JPS5865470A - Software protection circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to preventing program theft and eavesdropping by encrypting and decrypting software programs manufactured and used in a computer system.

Conventionally, there are roughly two methods for defending against this type of program theft and eavesdropping. The first method is to leave the program or data as is, but to prevent unauthorized access to the program or data, various keywords are applied to the hardware and software to prevent third parties from accessing the data or program.
This is a method that is monitored and prohibited on the system side, but in this method, the data generated from various data and programs are
Although it is necessary to manage the keys, there is a drawback that the contents can easily be viewed by a third party who steals the keys.

Also, the second method is a method that encrypts the content itself,
In order to encrypt each output data and program, it is necessary to equip various encryption devices or circuits 1 at all locations related to the input/output of data and programs.

The Niga method mentioned above also performs encryption and decryption without separating data and programs, so when connecting with other conveter systems, the same encryption and decryption equipment is required for the other system, and all encryption is performed without separating data and programs. Because the information is stored in the network, special measures are required for file management.It also has the disadvantage that it may not be possible to travel far to the communications station.

The present invention provides a set of encryption and decryption circuits between at least one CPU and the main memory including Cassisland memory, and further provides an encryption key circuit t as a control circuit for the encryption and decryption circuits. Therefore, we plan to unify encryption circuits and devices, and furthermore,
It is provided on a circuit that also allows for exit from communication circulation and facilitates the prevention of software program theft and eavesdropping.

The present invention does not encrypt data and programs as in the past, but instead incorporates an encryption/decryption WI& between the main memory and the CPU, and furthermore includes an encryption key circuit in the same position as one peripheral device. It is installed and only the program part is encrypted and decrypted.

Program encryption is performed when writing program instructions to the main memory. First, the encryption key circuit is activated, the encryption circuit is enabled, and each time the CPU writes to the memory, the instructions are encrypted. Since it is stored in memory, encryption can be performed regardless of the corresponding program, there is no need to create a key, and when an encrypted program is executed, one instruction of the program is read from the main memory. In this way, encryption and decryption are possible with the installation of L sets. [To], the circuit is simplified, and since the program itself is encrypted data except when it is executed, the only way to spy on the program is to see the encrypted data, so its contents can be preserved.

Next, embodiments of the present invention will be described with reference to the drawings.

In this actual jI column, writing to memory and reading will be explained separately.

b) When writing program instructions to the main memory using the writing program 2 to memory, cpul first activates the encryption key circuit 4, sets the encryption circuit 3t, and outputs the data when cpul writes to the memory. Every time the memory write control signal 5 is output, the encryption circuit 3t is activated and the encrypted program code is stored in the memory. Furthermore, in the case of writing the data section, the encryption key circuit 4 is not set, so the data simply passes through the encryption circuit and is stored in the memory in its original format.

-> Memory reading -) When executing a river transfer and -line program, Cpul first transfers one instruction to memory and executes it. decoding circuit 2 is set, decoding is performed every time an instruction is input from memory, and cp
Output to ul and executed.

As explained above, since the present invention is composed of three circuits, it is possible to unify the circuits, change and set the encryption method for each computer system, and it is possible to encrypt only the program part. By changing not only the encryption code method but also the encryption code method for each t-combinator system, even the same program on the same format system can be
Unless the encryption method and code are the same〉For other combinations-
It cannot be executed in a data system, and as a matter of course, the contents of the programs are all different codes even if they are the same program, so it is effective against plagiarism and eavesdropping on software programs. In addition, in communication with other computer systems, this system does not have any control over the circulation, so it is possible to send data to the ileum.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1... Central processing unit (cpu) e 2...
...Decryption circuit, 3...Encryption circuit, 4...
... Encryption key circuit, 5 ... Memory write control 1
41II116... Instruction Twitch control, 7.
... Encryption circuit activation, 8... Data bus.

Claims (1)

[Claims] It has at least 41 central processing units (hereinafter abbreviated as CPU') and a main memory, and this main memory has an instruction encryption/decryption circuit for instructions input to the CPU, and an instruction encryption/decryption circuit for instructions output to the main memory. Preventing software program theft and eavesdropping by providing an encryption circuit and an encryption key circuit for controlling the above-mentioned twice W&.1! :% mold and software protection circuit.