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.
