KR100468615B1 - Apparatus for protecting internal program - Google Patents

Abstract

An internal program code protection device of the present invention has an object of providing an internal program code protection device which prevents the leakage of an internal program by always using a latch circuit so that the memory where the instruction is loaded is the same as the memory where the data is loaded. .

In order to achieve the above object, the present invention includes an external storage means for storing a general program and outputting the stored data; Receives data from the external storage means, receives an external access signal and an enable signal, and externals the data from the external storage means or the internal data according to control by the correspondence of the external access signal and the enable signal. Micro control means for outputting to a port; And logic analysis means for analyzing the command and inputting the command to the micro control means via an external port and a data bus.

Description

Internal program code protection device {APPARATUS FOR PROTECTING INTERNAL PROGRAM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal program code protection device, and more particularly, to an internal program code protection device for preventing internal program code from being read externally in a system driven by a general microcontroller unit (MCU).

In general, the MCU acts as the brain of the system and has a complex program to control the entire system. These programs are important information for developers and must be protected. If this information is not protected, anyone could develop a similar system.

1 is a block diagram illustrating a conventional microcontroller. The conventional microcontroller includes an external ROM (Read Only Memory) 110 for storing a general program and outputting the stored program to the selector 122, and a system. The internal ROM 121 which stores the control program and outputs the stored program to the selector 122 and the external access signal EA receive data from the external ROM 110 when the external access signal is '1'. Receives the input to the accumulator 123, if the external access signal is '0' selector 122 for receiving data from the internal ROM 121 and output to the accumulator 123, and receives the data from the selector 122 The accumulator 123 temporarily stores data, performs a digit transfer and maintenance operation, and outputs data to the buffer 124. The data input from the accumulator 123 according to the command signal received from the command decoder 125 is stored. data The MCU 120 including a buffer 124 for outputting a command, a command decoder 125 for receiving a command output by the logic analyzer 130 through a data bus, decoding the same, and outputting the command to the buffer 124; And a logic analyzer 130 for analyzing and inputting instructions to the instruction decoder 125 via external ports and data buses.

The above-described conventional microcontroller enables the internal memory space and the external memory space to be used efficiently in order to use the memory space efficiently. The determination of whether to use the internal program or the external program is made by an external access signal. .

In the conventional apparatus, as shown in Fig. 2, a user mounts an external memory outside the system to read an internal program, and changes the value of the external access signal at an appropriate timing using a hacking program. ('1' to '0'), it is possible to read the internal program instead of the external program at the moment of reading the program through the selector 122, there is a problem that the internal program can not be protected.

An object of the present invention is to provide an internal program code protection device which prevents the leakage of an internal program by always equalizing the memory in which an instruction is loaded with the memory in which data is loaded by using a latch circuit. There is this.

1 is a block diagram showing a conventional microcontroller,

2 is an operation timing diagram illustrating a memory access process of a conventional microcontroller;

3 is a block diagram showing an internal program code protection device according to an embodiment of the present invention;

4 is an operation timing diagram illustrating an operation of an internal program code protection device according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

110: external ROM

120: MCU

130: logic analyzer

310: external storage means

320: micro control means

330: logic analysis means

In order to achieve the above object, the internal program code protection device of the present invention comprises: external storage means for storing a general program and outputting stored data; Receives data from the external storage means, receives an external access signal and an enable signal, and externals the data from the external storage means or the internal data according to control by the correspondence of the external access signal and the enable signal. Micro control means for outputting to a port; And logic analysis means for analyzing the command and inputting the command to the micro control means via an external port and a data bus.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention.

First, Figure 3 is a block diagram showing an internal program code protection device according to an embodiment of the present invention, the internal program code protection device of the present invention, the external storage means 310, micro control means 320 and logic analysis And means 330.

The external storage means 310 stores a general program and outputs the stored program to the micro control means 320 which will be described later.

In addition, the micro control unit 320 receives data from the external storage unit 310, receives an external access signal and an enable signal, and controls the external storage unit according to the control of the external access signal and the enable signal. It serves to output the data from the 310 or the internal data to the external port. Here, the micro control means 320 includes an internal storage means 321, a latch circuit 322, a selection means 323, an accumulator 324, a buffer 325, and an instruction decoder 326.

The internal storage means 321 mounted in the micro control means 320 serves to store a system control program and output the stored program to the selection means 323 described later. Here are the programs that the developer wants to protect.

In addition, the latch circuit 322 mounted in the micro control unit 320 receives an enable signal input from an external device through a clock terminal, receives an external access signal from an external device, and does not activate the enable signal. In the case of outputting the external access signal to the selection means 323 to be described later, and if the enable signal is activated to latch the external access signal at the time of the enable signal activation first to output to the selection means 323 to be described later Play a role.

On the other hand, the selection means 323 mounted in the micro control means 320 receives an external access signal from the latch circuit 322 and the external storage means when the external access signal is a first logic step '1'. Receives data of 310 and outputs it to the accumulator 324 which will be described later. If the external access signal is the second logic step '0', the accumulator 324 which receives the data of the internal storage means 321 will be described later. It plays a role as output.

In addition, the accumulator 324 mounted in the micro control means 320 receives the data from the selection means 323, temporarily stores the data, performs a digit transfer and maintenance operation, and a buffer 325 which describes the data later. It prints in).

On the other hand, the buffer 325 mounted in the micro control means 320 serves to output the data input from the accumulator 324 to the data bus according to the command signal input from the command decoder 326 to be described later. .

In addition, the command decoder 326 mounted in the micro control unit 320 receives the enable signal from the outside, and when the enable signal is activated, the logic analysis unit 330 described later through the data bus is provided. It receives a command to output and decodes it and outputs it to the buffer 325.

Meanwhile, the logic analyzing means 330 analyzes the command and inputs the command to the micro control means 320 through an external port and a data bus.

4 is an operation timing diagram illustrating an operation of an internal program code protection device according to an embodiment of the present invention. Referring to FIGS. 3 and 4, the operation of the internal program code protection device of the present invention will be described below.

First, when an externally enabled enable signal is input to the command decoder 326, the command decoder 326 reads a command of the logic analyzing means 330 through an external port and a data bus.

At this time, the activated enable signal is also input to the clock terminal of the latch circuit 322, and the latch circuit 322 latches the current external access signal.

Thereafter, when a memory access time for reading a program is reached according to a command execution process, the latch circuit 322 outputs the latched signal to the selection means 323.

Next, the selecting means 323 outputs data to the accumulator 324 according to the signal received from the latch circuit 322.

That is, the latch circuit 322 latches and outputs an external access signal at the time when the instruction is loaded, thereby matching the memory in which the instruction is loaded with the memory in which the data is loaded, thereby protecting the internal code.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited to the drawings shown.

The present invention has the advantage of making the system control program code unknown from the outside and protecting the internal program by always making the memory into which the instruction is loaded and the memory into which the data is loaded by using the latch circuit.

Claims (2)

External storage means for storing a general program and outputting the stored data; Receives data from the external storage means, receives an external access signal and an enable signal, and externals the data from the external storage means or the internal data according to control by the correspondence of the external access signal and the enable signal. Micro control means for outputting to a port; And Logic analysis means for analyzing a command and inputting the command to the micro control means via an external port and a data bus Internal program code protection device comprising a. The method of claim 1, wherein the micro control means, Internal storage means for storing the system control program and outputting the stored data; When the enable signal input from the outside is input to the clock terminal, the external access signal is received from the outside, and if the enable signal is not activated, outputs the external access signal, if the enable signal is activated A latch circuit for latching and outputting an external access signal when the enable signal is activated for the first time; Receives an external access signal from the latch circuit and receives and outputs data of the external storage means if the external access signal is a first logic step, and receives and outputs data of the internal storage means if the external access signal is a second logic step. Selection means; An accumulator configured to receive data from the selection means, temporarily store the data, perform digit transfer and maintenance, and output the data; A buffer configured to output data input from the accumulator to a data bus according to the input command signal; And When the enable signal is externally received and the enable signal is activated, the command decoder receives a command output by the logic analysis means through a data bus, decodes the command signal, and outputs the command signal to the buffer. Internal program code protection device comprising a.