Efficient identity-based multi-copy data sharing auditing scheme with decentralized trust management

The development of cloud storage provides convenient group data sharing services to us. In reality, not only can users upload data to the cloud, but more often they are inclined to download data from the cloud. Unfortunately, data stored on the cloud is not always trustworthy, and downloading Trojan or virus data can bring bad experiences to users. In certain cloud computing scenarios, with the aim of preventing data loss, both the original data and the corresponding data copies are stored. Consequently, the huge amounts of stored data copies result in large storage overhead to the cloud. In order to tackle all of the above problems, an efficient identity-based multi-copy data sharing auditing scheme with decentralized trust management is presented in this paper. In our scheme, the group manager detects shared data and generates short signatures for the data that can pass detection successfully before it is stored on the cloud. Further, the group manager calculates the trust value for users and enhances the management of user behavior according to it. Through adopting data merging, the total amount of data copies and the overhead of users and cloud are reduced in our scheme. In terms of security, our scheme can resist forgery attacks launched by three different adversaries. At last, we prove that our scheme is secure and practical through security and performance analysis, respectively.