It is crucial to ensure the privacy and authenticity of patients’ medical data in the medical insurance claim process, but in the current medical insurance claim process, there are some problems such as low efficiency, complex service, unreliable data and data leakage. Therefore, considering the privacy and sensitivity of patients’ medical data, we can improve the current issues by employing blockchain, smart contracts and zero-knowledge proof technology. In this paper, we propose a novel medical insurance claim scheme based on smart contracts, blockchain and zero-knowledge proof. Our scheme mainly involves two scenarios: medical insurance purchasing and medical insurance claiming. In the privacy-preserving transaction phases of the two scenarios, we can ensure the legitimacy and privacy of the transactions between the patients and the insurance companies by using a non-interactive zero-knowledge proof and the homomorphic encryption algorithm under the Decisional Bilinear Diffie–Hellman (DBDH) assumption. In the identity privacy-preserving phases of the two scenarios, we can ensure the legitimacy and the privacy of patients’ identities by integrating Schnorr protocol and Fiat–Shamir heuristic method. The security analysis, the computation cost and the communication cost of our scheme are given. Compared with our referred schemes, the performance evaluation shows that our scheme not only meets the requirements of the legality of the medical insurance claim, but also ensures the authenticity and privacy of the patients’ medical data. Moreover, the experimental results demonstrate that our scheme is feasible and has an acceptable time overhead.
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Blockchain Technology Applications and Security
Privacy-Preserving Technologies in Data
Advanced Steganography and Watermarking Techniques
Zero knowledge proofs are one of the most influential concepts in theoretical computer science. In the seminal definition due to Goldwasser, Micali and Rackoff dating back to the 1980s, a computationally-bounded verifier interacts with a powerful but untrusted prover, with the goal of becoming convinced that the input is in some language. In addition to the usual requirements of completeness and soundness, in a zero knowledge proof, we protect the prover's knowledge: assuming the prover is honest, anything that the verifier can deduce after interacting with the prover, it could have deduced by itself. Zero knowledge proofs have found many applications within theoretical computer science and beyond, e.g., in cryptography, client-cloud computing, blockchains and cryptocurrencies, electronic voting and auctions, and in the financial industry. We define and study the notion of distributed zero knowledge proofs, reconciling the computational notion of zero-knowledge with the communication-based paradigm of distributed graph algorithms. In our setting, a network of verifiers interacts with an untrusted prover to decide some distributed language. As is usually the case in distributed graph algorithms, we assume that the verifiers have local views of the network and each only knows its neighbors. The prover, on the other hand, is assumed to know the entire network graph, as well as any input that the verifier may possess. As in the computational centralized setting, the protocol we design should protect this knowledge. In particular, due to the dual role of the underlying graph in distributed graph algorithms, serving as both the communication topology and the input to the problem, our protocol must protect the graph itself. We construct communication-efficient distributed zero knowledge proofs for two central problems: the 3-coloring problem, one of the poster children of computational zero-knowledge, and for the spanning-tree verification problem, a fundamental building block for designing graph algorithms. We also give a general scheme for converting proof labeling-schemes to distributed zero-knowledge protocols with related parameters. Our protocols combine ideas from computational complexity, distributed computing, and cryptography.
Yinjie Gong, Y. J. Jin, Yuchan Li, Ziyi Liu · 5 authors
Thanks to the development in encryption technology and blockchain, cryptocurrency has already proven feasible and applicable. However, blockchain requires massive information including details of every transaction, the information of the dealer and buyer, which makes the privacy of every user on blockchain vulnerable. With the presence of Zcash, a new concept called Zero-Knowledge proof which focuses on proving and verifying identities appears in front of every researcher and engineer working on blockchain. Because of the enormous quantity of the ZKP schemes and the limited time, in this article, we have compared four main ZKP algorithms-ZK-SNARK, ZK-STARK, MPC protocol-based algorithms, and Bulletproof. By comparing these algorithms, we intend to give relevant engineers and researchers a general understanding of the advantages and disadvantages of these algorithms. In addition, we try to make the relevant people aware of the application scenarios of each ZKP.
Blockchain Technology Applications and Security
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques
Tao Feng, Pu Yang, Chunyan Liu, Junli Fang · 5 authors
The data generated in the Industrial Internet of Things (IIoT) has important research value. In the process of data sharing, data privacy, security, and data availability are important issues that cannot be ignored. This paper proposes a blockchain privacy protection scheme based on zero‐knowledge proof to realize the secure sharing of data among data owners, cloud service providers, and semitrusted cloud servers. First, the method of combining zero‐knowledge proof and smart contract is used to verify the availability of data between the data owner and the cloud service provider under the premise of protecting data privacy. Second, proxy reencryption technology is used to realize the secure sharing of data among authorized cloud service providers. In addition, data sharing transaction information between multiple parties and data hashes with digital signatures are stored on the blockchain to achieve public and verifiable data sharing information and data validity. Finally, the theoretical analysis of the scheme shows that the scheme meets the confidentiality requirements of security, integrity, and validity.
This paper presents a new short zero-knowledge argument for the range proof and arithmetic circuits without a trusted setup. In particular, it can achieve the shortest proof size of the proof system categories without a trusted setup. More specifically, when proving that a committed value is a positive integer less than 64 bits, except for negligible error in the 128-bit security parameter, the proof size is 576 bytes long, which is 85.7% the size of the previous shortest proof due to Bünzet al.(Bulletproofs, IEEE Security and Privacy 2018). Similarly, circuit satisfiability can be proven with less communication overhead. Nevertheless, computational overheads in both proof generation and verification are comparable with those of Bulletproofs. Bulletproofs is established as one of the important privacy-enhancing technologies for a distributed ledger due to its trustless feature and short proof size. In particular, it has been implemented and optimized in various programming languages for practical usage by independent entities since it was proposed. The essence of Bulletproofs is based on the logarithmic inner product argument with no zero-knowledge. This paper revisits Bulletproofs from the viewpoint of the first sublinear zero-knowledge argument for linear algebra due to Groth (CRYPTO 2009) and then propose Bulletproofs+, an improved variety of Bulletproofs. The main component is thezero-knowledge weighted inner product argument (zk-WIP)which enables to reduce both the range proof and the arithmetic circuit proof. It already has zero-knowledge properties, there is no additional information when reducing zk-WIP, and it incurs a minimal transmission cost during the reduction process. Note that zk-WIP has all characteristics of the inner product argument, such as an aggregating range proof and batch verification; thus, Bulletproofs+ is superior to Bulletproofs in all aspects.
As cryptocurrencies gain global traction, concerns over user privacy and transaction traceability have intensified. Public blockchains like Bitcoin and Ethereum inherently expose transactional data, compromising user anonymity. In response, various privacy-preserving cryptographic techniques have been developed to conceal user identities, transaction amounts, and flow paths without sacrificing security or decentralization. This paper explores key cryptographic solutions including ring signatures, zero-knowledge proofs (ZKPs), stealth addresses, and homomorphic encryption as applied in privacy-focused cryptocurrencies such as Monero and Zcash. The study evaluates the effectiveness, scalability, and regulatory implications of these protocols, providing insights into the future of anonymous digital finance.
Quang Nhat Tran, Benjamin Turnbull, Min Wang, Jiankun Hu
Biometric authentication is, over time, becoming an indispensable complementary component to traditional authentication methods that use passwords and tokens. As a result, the research interest in the protection techniques for the biometric template has also grown considerably. In this paper, we present a light-weight AI-based biometric authentication that operates based on the binary representation of a biometric instance. In details, a binary classifier will be trained using the binary strings that represent the intraclass and interclass biometric subjects. The Support Vector Machine and Multi-layer Perceptron Neural Network are chosen as the classifier to evaluate the fingerprint-based and iris-based authentication capability. Afterward, the authenticated biometric string is fed to a hash function to produce a hash value, which is to be used in a Zero-Knowledge-Proof Protocol for the purpose of privacy preservation. In order to improve the recognition of the classifier, we devise a simple yet efficient strategy to enhance the discriminativeness of the binary strings and name it the Composite Features Retrieval. We evaluated the proposed method with the four publicly available fingerprint datasets FVC2002-DB1, FVC2002-DB2, FVC2002-DB3, and FVC2004-DB2 and the iris dataset UBIRISv1. The promising performance shows this method's capability.
Makaro is a logic puzzle with an objective to fill numbers into a rectangular grid to satisfy certain conditions. In 2018, Bultel et al. developed a physical zero-knowledge proof (ZKP) protocol for Makaro using a deck of cards, which allows a prover to physically convince a verifier that he/she knows a solution of the puzzle without revealing it. However, their protocol requires several identical copies of some cards, making it impractical as a deck of playing cards found in everyday life typically consists of all different cards. In this paper, we propose a new ZKP protocol for Makaro that can be implemented using a standard deck (a deck consisting of all different cards). Our protocol also uses asymptotically less cards than the protocol of Bultel et al. Most importantly, we develop a general method to encode a number with a sequence of all different cards. This allows us to securely compute several numerical functions using a standard deck, such as verifying that two given numbers are different and verifying that a number is the largest one among the given numbers.
Jiale Sheng, Peiyun Zhang, Junliang Shu, Songjian Cai
The big data industry has developed rapidly. It is of great significance for the healthy development of the big data industry to connect data supply-demand and promote data circulation through data trading. However, the existing third-party data trading platforms have the ability to view and steal transaction data and true identity. It has become a potential threat to both parties and an obstacle to data trading. Based on the research of blockchain technology, smart contract, and cryptography technology, this paper proposes a data trading model based on a blockchain for the security of data trading. The model uses the Interstellar File System (IPFS) and zero-knowledge proof to solve the security of data. Firstly, IPFS and cryptography are used to store and access data files safely. Secondly, based on secure storage and access, a data trading request is broadcast to a blockchain network. And the blockchain responds to the transaction request. Then, to obtain the original data file, the ciphertext got from the blockchain is decrypted based on the response message. Finally, the zero-knowledge proof system in the model is used to pay transaction fees to both parties. This process protects the security of payments. Through this model, both parties can complete the data trading. It also protects the security of data. In this paper, the proposed scheme is implemented on the Ethereum platform. The experimental results show that the proposed data trading model performs well in the security of data trading.
Jehil Thakkar, Nigam Patel, Chailcy Patel, Kaushal Shah
In conventional voting systems, achieving transparency and reliability is challenging due to the centralized environment. With the advancement in technology, electronic voting has emerged. But in E-voting also, it is essential to maintain the privacy, confidentiality and integrity of the votes and voters, which is challenging. The blockchain technology that has triggered the start of a new era in the digital world is one possible solution. The immutability property and decentralized architecture of blockchain technology make it suitable to create a robust and secure E-voting system. It helps in conducting the elections by maintaining authentication, integrity, transparency, confidentiality and non-repudiation in the system. In this paper, we have evaluated the potential and feasibility of the blockchain system for electronic voting. We have addressed all the possible limitations in the current E-voting system. Using solidity language, we have implemented a small-scale sample E-voting system as a smart contract that includes everything from hosting the election, verifying the voters and counting the votes and have deployed it on an external network. The paper also shows how Zero-Knowledge Proof can help in creating privacy-preserving secure E-voting systems.
Due to the transparency of the blockchain, the data in the blockchain can be viewed by any joining node, and the privacy is weak. In order to better solve the problem of privacy protection in the current blockchain, for the application of e-commerce blockchain, the Pedersen commitment mechanism is adopted to hide the transaction amount, combined with zero-knowledge proof technology to realize the verification of the transaction amount. At the same time, an efficient range proof scheme based on polynomial commitment and vector inner-product commitment is used to verify whether the transaction amount and the balance of both parties are greater than zero. Finally, use the homomorphism promised by Pedersen to update the ciphertext ledger. The security analysis and efficiency test of the proposed blockchain privacy protection algorithm show that compared with the existing schemes, the proposed algorithm has the advantages of strong security and higher efficiency.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
In our day to day life, information security is a predominant topic. More specifically, (online) users expect to be asked for consent and that service providers handle their personal data with care and integrity. This urges the design of systems enforcing such expectations. The field of cryptography provides such powerful privacy-preserving tools. In this thesis, we consider one of those tools: pairings over elliptic curves. We strongly diverge from the general approach, i.e. taking already standardized curves regardless of the cryptographic protocol, and suggest curves satisfying chosen criteria. The given curves in this thesis have more efficient operations in the first pairing group than the curves from the literature. We follow by giving a group signature scheme, a primitive enabling the anonymity of its users among the group they belong to, designed using pairing over elliptic curves. This group signature is efficient when compared to the state-of-the-art, thanks to the very nice interaction between two randomizable signature schemes, allowing us to get rid of costly zero-knowledge proofs.
What is the funniest number in cryptography (Episode 2)? 0 [1]. The reason is that $\forall x, x \cdot 0 = 0$, i.e., the equation is satisfied no matter what $x$ is. We'll use zero to attack zero-knowledge proof (ZKP). In particular, we'll discuss a critical issue in a cutting-edge ZKP PLONK [2] C++ implementation which allows an attacker to create a forged proof that all verifiers will accept. We'll show how theory guides the attack's direction. In practice, the attack works like a charm and we'll show how the attack falls through a chain of perfectly aligned software cracks. In the same codebase, there is an independent critical ECDSA bug where (r, s) = (0, 0) is a valid signature for arbitrary keys and messages, but we won't discuss it further because it's a known ECDSA attack vector in the Google Wycheproof cryptanalysis project [3] that I worked on a few years ago. All bugs have been responsibly disclosed through the vendor's bug bounty program with total reward $\sim \$15,000$ (thank you).
Xuechun Mao, Lin You, Chengtang Cao, Gengran Hu · 5 authors
Biometric encryption, especially based on fingerprint, plays an important role in privacy protection and identity authentication. In this paper, we construct a privacy-preserving linkable ring signature scheme. In our scheme, we utilize a fuzzy symmetric encryption scheme called symmetric keyring encryption (SKE) to hide the secret key and use non-interactive zero-knowledge (NIZK) protocol to ensure that we do not leak any information about the message. Unlike the blind signature, we use NIZK protocol to cancel the interaction between the signer (the prover) and the verifier. The security proof shows that our scheme is secure under the random oracle model. Finally, we implement it on a personal computer and analyze the performance of the constructed scheme in practical terms. Based on the constructed scheme and demo, we give an anonymous cryptocurrency transaction model as well as mobile demonstration.
Zero-knowledge protocols (ZKPs) allow a party to prove the validation of secret information to some other party without revealing any information about the secret itself. Appropriate, effective, and efficient use of cryptographic ZKPs contributes to many novel advances in real-world privacy-preserving frameworks. One of the most important type of cryptographic ZKPs is the zero-knowledge range proofs (ZKRPs). Such proofs have wide range of applications such as anonymous credentials, cryptocurrencies, e-cash schemes etc. In many ZKRPs the secret is represented in binary then committed via a suitable commitment scheme. Though there exist different base approaches on bilinear paring-based and RSA-like based constructions, to our knowledge there is no study on investigating the discrete logarithm-based constructions. In this study, we focus on a range proof construction produced by Mao in 1998. This protocol contains a bit commitment scheme with an OR-construction. We investigate the effect of different base approach on Mao's range proof and compare the efficiency of these basis approaches. To this end, we have extended Mao's range proof to base-3 with a modified OR-proof. We derive the number of computations in modulo exponentiations and the cost of the number of integers exchanged between parties. Then, we have generalized these costs for the base-u construction. Here, we mainly show that comparing with other base approaches, the base-3 approach consistently provides approximately 12% efficiency in computation cost and 10% efficiency in communication cost. We implemented the base-3 protocol and demonstrated that the results are consistent with our theoretical computations.
Advanced Steganography and Watermarking Techniques