Marta Bellés-Muñoz, Miguel Isabel, José L. Muñoz, Albert Rubio · 5 authors
A zero-knowledge (ZK) proof guarantees that the result of a computation is correct while keeping part of the computation details private. Some ZK proofs are tiny and can be verified in short time, which makes them one of the most promising technologies for solving two key aspects: the challenge of enabling privacy to public and transparent distributed ledgers and enhancing their scalability limitations. Most practical ZK systems require the computation to be expressed as an arithmetic circuit that is encoded as a set of equations called rank-1 constraint system (R1CS). In this paper, we presentCircom, a programming language and a compiler for designing arithmetic circuits that are compiled to R1CS. More precisely, withCircom, programmers can design arithmetic circuits at a constraint level, and the compiler outputs a file with the R1CS description, and WebAssembly andC++programs to efficiently compute all values of the circuit. We also provide an open-source library calledcircomlibwith multiple circuit templates.Circomcan be complemented withsnarkjs, a library for generating and validating ZK proofs from R1CS. Altogether, our software tools abstract the complexity of ZK proving mechanisms and provide a unique and friendly interface to model low-level descriptions of arithmetic circuits.
Zengpeng Li, Mei Wang, Vishal Sharma, Prosanta Gope
Vehicle authentication is an essential component validating the vehicle’s identity and ensuring the integrity of transformed data for intelligent transport vehicles (ITS) in the vehicular ad hoc network (VANET). Easy to deploy and operate privacy-enhancing vehicle authentication mechanisms are the mainstay for the widespread ITS in the VANET. Very recently, VANET security architectures are constituting by IEEE 1609.2 group, NoW project, the SeVeCom project. However, these approaches heavily depend on the consuming public key infrastructure (PKI) and certification authorities (CA). In this work, walking along the research line, we attempt to design authentication protocols with two diverse factors for Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) networks, respectively, without depending on the stumbling block PKI/CA. In addition, a smooth projective hash function (SPHF) (a.k.a., a special case of the designated-verifier zero-knowledge proof system) guarantees any recipient can confirm the authenticity and integrity of the received messages without knowing the authentication factors. Thus, to optimize the communication round, SPHF is used to design a (group) two-factor authenticated key exchange (AKE) with low-interactive communication rounds. The proof-of-concept implementation indicates that the computation and communication overheads introduced by our solution are acceptable in real-world deployments. The security of the proposed approach is validated using Bellare-Pointcheval-Rogaway (BPR) model along with the experimental evaluation and the theoretical analysis.
With a growing reliance on the Internet, users are required to provide vast amounts of personal information in exchange for using online services. Once given over, the user releases all control and ownership of her/his information. Some users of the Internet rely on strong server-side protections and the assurances that the data will be used ethically in their best interests. Recent legislation actions have focused on limiting the amount of data required and regulating the usage of that data once collected. However, a new subset of cryptography, zero-knowledge proofs, may eliminate the need for users to relinquish their data. These zero-knowledge proofs combined with Blockchain technology could give users complete ownership of their information and provide them with the ability to revoke a third-parties access to it. This survey report is a review the current body of literature relating to this topic with the goal of understanding the feasibility of this solution.
Mina Namazi, Ross Duncan, Xiaojie Zhu, Erman Ayday
Individuals are encouraged to prove their eligibility to access specific services regularly. However, providing various organizations with personal data spreads sensitive information and endangers people's privacy. Hence, privacy-preserving identification systems that enable individuals to prove they are permitted to use specific services are required to fill the gap. Cryptographic techniques are deployed to construct identity proofs across the internet; nonetheless, they do not offer complete control over personal data or prevent users from forging and submitting fake data. In this paper, we design a privacy-preserving identity protocol called "zkFaith." A new approach to obtain a verified zero-knowledge identity unique to each individual. The protocol verifies the integrity of the documents provided by the individuals and issues a zero-knowledge-based id without revealing any information to the authenticator or verifier. The zkFaith leverages an aggregated version of the Camenisch-Lysyanskaya (CL) signature scheme to sign the user's commitment to the verified personal data. Then the users with a zero-knowledge proof system can prove that they own the required attributes of the access criterion of the requested service providers. Vector commitment and their position binding property enables us to, later on, update the commitments based on the modification of the personal data; hence update the issued zkFaith id with no requirement of initiating the protocol from scratch. We show that the design and implementation of the zkFaith with the generated proofs in real-world scenarios are scalable and comparable with the state-of-the-art schemes.
Diego F. Aranha, Youssef El Housni, Aurore Guillevic
Elliptic curves have become key ingredients for instantiating zero-knowledge proofs and more generally proof systems. Recently, there have been many tailored constructions of these curves that aim at efficiently implementing different kinds of proof systems. In this survey we provide the reader with a comprehensive overview on existing work and revisit the contributions in terms of efficiency and security. We present an overview at three stages of the process: curves to instantiate a SNARK, curves to instantiate a recursive SNARK, and also curves to express an elliptic-curve related statement. We provide new constructions of curves for SNARKs and generalize the state-of-the-art constructions for recursive SNARKs. We also exhaustively document the existing work and open-source implementations.
Abstract As a distributed public ledger technology in a peer‐to‐peer network, blockchain has been widely used in a variety of Internet interaction systems in recent years, such as market supervision, property rights protection, and digital identity. However, in blockchain environment, all historical transaction data are open and transparent, and adversaries may illegally access private transaction data, which makes privacy attacks a core issue that hinders the popularization and application of blockchain. Different privacy‐preserving technologies such as zerocoin and zerocash have been proposed. However, the large amount of proofs and the slow verification speed hinder the effective application of zero‐knowledge proofs (ZKPs) in blockchain. This article proposes a privacy‐preserving model based on zk‐SNARKs and hash chain for efficient transfer of assets, called zkChain. Different from traditional privacy‐preserving schemes, this scheme constructs a smaller proof based on hash chain, and the verification speed of the proof is faster. This scheme constructs ZKP based on the one‐way hash function and zk‐SNARKs. The proof is publicly recorded in the ledger after being verified by miners, and users use the proof to send privacy‐preserving transactions. In the above process, the zkChain scheme can achieve effective privacy protection of account balance and account address. We evaluated the computational and storage costs of the zkChain scheme based on libsnark, and establish a test network to evaluate the processing performance of the zkChain scheme.
M. M. Rakibul Hasan, Md. Mahinur Alam, Kanita Jerin Tanha
The present land document reservation process that is done manually provides a lot of insecurity, unsafely, and many scopes for land deed fraud in terms of storing land documents and maintaining the details of ownership of specific land property. So, the current land deed reservation and verification method don’t seem reliable and efficient. To make it a reliable and safe transaction, we will use blockchain technology. We have created a blockchain system for land deed authentication utilizing the data encryption algorithm SHA-256. Using this system, land deed transactions will be safer and can store, verify, and preserve all of the relevant information of a land deed document. This proposed architecture store retrieves and detects attempts to modify copies using a variety of approaches, including several efficient technologies like Zero Knowledge proof, Public-key cryptography, and IPFS; It generates far more efficient solutions than the other systems. This method has been put out as a potential means of thwarting fraudulent land deeds and bringing delight to the public.
Zhoujie Zhang, Tao Lei, Can Cui, Yunhao Huang · 8 authors
With the widespread application of power system digital technology and the advancement of dispatch control cloud construction, the development of power grid regulation business presents the basic characteristics of many business participants, frequent business interactions, and large data exchange. The alliance chain technology in blockchain technology has become an important basis for the research of this paper because of its native support for multi-party business scenarios. Based on the alliance blockchain technology, this paper designs a multi-channel data isolation scheme for the grid dispatching control business to achieve efficient data sharing within a controllable range. At the same time, in order to ensure the security of the private data in the grid dispatching control business in the business interaction process. Furthermore, this paper designs a business interaction process for private data based on the zero-knowledge verification algorithm. Combined with smart contract technology, it automatically completes the entire network verification process of data encryption and zero-knowledge credentials, and realizes data security interaction in secret scenarios.
Sarfraz Fayaz Khan, Sumit Kumar, Ramya Govindaraj, Sagar Dhanraj Pande
The bulk of blockchain-based identity authentication solutions are developed on public blockchain platforms, which still use centralized identity management and verification methodologies, making it difficult for microgrids to satisfy their demands for trusted access and fine-grained access control. As a result, a distributed identity authentication system capable of supporting multi-center operations is created using the FISCO BCOS alliance’s blockchain technology. To enable autonomous control of user identification, DID-based identity management protocol is developed; the distribution of terminal nodes in the micronetwork is also explored. It creates a zero-knowledge proof-based privacy-protecting credential. It establishes an open, transparent, and credible underlying identity architecture for users and upper-layer apps, ensuring that users’ trustworthy and verifiable identities are protected in a variety of privacy and security circumstances. It enables autonomous identity management, fine-grained access control, and secure data interchange. System trials and performance analysis demonstrate the intended system’s usability and effectiveness.
With the increasingly stringent regulatory requirements for data security all around the world, advanced privacy preserving data protection strategies and corresponding secure computation protocols are in urgent needs. The traditional methods for original data transaction and processing may conflict with the data regulation and laws. Thus, the object of data transaction nowadays is no longer the original data, but the encapsulated data services, which seal and combine various computing models and protocols that operate on local data. This paper concludes the cryptography based secure computation protocols including proxy re-encryption (PRE), multiparty computation (MPC), and zero-knowledge proof protocol ($ZK$), then organizes these protocols into smart contract-based layers on blockchain to support verifiable credentials and presentations, authorization-based data re-encryption, and MPC-based data secure computation as well as aggregations with$ZK$property.
Blockchain-based implementations of non-fungible tokens represent ownership of specific digital objects and are indivisible, irreplaceable and unique. However, there are currently two problems: 1) Due to the low throughput rate of the blockchain system, it cannot meet the needs of large-scale scenarios of non-fungible tokens assets. As the core technology of blockchain scaling, Layer2 has become an important factor affecting the performance of blockchain. 2) The current liquidity mechanism of non-fungible tokens greatly limits its liquidity. Therefore, this paper combines cryptographic zero-knowledge proof technology with off-chain scaling technology to design and implement a system architecture that can significantly improve the liquidity of non-fungible tokens. Firstly, this paper proposes a zk-rollup based off-chain scaling architecture RBHLT, on top of which a high liquidity protocol for non-fungible tokens is implemented. Analysis and experimental results show that RBHLT enables higher liquidity of non-fungible tokens while reducing transaction costs.
Blockchain Technology Applications and Security
Cloud Data Security Solutions
Advanced Steganography and Watermarking Techniques
Cryptocurrencies such as Bitcoin and Ethereum achieve decentralized payment by maintaining a globally distributed and append-only ledger. Recently, several researchers have sought to achieve privacy-preserving auditing, which is a crucial function for scenarios that require regulatory compliance, for decentralized payment systems. However, those proposed schemes usually cost much time for the cooperation between the auditor and the user due to leveraging complex cryptographic tools such as zero-knowledge proof. To tackle the problem, we present T-PPA, a privacy-preserving decentralized payment system, which provides customizable and efficient auditability by leveraging trusted execution environments (TEEs). T-PPA demands the auditor construct audit programs based on request and execute them in the TEE to protect the privacy of transactions. Then, identity-based encryption (IBE) is employed to construct the separation of power between the agency nodes and the auditor and to protect the privacy of transactions out of TEE. The experimental results show that T-PPA can achieve privacy-preserving audits with acceptable overhead.
Stefano Marzo, Royston Pinto, Lucy McKenna, Rob Brennan
Federated learning (FL) is a distributed machine learning<br> approach that enables remote devices i.e. workers to collaborate to compute<br> the fitting of a neural network model without sharing their data.<br> While this method is favorable to ensure data privacy, an imbalanced<br> data distribution can introduce unfairness in the model training, causing<br> discriminatory bias towards certain under-represented groups. In this paper,<br> we show that imbalance federated data decreases indexes of equity<br> i.e. differences in treatment for underrepresented classes. To address the<br> problem, we propose a federated learning framework called Z-Fed that 1)<br> balances the training without exchange of privacy protected data using<br> a zero knowledge proof (ZKP) technique, and 2) allows for the collection<br> of information on data distributions based on one or more categorical<br> features to produce metadata about population proportions. The proposed<br> framework infers the precise data distribution without exchanging<br> knowledge of the data categories and uses it to coordinate a balanced<br> training set. Z-Fed aims to mitigate the effect of imbalanced data in<br> FL while respecting privacy and without using mediators or probabilistic<br> approaches. Compared to a non-balanced framework, Z-Fed improves<br> fairness and equality measured in equal opportunities (EPD) by 53.54%,<br> equal odds (EOD) by 56.41%, and statistical parity (SPD) by 46.1% on<br> imbalanced UTK datasets, reducing biased predictions among subgroups.<br> EPD, EOD, and SPD measure the disparity of treatment between privileged<br> e.g. over-represented and non-privileged groups. Given the results<br> obtained, Z-Fed can reduce discriminatory behaviors and enhance trustworthy<br> of federated learning.
Open access
2 source records
Privacy-Preserving Technologies in Data
Imbalanced Data Classification Techniques
Artificial Intelligence in Healthcare and Education
Interactive proofs (IPs) and arguments are cryptographic protocols that enable an untrusted prover to provide a guarantee that it performed a requested computation correctly. Introduced in the 1980s, IPs and arguments represented a major conceptual expansion of what constitutes a “proof” that a statement is true. Traditionally, a proof is a static object that can be easily checked step-by-step for correctness. In contrast, IPs allow for interaction between prover and verifier, as well as a tiny but nonzero probability that an invalid proof passes verification. Arguments (but not IPs) even permit there to be “proofs” of false statements, so long as those “proofs” require exorbitant computational power to find. To an extent, these notions mimic in-person interactions that mathematicians use to convince each other that a claim is true, without going through the painstaking process of writing out and checking a traditional static proof. Celebrated theoretical results from the 1980s and 1990s such as IP = PSPACE and MIP = NEXP showed that, in principle, surprisingly complicated statements can be verified efficiently. What is more, any argument can in principle be transformed into one that is zero-knowledge, which means that proofs reveal no information other than their own validity. Zero-knowledge arguments have a myriad of applications in cryptography. Within the last decade, general-purpose zero-knowledge arguments have made the jump from theory to practice. This has opened new doors in the design of cryptographic systems, and generated additional insights into the power of IPs and arguments (zero-knowledge or otherwise). There are now no fewer than five promising approaches to designing efficient, general-purpose zero-knowledge arguments. This survey covers these approaches in a unified manner, emphasizing commonalities between them.
This paper presents a new method for quantum identity authentication (QIA) protocols. The logic of classical zero-knowledge proofs (ZKPs) due to Schnorr is applied in quantum circuits and algorithms. This novel approach gives an exact way with which a prover $P$ can prove they know some secret by encapsulating it in a quantum state before sending to a verifier $V$ by means of a quantum channel - allowing for a ZKP wherein an eavesdropper or manipulation can be detected with a fail-safe design. This is achieved by moving away from the hardness of the Discrete Logarithm Problem towards the hardness of estimating quantum states. This paper presents a method with which this can be achieved and some bounds for the security of the protocol provided. With the anticipated advent of a `quantum internet', such protocols and ideas may soon have utility and execution in the real world.
Open access
2 source records
Physical Unclonable Functions (PUFs) and Hardware Security
E-voting plays a vital role in guaranteeing and promoting social fairness and democracy. However, traditional e-voting schemes rely on a centralized organization, leading to a crisis of trust in the vote-counting results. In response to this problem, researchers have introduced blockchain to realize decentralized e-voting, but the adoption of blockchain also brings new issues in terms of flexibility, anonymity, and usability. To this end, in this paper, we propose WeVoting, which provides weight-based flexibility with solid anonymity and enhances usability by designing a voter-independent on-chain counting mechanism. Specifically, we use distributed ElGamal homomorphic encryption and zero-knowledge proof to achieve voting anonymity with weight. Besides, WeVoting develops a counter-based counting mechanism to enhance usability compared with those self-tallying schemes. By critically designing an honesty-and-activity-based incentive algorithm, WeVoting can guarantee a correct counting result even in the presence of malicious counters. Our security and performance analyses elaborate that WeVoting achieves high anonymity in weighed voting under the premise of meeting the basic security requirements of e-voting. And meanwhile, its counting mechanism is sufficient for practical demands with reasonable overheads.
Machine Learning as a Service is a promising service for individuals and companies who would like to delegate model training to third parties. The customers desire proof of the integrity of the model training to prevent potential backdoor attacks launched by the server, while the server desires to prove the integrity without revealing their intellectual assets, hyper-parameters of the training scheme. Zero-knowledge proof, a cryptographic tool can theoretically satisfy the above demand, but is still practically infeasible due to the inefficiency of proving. Thus, we propose zkMLaaS, a privacy-preserving and verifiable scheme for efficient training proof generation in the MLaaS scenario. zkMLaaS features a two-round challenge-response pro-tocol equipped with the random sampling. This greatly reduces the time cost of proof generation and ensures the integrity of training procedure simultaneously. We analyze the security of zkMLaaS and conduct comprehensive evaluation which shows it saves around$273\times$times compared with naive scheme.
Abstract The generation of the pseudonym in vehicular ad hoc networks (VANETs) usually requires the participation of a trusted center (TA), and it needs multiple interactions with the TA. To address these problems, we propose a novel traceable self-generated pseudonym based on the non-interactive zero-knowledge proof (NIZK) and consortium blockchain in VANETs. In our scheme, a self-generated pseudonyms method is introduced to eliminate excessive communication burden, and a consortium blockchain is composed of multiple roadside units (RSUs) to replace the TA. RSUs in the consortium blockchain verify the effectiveness of OBU’s self-generated pseudonyms through the consensus mechanism. Multiple trace authorities (TRAs) are designed to jointly tracking of the real identity of the OBU, which effectively prevents the abuse of supervision by the only supervisor.
<p>Cloud storage provides convenience in managing data for users. Data integrity becomes important because data owner (DO) loses control of their data once it is uploaded to the cloud server (CS). Public auditing is used to check data integrity in cloud storage. Traditional public auditing schemes introduce a third-party auditor (TPA) to help users check their data. However, TPA is assumed to be trusted in these schemes, which may not be practical. A dishonest TPA may provide a good report to DO without executing the auditing task timely. If the data loss could not be detected timely, it may cause a great loss to DO. In this paper we aim to solve these problems using blockchain technique. In our scheme DO, TPA and CS interact with blockchain via smart contracts. We utilize a time-locked deposit smart contract to incentive TPA and CS for their fulfillment in the auditing task honestly. Otherwise, they would be amerced. We use storage smart contracts to ensure the auditing process transparency, and utilize zero-knowledge proof to protect DO&rsquo;s privacy. The scheme is extended to support batch auditing to reduce the user&rsquo;s cost. Experimental results show that our scheme is efficient and practical.</p> <p>&nbsp;</p>
With the demand for security, the Internet companies and institutions have formed independent trust domains by utilizing different cryptographic settings, which brings up the problem of cross-domain authentication. To solve the cross-domain authentication problem, researchers have proposed many schemes that can be divided into two categories: centralized and blockchain-based. However, the challenges of privacy leakage, low efficiency, and incomplete cross-domain have not been effectively overcome in existing schemes. In this paper, we propose a Blockchain-based Privacy-preserving scheme for Cross-Domain Authentication (BPCDA). To realize complete cross-domain, the blockchain is introduced for building trust between different domains. For lightweight management, the Pedersen Commitment is adopted for identity voucher generation. In addition, the Non-Interactive Zero-Knowledge (NIZK) proof algorithm is utilized for mutual and anonymous authentication. The security analysis and the performance evaluation demonstrate that the proposed BPCDA is secure, privacy-preserving, and efficient.
Dec 1, 2022·2022 IEEE 24th Int Conf on High Performance Computing & Communications; 8th Int Conf on Data Science & Systems; 20th Int Conf on Smart City; 8th Int Conf on Dependability in Sensor, Cloud & Big Data Systems & Application (HPCC/DSS/SmartCity/DependSys)
Mobile communication technology has facilitated the rapid spread of convenient mobile payments. Leading third-party payment platforms (TPPs) such as Alipay, Paypal, and Wexpay, have launched popular mobile payment services. However, TPPs-led centralized mobile payments increase the risk of single-point failure and the leakage of user privacy. In this paper, we propose a blockchain-based decentralized privacy-preserving mobile payment scheme by utilizing threshold anonymous credentials. The integration of the blockchain and threshold cryptography technology enables mobile payment to possess fault tolerance for malicious attacks. Additionally, we leverage Pedersen commitments and zero-knowledge proofs to prevent users' sensitive transaction information from being leaked to curious entities on the transparent blockchain. Through performance analysis, we make clear that users in the proposed scheme have low computation overhead and storage costs in the payment process, and can adopt flexible payment strategies to execute micro-payments and large payments.
Shambhavi Balamuthu Sampath, M Sanjay, Numan Ahmed, Adi Bhagavath · 5 authors
Human dignity demands that personal information be hidden. Currently, due to the dominance of large internet companies/cloud service providers, the control over the identity is not with the identity holder, leading to privacy concerns. The need for decentralization of identity is because it gives back control of identity credentials to identity holders and allows them to control when, how, and with whom to share their credentials. Self-sovereign Identity is an arising concept, which provides a way for digital identification. It enables the entities to control their identity and data flow in the digital world while enhancing privacy and security. Major privacy concerns are because of the numerous attacks and data breaches that can happen when sensitive information like identity credentials is stored on a centralized system used by the existing systems. Therefore, we propose a blockchain based self-sovereign identity platform where the user’s mobile wallet application. The proof of the Identity credentials are kept in a decentralised storage system based on the blockchain. This platform provides a Zero-Knowledge Proof (ZKP) mechanism to verify the information.
Stefan More, Sebastian Ramacher, Lukas Alber, Marco Herzl
Authentication, authorization, and trust verification are central parts of an access control system. The conditions for granting access in such a system are collected in access policies. Since access conditions are often complex, dedicated languages -- policy languages -- for defining policies are in use. However, current policy languages are unable to express such conditions having privacy of users in mind. With privacy-preserving technologies, users are enabled to prove information to the access system without revealing it. In this work, we present a generic design for supporting privacy-preserving technologies in policy languages. Our design prevents unnecessary disclosure of sensitive information while still allowing the formulation of expressive rules for access control. For that we make use of zero-knowledge proofs (NIZKs). We demonstrate our design by applying it to the TPL policy language, while using SNARKs. Also, we evaluate the resulting ZK-TPL language and its associated toolchain. Our evaluation shows that for regular-sized credentials communication and verification overhead is negligible.