On the Security of an Mutual Verifiable Provable Data Auditing in Public Cloud Storage

Provable Data Possession (PDP) enables cloud users to verify the integrity of their outsourced data without retrieving the entire file from cloud servers. At present, to execute data checking, many PDP schemes is delegated to some proxy to implement remote data possession checking task. Because the proxy may store some state information in cloud storage servers, it makes that many PDP scheme are insecure. To solve this problem, Ren et al. proposed an mutual verifiable provable data possession scheme and claimed that their scheme is secure. Unfortunately, in this work, we show that their scheme is insecure. It exists forgery attack and replay attack. After giving the corresponding attacks, we give an improved scheme to overcome the above flaws. By analyzing, we show that our improved PDP scheme is secure under the ChosenTarget-CDH problem and the CDH problem.