Research On Lightweight And Secure File Retrieval And Sharing Scheme In Hybrid Cloud

With the development of cloud computing technology,number of users and data in the cloud environment are growing at an explosive speed.Hybrid cloud environment combines the benefits of public cloud's scalability,cost saving and private cloud's security,controllability,which has a wide range of application scenarios.At the same time,data security issues in hybrid cloud are becoming more and more serious.In order to protect the security of sensitive data,users usually encrypt it before uploading to cloud.However,how to locate files that contain specific information in massive encrypted files quickly and how to achieve fine-grained file sharing while keeping high security are urgently needed to be solved.Existing secure file sharing and retrieval mechanisms over encrypted data are generally limited by restricted application scenarios,simplex access policies,heavy computing tasks,and support for single keyword search only.It's difficult to apply those schemes to hybrid cloud directly.To solve the above problems,we propose a lightweight and secure file retrieval and sharing scheme in hybrid cloud.Based on the attribute-based encryption algorithm,our scheme achieves the conjunctive keyword search over ciphertext under data owner's authorization,and reduces the computing overheads of users by delegating most calculation tasks to the private cloud server.Besides,our scheme realizes the fine-grained multi-party file sharing and supports the "multi-read and multi-write" mechanism by introducting ABS algorithm.Security analysis shows that the our scheme guarantees the data confidentiality,is collusion resistance,supports fine-grained access control and signature unforgeability and anonymity.The performance evaluation shows that our scheme consumes less amount of computation in keyword index generation,trapdoor generation,encryption and decryption,signature generation and other phases,and can significantly reduce user's computing overheads.