Individuals and organizations are using databases to store personal information at an unprecedented rate. This creates a quandary for data providers. They are responsible for protecting the privacy of individuals described in their database. On the other hand, data providers are sometimes required to provide statistics about their data instead of sharing it wholesale with strong assurances that these answers are correct and complete such as in regulatory filings for the US SEC and other goverment organizations. We introduce a system, ZKSQL , that provides authenticated answers to ad-hoc SQL queries with zero-knowledge proofs. Its proofs show that the answers are correct and sound with respect to the database's contents and they do not divulge any information about its input records. This system constructs proofs over the steps in a query's evaluation and it accelerates this process with authenticated set operations. We validate the efficiency of this approach over a suite of TPC-H queries and our results show that ZKSQL achieves two orders of magnitude speedup over the baseline.
The correctness and reliability of data sources are the keys to the practicality of data collected by Internet of Things (IoT) devices. Attribute-based signature (ABS) is a cryptographic primitive for users to sign with their own attributes, which can be applied to the authentication process in IoT scenarios. The attribute authority is responsible for issuing the attribute key to the user in ABS. Multiple authorities can complete attribute management tasks to avoid the threat of a single authority. However, attribute authorities need to execute multiple interactions to collaborate to generate attribute keys for users, which brings a large transmission burden. In addition, a lot of resource-constrained terminals in the IoT mostly play the role of signer or verifier in authentication protocols. The signature generation and verification algorithms often have heavy pairing and exponentiation operations. Currently, no ABS scheme takes into account the efficiency of all participating entities simultaneously. In this article, we present an aggregated anonymous key issue (AAKI) protocol to reduce the transmission burden between multiple authorities. Meanwhile, the noninteractive zero-knowledge proof aggregate exponentiation (NI-ZKPoKAE) protocol is designed to aggregate the transmitted secret values in AAKI. To reduce the computational burden of signers and verifiers, Blakley secret sharing, where the Hadamard matrix is used more efficiently to handle the$(n, n)$-threshold, is used to construct an efficient and fine-grained multiauthority ABS (EFMA-ABS) scheme. This brings high efficiency to all three types of parties involved in IoT authentication. Our above-mentioned protocols have been proven to be feasible and effective.
Internet of things (IoT) development tends to reduce the reliance on centralized servers. The zero-trust distributed system combined with blockchain technology has become a hot topic in IoT research. However, distribution data storage services and different blockchain protocols make network interoperability and cross-platform more complex. Relay chain is a promising cross-chain technology that solves the complexity and compatibility issues associated with blockchain cross-chain transactions by utilizing relay blockchains as cross-chain connectors. Yet relay chain cross-chain transactions need to collect asset information and implement asset transactions via two-way peg. Due to the release of user transaction information, there is the issue of privacy leakage. In this article, we propose a cross-chain privacy protection protocol based on the Groth16 zero-knowledge proof algorithm and coin-mixing technology, which changes the authentication mechanism and uses a combination of generating functions to map virtual external addresses in transactions. It allows fast cross-chain anonymous transactions while hiding the genuine user’s address. The experiment shows that, in a zero-trust IoT context, our scheme can effectively protect user privacy information, accomplish controlled transaction traceability operations, and guarantee cross-chain transaction security.
The two main forms of healthcare data exchange among entities are business-to-business (B2B) and business-to-customer (B2C). The former uses the electronic data interchange (EDI) technology between healthcare institutions, while the latter is usually conducted by providing web-based interfaces for patients. This research argues that both forms have inherent security and privacy weaknesses. Furthermore, patients lack appropriate transparency and control over their own Personally Identifiable Information (PII). We explore the issues of medical record exchange, analyze them and suggest appropriate solutions in the form of a new model to mitigate them. The vulnerabilities, ranging from critical to minor, include the possibility of Man-in-The-Middle (MiTM) and supply chain attacks, weak cryptography, repudiable transactions, single points of failure (SPOF), and poor access controls. A novel model will be presented in this research for healthcare data sharing which applies the best security practices. The proposed unified model will counter the listed vulnerabilities. It automates the healthcare processes in decentralized architecture by utilizing the smart contracts for B2C transactions such as medicine purchase. The model is based on the Blockchain and zero-knowledge proofs. It is made with novel controls which represent the latest advancements in cybersecurity. It has the potential of setting a new cornerstone.
Abstract: Blockchain allows users and data providers to ensure authentication, authorization and data validity with proper multi-key exchange authentication for user identity and hash key for Blockchain so that the data is not just stored but also validated each time the user access. In this paper, we apply Zero Knowledge proof to a Strong rooms using RFID Card reader and Camera module IoT systems to prove that a prover without disclosing information such as public key enhances the anonymity of Blockchain
Redento B. Recio, Erich Wolff, Ashraful Alam, Sanjeev Routray · 8 authors
… the right to be counted is a struggle for legibility, visibility, and enlisting; it is a contingent and contextual struggle to lay claims to space and infrastructure in the city. (Routray, 2022a, p. 267). As signalled in the above quote, The Right to be Counted offers a unique perspective into the tactics deployed by communities to achieve urban citizenship in India. The book is structured around eight chapters and guides the reader through an investigation of how ‘the poor respond to the contradictory intentions and goals of various state agencies by either partaking in or subverting the quotidian practices of the state’ (Routray, 2022a, p. 266). It does so by delving into the experiences of the urban poor, who are portrayed as active agents in the production of new forms of citizenship in response to calculative state governmentality. The book is theoretically solid and empirically grounded and contributes to the literature on the right to the city. Centred on the concept of ‘numerical citizenship’, the book sheds light on how the urban poor struggle to be seen and accounted for in contemporary Delhi. Numerical citizenship is ‘the systematic, protracted, and incremental political process by which the poor become entrenched in the city’ (Routray, 2022a, p. 2). It involves the struggle of the urban poor ‘to be visible, to be identified, and to be recognised, and to be made eligible for food, shelter, and basic amenities and infrastructure in the city’ (Routray, 2022a, p. 2). The urban poor's incremental efforts to become visible to the local state are characterised by complex relationships in which the urban poor sometimes operate within the purview of state calculative governmentality and sometimes challenge and subvert governmental plans. In this sense, the book offers a timely and provocative expansion of the ideas of insurgent citizenship and other forms of representation as proposed by key authors such as James Holston (2009) and Asef Bayat (2000). The book draws on ethnographic insights to develop a series of arguments regarding numerical citizenship. Against a backdrop of the daily practices and institutionalised tactics deployed by city residents, the experiences discussed in the book illustrate how bureaucratic frameworks are applied in practice and how communities respond to them. In doing so, the book reveals how communities find ways to counter technocratic visions of the city and the processes that shape urbanisation (Wolff, 2020). These community narratives serve as immersive explorations of what it means to fight for recognition and access to public services for the residents of India and, to some extent, for millions of people in the Global South. The key arguments in this ethnographically rich volume contribute to the ongoing SEED conversation series focused on scholarship from peripheralised places, unpacking the spatial politics of uneven geographies of North and South as well as bringing marginalised indigenous, racial, sexual, gendered and ‘other’ narratives to the fore. SEED, the Space for Engagement and Epistemic Diversity, is an international platform hosted within the University of Melbourne's Informal Urbanism Research Hub.1 Routray's book is an epitome of scholarly work that enriches our understanding of the multiple forms, relations and spatial politics of grassroots political agency in different parts of the globe. In what follows, we offer our collective reflections on the book and Sanjeev, as the author, responds. Using a dialogical format, our respective voices are denoted in what follows as ‘review collective (RC)’ and ‘Sanjeev Routray (SR)’. Review collective (RC): Your book draws on an ethnographic study of three state-recognised settlements and their different levels of entrenchment in the city's political landscape. There is a rich discussion of the complex negotiations undertaken by the residents to be visible and assert their numerical strength. Your choice of research sites—a jhuggi jhopri (hutments) settlement, a transit camp and a resettlement colony—provides a nuanced understanding of the varying processes that shape the built environment in Delhi. The diverse research sites offer the opportunity to explore some of the similarities and differences among the various tactics that residents adopt to navigate their precarious living conditions and engage with state authorities. Your long engagement with the residents in your research sites and other urban poor networks in India comes alive through your writing about how caste, class and gender intersect in the urban poor's struggle for citizenship. You identify Muslim women and the oppressed castes as the most vulnerable groups, both facing severe daily struggles and often having restricted means to achieve socio-political mobility. Your descriptive account also shows that, as well as being spaces of discrimination, urban informal settlements can also be emancipatory spaces. Over time, the caste-specific clustering of houses merges with the surrounding settlements, leading to a more heterogeneous community. Additionally, residents adopt a myriad of ways to break caste oppression, such as changing surnames, engaging in identity-based politics and renaming their settlements. It is important to understand better what occurs when residents set aside their caste, class, gender differences and prejudices and come together to demonstrate their numerical solidarity. When do these differences flare up and fragment the community? Sanjeev Routray (SR): The primary objective of my book was to examine how the poor incrementally secure housing and a range of citizenship entitlements in the city. I show how they assert their numerical strength and deploy various tactics and counter-tactics to be visible, identified and counted in their political struggles. So, my first goal was to zero in on social spaces that provided an analytical anchor to examine the processes and temporal dynamics of settlement, displacement and resettlement at different historical conjunctures. As I have argued in the book, the social spaces do not represent stable categories or mental abstractions, as Lefebvre has reminded us in his work (Lefebvre, 1991). Rather, as I show, these spatial settings are suffused with social relations, which both enable and constrain the entrenchment of the poor in extraordinary ways in Delhi. As the state routinely under-enumerates and arbitrarily deems a considerable segment of the poor ineligible for housing and welfare, the primary challenge is to assert numerical strength and presence from a particular cutoff date. To claim welfare entitlements, the residents challenge state enumeration procedures and carry out a multitude of documentary and inscriptive struggles in the city. In all these neighbourhoods, the poor build varied social, economic and political relationships, forge kinship ties, and initiate alliances with politicians, state officials, activists and interlocutors across the social and political spectrum. Their fundamental aim is to systematically build collective solidarity, even if it is fraught, tenuous and often contingent. Despite the above overlaps, there are differences that underpin the tactics of the poor across these spaces. As the primary struggle of jhuggi jhopri residents is to build jhuggis, gain recognition from the local state, claim welfare services, prevent demolition and demand resettlement upon demolition, the poor routinely auto-archive their individual biographies and the life histories of the communities, especially if they intersect with key social and political events in the city, so as to establish authentic presence in the city. Moreover, in the jhuggi jhopri neighbourhood, the residents invoke the memory of their neighbours and kin if state officials reject their proof documents and deem them ineligible for resettlement. While the residents of the transit camp also fight against demolitions and claim basic services, they reclassify and recategorise themselves as ‘regular’ or ‘legal’ by challenging state enunciations and categories, including ‘transitory’, ‘temporary’ and ‘illegal’ through their unique legal tactics to contest their lack of numerical entrenchment in the city. In refining my arguments about collective solidarity, I have emphasised how the poor deploy their demographic calculus as a significant tactic in their claims to housing and citizenship entitlements in general terms. I have emphasised how the tactic of demographic calculus is preeminent in the resettlement neighbourhood as the residents leverage their numerical strength to contest host populations, nominate successful electoral candidates and assert numerical presence in demonstrations. As I have emphasised in the book, the poor do not represent a homogenous category. The collective solidarity marked by bhaichara (brotherhood) and ristedari (relationships) is often disrupted over material and identity-based struggles. For instance, the dalits (oppressed communities at the bottom of the caste hierarchy) of the jhuggi jhopri neighbourhood (oppressed communities at the bottom of the caste hierarchy) often remain alienated from the upper and intermediate-caste leaders and the language of the court due to their low literacy levels. When the court made a distinction between eligible petitioners and ineligible non-petitioners and approved resettlement flats only for the petitioners, a few dalit members expressed their disappointment. They even casually demanded a return of their monetary contributions as a threat. Often the dalit residents (who carried out ‘scavenging’ and recycling work and earned the least) lacked the time and social connections to navigate the labyrinthine bureaucratic structures to demand their entitlements. Similarly, the purchasers of flats/plots in the transit camp and resettlement neighbourhoods often appropriate scarce resources due to their relative economic power and social/political connections if you compare them with the original allottees. Nevertheless, the purchasers also have a precarious existence because the state may reject their sale-purchase affidavits as legitimate documents in offering housing in the city. Thus, at key historical conjunctures, the purchasers share the vulnerabilities of residents who lack legible error-free documents. To give you another example, the intermediaries who mediate between residents, state and different actors are divided along the lines of caste, gender, class, regional origin, and so on. While they engage in significant activities that support the residents, they often foster dependencies and arbitrary exclusions in their so called ‘public dealings’. Moreover, a stark division between male and female chiefs disrupts collective solidarity in the neighbourhood. Male chiefs consistently disparage the work of female chiefs by classifying various activities in gendered terms. They label their own work as contributing to ‘development’ in the neighbourhood, whereas they regard the work of female chiefs as merely contributing to domestic dispute resolutions. At times, the residents also resort to character assassination and rumour-spreading about female intermediaries despite receiving support from them. Most importantly, the passing of the Citizenship Amendment Act in 2019 has exacerbated the divisions between Hindu and Muslim residents. 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The access control (AC) system in an IoT (Internet of Things) context ensures that only authorized entities have access to specific devices and that the authorization procedure is based on pre-established rules. Recently, blockchain-based AC systems have gained attention within research as a potential solution to the single point of failure issue that centralized architectures may bring. Moreover, zero-knowledge proof (ZKP) technology is included in blockchain-based AC systems to address the issue of sensitive data leaking. However, current solutions have two problems: (1) systems built by these works are not adaptive to high-traffic IoT environments because of low transactions per second (TPS) and high latency; (2) these works cannot fully guarantee that all user behaviors are honest. In this work, we propose a blockchain-based AC system with zero-knowledge rollups to address the aforementioned issues. Our proposed system implements zero-knowledge rollups (ZK-rollups) of access control, where different AC authorization requests can be grouped into the same batch to generate a uniform ZKP, which is designed specifically to guarantee that participants can be trusted. In low-traffic environments, sufficient experiments show that the proposed system has the least AC authorization time cost compared to existing works. In high-traffic environments, we further prove that based on the ZK-rollups optimization, the proposed system can reduce the authorization time overhead by 86%. Furthermore, the security analysis is presented to show the system's ability to prevent malicious behaviors.
WebAssembly, or WASM for short, is a binary code format for a stack-based virtual machine, first published in 2018 and now becomes a main-steam technology for providing distributed serverless functions. Recently, the demand for privacy and trustless serverless functions has started to grow in cloud, edge, and grid computation, which poses a question for those serverless function providers: what feature they need to add to make WASM runtime more secure so that the application run on top it become trustless to their users. To address this, we leverage the technology ZKSNARK (zero-knowledge Succinct Non-interactive Argument of Knowledge), a powerful proof system that allows efficient verification of the evaluation problem of statements, to give WASM runtime the ability to provide trustless computation service. More precisely, we present ZAWA, a ZKSNARK backed virtual machine that emulates the execution of WASM bytecode and generates zero-knowledge-proofs for the emulation result. The proof generated by the ZAWA virtual machine can then be used to convince an entity, with no leakage of confidential information, that the result of the emulation enforces the semantic specification of WASM.
With the advent of the era of big data, privacy computing analyzes and calculates data on the premise of protecting data privacy, to achieve data 'available and invisible'. As an important branch of secure multi-party computation, the geometric problem can solve practical problems in the military, national defense, finance, life, and other fields, and has important research significance. In this paper, we study the similarity problem of geometric graphics. First, this paper proposes the adjacency matrix vector coding method of isomorphic graphics, and use the Paillier variant encryption cryptography to solve the problem of isomorphic graphics confidentiality under the semi-honest model. Using cryptography tools such as elliptic curve cryptosystem, zero-knowledge proof, and cut-choose method, this paper designs a graphic similarity security decision protocol that can resist malicious adversary attacks. The analysis shows that the protocol has high computational efficiency and has wide application value in terrain matching, mechanical parts, biomolecules, face recognition, and other fields.
Open access
Biometric Identification and Security
Advanced Steganography and Watermarking Techniques
All users have access to the details of all transactions through the public ledger thanks to the distributed characteristics of the blockchain. However, attackers may infer the identities of the parties through detailed transaction data, and impair the privacy of users. Among these data, the transaction value is one of the most important transaction data. Therefore, for the privacy protection during blockchain transactions, this paper, based on the homomorphic encryption technology, enabled the committer peer to update the ledger during the transaction without knowing the balance of the parties’ accounts and the transaction value. Meanwhile, the zero-knowledge proof scheme was introduced. It was proved by interval range that the committer peer can verify the validity of the transaction without knowing the transaction value.
Abstract The lattice-based cryptographic accumulators, which enable short zero-knowledge arguments of membership, have numerous applications in post-quantum privacy-preserving protocols. However, most efficient quantum-safe zero-knowledge arguments are PCP-based systems and rely on non-falsifiable assumptions. For non-PCP-based constructions using the state-of-the-art techniques on compressing lattice-based zero-knowledge proofs, the concrete size of the resulting proof for accumulators with $2^{32}$ members is at least 500 KB. In this paper, we propose a compact non-PCP zero-knowledge proof for the lattice-based Merkle-tree, which leads to an efficient post-quantum cryptographic accumulator. The complexity of our construction is logarithmic in $l\cdot n_{s}$, where $l$ and $n_{s}$ denote the depth of the underlying Merkle-tree and the size of a node, respectively, and the concrete size is only $143.7\ $KB when $l=32$. In particular, we provide an improved lattice-based Bulletproof with efficient knowledge extraction, which allows large challenge space but small soundness slack. Furthermore, the amortized technique can be applied to the Bulletproof without breaking the knowledge soundness due to our improved knowledge extraction. As a direct application, we present a practical lattice-based ring signature, which can achieve logarithmical signing/verifying computational complexity with the number of the ring, while the state-of-the-art constructions (CRYPTO 21) have linear computational complexity.
Arnab Roy, Matthias Johann Steiner, Stefano Trevisani
In this paper we propose the (keyed) permutation Arion and the hash function ArionHash over $\mathbb{F}_p$ for odd and particularly large primes. The design of Arion is based on the newly introduced Generalized Triangular Dynamical System (GTDS), which provides a new algebraic framework for constructing (keyed) permutation using polynomials over a finite field. At round level Arion is the first design which is instantiated using the new GTDS. We provide extensive security analysis of our construction including algebraic cryptanalysis (e.g. interpolation and Gröbner basis attacks) that are particularly decisive in assessing the security of permutations and hash functions over $\mathbb{F}_p$. From an application perspective, ArionHash aims for efficient implementation in zkSNARK protocols and Zero-Knowledge proof systems. For this purpose, we exploit that CCZ-equivalence of graphs can lead to a more efficient implementation of Arithmetization-Oriented primitives. We compare the efficiency of ArionHash in R1CS and Plonk settings with other hash functions such as Poseidon, Anemoi and Griffin. For demonstrating the practical efficiency of ArionHash we implemented it with the zkSNARK libraries libsnark and Dusk Network Plonk. Our result shows that ArionHash is significantly faster than Poseidon - a hash function designed for zero-knowledge proof systems. We also found that an aggressive version of ArionHash is considerably faster than Anemoi and Griffin in a practical zkSNARK setting.
As zero-knowledge proofs gain increasing adoption, the cryptography community has designed domain-specific languages (DSLs) that facilitate the construction of zero-knowledge proofs (ZKPs). Many of these DSLs, such as Circom, facilitate the construction of arithmetic circuits, which are essentially polynomial equations over a finite field. In particular, given a program in a zero-knowledge proof DSL, the compiler automatically produces the corresponding arithmetic circuit. However, a common and serious problem is that the generated circuit may be underconstrained, either due to a bug in the program or a bug in the compiler itself. Underconstrained circuits admit multiple witnesses for a given input, so a malicious party can generate bogus witnesses, thereby causing the verifier to accept a proof that it should not. Because of the increasing prevalence of such arithmetic circuits in blockchain applications, several million dollars worth of cryptocurrency have been stolen due to underconstrained arithmetic circuits. Motivated by this problem, we propose a new technique for finding ZKP bugs caused by underconstrained polynomial equations over finite fields. Our method performs semantic reasoning over the finite field equations generated by the compiler to prove whether or not each signal is uniquely determined by the input. Our proposed approach combines SMT solving with lightweight uniqueness inference to effectively reason about underconstrained circuits. We have implemented our proposed approach in a tool called QED 2 and evaluate it on 163 Circom circuits. Our evaluation shows that QED 2 can successfully solve 70% of these benchmarks, meaning that it either verifies the uniqueness of the output signals or finds a pair of witnesses that demonstrate non-uniqueness of the circuit. Furthermore, QED 2 has found 8 previously unknown vulnerabilities in widely-used circuits.
César Sabater, Florian Hahn, Peter Andreas, Jan Ramon
In this paper we study verifiable sampling from probability distributions in the context of multi-party computation. This has various applications in randomized algorithms performed collaboratively by parties not trusting each other. One example is differentially private machine learning where noise should be drawn, typically from a Laplace or Gaussian distribution, and it is desirable that no party can bias this process. In particular, we propose algorithms to draw random numbers from uniform, Laplace, Gaussian and arbitrary probability distributions, and to verify honest execution of the protocols through zero-knowledge proofs. We propose protocols that result in one party knowing the drawn number and protocols that deliver the drawn random number as a shared secret.
Yuri Bespalov, Lyudmila Kovalchuk, Hanna Nelasa, Roman Oliynykov · 5 authors
Sidechains are among the most promising scalability and extended functionality solutions for blockchains. Application of zero knowledge techniques (Latus, Mina) allows for reaching high level security and general throughput, though it brings new challenges on keeping decentralization where significant effort is required for robust computation of zk-proofs. We consider a simultaneous decentralized creation of various zk-proof trees that form proof-trees sequences in sidechains in the model that combines behavior of provers, both deterministic (mutually consistent) or stochastic (independent) and types of proof trees. We define the concept of efficiency of such process, introduce its quantity measure and recommend parameters for tree creation. In deterministic cases, the sequences of published trees are ultimately periodic and ensure the highest possible efficiency (no collisions in proof creation). In stochastic cases, we obtain a universal measure of prover efficiencies given by the explicit formula in one case or calculated by a simulation model in another case. The optimal number of allowed provers’ positions for a step can be set for various sidechain parameters, such as number of provers, number of time steps within one block, etc. Benefits and restrictions for utilization of non-perfect binary proof trees are also explicitly presented.
Justice Odoom, Huang Xiao-fang, Samuel Akwasi Danso, Benedicta Nana Esi Nyarko
Recently, blockchain technology has garnered support. However, an attenuating factor to its global adoption in certain use cases is privacy-preservation owing to its inherent transparency. A widely explored cryptographic option to address this challenge has been ring signature which aside its privacy guarantee must be double spending resistant. In this paper, we identify and prove a catastrophic flaw for double-spending attack in a Lightweight Ring Signature scheme and proceed to construct a new, fortified commitment scheme using the signer’s entire private key. Subsequently, we compute a stronger key image to yield a double-spending-resistant signature scheme solidly backed by formal proof. Inherent in our solution is a novel, zero-knowledge-based, secured and cost-effective smart contract for public key aggregation. We test our solution on a private blockchain as well as Kovan testnet along with performance analysis attesting to efficiency and usability and make the code publicly available on GitHub.
Abstract In view of the node security risks and key management vulnerabilities in heterogeneous sensor networks, a key management protocol for heterogeneous sensor networks based on zero trust security and chaotic neural networks (KMPHSN-ZTSCNN) was proposed. Taking advantages of the decomposition difficulty of singular matrix and chaotic classification characteristics of Hopfield overload chaotic neural network, the node registration and authentication of sensor network were achieved by blockchain and zero-knowledge proof. The channel state information (CSI) and the adjustable mathematical function were relied on to generate a dynamically changing key to complete continuous verification and achieve zero trust security authentications, thus ensuring data security. The protocol can dynamically allocate different keyspace sizes according to the security level of the group, the storage capacity if the nodeand computing capacity and can adapt to the asymmetric structure of heterogeneous sensor networks. Theoretical proof and experimental performance analysis results show that the protocol is feasible and can meet the security requirements of heterogeneous sensor networks.
Within the context of the big data age, data sharing is gradually rising with the embodiment of data value. Data value can increase through sharing, but there are security problems during the period of data sharing such as centralized deployment, malicious theft, and tampering, which greatly affect the security of data. Aiming at the common privacy leakage problem during data sharing, this research builds a data sharing platform on the chain based on blockchain technology, and combines the function encryption technology and zero-knowledge proof technology to realize the sharing of verifiable computing results, and proposes a sharing model. The purpose of this model is to enable the data owner to control the data sharing, so as to guarantee the security and privacy of the data while sharing, ensure that the original data is not leaked, and realize the availability and invisibility of the data. In addition, it is necessary to ensure the reliability of data processing results, eliminate the risk of unreliable data processing caused by original data encryption, and protect the legal right of data users.
In this article, we propose a blockchain-based fair and privacy-preserving data trading scheme that supports fine-grained data selling. First, to achieve fairness for trading participants, by incorporating attribute-based credentials, encryption, and zero-knowledge proof, we design a data trading scheme where a buyer first publishes the required data attributes on the blockchain, and a data seller can demonstrate data availability in ciphertext by only disclosing the required attributes to a data buyer and proving the authenticity of data. A data buyer transfers funds only if the correct key material is uploaded to the blockchain. Second, to guarantee fine-grained data trading and preserve identity privacy, we build a Merkle hash tree on the ciphertexts of data with a signature on its root node, which allows a data seller to split data into blocks and remove the sensitive information from the data without affecting data availability verification. The public key of the data seller is not leaked to the data buyer during the trading. Moreover, different trading transactions from the same data seller cannot be linked. We formally prove that our scheme achieves the desired security properties: fairness and privacy preservation. Simulation results demonstrate the feasibility and efficiency of the proposed scheme.
Md Ahmad, Gautami Tripathi, Farheen Siddiqui, Mohammad Afshar Alam · 7 authors
The overwhelming popularity of technology-based solutions and innovations to address day-to-day processes has significantly contributed to the emergence of smart cities. where millions of interconnected devices and sensors generate and share huge volumes of data. The easy and high availability of rich personal and public data generated in these digitalized and automated ecosystems renders smart cities vulnerable to intrinsic and extrinsic security breaches. Today, with fast-developing technologies, the classical username and password approaches are no longer adequate to secure valuable data and information from cyberattacks. Multi-factor authentication (MFA) can provide an effective solution to minimize the security challenges associated with legacy single-factor authentication systems (both online and offline). This paper identifies and discusses the role and need of MFA for securing the smart city ecosystem. The paper begins by describing the notion of smart cities and the associated security threats and privacy issues. The paper further provides a detailed description of how MFA can be used for securing various smart city entities and services. A new concept of blockchain-based multi-factor authentication named "BAuth-ZKP" for securing smart city transactions is presented in the paper. The concept focuses on developing smart contracts between the participating entities within the smart city and performing the transactions with zero knowledge proof (ZKP)-based authentication in a secure and privacy-preserved manner. Finally, the future prospects, developments, and scope of using MFA in smart city ecosystem are discussed.