Research And Development Of Sharing-oriented Secure File Folder Encryption System

With the development of technology, computers play a more and more important part in people's life, which are used everywhere, whether in work or in entertainment. And file is the main media of the creation, recording, processing and communication of the information in the computer. Thus, more and more fruitful files are produced by more and more dedicated enterprises and individuals. But these files are in a delicate position, whose copying and spreading are easy but unsafe. So more and more people are paying attention to the safety of files and expecting a system that can provide both convenience and security for files.To encode the sharing files, this paper presents a formula, through which local files are dealt with. What's more, it can authorize personal users or group users to set accessing limits on files. There are four sections in it: file processing client, authorization server, identity management server and decryption server. This dissertation focuses on the design and development of this document management formula. Specifically, the file processing client encrypts the files and stores them in local compound document structure, where their original directory tree structure. All information of the personal and group users and their corresponding limitation information are kept, too. Users can encrypt and decrypt them by pressing the encrypt/decrypt button, choosing from right key dual menu, or towing them. They can also check the encrypted files' inner catalogue structure and delete it, revise and rename some specific files. Permission and limitation information is open to view for all users. Besides, for users who are allowed to revise this, they can add and delete visitors and revise visitors' permission and limitation. Authorization server and identity management server are to be connected when group users are added. Moreover, decryption server is needed for decrypting the files.This system of file Encryption adopted two ways, to the current file data and policy information is encrypted using AES, the master key Encryption uses the IBE(Identity-based Encryption).The innovation of this paper is : the combination of folder encryption,enterprise of Unified Identity and authorization management, which makes security when passing and sharing encrypted files between individuals and groups of users; Security folder encryption and file encryption filter technology are combined to make sure the security when double-clicking to open the file in the folder, the temp file in the storage media is still encrypted. In this way it can prevent leaked documents.