Construction cost management using blockchain and encryption

Data accountability (i.e., data integrity and traceability) concerns existing construction cost management platforms due to the risk of data manipulation in a centralized paradigm. Blockchain is a promising technology that provides immutable and traceable data storage with a decentralized architecture. However, the transparency of blockchain conflicts with the confidentiality nature of cost information. Therefore, this paper presents a novel framework based on blockchain and encryption to preserve both data accountability and confidentiality in construction cost management. The proposed new framework involves the development of a cost data model containing the required confidential cost information to facilitate partially transparent recordings on the blockchain. An access control model based on symmetric and asymmetric encryption as well as proxy re-encryption mechanisms is developed to prevent unauthorized access to sensitive cost data on the blockchain and transfer data access in dynamic construction projects (i.e., construction projects involving new members continuously). Subsequently, encryption-integrated smart contracts are developed for automatic and secure cost activities on the blockchain. The framework is validated with a desirable latency (at the millisecond level), throughput (at the hundred level), and storage cost (at the MB level) in three illustrative cost management scenarios. The results indicate that project members can have accountable and confidential cost data for dispute resolution and cost analysis, respectively, as well as efficient cost data access transfer.