A Design of Privacy Data Encryption and Decryption System for Data Security in Clouds

With the rapid development of the IT technology, users increasingly rely on data. While cloud storage and other online service platform make user's privacy data protection become an important issue. In this paper, we have designed an encryption and decryption system for user's privacy data files, it can be used to encrypt and decrypt the privacy data. The system uses the DES algorithm to provide certain security to the data files, and supports a variety of data types and file types with good operability. Introduction Cloud storage is similar to cloud computing. It is derived and extended from the concept of cloud computing. It refers to a system that through cluster application grid technology and distributed file systems and other functions, to make a large variety of different types of storage devices through the application software work synergistically, and provides data storage and business access externally [1] [2]. Cloud storage usually means that source data or backup data will be placed in the storage pool that users can not determine outside, rather than placed in local data center or dedicated remote site. In fact, when using cloud storage service, internal privacy data in the cloud has a certain risk. Before migrating data to the cloud, whether it is public cloud or private cloud, the fundamental problem must be solved, that is data security issues. Users concern about that once privacy data is uploaded to the cloud, they can not have direct control over the remotely stored data [3].And security of privacy data depends on the service of cloud storage provider, but cloud storage provider can not manage these privacy data in the cloud comprehensively and effectively, and lots of unreliable factors can bring some security management issues [4].Nevertheless, the encryption of privacy data is the basic method to protect data. Before uploading privacy data to the cloud, it has been encrypted in the local, even if attackers stole the encrypted data, they would not know the real content of the data. Therefore, it ensures the security of privacy data in the cloud storage. When users need privacy data, the data can be obtained from the cloud and decrypted in the local as well. Functional Requirements Analysis At present, most of cloud platform providers have a series of powerful cloud storage services, For example, Hadoop provides cloud storage solutions, and Amazon cloud platform provides files and data storage service(Simple Storage Service, Amazon S3)etc [5], but they can not provide the data encryption service. Data in cloud is not directly controlled by users. Therefore, the problem of data security is becoming more and more prominent. From the user's point of view, it is necessary to solve the security problem fundamentally before using the cloud storage service. In this paper, we have designed an encryption and decryption system for data security in cloud. Privacy data is encrypted on the local computer before uploading to the cloud, stored in cloud server with encryption form, then obtained from the cloud server, and decrypted in the local. This approach can greatly improve the security of data in cloud.As shown in Figure 1. 4th International Conference on Mechatronics, Materials, Chemistry and Computer Engineering (ICMMCCE 2015) © 2015. The authors Published by Atlantis Press 714 Fig.1. System function diagram Data Encryption and Decryption Process According to the requirements, the program flow diagram can be designed. Users first enter a password parameter and keep it. The key is generated from the password parameter. Then users select the data file that need to be encrypted. According to the DES algorithm and the generated key , the system encrypts the data file. When users need the encrypted data, select corresponding ciphertext file and simultaneously enter the reserved password parameter, the system will perform the appropriate decryption operation. As shown in Figure 2. Fig.2. Data encryption and decryption program flow diagram System Main Function Modules The system mainly includes three modules: the client module, the key generating module, the encryption/decryption module. As shown in Figure 3. Fig.3. System main function module