| 摘要 |
The invention is a system for protecting the security of computer files. It has hardware elements, including a programmable auxiliary memory and control unit along with associated software elements. The security subsystem is installed on the host computer bus so that it resides in the control logic, address, and data signal path between the computer storage device and central processing unit. The security system is accessible by the computer operating system only during installation and initialization. Thereafter it is inaccessible to or by the operating system. Supervisor determined criteria for access permission to read, write and execute files are entered into the auxiliary memory system where they are protected from alteration. The security system will deny access to users with invalid entry criteria and refuse to write data to the file storage device when unauthorized operations have been attempted. When breaches of these types occur the security system can lock the computer against further activity until it is released by entry of a master password from supervisory or security personnel. The system maintains a protected area in the computer memory device where, among other data, file signatures of all valid files are retained. The protected area of memory also maintains appropriate signatures of all internal files in the security system so that they can be automatically checked for integrity.
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