Design And Implementation Of File Encryption System Based On Windows IFS Filter Driver

With the coming of information-based era, electronic documents gradually replaced the paper ones to be the absolutely necessary data storage mode in daily work and study. What accompanies the change is how to ensure the security of these electronic files, preventing the access or spread by the unauthorized users. Encryption is a rapid development science with the development of computer technology, which primary mission is to protect these important electronic documents to ensure the security of electronic data by data encryption.Windows, developed by Microsoft in 1980s, has now become the most extensive used personal computer operating system in the world after experiencing dozens of versions of the upgrades and improvements. So Windows data security has been paid attention by more and more people, Microsoft developed EFS encryption for the NTFS file partition from the beginning of Windows 2000, but data encryption has not yet been accepted by the most users because of the restrictions of the EFS. In order to overcome the restrictions and lack of use of the existing file encryption system, we designed a new file encryption product based on Windows IFS Filter Driver.In SecFile, we adopted a combination of hardware and software method to improve the security and ease of use of SecFile. Each SecFile user has a hardware token which stores the user's private key and personal information, which can simplify the use of SecFile and avoid the risk of the private key easy to be stolen when it is stored on the hard disk drive. In order to improve the security of the system, we adopted encryption authority control and withdrawal recovery of key token mechanism. For the encryption of document data content, we used symmetric encryption algorithm to enhance the performance of file encryption. The security of document key is ensured by user private key encryption.Each encrypted file and directory in SecFile has a corresponding encryption information file. Encryption information files are saved in a particular directory; they cannot be directly accessed by any user. Encryption information files contain the information of user's access control and some control information related to the encrypted files. Through encryption information files we can not only guarantee the integrity of encrypted files, but also easily achieve the encrypted files sharing and access control among many encrypted users.