From the earliest markets to today’s globally interconnected economies, exchanging money has been a defining feature of civilization. While historically centralized institutions have been in charge of securing and finalizing transactions, the advent of Bitcoin has marked the birth of decentralized finance. In this new paradigm, trust is no longer placed in a specific government, institution or corporation, but instead on mathematical proofs, protocol design and cryptographic assumptions. In an ever increasingly multipolar world - where financial censorship and transaction surveillance are becoming common coercion tools - the appeal of uncensorable money continues to grow. While a variety of decentralized financial systems exist, their interoperability remains a critical challenge. In this thesis, we study existing solutions and propose new methods for cross-system assets exchange. We first examine how to realize secure peer-to-peer (P2P) asset exchange protocols between two users. Such a task can be accomplished by a class of blockchain protocols known as atomic swaps, and we highlight the limitations of solutions that either require the underlying blockchain to support scripting or rely on a computionally intensive cryptographic primitive known as timelock puzzles. In order to improve on the current state of the art, we identify and propose a natural and minimal blockchain functionality called commit transactions, which we show to be sufficient to realize generic atomic swaps protocols. We next investigate how multiple users can establish a decentralized exchange service. Building on top of the traditional liquidity pool setting, we describe a system that extends to a cross-chain environment. We provide a costruction that, under an assumed setup mechanism, realizes an universal exchange protocol. Finally, we explore how such solutions can be realized in the most challenging setting of private and anonymous systems. Specifically, we focus into achieving compability with the most commonly traded private cryptocurrency, Monero. We propose a modifications to adapt Monero’s transaction scheme, ring confidential transactions (RingCT), to the newly proposed atomic swap protocol.
Florian Hirner, Florian Krieger, Constantin Piber, Sujoy Sinha Roy
Zero-knowledge proofs (ZKPs) are cryptographic protocols that enable one party to prove the validity of a statement without revealing any information beyond its truth. Central building blocks in many ZKPs are polynomial commitment schemes (PCS) where constructions with linear-time provers are especially attractive. Two such examples are Brakedown and its extension Orion, which enable linear-time and quantum-resistant proving by leveraging linear-time encodable Spielman codes. However, these PCS operate over large datasets, creating significant computational bottlenecks. For example, committing to and proving a degree 228 polynomial requires around 1.1 GB of data while taking 463 seconds on a high-end server CPU.This work addresses the performance bottleneck in Orion-like PCS by optimizing their most critical operations: Spielman encoding and Merkle commitments. These operations involve Gigabytes of data and suffer from random off-chip memory access patterns that drastically reduce off-chip bandwidth. We resolve this issue and introduce inverted expander graphs to eliminate random writes and reduce off-chip memory accesses by over 50%. Additionally, we propose an on-the-fly graph sampling method that avoids streaming large auxiliary data by generating expander graphs dynamically on-chip. We also provide a formal security proof for our proposed graph transformation. Beyond encoding, we accelerate Merkle Tree construction over large data sets through a scalable multi-pass SHA3 pipeline. Finally, we reutilize existing hardware components used in commitment to accelerate the so-called proximity and consistency checks during proof generation.Building upon these concepts, we present the first hardware architecture for PCS – with linear prover time – on an Xilinx Alveo U280 FPGA. In addition, we discuss the practical challenges of manually partitioning, placing, and routing our large-scale architecture to efficiently map it to the multi-SLR and HBM-equipped FPGA. The final implementation achieves a speedup of two orders of magnitude for full proof generation, covering commitment and proving steps. When combined with Virgo as an outer CP-SNARK protocol, our accelerator reduces end-to-end latency by up to 3.85x – close to the theoretical maximum of 3.9x.
This paper proposes a framework that integrates zero-knowledge proofs (ZKPs) and verifiable credentials (VCs) to achieve the synergistic optimization of transaction privacy and trusted identity authentication. First, a pseudonymous transaction protocol based on zk-SNARKs (zero-knowledge succinct non-interactive arguments of knowledge) is designed. The R1CS constraint system is used to construct a circuit that hides the transaction amount and address, resulting in a proof that takes up only 1.5 KB. Second, the W3C standard VC is introduced to enable off-chain identity attribute authentication. Users generate a “credential validity proof” using ZKPs and upload the proof along with the transaction to the chain. Finally, smart contracts verify the dual proofs, using Merkle tree aggregation to reduce verification overhead. An innovative “attribute-bound anonymous transaction” model is proposed to dynamically decouple transaction and identity attribute verification. Deployment on the Ethereum testnet demonstrates that this scheme reduces transaction correlation to approximately 0.3 %. Groth16 achieves a throughput of 142 transactions per second (TPS) in 798 ms at a scale of 200,000 gates.
В статье рассматриваются основы технологии нулевых доказательств знания (Zero-Knowledge Proofs, ZK), её значение для развития криптовалютных систем и децентрализованных финансов. Особое внимание уделено механизмам zk-SNARK и zk-STARK, а также их практическому применению в проектах Zcash, Ethereum, Polygon и zkSync. Проведен анализ проблем масштабируемости, вычислительной сложности и регуляторных рисков, связанных с использованием ZK-технологий. Отмечаются перспективы интеграции в архитектуру цифровых валют центральных банков и развитие инфраструктуры Web3 на базе ZK-решений
Sep 4, 2025·2025 IEEE 13th International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS)
This paper presents a cryptographic ZeroKnowledge Proof (ZKP) protocol that allows the prover (P) to convince the verifier (V) that they know a secret number X, which is consistent with k residues in a Redundant Residue Number System (RRNS), without revealing the number X itself. The use of RRNS in this protocol provides enhanced efficiency and computational parallelism by splitting operations across independent moduli. This approach combines zero-knowledge properties with high performance, addressing the simultaneous need for security, privacy, and scalability - particularly in authentication and secure transactions.
Smart contracts are software that runs in blockchain and expresses the rules of an agreement between parties. An incorrect smart contract might allow blockchain users to violate its rules and even jeopardize its expected security. Smart contracts cannot be easily replaced to patch a bug since the nature of contracts requires them to be immutable. More problems occur when a smart contract is written in a general-purpose language, such as Java, whose executions, in a blockchain, could hang the network, break consensus or violate data encapsulation. To limit these problems, there exist automatic static analyzers that find bugs before smart contracts are installed in the blockchain. This so-called off-chain verification is optional because programmers are not forced to use it. This paper presents a general framework for the verification of smart contracts, instead, that is part of the protocol of the nodes and applies when the code of the smart contracts gets installed. It is a mandatory entry filter that bans code that does not abide by the verification rules. Consequently, such rules become part of the consensus rules of the blockchain. Therefore, an improvement in the verification protocol entails a consensus update of the network. This paper describes an implementation of a smart contracts application layer with protocol-based verification for smart contracts written in the Takamaka subset of Java, that filters only those smart contracts whose execution in blockchain is not dangerous. This application layer runs on top of a consensus engine such as Tendermint and its derivatives Ignite and CometBFT (proof of stake), or Mokamint (proof of space). This paper provides examples of actual implementations of verification rules that check if the smart contracts satisfy some constraints required by the Takamaka language. This paper shows that protocol-based verification works and reports how consensus updates are implemented. It shows actual experiments as well as limits to its use, mainly related to the fact that protocol-based verification must be fast and its complexity must never explode, or otherwise, it would compromise the performance of the blockchain network.
Sep 4, 2025·2025 IEEE 13th International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS)
Privacy-preserving reputation systems are critical for decentralized Web3 environments, where trust must be managed without centralized authorities. This paper presents a blockchain-based protocol leveraging Subjective Logic (SL) and Hybrid Homomorphic Encryption (HHE) to securely aggregate reputation scores while preserving user privacy. Subjective Logic enables modeling trust with quantified u ncertainty, a llowing for m ore fl exible tr ust enforcement across decentralized identity systems, marketplaces, and DAOs. To enhance performance and confidentiality, we integrate the PASTA symmetric cipher for efficient encryption of auxiliary data. Our protocol enables encrypted reputation aggregation, smart contract-based trust enforcement, and selective disclosure via zero-knowledge proofs. The proposed design balances efficiency, scalability, and privacy, making it well-suited for dynamic Web3 ecosystems requiring decentralized, privacy-preserving trust mechanisms.
M Savitha Devi, Ningthoujam Chidananda Singh, Thoudam Basanta Singh
Abstract - Blockchain enabled systems are more and more adopted in healthcare for secured processing of data, but current smart contract usage in healthcare leaks private patient data on execution. The contributions of this paper are two-fold: (1) it proposes a new framework that combines ZKPs with healthcare smart contracts/transactions to achieve full privacy preservation and (2) it discusses the security, usability, and the efficiency of the framework at the same time. Our proposed framework is based on zero-knowledge proof systems zkSNARKs (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge) and zkSTARKs (Zero-Knowledge Scalable Transparent Argument of Knowledge) tailored for computer on medical data without revealing effectively. We conduct extensive analysis and prototype implementation to show that our framework is able to achieve perfect privacy preservation at a 1.87% computational overhead increase with respect to standard smart contracts. The system processes over 10,000 medical records with sub-second verification times and that meet the HIPAA requirements. Experimental results in diverse healthcare applications attest to the efficacy of the approach in practice, and show the substantial gain of privacy preservation (99.8% retention rate) and computational efficiency over the state-of-art algorithms. This paper bridges the gap between blockchain’s transparency and healthcare’s privacy requirements, laying the groundwork for secure and privacy-preserving blockchain based healthcare applications. Key Words: Zero-knowledge proofs, Smart contracts, Healthcare blockchain, Privacy preservation, zkSNARKs, zkSTARKs, Medical data security, HIPAA compliance
Michael Herbert Ziegler, Mariusz Nowostawski, Basel Katt
In this literature review, we critically examine the evolving landscape of privacy in blockchain systems, with a particular focus on the differentiation of privacy attacks and protective measures across three distinct layers: the on-chain layer; the off-chain layer; and on the infrastructure, i.e., peer-to-peer network layer. In this review, we categorize prevalent privacy attacks, such as transaction tracing, data leakage, and network surveillance, highlighting their implications at each layer. In addition, we evaluate a range of protective techniques, including cryptographic methods, zero-knowledge proofs, and other privacy-preserving protocols. We explore the compatibility of these privacy techniques with existing blockchain systems. By synthesizing current research and practical implementations, our aims are to provide a comprehensive understanding of privacy challenges and solutions in blockchain environments, identify gaps, and guide future developments in privacy-enhancing technologies within the blockchain ecosystem.
Statistical witness indistinguishability is a relaxation of statistical zero-knowledge which guarantees that the transcript of an interactive proof reveals no information about which valid witness the prover used to generate it. In this paper we define and initiate the study of QSWI, the class of problems with quantum statistically witness indistinguishable proofs. Using inherently quantum techniques from Kobayashi (TCC 2008), we prove that any problem with an honest-verifier quantum statistically witness indistinguishable proof has a 3-message public-coin malicious-verifier quantum statistically witness indistinguishable proof. There is no known analogue of this result for classical statistical witness indistinguishability. As a corollary, our result implies SWI is contained in QSWI. Additionally, we extend the work of Bitansky et al. (STOC 2023) to show that quantum batch proofs imply quantum statistically witness indistinguishable proofs with inverse-polynomial witness indistinguishability error.
Designing secure electronic voting systems that truly protect voter privacy, ensure vote accuracy, and allow independent verification continues to pose serious difficulties. Many current cryptographic approaches require excessive computational resources and use encryption keys that are too large for practical implementation. This paper proposes modifications to the Chaum, Pedersen and Cramer, Franklin, Schoenmakers, and Yung voting protocols by integrating elliptic curve cryptography (ECC), which offers stronger security per bit and more compact key representations. The use of ECC allows for reduced parameter sizes while maintaining resistance against known attacks, including those targeting the discrete logarithm problem. We present detailed adaptations of these protocols on elliptic curves and demonstrate how they preserve core security properties such as vote secrecy, universal verifiability, and resistance to double voting under a more efficient cryptographic framework. Our findings contribute to the development of scalable, high-assurance e-voting mechanisms suitable for modern digital infrastructures. The presented modifications significantly enhance the scalability and efficiency of e-voting systems without compromising cryptographic strength.
Machine learning as a service (MLaaS) has emerged as a prominent computing paradigm where users send sensitive data to cloud servers that subsequently return computed results. In MLaaS, ensuring the correctness of these results poses a significant challenge. While zero-knowledge proof (ZKP) presents a potential solution, they often come with substantial memory overhead. Moreover, there is insufficient attention given to the privacy risks associated with untrustworthy servers, which could jeopardize users' sensitive information. In this paper, we introduce$\text{Vp}^{3}\text{CNN}$, a three-party verifiable privacy-preserving convolutional neural network (CNN) inference scheme. In$\text{Vp}^{3}\text{CNN}$, users verify the correctness of CNN inference through a lightweight ZKP protocol grounded in vector oblivious linear evaluation. This protocol is designed to ensure that servers incur minimal memory overhead while maintaining the integrity of the verification process. Based on the optimization of the convolutional relation, the scheme reduces the computational cost associated with the verification process of the convolution operations. In addition,$\text{Vp}^{3}\text{CNN}$employs two non-colluded servers to protect user data privacy via secret sharing schemes. We implement our scheme in C++ and evaluate its performance using the MNIST and CIFAR-10 datasets. Experimental results demonstrate that, compared to existing methods,$\text{Vp}^{3}\text{CNN}$achieves a speedup of 4–5 times in convolution verification while maintaining nearly consistent communication overhead. Importantly,$\text{Vp}^{3}\text{CNN}$does not compromise the accuracy of CNN inference, achieving an accuracy of 97.8% on the MNIST dataset.
Elections and referendums play a vital role in a democratic society, which enable individuals to make collective decisions. In the Internet information era, electronic voting has replaced traditional paper voting. However, the centralized architecture of the electronic voting system is vulnerable to attacks and the voting records can be easily changed or even deleted. Blockchain, as a decentralized and trustworthy distributed network, offers new means for electronic voting systems. Current blockchain- based voting systems still face several challenges: they cannot achieve full verifiability in self-tallying, cannot tolerate invalid or abstained ballots, and cannot prevent Sybil attacks either. To address these challenges, we use some cryptographic primitives to construct a blockchain- based decentralized self-tallying verifiable referendum scheme to provide a transparent and secure remote electronic voting system. First, we use range zero-knowledge proofs to verify the ballot content, and for the first time, propose a novel method using bilinear pairing to verify decryption results, which significantly reduces computational burden and gas consumption during verification. Second, we ingeniously combine a threshold decryption system with a blockchain-based deposit mechanism: invalid or abstained ballots are excluded from the tally, and voters casting such ballots are incentivized to publish their partial private keys through the deposit mechanism, ensuring their exit from the decryption process without disrupting the election. We also establish an innovative access mechanism for smart contract that effectively prevents Sybil attacks. Theoretical analysis and experimental results demonstrate that our system is secure, feasible, and efficient.
The merging of Artificial Intelligence (AI) with the Internet of Things (IoT) has sparked a swift transformation in AIoT systems, allowing for real-time intelligence in smart cities, industries, and homes. Yet, these advancements bring about increasing worries regarding data privacy, device trust, and potential security threats-particularly with the emergence of quantum computing. This paper introduces a secure and privacy focused AIoT framework that integrates Federated Learning with Differential Privacy, Zero-Knowledge Proofs (ZKP) for device authentication, and Post-Quantum Cryptography(CRYSTALSKyber) to protect model updates on the blockchain. Unlike conventional methods that depend on cloud processing and expose sensitive data, this innovative system allows for on-device model training through TinyML, ensuring that data remains on the device. A practical implementation using ESP32-S3 devices in both a smart classroom and home environment showcases the framework's effectiveness. The results indicate a 12% boost in privacy, a 35% reduction in communication costs, and an 8.7% increase in model accuracy compared to traditional methods. This architecture tackles significant unresolved challenges in AIoT by securing data at the edge, preventing device spoofing, and preparing for future quantum threats-making it an excellent choice for privacy-sensitive, real-time AIoT applications.
Abstract Oblivious transfer is a type of message transfer in which a sender transmits one out of many potential pieces of information to the receiver, but she has no knowledge about the actual piece of information being received by the receiver. Oblivious transfer is a deceptively simple scheme that has many possible applications such as secure multiparty computation, private set intersection, federated learning, zero-knowledge proofs, accessing sensitive data etc. Security of most classical oblivious transfer protocols is based upon the unproven assumptions about the computational complexity of certain number theoretic problems such as integer factorization. So, existing classical protocols for oblivious transfer are only computationally secure and not unconditionally secure. Although many quantum oblivious protocols have been proposed lately, they are not simple and easy to implement. In the present work we propose a quantum oblivious transfer protocol that is efficient, simple and easily implementable with the existing quantum technology.
Bruno M. F. Ricardo, Lucas C. Cardoso, Leonardo T. Kimura, Marcos A. Simplício · 5 authors
In 2023, Barreto and Zanon proposed a three-round Schnorr-like blind signature scheme, leveraging zero-knowledge proofs to produce one-time signatures as an intermediate step of the protocol. The resulting scheme, called BZ, is proven secure in the discrete-logarithm setting under the one-more discrete logarithm assumption with (allegedly) resistance to the Random inhomogeneities in a Overdetermined Solvable system of linear equations modulo a prime number p attack, commonly referred to as ROS attack. The authors argue that the scheme is resistant against a ROS-based attack by building an adversary whose success depends on extracting the discrete logarithm of the intermediate signing key. In this paper, however, we describe a distinct ROS attack on the BZ scheme, in which a probabilistic polynomial-time attacker can bypass the zero-knowledge proof step to break the one-more unforgeability of the scheme. We also built a BZ variant that, by using one secure hash function instead of two, can prevent this particular attack. Unfortunately, though, we show yet another ROS attack that leverages the BZ scheme’s structure to break the one-more unforgeability principle again, thus revealing that this variant is also vulnerable. These results indicate that, like other Schnorr-based strategies, it is hard to build a secure blind signature scheme using BZ’s underlying structure.
Jingcheng Zhang, Yekai Zhou, Yingxuan Ren, Man Ho Au · 9 authors
Advancements in sequencing technologies grant individuals unprecedented access to their genomic data. However, existing data management systems or protocols are inadequate in privacy protection, limiting individuals' control over their genomic information, hindering data sharing, and posing challenges for biomedical research. Therefore, demand exists for an owner-governed system fulfilling owner authority, life cycle data encryption, and verifiability simultaneously. Here, we realized Governome, an owner-governed data management system empowering individuals with real-time control over their genomic data. Governome leverages a blockchain to manage transactions and permissions, granting data owners dynamic permission management with full transparency on data usage. It uses homomorphic encryption and zero-knowledge proofs to enable genomic data storage and computation in an encrypted and verifiable form throughout its life cycle. Governome can support versatile genomic applications. We implemented and tested individual variant query, cohort study, genome-wide association study (GWAS) analysis, and forensics on 2,504 1000 Genomes Project (1kGP) genomes, demonstrating its robustness and scalability. Governome is open-source at https://github.com/HKU-BAL/Governome.
Blockchain smart contracts are pivotal to decentralized applications, yet their security remains a critical challenge. This study analyzes a dataset of 1,000 smart contracts to investigate known vulnerabilities, audit practices, and exploit patterns. The results reveal that audited contracts are significantly less prone to exploitation, with 75% exhibiting no exploit history compared to 55% of non-audited contracts. "Integer Overflow" and "Unchecked Call" were identified as the most prevalent vulnerabilities, contributing to 60% and 50% exploit rates, respectively. The study highlights the importance of transparent audit reporting, as contracts without available reports were exploited in 35% of cases. Additionally, hidden vulnerabilities in ostensibly secure contracts underscore the evolving sophistication of blockchain threats. This research emphasizes the need for robust security practices, including stricter coding standards, comprehensive audits, and advanced vulnerability detection techniques such as formal verification and machine learning. Future works aim to integrate security tools into development workflows and foster industry-wide collaboration to standardize auditing practices, thereby enhancing the security and trustworthiness of blockchain ecosystems.
The Lattice Isomorphism Problem (LIP) is an emerging foundation for post-quantum cryptography thanks to the pioneering work of Ducas and van Woerden (EUROCRYPT '22). That work lays the foundation for LIP in cryptography with a zero-knowledge proof of knowledge (ZKPoK), a key-encapsulation mechanism, and a digital signature scheme which is further developed into the efficient signature Hawk (ASIACRYPT '22) using structured lattices. However, as compared to the development of lattice-based cryptography from the Short Integer Solution (SIS) and Learning with Errors (LWE) problems, LIP-based cryptography is yet to cover a rich variety of functionalities beyond the two basic ones: encrypting and digitally signing messages. This work is an effort to extend the landscape of LIP-based cryptography from the above basic primitives to more advanced ones by adapting techniques used in SIS-based and LWE-based primitives to LIP. We provide a public-key encryption (PKE) which encrypts plaintexts of integral vectors, and it comes with a zero-knowledge proof of plaintext knowledge. We use this PKE as a commitment scheme in the construction of a ZKPoK for quadratic relations, so this ZKPoK has a straightline extractor naturally. Using the same ZKPoK in non-interactive mode by Fiat-Shamir transformation, we introduce the first LIP-based blind signature scheme which is the blinded version of the digital signatures of Ducas and van Woerden. The security of our scheme stems from a new one-more Close Vector Problem (omCVP) assumption. This assumption is arguably an analogue of the one-more-SIS assumption by Agrawal et al. (CCS '22) and the one-more Short Vector Problem in Hawk signatures. To ensure confidence in omCVP, we provide a cryptanalysis attempt and convince that our parameter choice is in the safe zone.
This paper studies the practical aspects of adding zero-knowledge proofs of vote correctness to Internet voting, specifically to the IVXV system used in Estonia. We discuss various available alternatives and present a concrete instantiation based on Bulletproofs together with implementation details and benchmarking results. As IVXV currently uses the ElGamal cryptosystem with a 3072-bit prime modulus for vote encryption, but Bulletproofs work most efficiently on elliptic curves, a group switching solution is also implemented and benchmarked. Despite all the extra work required, our solution is very performant and well capable of sustaining the load of votes, even during peak vote submission periods.
Md Mehedi Hasan Emon, Md. Mazid-Ul-Haque, Most. Sharmin Ara Chowdhury, Kh. Mustafizur Rahman
This chapter explores the critical role of advanced cryptographic technologies in securing smart city applications across domains such as e-health, e-commerce, and e-banking. As urban environments become increasingly digitized, safeguarding sensitive data, ensuring transaction integrity, and protecting user privacy emerge as paramount challenges. The chapter explores a spectrum of cryptographic solutions, including blockchain, homomorphic encryption, zero-knowledge proofs, and quantum cryptography, that address these complexities. Through detailed analysis and real-world case studies, it highlights practical implementations and emerging trends that reinforce trust and resilience in smart city infrastructures. Moreover, the chapter discusses the policy and ethical dimensions necessary to balance security with usability and transparency. Finally, it provides a comprehensive framework for integrating cryptographic safeguards into the evolving digital fabric of smart cities, ensuring secure, scalable, and citizen-centric urban services.