Research And Implementation Of Cloud Storage Data Recoverability Proof Mechanism

In the information age of today,information technologies develop greatly.Among them the cloud computing and cloud storage are the most representative products.As an extension of cloud computing technology,cloud storage is a trend in the development of storage services which can provide massive storage services for cloud computing.With the ubiquity of cloud storage,there are a large number of consumers renting cloud storage services and storing their data into cloud.However,as users lose the direct control over their data,the integrity and availability of the outsourced data has become a big concern for users.Accordingly,how to verify the integrity of stored data and retrieve the availability of the corrupted data has become an urgent problem.Moreover,in most cases,user's data is not always static,and needs to be updated.So how to implement dynamic modification of data in a POR(Proof of Retrievability)scheme is also a problem that should not be ignored.In this thesis,we research the integrity auditing of data,the recovery of data and the dynamic updates of data in cloud storage.The main work is as follows.(1)For the recovery of cloud damaged data,we design an algorithm based on IDA for cloud storage.By employing the idea of matrix invertibility,we preprocess the original data to guarantee its retrievability.And the expansion multiple of the file can be controlled by selecting the different size of the encoding matrix.(2)In view of the dynamic modification of the cloud storage data,we further propose the concept of dynamic multi-fork hash tree.We can dynamically select the most appropriate hash tree fork number according to the number of data blocks and the frequency of data updates,minimizing the cost of dynamic updating.Security analysis proves the security performance,and the scheme can resist forge attack,replace attack and pollution attack.The experimental results show that the scheme has good performance.Moreover,regardless of the number of data blocks,we can always find the optimal number of forks for building and updating hash tree.(3)Based on the Aliyun platform,we design and implement a prototype system for data integrity audit and data recovery in cloud storage.We employ the Elastic Compute Service(ECS),Object Storage Service(OSS)and Relational Database Service(RDS).The system includes two major functions:data integrity audit and corrupted data recovery.The system further validates the effectiveness of the proposed scheme.