Lei Xu

• PhD
• Professor (Assistant) at Kent State University

Multi-scalar multiplication (MSM) is a fundamental component in many zero-knowledge succinct non-interactive argument systems (ZK-SNARKs) and a major performance bottleneck in proof generation for these schemes. One key strategy to accelerate MSM is through precomputation. Several algorithms, such as Pippenger’s and BGMW, along with their variation...

This paper investigates the use of Large Language Models (LLMs) to synthesize public opinion data, addressing challenges in traditional survey methods like declining response rates and non-response bias. We introduce a novel technique: role creation based on knowledge injection, a form of in-context learning that leverages RAG and specified persona...

This paper introduces UniTranslator, a visionary framework that re-imagines code translation as a collaborative endeavor among multiple, compact LLMs. By orchestrating the interaction of specialized agents, each focused on different aspects of the translation process and grounded in a deep understanding of programming concepts, UniTranslator achiev...

In this era, significant transformations in industries and tool utilization are driven by AI/Large Language Models (LLMs) and advancements in Machine Learning. There's a growing emphasis on Machine Learning Operations(MLOps) for managing and deploying these AI models. Concurrently, the imperative for richer smart contracts and on-chain computation...

The rapid growth of the blockchain ecosystem and the increasing value locked in smart contracts necessitate robust security measures. While languages like Solidity and Move aim to improve smart contract security, vulnerabilities persist. This paper presents Smartify, a novel multi-agent framework leveraging Large Language Models (LLMs) to automatic...

Logs are critical resources that record events, activities, or messages produced by software applications, operating systems, servers, and network devices. However, consolidating the heterogeneous logs and cross-referencing them is challenging and complicated. Manually analyzing the log data is time-consuming and prone to errors. LogBabylon is a ce...

The growing adoption of formal verification for smart contracts has spurred the development of new verifiable languages like Move. However, the limited availability of training data for these languages hinders effective code generation by large language models (LLMs). This paper presents ConMover, a novel framework that enhances LLM-based code gene...

Unit testing is crucial in software engineering for ensuring quality. However, it's not widely used in parallel and high-performance computing software, particularly scientific applications, due to their smaller, diverse user base and complex logic. These factors make unit testing challenging and expensive, as it requires specialized knowledge and...

The presence of sparsity in both input features and weights within convolutional neural networks offers a valuable opportunity to significantly reduce the number of computations required during inference. Moreover, the practice of compressing input data serves to diminish storage requirements and lower data transfer costs, ultimately enhancing over...

The introduction of large language models (LLMs) like ChatGPT and Google Palm2 for smart contract generation seems to be the first well-established instance of an AI pair programmer. LLMs have access to a large number of open-source smart contracts, enabling them to utilize more extensive code in Solidity than other code generation tools. Although...

Trusted execution environment (TEE) technology has found many applications in mitigating various security risks in an efficient manner, which is attractive for critical infrastructure protection. First, the natural of critical infrastructure requires it to be well protected from various cyber attacks. Second, performance is usually important for cr...

Recent advances in the blockchain research have been made in two important directions. One is refined resilience analysis utilizing game theory to study the consequences of selfish behavior of users (miners), and the other is the extension from a linear (chain) structure to a non-linear (graphical) structure for performance improvements, such as IO...

Cryptographic schemes like Fully Homomorphic Encryption (FHE) and Zero-Knowledge Proofs (ZKPs), while offering powerful privacy-preserving capabilities, are often hindered by their computational complexity. Polynomial multiplication, a core operation in these schemes, is a major performance bottleneck. While algorithmic advancements and specialized...

Bribery is a perilous issue in the real world, especially in an economical aspect. This fraudulence is unavoidable, and more importantly, it is more difficult to trace in case smart contracts are utilized for bribing on a distributed public blockchain. In our paper, we propose a new threat to the security of a blockchain system, cross-chain bribery...

We consider a natural generalization of the fundamental electoral manipulation problem, where a briber can change the opinion or preference of voters through influence. This is motivated by modern political campaigns where candidates try to convince voters through media such as TV, newspaper, Internet. Compared with the classical bribery problem, w...

In this paper, optimal tracking control is found for an input-affine nonlinear quadcopter using Single Network Adaptive Critics (SNAC). The quadcopter dynamics consists of twelve states and four controls. The states are defined using two related reference frames: the earth frame, which describes the position and angles, and the body frame, which de...

This paper introduces a near-optimal controller for the control of quadrotors. A quadrotor is described as a complex, twelve-state system. The paper simplifies the controller by considering it as two levels, the upper-level (kinematics) six-state controller and the lower-level (kinetics) twelve-state controller. An actor-critic optimal controller g...

Dynamic programming (DP) provides a systematic, closed-loop solution for optimal control problems. However, it suffers from the curse of dimensionality in higher orders. Approximate dynamic programming (ADP) methods can remedy this by finding near-optimal rather than exact optimal solutions. In summary, ADP uses function approximators, such as neur...

Intellectual Property (IP) includes ideas, innovations, methodologies, works of authorship (viz., literary and artistic works), emblems, brands, images, etc. This property is intangible since it is pertinent to the human intellect. Therefore, IP entities are indisputably vulnerable to infringements and modifications without the owner’s consent. IP...

Researchers have started to recognize the necessity for a well-defined ML governance framework based on the principle of decentralization and comprehensively defining its scope of research and practice due to the growth of machine learning (ML) research and applications in the real world and the success of blockchain-based technology. In this paper...

With the recent advances in concepts like decentralized “cloud” and blockchain-enabled decentralized computing environments, the legacy modeling and orchestration tools developed to support centrally managed cloud-based ICT infrastructures are challenged by such a new paradigm built on top of decentralization. On the other hand, decentralized “clou...

Since its launch in 2014, Amazon Echo family of devices has seen a considerable increase in adaptation in consumer homes and offices. With a market worth millions of dollars, Echo is used for diverse tasks such as accessing online information, making phone calls, purchasing items, and controlling the smart home. Echo offers user-friendly voice inte...

Performing neural network inference on encrypted data without decryption is one popular method to enable privacy-preserving neural networks (PNet) as a service. Compared with regular neural networks deployed for machine-learning-as-a-service, PNet requires additional encoding, e.g., quantized-precision numbers, and polynomial activation. Encrypted...

The resilience of a voting system has been a central topic in computational social choice. Many voting rules, like plurality, are shown to be vulnerable as the attacker can target specific voters to manipulate the result. What if a local differential privacy (LDP) mechanism is adopted such that the true preference of a voter is never revealed in pr...

The resilience of a voting system has been a central topic in computational social choice. Many voting rules, like {\it plurality}, are shown to be vulnerable. What if a local differential privacy (LDP) mechanism is adopted such that the true preference of a voter is never revealed in pre-election polls? In this case, the attacker can only infer st...

Modern computer systems tend to rely on large trusted computing bases (TCBs) for operations. To address the TCB bloating problem, hardware vendors have developed mechanisms to enable or facilitate the creation of a trusted execution environment (TEE) in which critical software applications can execute securely in an isolated environment. Even under...

In this paper, we study a generalization of the classic bribery problem known as electoral manipulation under media influence (EMMI). This model is motivated by modern political campaigns where candidates try to convince voters through advertising in media (TV, newspaper, Internet). When compared with the classical bribery problem, the attacker in...

As a massive amount of Internet of things (IoT) devices are being deployed for data collection, it is desirable to have a marketplace where both IoT device owners and data consumers can trade collected data freely and effectively. While it is possible to build a centralized data trading platform similar to existing commodity markets, it faces sever...

The bribery problem in election has received considerable attention in the literature, upon which various algorithmic and complexity results have been obtained. It is thus natural to ask whether we can protect an election from potential bribery. We assume that the protector can protect a voter with some cost (e.g., by isolating the voter from poten...

We describe the concept of software-defined manufacturing, which divides the manufacturing ecosystem into software definition and physical manufacturing layers. Software-defined manufacturing allows better resource sharing and collaboration, and it has the potential to transform the existing manufacturing sector.

Blockchain is a promising solution for Industry 4.0; however, it does not guarantee input data integrity. We propose a field-programmable gate array (FPGA)-based private blockchain system for the industrial Internet of Things, where the transaction generation is performed inside the FPGA in an isolated and enclaved manner.

This paper presents EDSC, a novel smart contract platform design based on the event-driven execution model as opposed to the traditionally employed transaction-driven execution model. We reason that such a design is a better fit for many emerging smart contract applications and is better positioned to address the scalability and performance challen...

The bribery problem in election has received considerable attention in the literature, upon which various algorithmic and complexity results have been obtained. It is thus natural to ask whether we can protect an election from potential bribery. We assume that the protector can protect a voter with some cost (e.g., by isolating the voter from poten...

The bribery problem in election has received considerable attention in the literature, upon which various algorithmic and complexity results have been obtained. It is thus natural to ask whether we can protect an election from potential bribery. We assume that the protector can protect a voter with some cost (e.g., by isolating the voter from poten...

The smart device owning rate such as smart phone and smart watch is higher than ever before and mobile payment has become one of the major payment methods in many different areas. At the same time, blockchain-based cryptocurrency is becoming a nonnegligible type of currency and the total value of all types of cryptocurrency has reached USD 200 bill...

Recent advances in the blockchain research have been made in two important directions. One is refined resilience analysis utilizing game theory to study the consequences of selfish behaviors of users (miners), and the other is the extension from a linear (chain) structure to a non-linear (graphical) structure for performance improvements, such as I...

Digital signatures are widely used to assure authenticity and integrity of messages (including blockchain transactions). This assurance is based on assumption that the private signing key is kept secret, which may be exposed or compromised without being detected in the real world. Many schemes have been proposed to mitigate this problem, but most s...

It is predicted that more than 20 billion IoT devices will be deployed worldwide by 2020. These devices form the critical infrastructure to support a variety of important applications such as smart city, smart grid, and industrial internet. To guarantee that these applications work properly, it is imperative to authenticate these devices and data g...

Access control is one of the fundamental security mechanisms of IT systems. Most existing access control schemes rely on a centralized party to manage and enforce access control policies. As blockchain technologies, especially permissioned networks, find more applicability beyond cryptocurrencies in enterprise solutions, it is expected that the sec...

Bitcoin brings a new type of digital currency that does not rely on a central system to maintain transactions. By benefiting from the concept of decentralized ledger, users who do not know or trust each other can still conduct transactions in a peer-to-peer manner. Inspired by Bitcoin, other cryptocurrencies were invented in recent years such as Et...

We consider the electoral bribery problem in computational social choice. In this context, extensive studies have been carried out to analyze the computational vulnerability of various voting (or election) rules. However, essentially all prior studies assume a deterministic model where each voter has an associated threshold value, which is used as...

Bribery in election (or computational social choice in general) is an important problem that has received a considerable amount of attention. In the classic bribery problem, the briber (or attacker) bribes some voters in attempting to make the briber’s designated candidate win an election. In this paper, we introduce a novel variant of the bribery...

Bribery is a perilous issue in the real world, especially in an economical aspect. This fraudulence is unavoidable, and more importantly, it is more difficult to trace in case smart contracts are utilized for bribing on a distributed public blockchain. In our paper, we propose a new threat to the security of a blockchain system, cross-chain bribery...

Blockchain has been used to build various applications, and the introduction of smart contracts further extends its impacts. Most of existing works consider the positive usage of smart contracts but ignore the other side of it: smart contracts can be used in a destructive way, particularly, they can be utilized to carry out bribery. The hardness of...

Public blockchains provide a decentralized method for storing transaction data and have many applications in different sectors. In order for users to track transactions, a simple method is to let them keep a local copy of the entire public ledger. Since the size of the ledger keeps growing, this method becomes increasingly less practical, especiall...

Bribery in election (or computational social choice in general) is an important problem that has received a considerable amount of attention. In the classic bribery problem, the briber (or attacker) bribes some voters in attempting to make the briber's designated candidate win an election. In this paper, we introduce a novel variant of the bribery...

Many consensus protocols are based on the assumption that participants are either “good” or “bad” but ignore the fact that they may be affected by direct or indirect economic interests involved in the corresponding smart contracts. We analyze consensus in decentralized environments and demonstrate that the system cannot guarantee correct execution...

Blockchain is a powerful and distributed platform for transactions which require a unified, resilient, transparent and consensus-based record keeping system. It has been applied to scenarios like smart city, supply chain, medical data storing and sharing, and etc. Many works have been done on improving the performance and security of such systems....

Termination of smart contracts is crucial for any blockchain system's security and consistency, especially for those supporting Turing-complete smart contract languages. Resource-constrained blockchain systems, like Ethereum and Hyperledger Fabric, could prevent smart contracts from terminating properly when the pre-allocated resources are not suff...

We consider the 4-block $n$-fold integer programming (IP), in which the constraint matrix consists of $n$ copies of small matrices $A$, $B$, $D$ and one copy of $C$ in a specific block structure. We prove that, the $\ell_{\infty}$-norm of the Graver basis elements of 4-block $n$-fold IP is upper bounded by $O_{FPT}(n^{s_c})$ where $s_c$ is the numb...

Modern supply chain is a complex system and plays an important role for different sectors under the globalization economic integration background. Supply chain management system is proposed to handle the increasing complexity and improve the efficiency of flows of goods. It is also useful to prevent potential frauds and guarantee trade compliance....

Public blockchains provide a decentralized method for storing transaction data and have many applications in different sectors. In order for users to track transactions, a simple method is to let them keep a local copy of the entire public ledger. Since the size of the ledger keeps growing, this method becomes increasingly less practical, especiall...

Public blockchains provide a decentralized method for storing transaction data and have many applications in different sectors. In order for a user to track transactions, a simple method is that every user keeps a local copy of the entire public ledger. Since the size of a ledger keeps growing, this method becomes increasingly less practical, espec...

As more applications are built on top of blockchain and public ledger, different approaches are developed to improve the performance of blockchain construction. Recently Intel proposed a new concept of proof-of-elapsed-time (PoET), which leverages trusted computing to enforce random waiting times for block construction. However, trusted computing c...

Security is a major concern in adopting cloud computing especially for processing private and/or sensitive data. FASTEN is an FPGA-based secure system for processing big data. It leverages the security features in modern FPGAs such as crypto engines and PUF. In FASTEN, the kernel functions for data processing are translated into hardware using a Hi...

Since Internet based applications have become the norm for most users, security has become a bigger concern than ever before, especially for applications like social networking and cloud based storage. Access control is one of the key techniques that can mitigate security concerns for web based applications. However, most existing access control me...

User privacy is an important issue in a blockchain based transaction system. Bitcoin, being one of the most widely used blockchain based transaction system, fails to provide enough protection on users' privacy. Many subsequent studies focus on establishing a system that hides the linkage between the identities (pseudonyms) of users and the transact...

Blockchain is a novel way to construct fully distributed systems and has the potential to disrupt many businesses including Uber and Airbnb within the sharing economy. Specifically, blockchain provides a method to enforce the agreement between a user and the physical property owner without using any trusted party, e.g., if a user pays the agreed mo...

Smart contracts are one of the most important applications of the blockchain. Most existing smart contract systems assume that for executing contract over a network of decentralized nodes, the outcome in accordance with the majority can be trusted. However, we observe that users involved with a smart contract may strategically take actions to manip...

Elliptic curve based cryptography has attracted a lot of attention because these schemes usually require less storage than those based on finite field. It is also used to construct bilinear pairing, which is an essential tool to construct various cryptography schemes. The security of a large portion of these schemes depends on the hardness of ECDLP...

Big data applications usually require flexible and scalable infrastructure for efficient processing. Cloud computing satisfies these requirements very well and has been widely adopted to provide big data services. However, outsourcing and resource sharing features of cloud computing lead to security concerns when applied to big data applications, e...

In cloud computing, it is often assumed that cloud vendors are trusted; the guest Operating System (OS) and the Virtua Machine Monitor (VMM, also called Hypervisor) are secure. However, these assumptions are not always true in practice and existin approaches cannot protect the data privacy of applications when none of these parties are trusted. We...

While most of the electronics industry is dependent on the ever-decreasing size of lithographic transistors, this scaling cannot continue indefinitely. To improve the performance of the integrated circuits, new emerging and paradigms are needed. In recent years, nanoelectronics has become one of the most important and exciting forefront in science...