Integrity Verification Of Multiple Replica Files Distributed Storage

Cloud storage is a cloud computing system, with the core of data storage and management. In order to provide data storage and services, cloud storage put different types of data storage services together by application softwares. This storage model is favored by more and more enterprises, and the utilization rate increased year by year. The requirements of cloud storage become more diverse. Because the CSP(Cloud Service Provider) is semi-trusted, users increasingly concern about their files stored in cloud provider is completed.With the advent of cloud storage mode, a large number of users select this model, and transplant their applications and data into the cloud. In order to save the local cost, some users don’t save the copy of data in local place. To ensure the copy of the storage in the cloud is completed, this paper proposes a distributed multiple copies integrity verification project based on the existing technology, which can ensure that the service providers store the copies of the user’s data completely. If one copy is accidentally damaged or lost, we can find the location of block of error file, and the damage file can be repaired and restored through the other copies. The third party auditor is introduced in the integrity verification scheme. It can support the public verification and audit the user’s files in the case that they haven’t saved the user’s file. It can identify and calculate professionally. It can access to the cloud server safely and send a challenge message instead of the user. Taking advantage of the many copies are storaged distributed, the cloud master server distributes counting process of the verification credential to multiple servers, the computation time is reduced and the efficiency of verification is improved. At the process of computing authentication credentials, the validation tags for each encrypted block is calculated through the homomorphism hash function, and all the copies is inspected according to the homomorphism hash technology. When the label is calculated, a random mask is introduced, which can resist the cloud server replacement, replay and collusion attack. The feasibility is explained through the correctness proof and simulation experiment.