The Design And Implementation Of Cloud Storage System Based On Homomorphic Encryption

In the modern information technology era, with the information rapidly increasing, information storage and management of data are becoming more and more difficult. Traditional local storage method has been increasingly difficult to meet the data storage and management needs, and cloud storage technology has become an effective way to solve the problem. However, most cloud storage platform neglected the security of users’data, users’information stored in the cloud storage platform directly without any encryption processing, which can easily lead to the leakage of users’data. In order to solve the problem of data privacy protection, data encryption in the cloud storage maybe is a good solution. Only a few cloud storage service products such as Dropbox, Wuala, telecom "e Cloud", encrypted users’data upload to ensure the security of users’ data, however, anyone, including the system administrator, hacker, unless he holds the decryption key, otherwise, even he got the clouds database, what he can get is just a pile of garbage characters, these encrypted data is difficult for cloud storage system to use, which wastes the advantage of cloud computing in high computational performance. And, when the encrypted data stored in the clouds formed a certain scale, the efficient retrieval of encrypted data has also become an urgent problem, the traditional information retrieval technology is difficult to meet the demand, encrypted data retrieval effectively in the the clouds become one of the major research topics.Homomorphic encryption is a form of encryption which directly performs ciphertext operation, such as statistical analysis and ciphertext retrieval, with operation results being automatically encrypted, which lets anyone manipulate what is encrypted, even without knowing the secret key. Therefore, in order to balance security and service demand in cloud computing, we introduce the concept of the homomorphism encryption. Through the study of latest homomorphism encryption scheme, a practical simple fully homomorphic encryption scheme, using only elementary modular arithmetic, derived from Gentry cryptosystem is proposed to ensure the privacy-preserving in cloud storage, in which encrypted data can be operated directly without affecting the confidentiality of the encryption systems, so that it can excellently realize the need of cipertext retrieval and other processing in cloud computing.This thesis utilised the client/server model to design the cloud storage system platform, and the work covered requirement analysis, framework design, functional module design and build up the frame, system development, system testing, and so on.