Multi-Authority Attribute-Based Encryption Scheme With Access Delegation for Cross Blockchain Data Sharing

To achieve fine-grained access control and address the data silos challenge in data sharing, the integration of blockchain with attribute-based encryption emerges as a promising solution. Nowadays, the growing interconnectedness among diverse blockchain applications has spurred the need for efficient cross-chain data sharing. However, existing single-authority attribute-based data sharing schemes are not suitable for such cross-chain scenarios involving multiple attribute authorities. Moreover, the frequent requirement for data owners to process cross-chain data requests significantly hampers practicality. In this context, we introduce a novel multi-authority attribute-based proxy re-encryption scheme that enables ciphertext policy updating and supports secure and efficient cross-chain data sharing. By introducing a proxy, the data owner is empowered to delegate access without leaking any valid information and flexibly sells data across blockchains through cross-chain access policies. Besides, our scheme leverages the relay chain to foster a decentralized and trustworthy ecosystem. The adoption of smart contracts automates the cross-chain data sharing process and ensures equitable distribution of benefits among participants. Additionally, our scheme integrates hybrid encryption with the decentralized data hosting platform, substantially mitigating the on-chain storage burden. Security analysis affirms that our scheme is semantically secure and resistant to collusion attack. Performance analysis and simulation experiments demonstrate the excellent efficiency and practicality of our scheme when conducting cross-chain data sharing.