Cross-chain bridges, one of the foundational infrastructures of blockchain, provide the infrastructure and solutions for inter-operability, asset liquidity, data transfer, decentralized finance, and cross-chain governance between blockchain networks. However, because cross-chain bridges often have to handle communication and asset transfers between multiple blockchains, they involve complex protocols and technologies. This complexity increases the likelihood of vulnerabilities and potential attacks. In order to ensure the security and reliability of cross-chain bridges, this article launches a thorough investigation of existing cross-chain bridge projects, clarifying bridging mechanisms, bridge types, and security features. The following part goes into the subject of security and sheds light on the considerable challenges faced by cross-chain bridges. It conducts a thorough analysis of security flaws, covering problems like smart contract vulnerabilities, centralization risks, liquidity issues, and oracle manipulations. Furthermore, this study promotes a compendium of security solutions and best practises, pointing the way toward a cross-chain bridge scenario that is more secure.

This paper presents a primary exploration of Bitcoin inscriptions. We dive into the technological underpinnings and offer a detailed comparative analysis between Bitcoin inscriptions and NFTs on other blockchains. Further, we explore a wide range of use cases and significant opportunities for future innovation, including inscription derivative protocols, Bitcoin Layer2 solutions, and interoperability techniques.

A smart contract is a computerised transaction agreement that carries out predefined terms without human involvement or third-party intermediaries. It serves as a trust intermediary in several industries, including finance, insurance, and supply chain management, in the blockchain 2.0 era. With the increasing interest in smart contracts, security has become a serious problem. Examining typical vulnerability types and vulnerability detection methodologies is of special importance. In this research, a comprehensive evaluation of common smart contract security vulnerabilities is conducted, and a three-tier threat model is then provided to classify the vulnerabilities. In addition, we examine fourteen existing smart contract analysis tools for finding vulnerabilities and classify them according to the main technique they apply. This article is designed to serve as a reference for people who wish to analyse deployed code and enhance existing detection techniques. At the conclusion, open issues and future research paths regarding smart contract vulnerability detection are presented.

The ubiquity of sensor technology through the Internet of Things and mobile devices has led to a surge in the generation of personal data. The use of personal data to provide personalized services and optimize business decision-making has recently become a popular trend. The data marketplace is one of the most critical places where companies can source data to organize the variety of data source formats and improve individuals’ data self-management (e.g., data access control and usage). This paper proposes a Databox-based delivery service via blockchain that provides data consumers with secure and controlled access to requested data sources of interest. It consists of a databox-based data delivery module and decentralized activities service module. The former is responsible for data delivery and the latter is to provide a one-stop data sharing service on blockchain. We implement a preliminary prototype and conduct an evaluation of system activities and smart contracts utility.

The security of crypto wallets is a major concern in light of the recent prevalence of thefts. Aiming at the problem that there is no complete and reliable security detection model for Android-based crypto wallets, this study provides an evaluation framework based on the standard Android application security detection and unique security assessment of crypto wallets. The framework presents an attack-based detection approach, which identifies potential wallet security issues by simulating attacks and exploiting vulnerabilities. Ten popular Android crypto wallets are evaluated and compared to validate the framework’s practicability and accuracy. The test results demonstrate that the framework can accurately reflect the performance security of wallets. Additionally, the study proposes the corresponding actions to address the identified common security threats in crypto wallets.

Federated Learning (FL) presents a privacy-compliant approach by sharing model parameters instead of raw data. However, how to motivate data owners to participate in and stay within an FL ecosystem by continuously contributing their data to the FL model remains a challenge. In this article, we propose a hybrid incentive mechanism based on blockchain to address the above challenge. The proposed mechanism comprises two primary smart contract-based modules, namely the reputation module and the reverse auction module. The former is used to dynamically calculate the reputation score of each FL participant. It employs a trust-jointed reputation scheme to balance the weights between trust values of parameters and bid prices. The latter is responsible for initiating FL auction tasks, calculating price rankings, and assigning corresponding token rewards. Experiments are conducted to evaluate the feasibility and performance of the proposed mechanism against the three typical threats. Experimental results indicate that our mechanism can successfully reduce incentive costs while preventing participants from colluding and over-bidding in the data sharing auction.