Blockchain-assisted data sharing supports deduplication for cloud storage

Offloading data to cloud storage has changed the way people live and work, which reduces data management costs and increases productivity. People can use their devices to download data from cloud storage regardless of location and time. It means that data can be shared across domains through cloud storage. However, offloading data to cloud storage brings convenience as well as various challenges, such as how to solve the performance bottleneck of cloud storage and how to achieve secure data sharing in cloud storage. Blockchain has played an important role in secure data sharing based on its tamper-evident nature. In this paper, a blockchain-assisted data sharing scheme is proposed which implements the detection of deduplicated data and completes the ciphertext combination after deduplication. In order to verify the legitimacy of the ciphertext, blockchain is used to assist in verifying the ciphertext based on its tamper-evident nature. Furthermore, partial ciphertext parameters are calculated at free time to improve server operation efficiency. Finally, we simulated all algorithm of the proposed scheme on the PBC library and the results show that it achieves a balance between usability and performance.