Research On Dynamic Data Encryption Based On Security Policy

With the arrival of the mobile Internet era, smart phone, tablet personal computer and other mobile devices become more and more popular in daily life. In the application process of such device, people produce, store, and transmit a lot of data. The amount of data and data types have greatly increased, many of which have different degrees of security requirements. In order to satisfy the security requirements of data, It should adopt appropriate safety measures to protect the data.Data encryption is an effective measure to ensure the data security. By putting a plaintext data and encryption key as input, adopt certain cryptographic algorithms perform encryption, form a meaningless cipher ways to ensure the confidentiality of the data. The effect and efficiency of data encryption depends mainly on two aspects, the first is the strength of the encryption algorithm and the speed of execution, the second is how to apply encryption algorithm. This thesis mainly study how to apply encryption algorithm. First, characteristics and scope of traditional full encryption methods and existing selective encryption methods were studied. Then using bit-plane decomposition method to analyze the plaintext data. According to different importance, divided the data into different portions. Furthermore, propose a method of select key blocks from important bit-plane and a block scrambling method based on chaotic. On this basis, we propose a dynamic data encryption method, select encryption algorithms with different characteristics to encrypt portions with different importance. In order to meet multi-level security requirements and improve the flexibility of data encryption. And then propose a data encryption transmission scheme based on security policy. Through the way of an encryption, decryption times step by step, not only ensure the high data encryption security strength also reduces the overhead of encryption. At the same time in this way can also control the partially decrypted data availability levels. Experiment results show that using this method for data encryption has high flexibility and execution efficiency, and has a certain application prospect.