JPH04181447A - Computer system - Google Patents

Abstract

PURPOSE:To execute the detection and recovery of illegally interposing the third person to a program and to make the processing secure, simple and highly speedy by providing address recognition logic for recognizing a check area and logic for recovering the program according to a sum check data, and integrating the logic into the computer system. CONSTITUTION:From the program of a main memory 1, the sum check data prepared by an address recognizing circuit 8 and a sum check preparing circuit 5 are compared with the sum check data in a local memory 2 by a sum check data comparator circuit 6. When non-coincidence is generated, it is judged that the program is reloaded by any illegal interposing, and the recovery processing is executed by a recovery circuit 7 based on the sum check data in the local memory 2 so as to automatically correct the address part corresponding to the sum check data. Thus, illegal interposing to the program can be detected without fail, the reliability is improved and the functions can be simplified.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for detecting and recovering programs that have been rewritten, added to, or deleted due to unauthorized intervention by a third party. be.

[Conventional technology]

Currently, as a detection function for program changes caused by unauthorized intervention, a program capacity check is widely used in which a program memorizes the final address of its own program, and if a program executes an instruction at an address larger than the final address, it is considered an error. It is.

However, with this method, a large load is placed on the program, which may lead to a decrease in the performance of the program. Interventions such as erasing or rewriting programs cannot be detected. I have a problem.

Another checking method is to treat the program as mere data in memory and detect it using FCC, etc., but a relatively large program requires a large amount of memory. In addition, multiple processing circuits are required for FCC creation and checking. As there is no effective recovery method, the problem eventually develops into a serious failure such as a system failure.

Regarding these detection power formulas, for example,
-191944 etc.

[Problem to be solved by the invention]

In the above conventional technology, y) no consideration is given to reliability, simplification, program performance, etc. of the check function;
There is a risk of slipping through the checks.

■) The detection program is complex. ■Can only be detected if rewriting or erasing is performed.

There were other problems.

The present invention aims to improve reliability, simplicity, and speed by detecting and recovering from unauthorized program intervention by a third party using hardware, and further reduces the capacity of programs, memory, etc. It can be used without being restricted.

[Means to solve the problem]

1-2 A local memory for storing program sum check data to achieve the purpose.

A part of the main memory is provided with logic to compare sum check data, address recognition logic to recognize the check area, and logic to recover the program using sum check data, and these are implemented in hardware. It is composed of , and is incorporated into a computer system.

[Effect]

According to the present invention, unauthorized intervention in a program can be reliably detected and recovered regardless of whether it is rewriting, adding, or erasing, so serious problems such as program runaway will not occur due to this.

Furthermore, by checking for unauthorized intervention using hardware, no extra load is placed on the program.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the present invention will be described with reference to FIG.

When the system is powered on, the program is saved to an external storage device (
When writing data to the main memory (not shown), etc., sum check data is created, and the data is stored in the local memory 2 of the hardware. At this time, the hardware needs to know the area where the sample check is performed, that is, the area where the program white is stored.

For this reason, the first address register 3.
A final address register 4 is provided, and the start address and final address of the program in the main memory 1 are set by an address recognition circuit 8 to control the check area.

When the program starts running, the program itself performs an idle check, and if the idle state continues for a certain period of time or more, the program instructs the hardware to perform its own sum check. Alternatively, a sum check instruction may be given to the hardware at regular intervals. When the hardware receives the sum check instruction, it sends the address=' from the program in the main memory to the withdrawal path 8, the new sum check data created by the sum check creation circuit 5, and the previously saved data in the local memory 2. The sum check data is compared by a sum check data comparison circuit 6. If a discrepancy occurs, it is determined that the program has been rewritten due to unauthorized intervention, and the recovery circuit 7 performs recovery processing based on the sum check data in the local memory 2, and a discrepancy occurs in the main memory 11:. Automatically corrects the address part corresponding to the sum check data.

If no mismatch occurs and all sum check data are the same, the hardware reports normal termination to the program.

In addition, if the user intentionally wants to change the program in main memory 1, such as when depacking a program, after changing the program in main memory 1, a special This can be handled by resetting the start address register 3, end address register 4, and sum check data in the local memory 2 using a changing means.

In this way, the present invention can detect and recover from unwarranted intervention in a program without placing an extra load on the program.

Although this embodiment has been explained using a program as an example, the present invention is applicable not only to programs.

As long as the information is in the main memory 1, it is valid even if it is data that is only for reference. It goes without saying that a partial area in the main memory is also effective as a sum check data storage area in place of a local memory on the hardware.

Furthermore, as an applied means of the present invention, by having a plurality of each of a plurality of start address registers 3 and a plurality of last address registers 4, and controlling them, it is possible to subdivide the check area on the memory, thereby achieving effective use of memory and efficiency. A good check can be made.

〔Effect of the invention〕

According to the present invention, it is possible to reliably detect unauthorized program intervention, automatically perform recovery processing, and detect unauthorized intervention at an early stage by checking for unauthorized intervention while the program is idle. It is possible to improve the reliability of the entire system.

Further, by performing the detection and recovery functions using hardware rather than using a program, the functions can be simplified.

Furthermore, by performing detection and recovery using hardware,
No extra load is placed on the program, and deterioration in program performance can be prevented.

[Brief explanation of drawings]

FIG. 1 shows a hardware configuration diagram that is an embodiment of the present invention. 1...Main memory, 2...Local memory, 3...
Start address register, 4... Final address register, 5... Sum check data creation circuit, 6... Sum check data comparison circuit, 7... Program recovery circuit.
8...Address recognition circuit. /(-N

Claims (1)

[Claims] 1. A program, a main memory for storing the program, a processor for operating the program, a local memory for storing a sum check of the program on hardware, or a main memory for storing the sum check. an address register and an address recognition circuit for indicating the program storage area in the main memory; a check circuit for comparing the program with the sum check data; and a check circuit for comparing the program with the sum check data. A computer system having a recovery circuit for recovering a program, wherein said computer system is capable of detecting program rewriting, addition, erasure, etc. due to unauthorized intervention in said program, and is capable of automatic recovery.