CN109214217B - Anti-cracking method for microcontroller chip - Google Patents

The invention provides a method for preventing a microcontroller chip from being cracked, which relates to the fields of industrial control, Internet of things, intelligent home, intelligent wearing equipment and the like, and comprises the following steps: s1: structuring the protection bit erasure request by a circuit; s2: automatically loading the record value of the erasing times through a circuit; s3: and judging whether the recording times of the circuit reach a set threshold value or not through the circuit, neglecting the erasing and writing request of the read-write protection bit after the recording times reach the set threshold value, and simultaneously generating an internal interrupt request of the chip. The maximum number of times that the read protection bit of the non-volatile memory data is erased is limited by the microcontroller chip internal circuit. When the recorded erasing times reach the rated value, the chip internal circuit ignores all erasing requests of the read protection bits, and the erasing requests of the read protection bits of the times can trigger the internal interruption of the microcontroller chip so as to inform the application program in the chip of illegal invasion.

Anti-cracking method for microcontroller chip

Technical Field

The invention relates to the fields of industrial control, Internet of things, intelligent home, intelligent wearing equipment and the like, in particular to a method for preventing cracking of a microcontroller chip.

Background

The applications and data of the microcontroller chip are typically stored in non-volatile memory internal to the chip. In order to prevent a pirate from directly reading out programs and data stored in the chip, the microcontroller chip generally defines one or several bytes of data in a nonvolatile memory in the chip as a read protection bit. Once the user program sets the read protection bit to valid data, the data stored inside the microcontroller chip cannot be accessed from the outside through the interface of the chip. If the user changes the protection bit from the active protection state to the inactive state, the microcontroller chip will erase all data stored in the entire nonvolatile memory inside the chip, and then change the read protection bit to the inactive state.

The current cracking method for protecting the internal data of the microcontroller chip aiming at the reading protection bit is as follows: the read protection bit is erased by the external device continuously requesting it, and the data written each time must be valid data capable of maintaining the read protection state. Therefore, when the continuous erasing times exceed the service life of the nonvolatile memory in the chip, the read protection bit of the microcontroller chip can be changed into an invalid value and the whole erasing action of the nonvolatile memory cannot be triggered. And then the pirate can read all the data in the chip through the interface of the chip to finish the pirate.

There is therefore a need for a mechanism to prevent brute force cracking of the read protection bits of non-volatile memory data in a microcontroller chip.

Disclosure of Invention

The invention aims to provide a method for preventing a microcontroller chip from being cracked, which has the characteristic of preventing a read protection bit of nonvolatile memory data in the microcontroller chip from being cracked.

The invention is realized by the following technical scheme:

a method for preventing cracking of a microcontroller chip comprises the following steps:

s1: recording the read protection bit erasing request through a circuit;

s2: automatically loading the record value of the erasing times through a circuit;

s3: judging whether the recording times of the circuit reach a set threshold value or not through the circuit, and ignoring the read protection bit erasing request after the recording times reach the set threshold value;

wherein, the set threshold is smaller than the erasing operation life of the nonvolatile memory of the chip, and the circuit allows the program to read the recorded value of the erasing times, but does not allow the program to rewrite the recorded value of the erasing times.

Preferably, the chip internal interrupt request is generated while the read protection bit erasure request is ignored in S3.

Preferably, in S3, when the number of times of recording does not reach the set threshold, the circuit increments the erasure recording value by 1, and writes the result back to the recording address.

Preferably, the read protection bit is erased by circuitry after the result is written back to the record address.

Compared with the prior art, the invention has the following advantages:

the maximum number of times that the read protection bit of the non-volatile memory data is erased is limited by the microcontroller chip internal circuit. And opening up a new number of times of erasing and writing the read protection data in the address recording chip in the nonvolatile memory, adding 1 to the value in the recording address by the read protection bit every time of erasing and writing, and simultaneously, the value of the address cannot be rewritten by a user program. When the recorded erasing times reach the rated value, the chip internal circuit ignores all erasing requests of the read protection bits, and the erasing requests of the read protection bits of the times can trigger the internal interruption of the microcontroller chip so as to inform the application program in the chip of illegal invasion.

Drawings

Fig. 1 is a flow chart diagram of a method for preventing a microcontroller chip from being cracked.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A method for preventing microcontroller chips from cracking, as shown in fig. 1, comprises the following steps:

s1: recording the read protection bit erasing request through a circuit;

s2: automatically loading the record value of the erasing times through a circuit;

s3: judging whether the recorded times of the circuit reach a set threshold value or not through the circuit, ignoring a read protection bit erasing request after the recorded times reach the set threshold value, and generating a chip internal interrupt request;

when the recording times do not reach the set threshold value, the circuit adds 1 to the erasing record value and writes the result back to the recording address

In this embodiment, the erase/write operation threshold of the read protection bit set in the circuit is smaller than the erase/write operation lifetime of the nonvolatile memory.

In the present embodiment, the circuit allows the program to read the recorded value of the number of times of erasing operation, but does not allow the program to rewrite the recorded value of the number of times.

Compared with the prior art, the invention has the following advantages:

the maximum number of times that the read protection bit of the non-volatile memory data is erased is limited by the microcontroller chip internal circuit. And opening up a new number of times of erasing and writing the read protection data in the address recording chip in the nonvolatile memory, adding 1 to the value in the recording address by the read protection bit every time of erasing and writing, and simultaneously, the value of the address cannot be rewritten by a user program. When the recorded erasing times reach the rated value, the chip internal circuit ignores all erasing requests of the read protection bits, and the erasing requests of the read protection bits of the times can trigger the internal interruption of the microcontroller chip so as to inform the application program in the chip of illegal invasion.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.