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Blockchain is a new distributed infrastructure and computing paradigm, which has been widely used in various fields. For example, utilizing a chain data structure to verify and restore data, using a distributed node consensus algorithm to generate and update data, applying cryptography to ensure safe data transmission, and employing intelligent contracts composed of automated script code to manipulate data. Data, seen as an essential production factor, promotes the rapid development of blockchain. However, opportunities and challenges coexist, and data security on the blockchain is one of the key points that need attention. This paper introduces data security and the technical framework for deblocking, focusing on the techniques of zero knowledge proof, K-Anonymity, secure multi-party computing, ring signature, homomorphic encryption, trusted execution environment, and the association of these data security protection technologies with blockchain, and compares several data security protection technologies. In this survey, the focus of blockchain data security is structured by first mentioning the source of the data, then combining the characteristics of integration and non-tampering to the blockchain to solve the problems of traditional data security, and lastly, using data security technology to solve the blockchain data security on the Internet to achieve the ecological security of the blockchain. • Review the development of blockchain and existing data security technologies. • Expound on the current data security situation and the development of blockchain. • Detailed combining the development and status of data security technologies. • Prospect the future development of blockchain and data security. [ABSTRACT FROM AUTHOR]

Blockchain technology has gained increasing attention in the construction sector. The process of developing a blockchain-based application that fits user requirements largely depends on the selection of a suitable consensus protocol, which acts as the centerpiece of blockchain architecture. In distributed networks, consensus protocols not only help maintain data consistency among all stakeholders, but also allow users to work together and stay secure. However, limited efforts have been delivered to analyze and compare existing consensus protocols under various construction scenarios, leading to uncertainties when applying blockchain technology in the construction domain. Therefore, this paper performs a critical review extracting literatures from (1) blockchain-based applications in the construction industry, and (2) existing blockchain consensus protocols. Additionally, a mixed method that integrates qualitative and quantitative analysis is proposed to evaluate the suitability of mainstream consensus protocols for various construction-related applications. Based on the selection criteria and efficiency requirements of consensus protocols generated, a recommendation strategy is also presented for consensus protocol selection under different construction scenarios. This study contributes to the following: (1) it helps construction stakeholders to understand the consensus process in a specific construction application case, and (2) it provides lucid reference guidance in developing a robust blockchain-based system underlying an appropriate consensus protocol. • Reviewed blockchain applications in the construction industry to categorize its implementations. • Identified mainstream consensus protocols and compared their features via four dimensions. • Proposed a qualitative and quantitative analysis method for consensus evaluation. • Generated criteria and requirements for consensus selection under different construction scenarios. • Evaluated consensus suitability and proposed a recommendation strategy for blockchain-based applications. [ABSTRACT FROM AUTHOR]

Integrating building information modeling (BIM) with emerging blockchain technology has gained considerable attention in addressing design collaboration problems like poor data security, weak traceability, and low transparency in off-site construction. However, blockchain implementations in off-site construction design, especially with openBIM standards, currently lack standardized workflow management and methods for ensuring data completeness within the blockchain environment. To bridge these gaps, this paper presents a novel blockchain-enabled platform-as-a-service (PaaS), specifically tailored for off-site construction to enhance interoperability and collaborative design efficiency using openBIM standards. The proposed PaaS offers two significant intellectual contributions: (1) a data contract system that manages openBIM workflow standardization and (2) a data escrow system that ensures the completeness and integrity of openBIM data. The data contract system utilizes an innovative asynchronous smart contract algorithm to streamline workflow checks, while the data escrow system introduces a new blockchain-driven data-checking strategy to ensure openBIM completeness at the data level. Besides, a PaaS architecture is developed to clarify the interaction logic between these two systems. The PaaS is validated and evaluated in openBIM-based design collaborations from a real-world project, with results indicating improvements: a 38% time-saving in design issue coordination and a 32% reduction in design data delivery time. Furthermore, the platform received favorable feedback from project participants, validating the approach and confirming the PaaS as a valuable tool for enhancing design collaboration in off-site construction. • Proposed a BIM-based blockchain framework for production management utilizing openBIM standards • Developed a standardized object/process-oriented semantically enriched Asset Information Model (AIM) • Proposed a data contract system with prefab-related data structures for automatic digitalization transformation • Integrated IDS with blockchain to build a transparent and consistent information-sharing strategy • Designed a data escrow system integrating with blockchain technology for openBIM data completeness checking [ABSTRACT FROM AUTHOR]