JP2001265658A - Nonvolatile preservation device content secrecy keeping method and nonvolatile preservation device content secrecy keeping structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent data preserved inside a flash memory from being stolen, corrected or changed by randomly combining the data and making the data of a non-transmission restoration process useless. SOLUTION: Blocking is advanced by a program preserved inside the flash memory, rotation is advanced on the basis of the blocks, a preserved address is scrambled and the data inside an original address are preserved inside a new address after the rotation. At the time of reading the data, the read order of a random number is generated by a random number generator and accurate data and dummy data are included in the read data. The dummy read data are filtered, address rotation is recovered and restored and they are turned to original data. By scrambling the address, the data are turned to the useless data when they are directly read.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonvolatile storage device content confidentiality holding method and a nonvolatile storage device content confidentiality holding structure.

[0002]

2. Description of the Related Art As shown in FIG. 1, in a conventional computer structure, an MCU (micro controller unit) is mainly used, a flash memory 10 is provided outside the structure, and a program is stored in the flash memory 10. . Also, conventional encoding / decoding protection systems have not provided any protection for the flash memory 10.

[0003]

Therefore, it is difficult to protect the contents of the program stored in the flash memory 10, and a person who is accustomed to decryption can easily read the program stored in the flash memory 10. did it. For example, the user's encryption can be checked by a program stored in the flash memory 10, the decoded part of the user's identity can be proved, and all the sources of the system can be fully disclosed. Or "SOFT IN CIRCUIT EMU
Using software such as "LATOR" and "SOFT ICE"
It is also possible to read the flash memory 10 directly, enter the system, and steal the source without decrypting or changing the program and without knowing the password.

[0004] In addition, manufacturers of mobile phones usually provide
The DSPs are produced using programs developed by the user, and all of these programs are stored in the flash memory 10 with respect to important data that the user does not want to be known to others, such as mobile phone functions and reception capabilities. In short, these important data were as public as possible, and flash memory was a security blind spot in system-protected decoding / encoding systems.

In order to solve this problem, a conventional solution as shown in FIG.
Is installed in the same IC 20, and the program in the flash memory is stolen,
It is prevented from being modified, deciphered, etc. However, in this method, although there is little possibility of being decoded, the manufacturing process cost is greatly increased because the flash memory 10 and the logic element of the MCU are different manufacturing processes.

[0006]

According to the present invention, the timing of reading / writing the flash memory is at the time of general startup or program installation. However, since these two types of situations rarely occur, a little logic design is required. And use specially designed software to achieve flash memory protection.

[0007] Further, a program performs an appropriate size block processing, and performs address scrambling (scramblin).
Using g) and random numbers, a new combination is generated according to the address change in the data arrangement, and the original data cannot be recovered unless the return method is used, thereby providing security of flash memory protection. . Further, it eliminates the need for a lot of manufacturing process costs.

The program stored in the flash memory is used to advance the block (blockbased), the rotation is advanced based on these blocks, the stored address is scrambled, and the data in the original address is rotated. Save in the new address later. When reading data, a random number generator (random number)
generator) to generate a reading order of random numbers, and include accurate data and dummy data in the read data. Further, the dummy read data is filtered, and the address rotation is restored to the original data. As a result, the data is read directly by scrambling the address to render it useless, and the data is protected in the flash memory without being stolen, corrected, changed, or the like.

In particular, by randomly combining data by address scrambling, the data in the non-transparent return process is rendered useless, and the data stored in the flash memory is prevented from being stolen, corrected, or changed.

Hereinafter, the structural design and technical principle of the present invention will be described to further clarify the features of the present invention.

[0011]

The first embodiment of the present invention will be described below.

As shown in FIG. 3, an MCU or DSP
Before the data is read or written into the flash memory 10, the data processing or return is performed by the memory data security chip 30. The internal structure of the memory data security chip 30 is shown in FIG.

The address scrambler 31 rotates according to a blocking program, and the original address scramble provides a set of new addresses and stores the original data. Further, the program is written into the flash memory 10 at the new address.

The random number generator 32 generates a set of random orders and sequentially reads data in the flash memory 10.

The decoder 33 filters the dummy data from the random number read address data. Also, the reverse program block acquires the original data and the address and provides it to the MCU (or DSP).

Next, a second embodiment of the invention will be described. The following are two operations of writing and reading the MCU into and from the flash memory 10.

[Write Order] Encoding operation for data: Software performs block based processing by a program. In general, a block basis is created by 8 × 8, rotation is performed based on these blocks, an address scrambler 31 immediately scrambles the stored address, and rotates the data in the original address after rotation. In the new address. In the following, for simplicity, the description will be made using 4 × 4 blocks.

The left side of FIG. 5 is the original data of the block, and the data stored at the address 80h is 001.
1, the data stored at address 81h is 1011; the data stored at 82h is 1100;
The data stored by h is 1010. After rotation (in this embodiment, 90 degrees to the right, but not limited to the direction of rotation), the 4 × 4 program block is as shown on the right side of FIG. The rotation saved by the new address 80'h is 1110, the rotation saved by 81'h is 0100,
The rotation that 82'h saves is 1011 and 83'h
Let 0011 be the rotation saved by. Where two 4x
In contrast to the four blocks, it can be understood that the rightmost vertical data in the right diagram is the original 80h data. Thus, the data quality in the corresponding address is completely scrambled. Since the data stored in the flash memory 10 is scrambled, the data read from the flash memory 10 is completely different from the original data.

As shown in FIG. 6, the steps of the writing operation can be summarized in a diagram. Step a. Step of program blocking. Step b. The rotating block scrambles the address of the original data to generate a new address. Step c. Saving the original data at the new address. Step d. Flash memory 1 with new address
Step of writing to zero.

[Read Order] -Decoding Operation for Data A set of random orders is generated by using a random number generator 32, and the data in the flash memory 10 is read according to the random order. , Are temporarily stored in the buffer 34 (SRAM). These read data include data written in the above-described writing order and dummy data. Therefore, at the time of data return, the dummy data is always filtered first to search for a necessary correlation address. Based on the filtered dummy address data, the decoder 33 reverses this block again to acquire the original data and address, and provides the MCU and DSP with the original data and address for use. The flash memory 10 is an MCU or DSP
, And according to the random number reading order provided by the random number generator 32, the required data and the dummy data are arranged in an unrecognizable order. Therefore, it is very difficult to decode the read data contents.

The reading operation can be summarized in the step diagram of FIG. Step a. Generating a set of random number reading orders using the random number generator 32; Step b. The order of step a is the flash memory 1
Reading from 0 and temporarily storing the data in the shock absorber 34; Step c. The temporary storage value of the buffer 34 filters the dummy data. Step d. The reverse rotation block gets the original address and data.

In addition, each system has a single address mapping order, with the memory data security chip 30 using a single key 35 in the read order. Thus, the address data also filters dummy data and useful address data. The key 35 is provided in the memory data security chip 30 or in a smart card (smart car).
d) is stored during.

Next, a third embodiment will be described.

The address is a linearity increase. During this simple change, it is possible to easily find the address where the necessary program is located. In this embodiment, the original random number in the chip 40 is randomly adjusted to the true address, and a set of new random numbers is set. Generate address storage data and make simple changes.

As shown in FIG. 8, the program stored in the MCU is read out in byte units (BYTE) for each chip 40 and stored in a register 41 in the chip 40. Provide flash memory with a very small capacity. As described above, the flash memory 10 delivered in the chip 40
Is difficult to manufacture and expensive, but one PR
It is very easy to make OM42. The random number produced by the random number generator 43 is entered in the PROM 42 and a conversion table is created (not shown) to control the correspondence between the original address and the post-rotation address. Furthermore, the data in the original address is written out with a random number, written again into the flash memory 10 for random address rotation, and the spread of addresses makes direct reading of data useless, making it difficult to steal, modify, change, etc. the data. Thus, the flash memory 10 is protected. Here, the random number generator 43 performs random generation, and the conversion table produced by the actually manufactured chip 40 is not the same, and is not limited to one method for covering the original data in the flash memory 10.

In addition, for the original address, the complement operation is advanced first, and the random address is advanced, thereby increasing the difficulty of decoding.

Hereinafter, the description will be made with reference to a 4-bit address as shown in FIG. A3 to A0 are original addresses, m3
Ｍm0 is a random number address. Arrows shown in the figure indicate a random correspondence between the two.

A3 is 0011, A2 is 0010, and
A1 is data of 0001, and A0 is data of 0000. This is complemented with respect to the original address, so that m3 = A2, m2 = A0, m1 = A3, and m0 = A1. That is, m3 is 0110 and m2 is 0
010, m1 is 0111, and m0 is 001
It is set to 1. Since the storage flash memory 10 stores the new address, the original address becomes more difficult to read.

When reading, the PROM 42 restores the original data with the stored conversion table.

Also, after the computer is started, by reading the flash memory 10 sequentially from the first data, the degree of difficulty in decoding increases. In addition, the random number generator 43 inserts unnecessary data at random between necessary data using a period during which data is read, and the computer forms a false reading state for the inserted data reading. I do. As a result, an accurate address order and accurate data cannot be obtained.

[0031]

As described above, the present invention makes use of address scrambling and random numbers to generate a new combination in accordance with a change in address in the data arrangement of the blocking process. Also make it impossible to obtain original data. This allows
Existing encoding / decoding protection systems can provide an effective solution and countermeasure against the drawback that the flash memory cannot be protected.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a conventional computer.

FIG. 2 shows a conventional MCU and flash memory having the same I
It is the structural drawing put in C.

FIG. 3 is a system structural diagram of the present invention.

FIG. 4 is an internal structural diagram of the memory data security chip of FIG. 3;

FIG. 5 is a chart before and after data rotation according to the present invention.

FIG. 6 is a step diagram of a writing operation according to the present invention.

FIG. 7 is a step diagram of a reading operation according to the present invention.

FIG. 8 is a structural diagram of a third embodiment of the present invention.

FIG. 9 is a chart before and after data rotation of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flash memory 20 IC 30 Memory data security chip 31 Address scrambler 32 Random number generator 33 Decryptor 34 Buffer 35 Key 40 Chip 41 Register 42 PROM 43 Random number generator

Claims (9)

[Claims] In a method for protecting data stored in a flash memory, a program stored in a flash memory is used to advance a block, rotate based on the block, scramble a stored address, and obtain an original address. Write the data in the new address again in the new address after rotation, and when reading the data, generate a random number reading order by the random number generator, include the accurate data and dummy data in the read data, and read the dummy read data. A method of recovering the address rotation to restore the original data to the original data and making the data useless even if the data is directly read by scrambling the address. 2. The writing order includes: a. Step of program blocking, b. A rotating block scrambling the address of the original data to generate a new address; c. Storing the original data at the new address; d. 2. The method according to claim 1, further comprising the step of: writing in the flash memory with the new address. 3. The method according to claim 2, wherein said step (a) comprises 8 bits × 8 bits as one block, which is used as a basis for rotation. 4. The method of claim 1, wherein the reading order comprises: a. Generating a set of random number reading orders using a random number generator; b. Reading the data from the flash memory and temporarily storing the data in the buffer according to the above step a; c. Buffering the temporary storage value to filter the dummy data; d. 2. The method of claim 1, wherein the reverse rotation block obtains the original address and data. 5. In a structure in which a memory data security chip is provided between an MCU or DSP and a flash memory to encrypt data in a write-in and read-out flash memory, an address scrambler comprises a block program. The original address is scrambled to provide a new set of addresses, the original data is stored and written to flash memory with the new address, and the random number generator generates a set of random orders. Then, the data in the flash memory is read in order, the decoder filters the address data of the random number reading, outputs dummy data, and the reverse program block obtains the original data and the address and sends it to the MCU (or DSP). Non-volatile storage characterized by providing Device content confidentiality structure. 6. The nonvolatile storage device as claimed in claim 5, wherein said memory data security chip has a single key, creates a single address mapping order, and filters dummy data. Confidentiality structure. 7. The memory data secret protection chip comprises a PRO
In a method for protecting data stored in a flash memory provided in a flash memory of M or a relatively small space, a random number generator produces a random number, puts it into a PROM, creates a conversion table, and stores an original address and The non-volatile storage device is characterized in that the correspondence between the addresses after rotation is controlled, the data in the original address is written out by the random number, and the flash memory is written again by rotating the flash memory to the random address. Retention method. 8. The method according to claim 7, further comprising the step of performing a complement operation on the original address before adjusting the random address. 9. In the reading, unnecessary data is randomly inserted between required data by using a random number generator, and a computer reads the inserted data to form a false reading situation. 8. The method according to claim 7, wherein the content of the nonvolatile storage device is kept secret.