| With the extensive application of computer technology, computers play anincreasingly important role in people’s lives, the importance of document security forpeople has been improving. But the stealing documents technology emerging recentlyposes a serious threat. Traditional encryption policy can not meet user needs fordocument protection security. Aiming at this problem, it is a great significance toresearch a higher intensity of the file protection method.This paper firstly describes related concepts of the PKCS Cryptographic TokenInterface Standard and encryption/decryption mechanism; Then introduced the principleof transparent file encryption and the file system filter driver framework; Finally,describes system architecture and implementation process in detail. The whole system isdivided into two modules: application of control program and filter driver. Applicationof control program primarily complete user login and other related property functions,and the encryption and decryption functions of file and key; filter driver primarily filterfile operations and make corresponding treatment. To improve transfer efficiency ofdata, this system applies for64KB of shared memory area, it is used for data transferbetween application layer and driver layer.Aiming at the synchronization problems of file encryption logo and file, the methodof file encryption logo saved in the file header is proposed, and the key of file is savedin file header at the same time. To improve the security of key, symmetric algorithmsand asymmetric algorithms are combined, that is file encryption and decryption usingsymmetric algorithm, key encryption and decryption using asymmetric algorithm, andthe key is saved in the file header.Finally, experiment and analysis of test results are provided. Experiments showedthat the proposed method has stronger of file protection strength and more security,compared with the traditional methods of file encryption and decryption. |
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