.S. Office of Naval Research under Contract N00014-11-1-0382, DARPA N11AP20006, Google Faculty Research award, the Alfred P. Sloan Fellowship, Microsoft Faculty Fellowship, and Packard Foundation Fellowship. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of Defense or the U.S. Government.
Zhiyuan Xue, Miao Wang, Qiuyue Zhang, Yunfeng Zhang · 5 authors
Blockchain is a decentralized distributed ledger technology. The public chain represented by Bitcoin and Ethereum only realizes the limited anonymity of user identity, and the transaction amount is open to the whole network, resulting in user privacy leakage. Based on the existing anonymous technology, the concealment of the sender, receiver, amount of the transaction, and does not disclose any information, which makes the supervision difficult. Therefore, the design of blockchain scheme with privacy protection and supervision functions is of great significance. In this paper, a blockchain transaction model with both privacy and supervision function is proposed. It uses probability encryption to realize the hiding of the true identity of the blockchain transaction, and uses the commitment scheme and zero-knowledge proof technology to realize the privacy protection and guarantee legitimacy verification of the transaction. With the use of encryption technology, the regulators can supervise blockchain transactions without storing the users' information, which greatly reduces the pressure on storage, computing and key management. In addition, it does not rely on specific consensus mechanism and can be used as an independent module. The security performance analysis shows that the proposed scheme has great practicability and has potential application in many fields.
Benjamin Körbel, Marten Sigwart, Philip Frauenthaler, Michael Sober · 5 authors
Offloading of computation, e.g., to the cloud, is today a major task in distributed systems. Usually, consumers which apply offloading have to trust that a particular functionality offered by a service provider is delivering correct results. While redundancy (i.e., offloading a task to more than one service provider) or (partial) reprocessing help to identify correct results, they also lead to significantly higher cost. Hence, within this paper, we present an approach to verify the results of offchain computations via the blockchain. For this, we apply zero-knowledge proofs to provide evidence that results are correct. Using our approach, it is possible to establish trust between a service consumer and arbitrary service providers. We evaluate our approach using a very well-known example task, i.e., the Traveling Salesman Problem.
Lorenzo Andolfo, Luigi Coppolino, Salvatore D’Antonio, Giovanni Mazzeo · 8 authors
The majority of financial organizations managing confidential data are aware of security threats and leverage widely accepted solutions (e.g., storage encryption, transport-level encryption, intrusion detection systems) to prevent or detect attacks. Yet these hardening measures do little to face even worse threats posed on data-in-use. Solutions such as Homomorphic Encryption (HE) and hardware-assisted Trusted Execution Environment (TEE) are nowadays among the preferred approaches for mitigating this type of threat. However, given the high-performance overhead of HE, financial institutions -- whose processing rate requirements are stringent -- are more oriented towards TEE-based solutions. The X-Margin Inc. company, for example, offers secure financial computations by combining the Intel SGX TEE technology and HE-based Zero-Knowledge Proofs, which shield customers' data-in-use even against malicious insiders, i.e., users having privileged access to the system. Despite such a solution offers strong security guarantees, it is constrained by having to trust Intel and by the SGX hardware extension availability. In this paper, we evaluate a new frontier for X-Margin, i.e., performing privacy-preserving credit risk scoring via an emerging cryptographic scheme: Functional Encryption (FE), which allows a user to only learn a function of the encrypted data. We describe how the X-Margin application can benefit from this innovative approach and -- most importantly -- evaluate its performance impact.
Daniël Reijsbergen, Zheng Yang, Aung Htein Maw, Tien Tuan Anh Dinh · 5 authors
Smart grids leverage data from smart meters to improve operations management and to achieve cost reductions. The fine-grained meter data also enable pricing schemes that simultaneously benefit electricity retailers and users. Our goal is to design a practical dynamic pricing protocol for smart grids in which the rate charged by a retailer depends on the total demand among its users. Realizing this goal is challenging because neither the retailer nor the users are trusted. The first challenge is to design a pricing scheme that incentivizes consumption behavior that leads to lower costs for both the users and the retailer. The second challenge is to prevent the retailer from tampering with the data, for example, by claiming that the total consumption is much higher than its real value. The third challenge is data privacy, that is, how to hide the meter data from adversarial users. To address these challenges, we propose a scheme in which peak rates are charged if either the total or the individual consumptions exceed some thresholds. We formally define a privacy-preserving transparent pricing scheme (PPTP) that allows honest users to detect tampering at the retailer while ensuring data privacy. We present two instantiations of PPTP, and prove their security. Both protocols use secure commitments and zero-knowledge proofs. We implement and evaluate the protocols on server and edge hardware, demonstrating that PPTP has practical performance at scale.
Geoffrey Goodell, Hazem Danny Al-Nakib, Paolo Tasca
Objective : to present the new approach to perform monetary transactions with digital currency. Methods : abstract-logical, analytical methods. Results : in recent years, electronic retail payment mechanisms, especially e-commerce and card payments at the point of sale, have increasingly replaced cash in many developed countries. As a result, societies are losing a critical public retail payment option, and retail consumers are losing important rights associated with using cash. To address this concern, we propose an approach to digital currency that would allow people without banking relationships to transact electronically and privately, including both e-commerce purchases and point-of-sale purchases that are required to be cashless. The article shows the advantages of cash payments compared to non-cash ones and defines the possibility to transform these advantages into the central bank digital currencies. The disputable issues of commercial banks development under the spread of digital currencies are discussed. The architecture of digital currencies is described, including distributed ledgers technology. It was shown that, for the digital currency to function effectively, it is necessary to include the privacy of end-users into its architecture; measures to achieve that are determined. Scientific novelty : the approached proposed in the article should be used to develop the digital currencies infrastructure. It should be government-backed, privately-operated and ensure that every transaction is registered by a bank or money services business, relying upon non-custodial wallets backed by privacy-enhancing technology, such as blind signatures or zero-knowledge proofs, to ensure that transaction counterparties are not revealed. This approach can also facilitate more efficient and transparent clearing, settlement, and management of systemic risk. We argue that our system can restore and preserve the salient features of cash, including privacy, owner-custodianship, fungibility, and accessibility, while also preserving fractional reserve banking and the existing two-tiered banking system. Practical significance : the proposed approach can be applied in the practical organization of perform monetary transactions using digital currencies. The article was first published in English language by Future Internet. For more information please contact the editorial office. For original publication: Goodell G., Al-Nakib H. D., Tasca P. A Digital Currency Architecture for Privacy and Owner-Custodianship, Future Internet, 2021, 13, 130. https://doi.org/10.3390/fi13050130 Publication URL: https://www.mdpi.com/1999-5903/13/5/130
Amina Bassit, Florian Hahn, Joep Peeters, T.A.M. Kevenaar · 6 authors
Biometric verification has been widely deployed in current authentication solutions as it proves the physical presence of individuals. Several solutions have been developed to protect the sensitive biometric data in such systems that provide security against honest-but-curious (a.k.a. semi-honest) attackers. However, in practice, attackers typically do not act honestly and multiple studies have shown severe biometric information leakage in such honest-but-curious solutions when considering dishonest, malicious attackers. In this paper, we propose a provably secure biometric verification protocol to withstand malicious attackers and prevent biometric data from any leakage. The proposed protocol is based on a homomorphically encrypted log likelihood-ratio (HELR) classifier that supports any biometric modality (e.g., face, fingerprint, dynamic signature, etc.) encoded as a fixed-length real-valued feature vector. The HELR classifier performs an accurate and fast biometric recognition. Furthermore, our protocol, which is secure against malicious adversaries, is designed from a protocol secure against semi-honest adversaries enhanced by zero-knowledge proofs. We evaluate both protocols for various security levels and record a sub-second speed (between 0.37s and 0.88s) for the protocol secure against semi-honest adversaries and between 0.95s and 2.50s for the protocol secure against malicious adversaries.
Behzad Abdolmaleki, Hamidreza Khoshakhlagh, Helger Lipmaa
No abstract is available for this record.
Jonathan Heiss, Anselm Busse, Stefan Tai
Prior to provisioning sensor data to smart contracts, a pre-processing of the data on intermediate off-chain nodes is often necessary. When doing so, originally constructed cryptographic signatures cannot be verified on-chain anymore. This exposes an opportunity for undetected manipulation and presents a problem for applications in the Internet of Things where trustworthy sensor data is required on-chain. In this paper, we propose trustworthy pre-processing as enabler for end-to-end sensor data integrity in data on-chaining workflows. We define requirements for trustworthy pre-processing, present a model and common workflow for data on-chaining, select off-chain computation utilizing Zero-knowledge Proofs (ZKPs) and Trusted Execution Environments (TEEs) as promising solution approaches, and discuss both our proof-of-concept implementations and initial experimental, comparative evaluation results. The importance of trustworthy pre-processing and principle solution approaches are presented, addressing the major problem of end-to-end sensor data integrity in blockchain-based IoT applications.
Matteo Campanelli, Hamidreza Khoshakhlagh
No abstract is available for this record.
Shihui Fu, Guang Gong
No abstract is available for this record.
Chen Wang, Jian Shen, Pandi Vijayakumar, Brij B. Gupta
With global economic integration, transnational trade plays an important role, and maritime transportation is one of the important means of freight transportation. It is of great significance to build a secure and efficient maritime transportation system (MTS). The introduction of Internet of things technology makes MTS more perfect. The IoT-enabled MTS is composed of marine terminals and on-board sensors, land-based data centers and base stations, as well as satellite networks. Many researchers have carried out significant work to aggregate data in MTS. However, because the terrestrial base stations cannot cover most of the sea area, the isolated maritime terminals, those who drive to the area without base station coverage, need the assistance of satellite networks to complete the contact with the data center. In this paper, we propose an attribute based secure data aggregation scheme for isolated IoT-enabled MTS. In the novel scheme, the constant attributes of a maritime terminal are utilized to generate its certification. In addition, on-board sensors are introduced in the system to help aggregate the status and surrounding environment of the maritime terminal. These monitoring data are encrypted by the sensors and transmitted to the data center for the trustworthiness evaluation of the isolated maritime terminal. Besides, the zero-knowledge proof is utilized to confirm the legitimacy of participating users. What's more, the security analysis and the simulation results show that the novel scheme is secure and efficient for IoT-enabled MTS.
Olivier Blazy, Xavier Bultel, Pascal Lafourcade, Octavio Pérez Kempner
No abstract is available for this record.
Soonhyeong Jeong, Byeongtae Ahn
Recently, blockchain technology accumulates and stores all transactions. Therefore, in order to verify the contents of all transactions, the data itself is compressed, but the scalability is limited. In addition, since a separate verification algorithm is used for each type of transaction, the verification burden increases as the size of the transaction increases. Existing blockchain cannot participate in the network because it does not become a block sink by using a server with a low specification. Due to this problem, as the time passes, the data size of the blockchain network becomes larger and it becomes impossible to participate in the network except for users with abundant resources. Therefore, in this paper, we studied the zero knowledge proof algorithm for general operation verification. In this system, the design of zero-knowledge circuit generator capable of general operation verification and optimization of verifier and prover were also conducted. Also, we developed an algorithm for optimizing key generation. Based on all of these, the zero-knowledge proof algorithm was applied to and tested on the virtual machine so that it can be used universally on all blockchains.
Suthee Ruangwises
Sudoku is a famous logic puzzle where the player has to fill a number between 1 and 9 into each empty cell of a $9 \times 9$ grid such that every number appears exactly once in each row, each column, and each $3 \times 3$ block. In 2020, Sasaki et al. developed a physical card-based protocol of zero-knowledge proof (ZKP) for Sudoku, which enables a prover to convince a verifier that he/she knows a solution of the puzzle without revealing it. Their protocol uses 90 cards, but requires nine identical copies of some cards, which cannot be found in a standard deck of playing cards (consisting of 52 different cards and two jokers). Hence, nine identical standard decks are required to perform that protocol, making the protocol not very practical. In this paper, we propose a new ZKP protocol for Sudoku that can be performed using only two standard decks of playing cards, regardless of whether the two decks are identical or different. In general, we also develop the first ZKP protocol for a generalized $n \times n$ Sudoku that can be performed using a deck of all different cards.