Improved group-oriented proofs of cloud storage in IoT setting

In the IoT setting, many resource constrained devices outsource their collected data to the Cloud. To ensure the outsourced data has not been lost, these devices need some mechanism to check the integrity of their data. Furthermore, in some settings, ad hoc devices need to act as a group, and in this group, any member may require to verify the integrity of outsourced cloud storage. Aiming at solving this problem, in AISACCS'15, first proposed the concept of group-based proofs of storage (GPoS). In GPoS, a group manager can authorize data owners as group members, and then these group members can outsource files to the cloud storage server; later, each member can verify the integrity of the outsourced cloud storage. They also give a concrete construction of GPoS. Unfortunately, in this paper, we find their scheme is not secure. Recently, also proposed a dynamic group-based integrity auditing protocol for outsrouced cloud storage; we also show their scheme is not secure either. Finally, we give an improved scheme and roughly analysis to its security and performance.