WO2007059701A1

WO2007059701A1 - A system encrypting method adopting a multiple use supplementary single-chip microcomputer

Info

Publication number: WO2007059701A1
Application number: PCT/CN2006/003122
Authority: WO
Inventors: Yaoliang Lin; Jinhua Fan; Qingjiang Zeng
Original assignee: Xiamen Overseas Chinese Electronic Co., Ltd
Priority date: 2005-11-24
Filing date: 2006-11-20
Publication date: 2007-05-31
Also published as: CN100461063C; CN1971470A

Abstract

A system encrypting method adopting a multiple use supplementary single-chip microcomputer is disclosed. The method adopts a single-chip microcomputer built-in a burning (prevent being read out) program memory instead of a supplementary microprocessor whose function is simple relatively and the software code amount is small (such as a power supply managing supplementary microprocessor) in a multi-microprocessor system. A password verifying according to an appoint encrypting protocol algorithm is added to the main processor program and the supplementary single-chip microcomputer program, thus the program can not be read out and it could not be copied, therefore achieving the purpose of encrypting the system.

Description

System encryption method using multi-purpose auxiliary single chip microcomputer

The present invention relates to a computer program encryption method, and more particularly to a system encryption method using a multi-purpose auxiliary chip microcomputer.

Background technique

At present, in a complex control system using a microprocessor, due to the large amount of software programs, the required program memory (ROM) is relatively large, and the commonly used architecture is a two-chip structure of the microprocessor + program memory. From the convenience of development and the operability of production, the program memory generally uses rewritable program memory (FLASH R0M). o Due to the inherent characteristics of FLASH ROM, the program can be read and copied, so that the system can also be There is no confidentiality in the case of copying. In order to solve this problem, data reading is usually introduced between the microprocessor and the FLASH ROM to introduce a programmable logic device for encryption. However, since the programmable logic device is expensive, the use convenience is poor, and the hardware circuit needs to be added, the system is complicated. Maintainability is relatively poor.

The existing complex control system usually consists of the main processor 1 ', program memory 2' (ROM / Flash) and the auxiliary microcontroller 3', the system schematic block diagram shown in Figure 1, the main processor 1 'complete the main data operation processing And the control function, ROM/Flash is the program memory 2' of the main processor, the auxiliary MCU 3' is used to complete various control and other simple control functions during system standby, and between the auxiliary MCU 3' and the main processor 1' Communication using I ² C bus. The confidentiality of existing complex control systems is still very low. For hardware circuits, the copying is very simple, and the confidentiality we are talking about is generally for software programs. In the system of this configuration, the software program of the main processor 1' is stored in the program memory 2' (ROM/Flash), and due to the inherent characteristics of the ROM/Flash, the software program stored therein is easily copied; The software program of the auxiliary MCU 3' is stored in its built-in program memory. If it is not copy-protected, it can be easily copied. Even if the program memory is burned (anti-read), the software program can be prevented from being copied. However, since the auxiliary MCU 3' is simple in function and small in software program, it is easy to write a software program that matches the main processor 1', and the time required is small. Even some systems are removing the auxiliary MCU 3'. In this case, the main functions of the system can be completed, so it is very simple to copy the entire system. Summary of the invention

The object of the present invention is to overcome the deficiencies of the prior art and provide a special programmable logic that is not required. Device, easy to use system encryption method.

The present invention is based on the principle of adding a cryptographically calibrated encryption protocol algorithm to a host processor software program and an auxiliary microcontroller software program based on a single-chip microcomputer with a built-in burn-in (anti-read) program memory. The method of verification makes the system start the protection function when the password verification error occurs, and achieves the purpose of system encryption.

The technical solution adopted by the present invention to solve the technical problem thereof is: a system encryption method using a multi-purpose auxiliary single-chip microcomputer, and the encryption and verification include the following steps:

a main processor software program and an auxiliary single chip software program having a predetermined encryption protocol algorithm are respectively stored in a program memory of the main processor and a program memory of the single chip microcomputer, wherein the agreed encryption protocol algorithm is a reversible algorithm or an irreversible algorithm;

One or more checkpoints entering the running encryption protocol communication are provided in the main processor software program; the auxiliary single-chip microcomputer software program is solidified in the program memory of the single-chip microcomputer by using a burn-in method; b. starting the system work, main processing The main processor software program is run, and the auxiliary single chip computer runs the auxiliary single chip software program;

c. When the main processor software program runs to the checkpoint, the host processor generates a random number as the plain code, and sends it to the auxiliary single chip through the communication bus between the main processor and the auxiliary single chip microcomputer;

d. The auxiliary chip transmits the received clear code sent by the main processor according to the agreed encryption protocol algorithm to generate a password, and sends the password to the main processor through the communication bus between the main processor and the auxiliary single chip;

e. The main processor decrypts and restores the password sent by the auxiliary MCU according to the agreed encryption protocol algorithm into a clear code, and compares the decrypted and restored plain code with the original generated plain code; or

The main processor encrypts the random number generated by itself according to the agreed encryption protocol algorithm to generate a password, and compares the password with the password sent by the auxiliary MCU;

f. When the corresponding two clear codes or two passwords are consistent, the main processor continues to run the subsequent software program or includes repeating step c;

When the corresponding two clear codes or two passwords are inconsistent, the main processor refuses to run the subsequent software program, and the system ends running.

The system encryption method of the present invention is to change the auxiliary single-chip microcomputer into a single-chip microcomputer with a built-in burn-in (anti-read) program memory in the hardware circuit of the existing complex control system, and the other hardware structures are completely the same. In the software program, an encryption protocol is used in the communication between the main processor and the auxiliary single chip, thereby achieving the purpose of system encryption.

In the system encryption method of the present invention, one checkpoint can be set, for example, before the system needs to perform a task; and the checkpoint can also be set, for example, during the running of the software program.

When the software program runs to the checkpoint, the host processor generates a random number and sends it to the auxiliary microcontroller. After receiving the random number, the auxiliary microcontroller generates a password according to the agreed encryption protocol algorithm and sends it back to the main processor.

In the main processor, according to the reversible algorithm or the irreversible algorithm in the agreed encryption protocol algorithm, the corresponding method is used for comparison check. When the agreement encryption protocol algorithm selects the reversible algorithm, the main processor decrypts the password sent by the auxiliary single chip to the clear code according to the agreed encryption protocol algorithm, and compares the clear code with the random number originally generated by the main processor, that is, the clear code. If they are equal, the communication is successful, and the main processor executes the corresponding task. If it is not equal, the communication fails, the main processor does not perform the corresponding task; when the agreed encryption protocol algorithm selects the irreversible algorithm, the main processor encrypts according to the agreement. The protocol algorithm converts the generated random number into a password, and compares the password with the password sent back by the auxiliary MCU. If they are equal, the communication is successful, and the main processor performs the corresponding task. If it is not equal, the communication fails. The processor does not perform the corresponding task.

The system encryption method of the present invention makes the illegal copying of the system more difficult. Although the software program of the main processor in ROM/Rash can still be copied, since the auxiliary MCU uses a MCU with built-in burn-in (anti-read) program memory, its software program cannot be copied, and in the case of no auxiliary MCU. Next, the whole system does not work; if you want to make the system work by separately writing the auxiliary MCU software program, since the password during communication is generated by the random number through the encryption protocol, the cracking is very difficult. Therefore, the entire system has a very high safety factor, which greatly reduces the possibility of the system being copied.

In the system encryption method of the present invention, the main processor and the external program memory are communicated and stored in an unencrypted manner, which facilitates maintenance work such as modification and upgrade of the software program. The key points in the running of the main processor's software program are password verified, and the checkpoint is set at the key point of the software program operation.

In a multi-microprocessor system, the present invention uses a single-chip microcomputer with a built-in burn-in (anti-read) program memory to replace a secondary microprocessor (for example, a power management auxiliary microprocessor) having a relatively simple function and a small software program. And adding a method of cryptographic verification of the cryptographic protocol algorithm in the main processor software program and the auxiliary single-chip software program. The beneficial effect is that, because the auxiliary single chip adopts the built-in burned (anti-proof Read the program memory of the MCU, the software program can not be copied, and the whole system does not work without the auxiliary MCU. If you want to make the system work by separately writing the auxiliary MCU software program, the password is the random number when communicating. After the encryption protocol is generated, the difficulty of cracking is very large, so the whole system has a very high security factor, which greatly reduces the possibility of the system being copied.

The system encryption method of the present invention has the following advantages:

1) Using algorithmic encryption, using mature authoritative algorithms to ensure that the system is not vulnerable to attacks such as communication waveform analysis and replication;

2) Using a safe small single-chip microcomputer, because it has built-in burn-in (anti-readout) function, it cannot read and crack software program information. If you try to grind and open the chip, the chip break will make the data unreadable, which improves the security of the system. Sex

3) The auxiliary MCU can also undertake other tasks and complete the encryption with relatively high security performance at a small cost, which greatly increases the cost and cost of decryption;

4) The encryption process is simple, does not affect the original hardware design and modification of the main processor software program, upgrade and other production and after-sales maintenance work.

DRAWINGS

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments; however, a system encryption method using a multi-purpose auxiliary single chip microcomputer of the present invention is not limited to the embodiment.

1 is a schematic view showing the structure of a conventional complex control system;

Figure 2 is a schematic view showing the structure of the system of the present invention;

3 is a schematic flow chart of system encryption/verification of the first embodiment of the present invention;

4 is a schematic flow chart showing the encryption of the irreversible algorithm of the first embodiment of the present invention;

Figure 5 is a block diagram of the system structure of the LCD TV;

6 is a schematic flow chart showing the encryption of the reversible algorithm of the second embodiment of the present invention.

detailed description

Embodiment 1 Referring to FIG. 2 to FIG. 4, a system encryption method using a multi-purpose auxiliary single-chip microcomputer according to the present invention is based on using a single-chip microcomputer with a built-in burn-in (anti-read) program memory. The main processor software program and the auxiliary MCU software program add a password verification method of the encryption protocol algorithm, and since the software program of the MCU cannot be illegally read out, the system software program cannot be copied, and the system encryption is achieved. Its system hardware usually includes the main processor 1, ROM / Flash program Memory 2, auxiliary microcontroller 3. The unencrypted communication and storage between the main processor 1 and the external program memory 2 facilitates maintenance work such as modification and upgrade of the software program. The main processor 1 performs password verification at a plurality of key points of the software program running, that is, the check point is set at each key point of the software program running.

The system encryption method includes the following steps:

Step a. The main processor software program and the auxiliary single chip software program provided with the agreed encryption protocol algorithm are respectively stored in the program memory 2 of the main processor 1 and the program memory of the single chip microcomputer 3. The agreed encryption protocol algorithm is an irreversible algorithm. ;

In the main processor software program, a plurality of checkpoints for entering the running encryption protocol communication are provided; the auxiliary single-chip microcomputer software program is solidified in the program memory of the single chip microcomputer 3 by using a burn-in method; Step b. Starting the system work, the main processing The device 1 runs the main processor software program, and the auxiliary MCU 3 runs the auxiliary MCU software program, as shown in block 101 and block 102;

Step c. When the main processor software program runs to the checkpoint, the host processor 1 generates a random number, and sends it as the clear code to the auxiliary microcontroller 3 through the communication bus 13⁄4 between the main processor 1 and the auxiliary microcontroller 3. , as shown in block 103, block 104, and block 105;

Step d. After receiving the clear code sent by the main processor 1 received by the auxiliary single chip microcomputer 3, the password is encrypted according to the agreed encryption protocol algorithm, and the password is passed through the communication bus between the main processor 1 and the auxiliary single chip 3. I ² C is sent to the main processor 1, as indicated by block 106, block 107, block 108;

Step e. The main processor 1 encrypts the random number generated by itself according to the agreed encryption protocol algorithm to generate a password, and compares the password with the password sent by the auxiliary MCU 3, as in block 109, block 110. , shown in block 111;

f. When the corresponding two passwords match, the main processor 1 continues to run the subsequent software program and includes repeating step c, as indicated by block 112;

When the corresponding two passwords are inconsistent, the main processor 1 refuses to run the subsequent software program, and the system ends the operation.

4 is a schematic flow chart of encryption of an irreversible algorithm;

Clear code =Randoml6

Key =0x55aa

Encryption Algorithm:

0x55aa In the main processor 1, a 16-bit number is first randomly generated by the main processor 1, as shown in block 201; the 16-bit random number is sent as a plain code to the auxiliary microcontroller 3, as shown in block 202;

In the auxiliary MCU 3, the clear code sent by the main processor 1 is encrypted, that is, the random number is shifted to the right by one bit, and then X055aa is XORed to form a password, as shown in block 203; The password is sent back to the main processor 1, as shown in block 204;

In the main processor 1, the 16-bit random number generated by itself is encrypted by the same encryption algorithm as that in the auxiliary single-chip microcomputer 3, that is, the random number is shifted to the right by one bit, and then X055aa is XORed. The password is formed, as shown in block 205; then, the main processor 1 compares the password generated by itself with the password sent by the microcontroller 3, as shown in block 206, if the two are equal, the main processor 1 continues. Run, see block 207, if the two are not equal, the representation is incorrect, the main processor 1 refuses to run, see block 208.

The transmission of the clear code and password is done directly and quickly via the I ² C bus. Due to the participation of random numbers, the cost of cracking the system software program is greatly improved by the logic analysis of the communication waveform of the I ² C bus.

Although the software program of the main processor in the ROM/Flash can still be copied, the system encryption method of the present invention is adopted, and since the auxiliary single chip microcomputer 3 is a single-chip microcomputer with a built-in burn-in (anti-read) program memory, the software program thereof is used. It is difficult to be copied, and in the absence of the auxiliary MCU 3, the whole system does not work; if you want to make the system work by separately writing the auxiliary MCU software program, since the password during communication is generated by the random number through the encryption protocol, the crack is generated. The difficulty is very large, so the entire system has a very high safety factor, greatly reducing the possibility of the system being copied.

A specific embodiment of the encryption method of the present invention for use in an LCD TV is shown in Fig. 5. The video signals input by various signal channels (RF, AV, VGA, HDTV, etc.) of the LCD TV system are directly (or subjected to necessary processing) connected to the SWITCH channel selection control IC, and the SWITCH channel selection control IC inputs the video of the selected channel. The signal is sent to the main processor 1, and the main processor 1 passes the various optimization processes and outputs the image to the liquid crystal display to display the image.

The core of this system is the main processor 1, which performs most of the control and image processing functions. The main processor 1 is externally connected with ROM7Flash2 for storing the main processor software program, and the main processor 1 is connected through the I ² C bus. The auxiliary MCU 3 is connected.

By using the encryption method of the invention, a single-chip microcomputer with a built-in burn-out (anti-readout) program memory is selected for the auxiliary single-chip microcomputer 3, and an agreement is added in the main processor software program and the auxiliary single-chip microcomputer software program. Password verification of the secret protocol algorithm. Thus, even if the software program of the main processor 1 may be copied, since the software program of the auxiliary microcontroller 3 cannot be copied, the main processor 1 cannot establish normal communication with the auxiliary microcontroller 3, so the main processor 1 does not By performing any task, the entire system will not work properly. Therefore, it is possible to effectively prevent the occurrence of the main processor software program being copied and used in the LCD TV. In addition to completing the communication with the password verification of the encryption protocol algorithm of the main processor 1, the auxiliary microcomputer 3 can also perform power management of the television, that is, control the power supply in the state of work, standby, shutdown, and the like.

Embodiment 2 Referring to FIG. 6, a system encryption method using a multi-purpose auxiliary single-chip microcomputer according to the present invention is different from the first embodiment in that the encryption protocol algorithm used is a reversible algorithm; therefore, in step e The main processor 1 decrypts and restores the password sent by the auxiliary single chip microcomputer 3 to the clear code according to the encryption protocol algorithm of the reversible algorithm, and compares the decrypted and restored plain code with the original generated plain code;

In step f: when the corresponding two clear codes are consistent, the main processor 1 continues to run the subsequent software program or includes repeating step c;

When the corresponding two clear codes are inconsistent, the main processor 1 refuses to run the subsequent software program, and the system ends the operation.

6 is a schematic flow chart of encryption of a reversible algorithm;

Clear code: Randoml6

Key =0x55aa

The encryption algorithm: ^A cryptographic key codes = -Randoml6 ^A 0x55aa

Decryption algorithm: Clear code = cryptographic key - (Randoml6 ^A 0x55aa) ^A 0x55aa

In the main processor 1, a 16-bit number is first randomly generated by the main processor 1, as shown in block 301; the 16-bit random number is sent as a plain code to the auxiliary microcontroller 3, as shown in block 202;

In the auxiliary MCU 3, the clear code sent by the main processor 1 is encrypted, that is, the random number is XORed with 0x55aa to form a password, as shown in block 303; then, the password is sent back to the main processor 1, See block 204;

In the main processor 1, the password sent by the auxiliary single chip microcomputer 3 is decrypted, that is, the password of the auxiliary single chip microcomputer 3 is again XORed with 0x55aa and restored to the clear code, as shown in block 305; the main processor 1 will itself The randomly generated 16-bit number (that is, the clear code sent to the single-chip microcomputer) is compared with the clear code decoded by the auxiliary single-chip microcomputer 3 after being decoded, as shown in block 306, if the two are equal, it means Correctly, the main processor 1 continues to operate, as shown in block 307, if the two are not equal, the representation is incorrect, and the main processor 1 refuses to operate, see block 308.

Industrial applicability

The invention encrypts the system by means of a cryptographic protocol by communication between the single chip microcomputer with the built-in burning program memory and the main processor, and does not need other devices, and has a clever idea, a simple structure and good industrial applicability.

Claims

Rights request

1. A system encryption method using a multi-purpose auxiliary single-chip microcomputer, the system comprising a main processor, a program memory and a auxiliary single-chip microcomputer, the auxiliary single-chip microcomputer is a single-chip microcomputer with a built-in burn-in program memory, and between the auxiliary single-chip microcomputer and the main processor The communication adopts an encryption protocol. During the running of the system, the main processor sends digital information to the auxiliary single-chip microcomputer multiple times, and the auxiliary single-chip microcomputer sends back a password corresponding to the digital information to the main processor, and the main processor checks the password. And when the password verification error occurs, the protection function is activated to achieve system encryption.

2. The system encryption method using a multi-purpose auxiliary single-chip microcomputer according to claim 1, wherein the main processor is connected to the auxiliary single-chip microcomputer through a communication bus, and the main processor passes the data or the program bus and the program memory. connection.

3. A system encryption method using a multi-purpose auxiliary single chip according to claim 1 or 2, wherein: the encryption and verification comprises the following steps:

a main processor software program and an auxiliary single chip software program having a predetermined encryption protocol algorithm are respectively stored in a program memory of the main processor and a program memory of the single chip microcomputer, and the agreed encryption protocol algorithm is a reversible algorithm;

The main processor program is provided with one or more checkpoints for entering the communication protocol of the running encryption protocol; the auxiliary single-chip microcomputer program is solidified in the program memory of the single-chip microcomputer by using a burn-in method; b. starting the system work, the main processor is running The main processor software program, the auxiliary single chip computer runs the auxiliary single chip software program;

c When the main processor software program runs to the checkpoint, a random number is generated by the main processing unit as the clear code, and is sent to the auxiliary single chip through the communication bus between the main processor and the auxiliary single chip;

d. The auxiliary microcontroller transmits the received clear code sent by the main processor according to the agreed encryption protocol algorithm to generate a password, and sends the password to the main processor through the communication bus between the main processor and the auxiliary single chip;

e. The main processor encrypts the random number generated by itself according to the agreed encryption protocol algorithm to generate a password, and compares the password with the password sent by the auxiliary MCU;

f. When the corresponding two passwords match, the main processor continues to run subsequent programs or includes repeated steps

C;

When the corresponding two passwords are inconsistent, the main processor refuses to run the subsequent program, and the system ends running.

4. A system encryption method using a multi-purpose auxiliary single chip according to claim 1 or 2, wherein: the encryption and verification comprises the following steps:

a main processor software program and an auxiliary single chip software program having a predetermined encryption protocol algorithm are respectively stored in a program memory of the main processor and a program memory of the single chip microcomputer, wherein the agreed encryption protocol algorithm is an irreversible algorithm;

c When the main processor program runs to the checkpoint, the host processor generates a random number as the plain code to send to the auxiliary microcontroller through the communication bus between the main processor and the auxiliary microcontroller;

e. The main processor decrypts and restores the password sent by the auxiliary MCU according to the agreed encryption protocol algorithm into a clear code, and compares the decrypted and restored plain code with the original self-generated clear code;

f. When the corresponding two clear codes match, the main processor continues to run subsequent programs or includes repeated steps

C

When the corresponding two clear codes are inconsistent, the main processor refuses to run the subsequent program, and the system ends running.

5. A television set adopting a system encryption method of a multi-purpose auxiliary single-chip microcomputer, the main processor is externally loaded with a program memory, and the power management auxiliary processor is a single-chip microcomputer with a built-in burn-in program memory, in the auxiliary single-chip microcomputer and the main processor The communication between the two uses an encryption protocol; during the operation of the television system, the main processor sends digital information to the auxiliary microcontroller, and the auxiliary microcontroller sends back a password corresponding to the digital information to the main processor, and the main processor performs the calibration on the password. Check, and start the protection function when the password verification error occurs, to achieve system encryption.