Secure and efficient data collaboration in cloud computing: Flexible delegation via hierarchical attribute-based signature

Data collaboration allows multiple parties to jointly share and modify data stored in the cloud server. As unauthorized users may create or modify the shared data as they want by tampering with requests sent by authorized users to replace them with what the unauthorized users want to send, secure data collaboration in cloud computing requires data integrity protection of requests and precise privilege verification of users. However, while maintaining data integrity, it is difficult for current signature schemes to achieve the following demands: fine-grained access control, high scalability, a flexible and controllable hierarchical delegation mechanism, and efficient signing and verification. Therefore, we designed a scalable and flexible hierarchical attribute-based signature (HABS) model and proposed a signing policy HABS construction using the linear secret sharing scheme to construct an access structure. Furthermore, we proved the unforgeability of our HABS scheme in the standard model. We also analyzed and tested the performance of our HABS scheme and related scheme, and we found that our scheme has less signing computation consumption in large-scale systems with complex policies. Finally, we provided a specified application scenario of HABS used in data collaboration based on cloud computing.