JPH0245849A - Program protecting method to use memory card - Google Patents

Abstract

PURPOSE:To protect the contents of a program to be stored in a ROM and to simultaneously prevent the unfair copy of the program with the third person by directly accessing the ROM in a memory card from a host CPU and controlling the output of the ROM in the memory card with a microprocess which is provided in the memory card. CONSTITUTION:When a fair user executes the protected program, the fair user stores an interruption processing program to a part, which is not overlapped with a memory card 6, on a main storage 3 in advance. When the memory card 6 is connected through a bus adapter 5 to a system bus 2, out of the address areas of the main storage 3, a part from an (n) address to an M address is allocated to a ROM8 and a RAM9 in the memory card 6 like being shown in a figure. Next, the program to be stored to the ROM8 in the memory card 6 and to be the subject of the protection is executed by a host CPU1.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a program protection method using a slotted memory card to prevent a program executed by an information processing system from being illegally copied. .

[Conventional technology]

Figure 7 shows a program created by a third party being executed by a conventional information processing system such as that described in the literature ([Microcomputer Interface Technology], February 20, 1980, Maitenku Co., Ltd.). In Figure 0, which is a block diagram showing the basic configuration of the
l is the central processing unit (hereinafter referred to as host) that executes the program
2 is a system bus that connects the CPU with the main memory that stores programs and data, and a drive device that drives a flexible disk that stores programs created by a third party, 3 is a main storage device, and 4 is a system bus that connects the CPU Third
A storage medium such as a flexible disk that stores programs created by a person.

Next, the protection operation will be explained. When storing a program to be protected on the storage medium 4, a part of the program to be protected is stored in an area that cannot be read by a normal copying program.

To run this protected program, first,
By loading a dedicated reading program from the storage medium 4 to the main storage device 3 via the system bus 2, and sequentially executing the dedicated reading program on the host 1-CPUI via the system bus 2, A program to be protected is read into the main storage device 3 via the system bus 2 and sequentially executed by the host CPU 1.

However, if a protected program is copied to another storage medium 4 using a normal copying program, part of the program stored in an area that cannot be read normally will be
Since the program is not copied onto the copied storage medium, even if the program on the copied medium is executed, it will not function normally, and the program on the storage medium 4 will be protected.

[Problem to be solved by the invention]

Since the conventional program protection method is configured as described above, it is possible to copy the entire storage medium 4 or easily analyze the contents of a dedicated reading program in order to read the dedicated reading program onto the main storage device 3. However, there is a problem in that a part of the program stored in a part that is not normally read may be revealed and copied.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a program protection method using a memory card that prevents a program stored in the memory card from being copied.

[Means for Solving the Problems] A program protection method according to the present invention includes a memory card that includes a built-in microprocessor, a read-only memory (ROM), and a random access memory (RAM), and a system that uses this memory card. In an information processing system equipped with a bus adapter that is directly connected to a bus, the micro processor in the memory card determines whether the access to the memory card is legitimate or unauthorized and switches the system bus in the memory card to access data from the ROM and RAM. It is designed to prevent copying by controlling human output.

[Function] In the present invention, when the microprocessor in the memory card detects that an address arbitrarily set in a program stored in the memory card is accessed, the memory In addition to switching the bus in the card, an interrupt is generated to the host CPU, and the contents of the program counter at the time of the interrupt are sent from the host CPU's interrupt processing program to the microprocessor in the memory card. The value of the address is compared with the address detected by the microprocessor, and if they do not match, it is determined that copying has occurred, thereby protecting the program.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1 is the host CPtJ that executes the program to be protected, 2 is the system bus that connects the host CPU 1 and the main memory, etc., 3 is the main memory that stores data, etc., and 5 is the card that connects to the system bus 2. A bus adapter 6 is a memory card storing a program to be protected; FIG. 2 shows an example of the internal configuration of the memory card 6; 7 is a memory directly connected to the system bus via the bus adapter 5; The bus 8 inside the card stores the program to be protected, and also has the function of detecting access to a specific address within the program and generating an interrupt to the built-in microprocessor. ROM, 9 is a RAM that stores data required when the host CPU 1 executes a program stored in the ROMB, and 10 is a RAM that stores data necessary when the program stored in the ROMB is executed by the host CPU 1; Analyzes the interrupt that occurs, generates an interrupt to the host CPU 1, generates a signal to control the bus switching 5W12 that controls the output from the ROMB, and then
The built-in microprocessor 11 that analyzes data transmitted from the UI is a ROM that stores a program to be executed by the built-in microprocessor 1o. FIG. 3 shows the memory allocation on the boss CPU (al is the address space of the main storage device 3, and (b) and (C) are the address spaces allocated to the memory card 6.

The addresses from address n to address M overlap between the main storage device 3 and the memory card 6, but when the memory card 6 is directly connected to the system bus 2 via the bus adapter 5, the memory card The storage area on the main storage device 3 is allocated to the upper storage area, and the area on the main storage device 3 is separated from the system bus. Third
In the figure, bus switching 3W12 is a storage location of data having a specific address arbitrarily set by the program supplier within the area where the program to be protected is stored.

Next, the protection operation according to the present invention will be explained with reference to the flowcharts of FIGS. 4 to 6. Figure 4 shows Hos) CP
In the flowchart of the interrupt processing program executed on the UI, when this program sends the contents of the interrupt generation program counter to the memory card in step SL, it proceeds to step S2 to permit restart, and if it is not permitted, it proceeds to step S3.
In step S4, the check result is read from the memory card and the process returns to step S2. If permission is granted, the process resumes from the interrupted point in step S4 and ends. FIG. 5 is a flowchart of an interrupt processing program executed by the memory card 6, which saves the interrupt generation address in step S1 and switches the bus switching SW in step S2.
In step S3, an interrupt is generated to the host CPU. Thereafter, address data from the host CPU is read in step S4, and the saved address and data are compared in step S5. If they match, the bus switching SW is returned to its original state in step S6, and if they do not match, the process ends. Furthermore, FIG. 6 is a flowchart of a program for a third party to copy the contents of the memory card onto the main storage device 3. In step St, when the data at address 1 in the memory card is read into the register of the host CPU, step In S2, the data read into the register of the host CPU is written to address P of the main storage device 3. After that, when the entire area is completed in step S3, this process is repeated again.

Now, in order to copy the program to be protected stored on the memory card 6, in order to move it to an address area that is not allocated in the memory card on the main storage device 3, as shown in FIG. A copying program is stored in the free area (addresses 0 to n-1) of the main storage device 3 and executed by the CPU 1 of the host computer. When copying is started and an attempt is made to read the contents of a specific address Ar in the memory card 6, the built-in CPU 1' of the memory card 6
An interrupt occurs at memory card 6 shown in FIG.
The program stored in the ROMII of the built-in cput
It is executed at o. Built-in CPU10 first has bus switching 5W
12 so that the contents of the ROM are not transmitted to the system bus, and then generates an interrupt to the host CPUI. However, since the host CPU 1 does not have a program to handle this interrupt, the copying program is stopped, and the program stored in the ROM 8 in the memory card 6 is therefore protected.

Next, a case will be described in which the interrupt processing program of the example host CPU shown in FIG. 4 is revealed to a malicious third party who attempts to execute copying. Similarly to the above case, start the copy program shown in Part 6 and the program shown in FIG.
(address n-1) and executed sequentially by the host CPU 1. When copying is started and the content of a specific address Ar in the memory card 6 is to be read, an interrupt occurs in the built-in CPU10 of the memory card 6, and the program stored in the ROM 11 in the memory card 6 shown in FIG. It is executed by the built-in CPU10.

For the built-in CPU10, first write the specific address Ar↑, 9
Then, switch the bus switch 5W12 and switch the system to RO.
After preventing the contents of M8 from being transmitted correctly, host C
Generates an interrupt to the PUI. When the host CPU 1 detects an interrupt from the memory card, the contents of all registers at the time of occurrence of the interrupt are saved, and then the interrupt processing program shown in FIG. 4 is executed. In the interrupt processing program shown in FIG. 4, the value of the program counter at the time when the interrupt from the memory card 6 occurs is read from the contents of the saved register and transmitted to the memory card 6.

The built-in CPU10 of the memory card 6 uses the host CPU
Check the program counter value sent from
It is matched with a pre-stored specific address value Ar. However, at the time the interrupt occurred, the CPU
The address of the copying program shown in FIG.
Since the value of the program counter sent from the host CPUI and the value of the program counter never match, the built-in CPU10 determines that the reading is invalid and resumes processing on the host CPUI side without returning the bus switching 5W12 to its original state. Allow.

In the host CPU 1, the copy program continues to be executed, but data after a specific address Ar is not guaranteed, and the contents of the program stored in the ROM 8 in the memory card 6 are protected against copying.

Next, a case in which a legitimate user executes a protected program will be explained. An authorized user stores in advance the interrupt processing program shown in FIG. 4 in a portion of the main storage device 3 that does not overlap with the memory card 6. By connecting the memory card 6 to the system bus 2 via the bus adapter 5, as shown in FIG. Allocate to ROMB and RAM9 within. Next, the program to be protected stored in the ROMB in the memory card 6 is executed by the host CPtJ1. When attempting to read and execute the contents of a specific address Ar from the host CPU, the built-in CPU in the memory card 6
An interrupt occurs in Ul0, and the ROMI in memory card 6
The program shown in the fifth V stored in I is executed by the built-in CPU I0 in the memory card 6. Built-in CPU
In l0, first, the specific address Ar where the interrupt occurred
and switch the bus switching 5W12 to prevent the contents of the ROM 8 in the memory card 6 from being read out to the system bus 2 on the main body side via the system bus 7 in the memory card 6, Generates an interrupt to the host CPUI. The host CPUI saves all registers in the CPUI and executes the interrupt processing program shown in FIG. 4. The contents of the program counter saved at this time are the specific address Ar where the interrupt occurred. The host CPUI sends the contents of the saved program counter, that is, the specific address Ar, to the memory card 6. The memory card 6 compares the contents of the program counter sent from the host CPtJ 1 with the value ^r of the specific address where the interrupt occurred, which is stored in advance in the 15EcPU 10 in the memory card 6. The contents of the program counter and the built-in CPU built into the memory card 6
The value of a specific address stored as 0 is the address value ^r
Since they match, return the bus switching 5W12 to its original state and change the contents of the ROMB in the memory card 6 to the system bus 7.
．． 2 so that it can be read correctly into the host CPUI, and the processing on the CPUI side is resumed from the interrupted point. In this case, correct information is transmitted to the host CPU 1, so that the process is executed correctly.

In the above embodiment, the value of the program counter when an interrupt occurs in the interrupt processing program of the CPU (host) is sent to the memory card 6. You may also send the contents. Furthermore, in the above embodiment, the memory card 6
The bus switching 5W12 in the internal memory card 6 is provided between the ROMB and the bus 7 in the memory card 6;
and the bus 7.

(Effects of the Invention) As explained above, according to the present invention, the ROM in the memory card can be directly accessed from the host CPU, and the output of the ROM in the memory card can be controlled by the microprocessor provided in the memory card. So, R.O.
The contents of the program stored in M can be protected and prevented from being copied by a third party.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a system for explaining a program protection method according to an embodiment of the present invention, FIG. 2 is a block diagram of the internal configuration of a memory card, and FIG. 3 is a block diagram of a host CP.
The memory allocation on the U is shown in the figure, Figure 4 is a flowchart of the interrupt processing program executed by the host CPU, Figure 5 is a flowchart of the interrupt processing program executed by the memory card, and Figure 6 is the memory allocation by a third party. FIG. 7 is a flowchart of a program for copying the contents of a card onto the main storage device, and is a block diagram of a conventional information processing system. 1...Host CPU, 2...System bus, 3...
- Main storage device, 5... bus adapter, 6... memory card, 8... ROM, 9... RAM. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 9: RAM Figure Figure Figure Procedure Amendment 1 (voluntary) 1. Indication of the incident Patent Application No. 196861 2. Name of the invention Program protection method using a memory card 3. Amendment 5. Target of amendment 6. Contents of amendment (1) "Upon completion" on page 8, line 20 of the specification is corrected to "until completion." (2) "Move" in line 4 on page 9 is corrected to "copy."that's all

Claims (1)

[Claims] Built-in microprocessor and read-only memory (RO
M) In an information processing system equipped with a memory card equipped with random access memory (RAM) and a bus adapter that directly connects this memory card to a system bus, whether access to the memory card by a microprocessor in the memory card is legitimate. A program protection method using a memory card, characterized in that the system bus in the memory card is switched after determining whether it is fraudulent, and input/output from ROM and RAM is controlled to prevent copying.