Yan Zhuang, ChiâRen Shyu, Shenda Hong, Pengfei Li · 5 authors
BACKGROUND: Patient tokenization is a novel approach that allows anonymous patient-level linkage across healthcare facilities, minimizing the risk of breaching protected health information in health information exchange (HIE). Most patient tokenization is the centralized approach that is unable to address data security concerns fundamentally. Non-Fungible Tokens (NFT), which are non-transferable cryptographic assets on the blockchain, have the potential to provide secure, decentralized, and trustworthy patient tokenization. Self-Sovereign Identity (SSI) is a user-centric approach to verify the ownership of NFTs in a decentralized manner. METHODS: We have developed a blockchain architecture that contains four modules: (1) Creation module for NFTs creation, (2) Linkage module to link the local patients' accounts to their NFTs, (3) Authentication module that allows patients to permit healthcare providers to access their token, and (4) Exchange module, which involves the HIE process and the validation of the legitimacy of the token through SSI. RESULTS: A case study has been conducted on the proposed architecture. Over 3 million transactions have been completed successfully with a blockchain validation and written time of 1.17 s on average. A stability test has also been conducted with a higher throughput of 200 transactions per second running for an hour with an average transaction processing time of 1.42 s. CONCLUSIONS: This study proposed a blockchain architecture that achieves SSI-enabled NFT-based patient tokenization. Our architecture design, implementation, and case studies have demonstrated the feasibility and potential of NFT with SSI to establish a secure, transparent, and patient-centric identity management and HIE.
Francesco Bruschi, Donatella Sciuto, Tommaso Paulon, Andrea Marchesi
Blockchain technology allows players to own in-game assets and to be rewarded with NFTs or tokens for their game achievements, thus can be a game changer for all the gaming industry. One central issue is how to check that conditions for achievements are met (e.g., that the player completed level 10). Current approaches open cheating backdoors (e.g. if the client checks the conditions) or introduce centralization points (if a backend checks the condition). Ideally, we would like to ârunâ games on chain, but so far that has not been possible due to the high computational cost, especially on Ethereum; however, the development of technologies like proofs of computation can solve this problem. Being able to run games on the blockchain, new decentralized rewarding systems can be built to ensure the fair and transparent rewarding of game achievements.
Cybersecurity information sharing (CIS) is important in different business processes to secure data transmission, because it comprises Internet of Things (IoT) connectivity, workflow automation, collaboration, and communication. The shared information is influenced by intermediate users and alters the originality of the information. Although risk factors such as confidentiality and privacy of the data are reduced when using a cyber defense system, existing techniques rely on a centralized system that may be damaged during an accident. In addition, private information sharing faces rights issues when accessing sensitive information. The research issues influence trust, privacy, and security in a third-party environment. Therefore, this work uses the Access Control Enabled Blockchain (ACE-BC) framework to enhance overall data security in CIS. The ACE-BC framework uses attribute encryption techniques to manage data security, while the access control mechanism limits unauthorized user access. The effective utilization of blockchain techniques ensures overall data privacy and security. The efficiency of the introduced framework was evaluated using experimental results, and the experimental outcome indicated that the recommended ACE-BC framework enhanced the data confidentiality ratio (98.9%), the throughput ratio (98.2%), the efficiency ratio (97.4%), and the latency rate (10.9%) when compared to other popular models.
Johannes Rude Jensen, Victor von Wachter, Omri Ross
Multi-block MEV (MMEV) denotes the practice of securing k-consecutive blocks in an attempt at extracting surplus value by manipulating transaction ordering. Following the implementation of pro-poser/builder separation (PBS) on Ethereum, savvy builders can secure consecutive block space by implementing targeted bidding strategies through relays. To estimate the extent to which this practice might be taking place today, we collect data on all bids submitted by builders through relays in the period from the 15th of September (the merge) 2022 until the 31st of January 2023. We hypothesize that builders might secure consecutive blocks in order to deploy sophisticated MMEV strategies, such as creating artificial momentum in Uniswap pools, by withholding and prioritizing transactions from the mempool. In this talk proposal, we present preliminary and non-conclusive results, indicating the builders employ super-linear bidding strategies to secure consecutive block space. We hypothesize that builders act rationally and increase bids only if this is profitable. With this WIP talk proposal, we hope to stimulate an interesting discussion on the feasibility of sophisticated MMEV strategies at SBC23, with the aim of collecting feedback from researchers and practitioners working on MEV.
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.
Seyed M. Hosseini, Joaquim Ferreira, Paulo Bartolomeu
The popularity of the Internet of Things (IoT) and Industrial IoT (IIoT) has caused a rapid increase in connected entities and exposed its lack of adequate Identity Management (IdM). Traditional IdM systems are highly dependent on central authorities; any failure can potentially compromise the entire system. To eliminate the drawback of central authorities and evolve IdM systems to meet increasingly stringent security requirements, the Decentralized Identification approach has been proposed. This approach often relies on blockchain technology to provide a secure and tamper-proof method of managing and verifying identities. Therefore, this article investigates the capabilities of blockchain-based decentralized identification for the IoT domain, with an emphasis on the heterogeneity of online devices. It describes a number of features and specifications of decentralized identification with a specific focus on Self-Sovereign Identity (SSI), a model in which entities own their identities. The article concludes with a discussion of technical aspects as well as potential obstacles and constraints to the implementation of decentralized identification in the context of the Internet of Things.
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 proversâ 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.
Very recent attacks like ladder leak demonstrated feasibility to recover private key with side channel attacks using just one bit of secret nonce. ECDSA nonce bias can be exploited in many ways. Some attacks on ECDSA involve complicated Fourier analysis and lattice mathematics. In this paper will enable cryptographers to identify efficient ways in which ECDSA can be cracked on curves NIST256p, SECP256k1, NIST521p and weak nonce, kind of attacks that can crack ECDSA and how to protect yourself. Initially we begin with ECDSA signature to sign a message using private key and validate the generated signature using the shared public key. Then we use a nonce or a random value to randomize the generated signature. Every time we sign, a new verifiable random nonce value is created and way in which the intruder can discover the private key if the signer leaks any one of the nonce value. Then we use LenstraâLenstraâLovasz (LLL) method as a black box, we will try to attack signatures generated from bad nonce or bad random number generator (RAG) on NIST256p, SECP256k1 curves. The analysis is performed by considering all the three curves for implementation of Elliptic Curve Digital Signature Algorithm (ECDSA).The comparative analysis for each of the selected curves in terms of computational time is done with leak of nonce and with LenstraâLenstraâLovasz method to crack ECDSA. The average computational costs to break ECDSA with curves NIST256p, NIST521p and SECP256k1 are 0.016, 0.34, 0.46 respectively which is almost to zero depicts the strength of algorithm. The average computational costs to break ECDSA with curves SECP256K1 and NIST256p using LLL are 2.9 and 3.4 respectively.
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 signerâs 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.
Keunok Kim, Jihyeon Ryu, Hakjun Lee, Youngsook Lee · 5 authors
Federated authentication, such as Google ID, enables users to conveniently access multiple websites using a single login credential. Despite this convenience, securing federated authentication services requires addressing a single point of failure, which can result from using a centralized authentication server. In addition, because the same login credentials are used, anonymity and protection against user impersonation attacks must be ensured. Recently, researchers introduced distributed authentication schemes based on blockchains and smart contracts (SCs) for systems that require high availability and reliability. Data on a blockchain are immutable, and deployed SCs cannot be changed or tampered with. Nonetheless, updates may be necessary to fix programming bugs or modify business logic. Recently, methods for updating SCs to address these issues have been investigated. Therefore, this study proposes a distributed and federated authentication scheme that uses SCs to overcome a single point of failure. Additionally, an updatable SC is designed to fix programming bugs, add to the function of an SC, or modify business logic. ProVerif, which is a widely known cryptographic protocol verification tool, confirms that the proposed scheme can provide protection against various security threats, such as single point of failure, user impersonation attacks, and user anonymity, which is vital in federated authentication services. In addition, the proposed scheme exhibits a performance improvement of 71% compared with other related schemes.
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.
We provide a generic construction to turn any classical Zero-Knowledge (ZK) protocol into a composable (quantum) oblivious transfer (OT) protocol, mostly lifting the round-complexity properties and security guarantees (plain-model/statistical security/unstructured functions...) of the ZK protocol to the resulting OT protocol. Such a construction is unlikely to exist classically as Cryptomania is believed to be different from Minicrypt. In particular, by instantiating our construction using Non-Interactive ZK (NIZK), we provide the first round-optimal (2-message) quantum OT protocol secure in the random oracle model, and round-optimal extensions to string and k-out-of-n OT. At the heart of our construction lies a new method that allows us to prove properties on a received quantum state without revealing additional information on it, even in a non-interactive way, without public-key primitives, and/or with statistical guarantees when using an appropriate classical ZK protocol. We can notably prove that a state has been partially measured (with arbitrary constraints on the set of measured qubits), without revealing any additional information on this set. This notion can be seen as an analog of ZK to quantum states, and we expect it to be of independent interest as it extends complexity theory to quantum languages, as illustrated by the two new complexity classes we introduce, ZKstatesQIP and ZKstatesQMA.
Summary The idea of hash timeâlock contracts (HTLCs) has been around from 2013. Nowadays these contracts power the majority of atomic swaps making decentralized exchange of tokens possible. On the other hand, HTLCs also have some flaws. For example they can only be instantiated between two parties. This is highly inefficient when many participants want to exchange tokens between the same pair of blockchains at the same time, because the number of transactions increases linearly in the number of participants. To solve this problem, in this article, we present MPâHTLC. MPâHTLC lets multiple users exchange tokens on different blockchains in a single instantiation of the protocol without any leader election. We prove that in case of a UTXOâbased blockchain the number of transactions remains constant regardless the number of participants. We are able to maintain the security assumptions of HTLCs using multiparty computation in the creation of the secret preimage and threshold signatures to manage transaction signing. We also present an implementation for each of the aspects of the protocol.
We present a Solidity smart contract implementation of the TAVS e-voting protocol. The Two Authorities Electronic Voting Scheme (TAVS) is a voting scheme that achieves universal verifiability with a reduced time-complexity both for the elector and the voting system. TAVS security derives from the RSA cryptosystem it employs, and the assumption of two entities that do not share information. We present a Solidity implementation which replaces one of these entities with an immutable smart contract in Ethereum based networks. By doing so, our implementation extends the security properties of TAVS and achieves a higher degree of resilience, verifiability, and availability. We open source the code of the implementation.
Blockchain databases have attracted widespread attention but suffer from poor scalability due to underlying non-scalable blockchains. While blockchain sharding is necessary for a scalable blockchain database, it poses a new challenge named on-chain cross-shard database services. Each cross-shard database service (e.g., cross-shard queries or inter-shard load balancing) involves massive cross-shard data exchanges, while the existing cross-shard mechanisms need to process each cross-shard data exchange via the consensus of all nodes in the related shards (i.e., on-chain) to resist a Byzantine environment of blockchain, which eliminates sharding benefits. To tackle the challenge, this paper presents GriDB, the first scalable blockchain database, by designing a novel off-chain cross-shard mechanism for efficient cross-shard database services. Borrowing the idea of off-chain payments, GriDB delegates massive cross-shard data exchange to a few nodes, each of which is randomly picked from a different shard. Considering the Byzantine environment, the untrusted delegates cooperate to generate succinct proof for cross-shard data exchanges, while the consensus is only responsible for the low-cost proof verification. However, different from payments, the database services' verification has more requirements (e.g., completeness, correctness, freshness, and availability); thus, we introduce several new authenticated data structures (ADS). Particularly, we utilize consensus to extend the threat model and reduce the complexity of traditional accumulator-based ADS for verifiable cross-shard queries with a rich set of relational operators. Moreover, we study the necessity of inter-shard load balancing for a scalable blockchain database and design an off-chain and live approach for both efficiency and availability during balancing. An evaluation of our prototype shows the performance of GriDB in terms of scalability in workloads with queries and updates.
Maryam Sheikhi Garjan, N. Gamze ORHON KILIĂ, Murat Cenk
The increasing demand for secure and anonymous transactions raises the popularity of ring signatures, which is a digital signature scheme that allows identifying a group of possible signers without revealing the identity of the actual signer. This paper presents efficient supersingular isogeny-based ring signature and linkable ring signature schemes that will find potential applications in post-quantum technologies. We develop the ring signature scheme by applying the Fiat-Shamir transform on the sigma protocol for a ring which we obtain from the supersingular isogeny-based interactive zero-knowledge identification scheme by adopting the scheme for a ring. We also extend our ring signature protocol with an additional parameter, i.e., a tag that provides to detect if a signer issues two signatures concerning the same ring by preserving anonymity and linkable anonymity. The signature size of our ring signature protocols increases logarithmically in the size of the ring thanks to the Merkle trees. We show the security proofs and efficiency analyses of the protocols offered. Moreover, we provide the implementation results of the supersingular isogeny-based ring signature, which offers small signature sizes for NIST post-quantum security levels.
Sai Batchu, Michael J. Diaz, Lauren Ladehoff, Kevin T. Root · 5 authors
Aim: Conventional techniques to share and archive spinal imaging data raise issues with trust and security, with novel approaches being more greatly considered. Ethereum smart contracts present one such novel approach. Ethereum is an open-source platform that allows for the use of smart contracts. Smart contracts are packages of code that are self-executing and reside in the Ethereum state, defining conditions for programmed transactions. Though powerful, limited attempts have been made to showcase the clinical utility of such technologies, especially in the pre- and post-operative imaging arenas. Herein, we therefore aim to propose a proof-of-concept smart contract that stores intraoperative three-dimensional (3D) augmented reality surgical navigation (ARSN) data and was tested on a private, proof-of-authority network. To the author's best knowledge, the present study represents a first-use case of the Interplanetary File Storage protocol for storing and retrieving spine imaging smart contracts. Methods: The content identifier hashes were stored inside the smart contracts while the interplanetary file system (IPFS) was used to efficiently store the image files. Insertion was achieved with four storage mappings, one for each of the following: fictitious patient data, specific diagnosis, patient identity document (ID), and Gertzbein grade. Inserted patient observations were then queried with wildcards. Insertion and retrieval times for different record volumes were collected. Results: It took 276 milliseconds to insert 50 records and 713 milliseconds to insert 350 records. Inserting 50 records required 934 Megabyte (MB) of memory per insertion with patient data and imaging, while inserting 350 records required almost the same amount of memory per insertion. In a database of 350 records, the retrieval function needs about 1,026 MB to query a record with all three fields left blank, but only 970 MB to obtain the same observation from a database of 50 records. Conclusions: The concept presented in this study exemplifies the clinical utility of smart contracts and off-chain data storage for efficient retrieval/insertion of ARSN data.
Blockchain is a method of recording information that makes it not feasible for the system to be replaced, attacked, or manipulated. A blockchain is equipped with a notebook that copies and processes the various procedures across the network of computers participating in the blockchain. Digital signature algorithm is one of the cryptographic protocols used by the blockchain. In this work, we introduce a new digital signature scheme based on error correcting codes. In the scheme constructed on a [n, k, d]â code over đœq, which is d â„ 2t + 1, and the size of the signature length is n â k. The signature verification is based on the bounded distance decoding of the code. Since the verification space is đœqn, the proposed scheme has an improved performance in terms of working in a wider space.
M. Thirumaran, S. Tiroumalmouroughane, M. Sathish Kanna
In large democracy like India with about 83.4 crore voters it is estimated that about 50,000 crore rupees is spent on election and it takes about 6 weeks to conduct election. So the approach of election followed in India is costly both in terms of time and money. In order to reduce the cost of time and money, in last few decades numerous methods have already been developed and one of them is to use online voting system that providers the comfort of voting from remote location. But traditional online system has its own drawbacks like data tampering, privacy breach, etc. Blockchain technology is proposed, that incorporates cryptographic properties. Blockchain technology is simply defined as a decentralized, distributed ledger that maintains the provenance of a digital asset and is considered to be utmost secure. To avoid single point of failure, two step authentication process is used which include OTP verification and Biometric authentication. To ensure the anonymity of the votes, Identity-based ring signature scheme is used.
Open access
Internet Traffic Analysis and Secure E-voting
Advanced Steganography and Watermarking Techniques
We consider a project (model) owner that would like to train a model by utilizing the local private data and compute power of interested data owners, i.e., trainers. Our goal is to design a data marketplace for such decentralized collaborative/federated learning applications that simultaneously provides i) proof-of-contribution based reward allocation so that the trainers are compensated based on their contributions to the trained model; ii) privacy-preserving decentralized model training by avoiding any data movement from data owners; iii) robustness against malicious parties (e.g., trainers aiming to poison the model); iv) verifiability in the sense that the integrity, i.e., correctness, of all computations in the data market protocol including contribution assessment and outlier detection are verifiable through zero-knowledge proofs; and v) efficient and universal design. We propose a blockchain-based marketplace design to achieve all five objectives mentioned above. In our design, we utilize a distributed storage infrastructure and an aggregator aside from the project owner and the trainers. The aggregator is a processing node that performs certain computations, including assessing trainer contributions, removing outliers, and updating hyper-parameters. We execute the proposed data market through a blockchain smart contract. The deployed smart contract ensures that the project owner cannot evade payment, and honest trainers are rewarded based on their contributions at the end of training. Finally, we implement the building blocks of the proposed data market and demonstrate their applicability in practical scenarios through extensive experiments.
The Internet of Things (IoT) is ubiquitous in our lives. However, the inherent vulnerability of IoT smart devices can lead to the destruction of networks in untrustworthy environments. Therefore, authentication is a necessary tool to ensure the legitimacy of nodes and protect data security. Naturally, the authentication factors always include various sensitive usersâ information, such as passwords, ID cards, even biological information, etc. How to prevent privacy leakage has always been a problem faced by the IoT. Zero-knowledge authentication is a crucial cryptographic technology that uses authenticates nodes on the networks without revealing identity or any other data entered by users. However, zero-knowledge proof (ZKP) requires more complex data exchange protocols and more data transmission compared to traditional cryptography technologies. To understand how zero-knowledge authentication works in IoT, we produce a survey on zero-knowledge authentication in privacy-preserving IoT in the paper. First, we overview the IoT architecture and privacy, including security challenges and open question in different IoT layers. Next, we overview zero-knowledge authentication and provide a comprehensive analysis of designing zero-knowledge authentication protocols in various IoT networks. We summarize the advantages of ZKP-based authentication in IoT. Finally, it summarizes the potential problems and future directions of ZKP in IoT.