A collusion-resistant certificateless provable data possession scheme for shared data with user revocation

Cloud storage service can provide a lot convenience for users to collect, store and share data within a group. However, there are some secure issues, one of which is that the cloud server may cheat users for a good reputation when the data is lost. A classical solution to deal with it is provable data possession (PDP) protocols. Most of PDP protocols are relied on either the public key infrastructure or identity-based cryptography. However, certificate management and key escrow issues place a significant burden on this. Furthermore, revoking the group's illegal users is a critical issue for PDP schemes. To address these problems, we put forward a certificateless PDP scheme for shared data with user revocation. Our proposed scheme not only achieves efficient user revocation but also withstands collusion attack. We also give a formal proof of security of our proposed scheme without random oracle model. Experimental results and analysis show that our scheme is quite effective in data auditing, verification, and user revocation.