Achieving Proof of Shared Ownership for the Shared File in Collaborative Cloud Applications

Collaborative cloud applications are increasingly popular in our daily life, and generate plenty of cooperative files. The ownerships of these files are jointly shared by all participants. However, it is still a challenge to keep secure access and storage to those shared files, while ensuring the cloud storage efficiency. To tackle this problem, in this paper, we formalize a novel notion called Proof of Shared oWnership (PoSW), and propose a specific PoSW scheme to implement both secure ownership verification and data deduplication. In the PoSW scheme, we employ the convergent encryption algorithm to protect the content confidentiality of the shared file, introduce the secret file dispersal and secret sharing algorithm to implement the shared authorization and file ownership, and construct a novel interaction protocol between the file owners and the cloud server to verify the shared ownership and achieve deduplication to the shared file. Security analysis and performance evaluation show the security and efficiency of the proposed scheme.