基于DES加解密技术的电子文档访问控制方法

电子文档的在线阅览已经非常普遍.付费用户可以下载文档或在线阅读文档的全部内容，而普通用户则只允许预览有限的内容.通过这种方式可以在一定程度上实现对电子文档使用范围的控制.但该方式的不足在于，付费用户下载文档后，可以随意将下载的文档转发给他人.因而，如何在文档被下载后依然能对其使用范围进行限制，从而更好地实现版权保护，值得研究和摸索.本课题重点研究电子文档的线上线下访问控制方法：通过对注册用户权限的限制实现电子文档的线上访问控制，基于DES加解密等技术控制下载文档的线下使用范围.实验结果表明，本文所提出的基于DES加解密技术的电子文档线上线下访问控制方法，能够更加有效地对电子文档的访问权限进行控制，具有更强的版权保护力度.

Method for Electronic Documents' Access Control Based on DES

Online reading of electronic documents has been very common. Documents could be downloaded or their full content could be read online by those users who have paid for them, while limited content could be previewed by the common users. By this way, documents'' owners can realize the control of the use of electronic documents to a certain extent. But there are imperfections in the way. If one user has pay for the documents and downloaded them, he or she could send them to others without any restriction. Therefore, in order to achieve better copyright protection, it is worthy of study and exploring access control method on how to still make some restrictions on documents when they are downloaded. This paper focuses on the method for making some access restrictions on the electronic documents both online and offline. For online documents, access restrictions would be done on registered users, while DES encryption and decryption is used for controlling the downloaded documents. Experimentations show that the proposed method based on DES encryption and decryption technology could control the access to electronic documents more efficiently and give a stronger force on copyright protection.