Cross trust: A decentralized MA-ABE mechanism for cross-border identity authentication

With an increasing demand for authenticated data exchange between jurisdictions, ensuring the privacy and security of data interactions is crucial for national security, public health, and economic vitality, becoming a fundamental national infrastructure. Current solutions can be categorized into two types: fully decentralized autonomous systems based on blockchains or centralized solutions that rely on authoritative centers such as certification authorities (CAs). In reality, a balance needs to be struck between guaranteed authority and privacy independence. A certain authority is needed as an authorization guarantee, and decentralization is required to ensure privacy and the independence of the authority. This paper proposes a novel scheme, CT-MA-ABE (Cross-Trust Multiple Authorization Attribute-Based Encryption), to address these issues by implementing MA-ABE for cross-border institutional authorization interactions, utilize blockchain certification authority (BCA) for credibility and encryption-based authorization to protect attribute data privacy. This solution integrates the role of 'notary' in cross-border interactions, addressing the supervision problem in fully decentralized approaches while also considering the trust issue in centralized systems. This paper also introduces the Universal Certificate Authority Pool (UCAP), an innovative hybrid federated authorization method, creatively utilizing the implied authorization conditions of attributes to create a flexible and transitive authorization mechanism based on attribute relationships and extensions, enhancing privacy protection and improving the speed of authorization matrix calculation. The successful deployment of the system between the legal jurisdictions in South China, Zhuhai and Macau as a critical infrastructure component for securing data interactions further demonstrates its effectiveness as a reliable and secure solution.