Confidentiality of Data in Public Cloud Storage Using Hybrid Encryption Algorithms

Abstract

Cloud computing is a recent technology that uses the Internet, central servers to organize the data and applications, which the user can access, cloud computing enables individuals and organizations to gain access to huge computing resources without capital investment. one of the main drawbacks of cloud computing is data security. when data migrate to the cloud, is fully controlled by cloud service provider not by the data owner. As a result, user data is not secure at the server side. Security goals of data cover three points namely: Availability, Confidentiality, and Integrity [1]. This thesis handled Confidentiality of file using hybrid of symmetric encryption algorithms (AES with key (128), AES with key (256) and Blowfish),the proposed technique based on providing data confidentiality by the software, each user wants to upload to, or download a file from the cloud storage which must be passed to the software. Where the software performs encoding process by splitting it into three blocks with different sizes and selecting algorithms randomly to encrypt blocks of file before uploading and saving the information's of encoding process in local database, also the software performs the decoding process by retrieving the information's of encoding process to decrypt the file after downloading it from the cloud storage.the thesis was checked the randomness of sequence binary bits of file, and evaluate the time of the encoding and decoding processes of this proposed method and compared it with time of encryption algorithms: AES-128, AES-256, Blowfish.