Research And Implemention Of Encryption And Decryption For Linux Private File

Nowadays, a lot of the government, military, bank, and other classified departments are using Linux operating system, because of its openness, stability and security. A lot of secret data are saved as files in Linux operating system, so the security of the operating system is crucial to those departments. In Linux, a two-dimtionnal structure is used to ensure the safety of file access, that is the file users in Linux system are divided into file owner, user in same group, and other user; and access privileges of each visitor are divided into reading, writing and execution. This method could prevent files operations of illegal user, but for some high secret department, this two-dimensional structure is too simple to guard the high security of files, so it is necessary to strengthen the file system security of Linux system.A most popular file encryption algorithmcalled Blowfish is used in this thesis. Blowfish is a symmetrical encryption algorithm; it has a faster operation speed, and the key length is variable. The users can set the length of the password for different security levels. Encrypting File System is developed in an open Linux platform, and based on Linux-2.6.26kernel version and Ext2file system. The application does not care about file encryption process, only need to call the relevant system calls to get efficient, safe, dynamic and transparent encryption. The encrypted files can be saved on hard disks like the original Ext2files. This system would not change the existing Linux system file structure, and both encrypted and unencrypted files can be read and written.This thesis analyzes the design and implmentation of encryption and decryption of Linux system, and introduces a new encryption method based on Linux core. Such ideas to develop Encrypting File System for Linux file systems have a certain reference value for researchers and developers.