Public integrity auditing for dynamic group cooperation files with efficient user revocation

With the rise of online cloud files, more and more online files are generated by group cooperation in recent years. However, there exist many security problems to be solved urgently for online cooperation files, such as how to verify the integrity of group cooperation files and realize its dynamic update and how to further trace the identity of signer (i.e., operator) who upload or update the group cooperation files. To address the above problems, we propose a secure public integrity auditing scheme for group cooperation files in this paper, named PAGCF. First, PAGCF not only can verify the integrity of group cooperation files, but also supports the dynamic update of group cooperation files via the skip list. Second, any legitimate user can trace the identity of signer to resist malicious tampering and workload disputes of group users. Additionally, PAGCF also achieves user stateless without requiring users to maintain a list locally. Third, PAGCF not only can realize effective group user revocation so that revoked users lose privileges to update the group cooperation file and trace the identity of signer, but also can resist the collusion attack of malicious adversaries and revoked users. Finally, numeric analyses and experiment results demonstrate the efficiency of our proposed scheme.