Memory managment method
In the conventional method of maintaining the confidential a program, wherein a program to be executed in an information processing device is stored in a hard disk, etc., in an encrypted state and the program is decrypted when it is executed, because a decrypted program is written in memory, the program may be illicitly analyzed by a third person. Provided is memory management method wherein code information or data of a program written in a virtual memory is data which is encrypted and inaccessible by a CPU, and when code fetching or data access to the encrypted area occurs, an interruption process is performed wherein with respect to a management unit of the memory management device including the area, an inaccessible state is changed to an accessible state to perform decryption.
1. A memory management method that is for processing code information of a program loaded into a virtual memory, the method comprising:
encrypting the code information, and varying the code information to data, where data reading or data writing is impossible from a CPU;
when receiving the data reading request or the data writing request by the CPU for the code information, executing an interrupt process;
as a result of the execution of the interrupt process, varying the inaccessible state of a management unit of a memory management device including the encrypted area to an accessible state, and for decrypting the data; and
when the data reading request or data writing request designates information of other management unit, executing a recursive process for re-encrypting the data of the management unit, where the data reading request or the data writing request has become possible by the step for executing the interrupt process.
2. The memory management method according to claim 1 ,
wherein the encryption is executed before a program counter designates an entry address of an executable file upon program activation.
3. A non-transitory computer-readable storage medium storing a program for causing a computer to execute a process for code information of a program loaded into a virtual memory, comprising:
encrypting the code information, and varying the code information to data, where data reading or data writing is impossible from a CPU;
when receiving the data reading request or the data writing request by the CPU for the code information, executing an interrupt process and, as a result of the execution of the interrupt process, varying the inaccessible state of a management unit of a memory management device including the encrypted area to an accessible state, and for decrypting the data; and
when the data reading request or data writing request designates information of other management unit, executing a recursive process for re-encrypting the data of the management unit, where the data reading request or the data writing request has become possible by the step for executing the interrupt process.
4. The non-transitory computer-readable storage medium according to claim 3 ,
wherein the encryption is executed before a program counter designates an entry address of an executable file upon program activation.