Proofs are powerful tools for integrity and privacy, enabling the verifier to delegate a computation and still verify its correct execution, and enabling the prover to keep the details of the computation private. Both CCP and ZKP can achieve soundness and zero-knowledge but with important differences. CCP relies on hardware trust assumptions, which yield high performance and additional confidentiality protection for the prover but may be unacceptable for some applications. CCP is also often easier to use, notably with existing code, whereas ZKP comes with a large prover overhead that may be unpractical for some applications.
Condorcet voting is widely regarded as one of the most important voting systems in social choice theory. However, it has seen little adoption in practice, due to complex tallying and the need to break ties when there is a Condorcet cycle. Several online Condorcet voting systems have been developed to perform digital tallying and tie-breaking procedures, but they require voters to completely trust the server. Additionally, many end-to-end (E2E) verifiable e-voting systems require trustworthy authorities to perform complex decryption and tallying operations. We propose VERICONDOR, the first E2E verifibbolable Condorcet e-voting system without tallying authorities. VERICONDOR allows a voter to fully verify the tallying integrity by themselves while providing strong protection of ballot secrecy. We present novel zero-knowledge proof techniques to prove the well-formedness of an encrypted ballot with exceptional efficiency. VERICONDOR supports ranking candidates with strict preference, as well as indifference. The computational cost is exceptionally efficient for strict preferences at \(\mathcal{O}(n^{2})\) per ballot for \(n\) candidates, while remaining practical for indifferences at \(\mathcal{O}(n^{3})\) . In the case of ties, we show how to apply known Condorcet methods to break them in a publicly verifiable manner. Finally, we present a proof of concept implementation and evaluate its performance.
Abstract High voter turnout in elections and referendums is desirable to ensure a robust democracy. Secure electronic voting is a vision for the future of elections and referendums. Such a system can counteract factors hindering strong voter turnout such as the requirement of physical presence during limited hours at polling stations. However, this vision brings transparency and confidentiality requirements that render the design of such solutions challenging. Specifically, the counting implementation must support reproducibility, and the choice of individual voters must remain confidential. In this paper, we propose and evaluate a novel referendum protocol that ensures transparency, confidentiality, and integrity, in trustless networks. The protocol is built by combining secure multi-party computation and distributed ledger technology, e.g., a Blockchain. The persistence and immutability of the protocol communication allow verifiability of the referendum outcome by any participant. Voters therefore do not need to trust third parties. We provide a formal description and conduct a thorough security evaluation of our proposal.
Tatami puzzles are pencil puzzles with an objective to partition a rectangular grid into rectangular regions such that no four regions share a corner point, as well as satisfying other constraints. In this paper, we develop a physical card-based protocol called Tatami printer that can help verify solutions of Tatami puzzles. We then use the Tatami printer to construct zero-knowledge proof protocols for two such puzzles: Tatamibari and Square Jam. These protocols enable a prover to show a verifier the existence of the puzzles' solutions without revealing them.
Zero-Knowledge Proofs (ZKPs) are cryptographic tools that enables one party, known as the prover, to prove to another party, the verifier, that a certain statement is true without revealing any information beyond the validity of the statement itself. We introduce the Neutrosophic One-Round Zero-Knowledge Proof protocol (N-1-R) ZKP, which is an extension of the One-Round (1-R) ZKP in the realm of Neutrosophic numbers. The N-1-R ZKP is the first Neutrosophic ZK protocol.
Federated Learning (FL) has become a transformative approach in machine learning, allowing decentralized training of models across multiple devices while preserving data privacy. This paradigm addresses critical concerns related to data privacy, security, and communication overhead, making it particularly relevant for applications in domains such as healthcare, finance, and the Internet of Things (IoT). Resource-constrained FL extends this concept to environments where computational, communication, and energy resources are limited, such as edge networks and IoT devices. This extension focuses on optimizing various aspects of the learning process to enable effective model training even in resource-limited settings. The primary aim of this survey is to provide a comprehensive and structured overview of the current state of research in FL and resource-constrained FL. By examining 62 key publications, this survey synthesizes insights and developments across these domains, highlighting advancements, challenges, and gaps that exist. This survey aims to provide a holistic view of the advancements and ongoing challenges in FL and resource-constrained FL. It identifies research gaps and proposes future directions, such as improving communication efficiency, developing adaptive learning algorithms, and enhancing resource management strategies. This survey serves as a valuable resource for researchers, practitioners, and stakeholders in the field, offering practical insights and guiding future exploration and innovation in FL and its applications in resource-constrained environments.
Zero-Knowledge Proofs (ZKPs) are an emergent paradigm in verifiable computing. In the context of applications like cloud computing, ZKPs can be used by a client (called the verifier) to verify the service provider (called the prover) is in fact performing the correct computation based on a public input. A recently prominent variant of ZKPs is zkSNARKs, generating succinct proofs that can be rapidly verified by the end user. However, proof generation itself is very time consuming per transaction. Two key primitives in proof generation are the Number Theoretic Transform (NTT) and Multi-scalar Multiplication (MSM). These primitives are prime candidates for hardware acceleration, and prior works have looked at GPU implementations and custom RTL. However, both algorithms involve complex dataflow patterns -- standard NTTs have irregular memory accesses for butterfly computations from stage to stage, and MSMs using Pippenger's algorithm have data-dependent memory accesses for partial sum calculations. We present SZKP, a scalable accelerator framework that is the first ASIC to accelerate an entire proof on-chip by leveraging structured dataflows for both NTTs and MSMs. SZKP achieves conservative full-proof speedups of over 400$\times$, 3$\times$, and 12$\times$ over CPU, ASIC, and GPU implementations.
Secure data exchange has become a critical requirement for modern intelligent systems that operate across distributed and heterogeneous environments. As artificial intelligence applications increasingly rely on collaborative data sharing among organizations, devices, and platforms, ensuring trust, integrity, and privacy in the exchanged information becomes a fundamental challenge. Traditional centralized security mechanisms often fail to provide sufficient transparency and tamper resistance, especially when multiple stakeholders with varying trust levels are involved. Blockchain technology, with its decentralized ledger architecture and cryptographic validation mechanisms, offers a promising solution to address these issues. This research proposes a trust-aware intelligent systems framework that leverages blockchain technology to facilitate secure and reliable data exchange across distributed intelligent environments. The framework integrates trust evaluation models with blockchain-based distributed ledgers to ensure that data transactions are verified, immutable, and traceable.
In sectors such as finance and healthcare, where data governance is subject to rigorous regulatory requirements, the exchange and utilization of data are particularly challenging. Federated Learning (FL) has risen as a pioneering distributed machine learning paradigm that enables collaborative model training across multiple institutions while maintaining data decentralization. Despite its advantages, FL is vulnerable to adversarial threats, particularly poisoning attacks during model aggregation, a process typically managed by a central server. However, in these systems, neural network models still possess the capacity to inadvertently memorize and potentially expose individual training instances. This presents a significant privacy risk, as attackers could reconstruct private data by leveraging the information contained in the model itself. Existing solutions fall short of providing a viable, privacy-preserving BRFL system that is both completely secure against information leakage and computationally efficient. To address these concerns, we propose Lancelot, an innovative and computationally efficient BRFL framework that employs fully homomorphic encryption (FHE) to safeguard against malicious client activities while preserving data privacy. Our extensive testing, which includes medical imaging diagnostics and widely-used public image datasets, demonstrates that Lancelot significantly outperforms existing methods, offering more than a twenty-fold increase in processing speed, all while maintaining data privacy.
A health record is a crucial component of patient follow-up, encompassing healthcare professionals' observations, prescriptions, diagnoses, and all relevant data about the patient. Multiple stakeholders—including the patient, doctor, and pharmacist—are involved in the management and sharing of this record. Electronic Medical Records (EMRs) can be accessed by authorized individuals from anywhere, facilitating the sharing of information among various healthcare providers. However, this sharing process requires strict security and confidentiality measures. Current medical systems face challenges such as potential system failures and malicious attacks, which can undermine service reliability. Additionally, managing centralized access control can be difficult. This paper introduces SEMRAchain, a system integrating role-based access control (RBAC), attribute-based access control (ABAC), and smart contracts. This combination enables decentralized, fine-grained, and dynamic access management for EMR systems. By leveraging blockchain technology as a secure distributed ledger, SEMRAchain offers stakeholders not only visibility but also trustworthiness, credibility, and immutability.
A cryptocurrency is a digital currency that enables online transactions for various products and services. Cryptocurrencies are deployed over public blockchains which have the transactions duplicated and dispersed across multiple nodes within a computer network. This decentralized mechanism is devised in order to achieve reliability in a network consisting of unreliable nodes. Privacy, anonymity and security have become crucial in this context. For that reason, formal and mathematical approaches are gaining popularity in order to guarantee the correctness of the cryptocurrency implementations. Mimblewimble is a privacy-oriented cryptocurrency technology which provides security and scalability properties that distinguish it from other protocols of its kind. Mimblewimble combines confidential transactions, CoinJoin and cut-through to achieve a higher level of privacy and security, as well as, scalability. In this work, we present and discuss these security properties and outline the basis of a model-driven verification approach to address the certification of the correctness of the protocol implementations. In particular, we propose an idealized model that is key in the described verification process. Then, we identify and precisely state the conditions for our model to ensure the verification of relevant security properties of Mimblewimble. In addition, we analyze the Grin and Beam implementations of Mimblewimble in their current state of development. We present detailed connections between our model and their implementations regarding the Mimblewimble structure and its security properties. Finally, we analyze the Litecoin soft-fork that enhances privacy over the blockchain based on Mimblewimble features.
ABSTRACT The healthcare industry has undergone a digital transformation in recent years, with the adoption of electronic health records (EHRs) becoming increasingly prevalent. While this digitization offers various advantages, concerns regarding the security and privacy of sensitive medical data have also intensified. Data breaches and cyber‐attacks targeting healthcare organizations have underscored the need for robust solutions to protect patient data. Blockchain technology has emerged as a promising solution due to its decentralized and immutable nature, which ensures secure and transparent data recording. This paper proposes a novel approach that combines blockchain with advanced encryption scheme and privacy protection technique to establish a secure and privacy protected medical data sharing environment. The proposed system consists of three phases such as initialization phase, data processing phase, and authentication phase. The hybrid Feistal‐Shannon homomorphic encryption algorithm (HFSHE) is proposed to encrypt the medical data to ensure data confidentiality, integrity, and availability. Ring signature is integrated to the system to provide additional anonymity and protect the identities of the participants involved in data transactions. In addition, the smart contract developed performs authentication checks on users, generates a time seal, and verifies the ring signature. Through this enhancement, the system becomes more resilient to both external and internal threats, enhancing overall security as well as privacy. A comprehensive security analysis is conducted to compare the proposed method's performance against existing techniques. The results demonstrate the effectiveness of the proposed approach in safeguarding sensitive medical information within the blockchain ecosystem.
José Manuel Bernabé Murcia, Eduardo Cánovas, Jesús García-Rodríguez, Alejandro Molina Zarca · 5 authors
The adoption of the Computing Continuum is characterised by the seamless integration of diverse computing environments and devices. In this dynamic landscape, sharing resources across the continuum is becoming a reality and security must move an step forward, specially in terms of authentication and authorisation for such a distributed and heterogeneous environments. The need for robust identity management is paramount and, in this regard, Decentralised Identity Management (DIM) emerges as a promising solution. It leverages decentralised technologies to secure and facilitate identity interactions across the Computing Continuum. Particularly, to enhance security and privacy, it would be desirable to apply the principles of Self-Sovereign Identity (SSI). In this paradigm, users have full ownership and control of their digital identities that empowers individuals to manage and share their identity data on a need-to-know basis. These mechanisms could contribute to improve security properties during continuum resource management operations. In this context, this paper presents the design, workflows and implementation of a solution that provides authentication/authorisation features to distributed zero-trust based infrastructures across the continuum, enhancing security in resource sharing and resource acquisition stages. To this aim, the solution relies on key aspects like decentralisation, interoperability, trust management and privacy-enhancing capabilities. The decentralisation leverages distributed ledger technologies, such as blockchain, to establish a decentralised identity ecosystem. The solution prioritises interoperability, enabling nodes to seamlessly access and share their identities across different domains and environments. Trustworthiness is at the core of DIM, and privacy is also considered, incorporating privacy-preserving techniques that individuals to selectively disclose identity attributes while safeguarding sensitive information. The implementation includes different operations for allowing continuum frameworks to be enhanced with decentralised authentication and authorisation features. The performance has been evaluated measuring the impact for the adoption of the solution. The most expensive task, the self-identity generation, takes only a few seconds (in our deployment) and it is only executed once. Authorisation tasks operate in the millisecond range, which is a totally invaluable time if incorporated into resource acquisition processes in frameworks such as Liqo, used in the scope of FLUIDOS project.
Mochan Fan, Zhipeng Zhang, Zonghang Li, Gang Sun · 7 authors
Vertical Federated Learning (VFL), which draws attention because of its ability to evaluate individuals based on features spread across multiple institutions, encounters numerous privacy and security threats. Existing solutions often suffer from centralized architectures, and exorbitant costs. To mitigate these issues, in this paper, we propose SecureVFL, a decentralized multi-party VFL scheme designed to enhance efficiency and trustworthiness while guaranteeing privacy. SecureVFL uses a permissioned blockchain and introduces a novel consensus algorithm, Proof of Feature Sharing (PoFS), to facilitate decentralized, trustworthy, and high-throughput federated training. SecureVFL introduces a verifiable and lightweight three-party Replicated Secret Sharing (RSS) protocol for feature intersection summation among overlapping users. Furthermore, we propose a (42)-sharing protocol to achieve federated training in a four-party VFL setting. This protocol involves only addition operations and exhibits robustness. SecureVFL not only enables anonymous interactions among participants but also safeguards their real identities, and provides mechanisms to unmask these identities when malicious activities are performed. We illustrate the proposed mechanism through a case study on VFL across four banks. Finally, our theoretical analysis proves the security of SecureVFL. Experiments demonstrated that SecureVFL outperformed existing multi-party VFL privacy-preserving schemes, such as MP-FedXGB, in terms of both overhead and model performance.
This study proposes a blockchain-based system that utilizes fully homomorphic encryption to provide data security and statistical privacy when data are shared with third parties for analysis or research purposes. The proposed system not only provides security of data in transit, at rest, and in use but also assures privacy and computational integrity for simple statistical computations. This is achieved by leveraging the attributes of the blockchain technology, which provides availability and data integrity, combined with homomorphic encryption, which provides confidentiality of data in use. The computations are performed on smart contracts residing on the blockchain, providing computational integrity. The proposed system is implemented on the Zama blockchain and performs statistical operations including mean, median, and variance on encrypted data. The results indicate that it is possible to perform fully homomorphic computations on the blockchain. Even though current computing limitations on the blockchain do not allow running the system for large data sets, the technology is available, and with advancements toward more efficient homomorphic operations on blockchains, the proposed system will provide an ultimate solution for providing the much-desired security properties in applications, including data and statistical privacy, confidentiality, and integrity at rest, in transit, and in use.
Federated Learning (FL) addresses the challenges posed by data silos, which arise from privacy, security regulations, and ownership concerns. Despite these barriers, FL enables these isolated data repositories to participate in collaborative learning without compromising privacy or security. Concurrently, the advancement of blockchain technology and decentralized applications (DApps) within Web 3.0 heralds a new era of transformative possibilities in web development. As such, incorporating FL into Web 3.0 paves the path for overcoming the limitations of data silos through collaborative learning. However, given the transaction speed constraints of core blockchains such as Ethereum (ETH) and the latency in smart contracts, employing one-shot FL, which minimizes client-server interactions in traditional FL to a single exchange, is considered more apt for Web 3.0 environments. This paper presents a practical one-shot FL system for Web 3.0, termed OFL-W3. OFL-W3 capitalizes on blockchain technology by utilizing smart contracts for managing transactions. Meanwhile, OFL-W3 utilizes the Inter-Planetary File System (IPFS) coupled with Flask communication, to facilitate backend server operations to use existing one-shot FL algorithms. With the integration of the incentive mechanism, OFL-W3 showcases an effective implementation of one-shot FL on Web 3.0, offering valuable insights and future directions for AI combined with Web 3.0 studies.
In the era of cloud computing, guaranteeing the safety and effectiveness of data management is of utmost importance. This investigation presents a novel approach that amalgamates the sharding concept, encryption, zero-knowledge proofs (zkp), and blockchain technology for secure data retrieval and data access control to improve data security, efficiency in cloud storage and migration. Further, we utilize user-specific digital wallets for secure encryption keys in order to encrypt the file before storing into the cloud. As Large files (greater than 50 MB) or Big data files (greater than 1 TB) require greater computational complexity, we leverage the sharding concept to enhance both space and time complexity in cloud storage. Hence, the large files are divided into shards and stored in different database servers. We also employ a blockchain smart contract to enhance secure retrieval of the file and also a secure access method, which ensures the privacy of the user. The zk-snark protocol is utilized to ensure the safe transfer of data between different cloud services. By utilizing this approach, data privacy is preserved, as only the proof of the data’s authenticity is shared with the verifier at the destination cloud, rather than the actual data themselves. The suggested method tackles important concerns related to data protection, privacy, and efficient resource utilization in cloud computing settings by ensuring it meets all the cloud policies required to store data. Since the environment maintains the privacy of the user data and the raw data of the user is not stored anywhere, the entire environment is set up as a Zero trust model.
In this study, a new data-sharing method is proposed that uses a private InterPlanetary File System—a decentralized storage system operated within a closed network—to distribute data to external entities while making its authenticity verifiable. Among the two operational modes of IPFS, public and private, this study focuses on the method for using private IPFS. Private IPFS is not open to the general public; although it poses a risk of data tampering when distributing data to external parties, the proposed method ensures the authenticity of the received data. In particular, this method applies a type of zero-knowledge proof, namely, the Groth16 protocol of zk-SNARKs, to ensure that the data corresponds to the content identifier in a private IPFS. Moreover, the recipient’s name is embedded into the distributed data to prevent unauthorized secondary distribution. Experiments confirmed the effectiveness of the proposed method for an image data size of up to 120 × 120 pixels. In future studies, the proposed method will be applied to larger and more diverse data types.
Abstract Sumplete is a logic puzzle generated by ChatGPT in March 2023. The puzzle consists of a rectangular grid, with each cell containing an integer. Each row and column also has an integer called target value assigned to it. The objective of this puzzle is to cross out some numbers in the grid such that the sum of uncrossed numbers in each row and column is equal to the corresponding target value. In this paper, we prove that Sumplete is NP-complete. We also propose a physical zero-knowledge proof protocol for the puzzle using physical cards.
Chenfei Nie, Yannan Li, Yuxin Yang, Yuede Ji · 5 authors
Federated learning (FL) is an emerging distributed learning paradigm without sharing participating clients' private data. However, existing works show that FL is vulnerable to both Byzantine (security) attacks and data reconstruction (privacy) attacks. Almost all the existing FL defenses only address one of the two attacks. A few defenses address the two attacks, but they are not efficient and effective enough. We propose BPFL, an efficient Byzantine-robust and provably privacy-preserving FL method that addresses all the issues. Specifically, we draw on state-of-the-art Byzantine-robust FL methods and use similarity metrics to measure the robustness of each participating client in FL. The validity of clients are formulated as circuit constraints on similarity metrics and verified via a zero-knowledge proof. Moreover, the client models are masked by a shared random vector, which is generated based on homomorphic encryption. In doing so, the server receives the masked client models rather than the true ones, which are proven to be private. BPFL is also efficient due to the usage of non-interactive zero-knowledge proof. Experimental results on various datasets show that our BPFL is efficient, Byzantine-robust, and privacy-preserving.
This study proposes an privacy-protection method for blockchain transactions based on lightweight homomorphic encryption, aiming to ensure the security of transaction data and user privacy, and improve transaction efficiency. We have built a blockchain infrastructure and, based on its structural characteristics, adopted zero-knowledge proof technology to verify the legitimacy of data, ensuring the authenticity and accuracy of transactions from the application end to the smart-contract end. On this basis, the Paillier algorithm is used for key generation, encryption, and decryption, and intelligent protection of blockchain transaction privacy is achieved through a secondary encryption mechanism. The experimental results show that this method performs well in privacy and security protection, with a data leakage probability as low as 2.8%, and can effectively defend against replay attacks and forged-transaction attacks. The degree of confusion remains above 0.9, with small fluctuations and short running time under different key lengths and moderate CPU usage, achieving lightweight homomorphic encryption. This not only ensures the security and privacy of transaction data in blockchain networks, but also reduces computational complexity and resource consumption, better adapting to the high-concurrency and low-latency characteristics of blockchain networks, thereby ensuring the efficiency and real-time performance of transactions.
The goal of this thesis is to verify smart contracts in Blockchain. In particular, we focus on smart contracts in Bitcoin and Solidity. In order to specify the correctness of smart contracts, we use weakest preconditions. For this, we develop a model of smart contracts in the interactive theorem prover and dependent type programming language Agda and prove the correctness of smart contracts in it. In the context of Bitcoin, our verification of Bitcoin scripts consists of non-conditional and conditional scripts. For Solidity, we refer to programs using object-oriented features of Solidity, such as calling of other contracts, full recursion, and the use of gas in order to guarantee termination while having a Turing-complete language. We have developed a simulator for Solidity-style smart contracts. As a main example, we executed a reentrancy attack in our model. We have verified smart contracts in Bitcoin and Solidity using weakest precondition in Agda. Furthermore, Agda, combined with the fact that it is a theorem prover and programming language, allows the writing of verified programs, where the verification takes place in the same language in which the program is written, avoiding the problem of translation from one language to another (with possible translation mistakes).