Protection of Secrets by File Access Control with Common Key Cipher and Message Digests of Program Files

Nowadays, PC is normally used in companies and information which contains secrets is often managed on PCs. Protection of the information is one of the important things in nowadays society. Virtual machine is one of the solutions of the problem since guest OS can be observed by hypervisor. However, in this case, sending secrets to outside cannot be prevented. Moreover, the observation sometimes decreases usability since many actions of users such as using USB drive are prohibited. Therefore, in this paper, we propose a method that encrypts messages between a server and a client with a key which is provided from a server. In our method, secret information is encrypted so that any application software program cannot open files without correct keys. When application software programs which are registered on the list access files with secrets, Virtual machine decrypts the files and it pass through them to the application software programs. That is, only registered application software programs can open and edit specific files without any special custom to the programs. Of course, the method does not prevent other software programs from accessing files without secrets. In our proposed method, secrets can be kept without customizing application software programs and usability of computers does not decrease since there is no limitation in using computers.