JP3539360B2 - Illegal operation prevention device for highly integrated circuits - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is used for controlling electronic devices requiring high security such as a game machine and an IC card, and has a high degree of integration represented by, for example, ASIC (Application Specific Integrated Circuits). The present invention relates to an unauthorized operation prevention device suitable for application to an integrated circuit having
[0002]
[Prior art]
In recent years, with the miniaturization and speeding up of electronic devices, high integration and high speed have also been required for integrated circuits (ICs) to be mounted, and custom ICs such as the ASICs have been widely used. I have. Further, such an integrated circuit is very suitable for application to a product which is small and requires high security, and has a great effect when used for controlling an electronic device such as a game machine or an IC card. Is raised.
[0003]
By the way, as for the above-mentioned gaming machines, IC cards, etc., there is a concern about unauthorized operation from the outside, and particularly for applications in which security is strongly considered, unauthorized operations (for example, opening of products, irradiation of strong electromagnetic waves, When an IC removal is detected, illegality detection data corresponding to these illegal operations is written to a predetermined address of a writable memory (non-volatile RAM, EEPROM, or the like) built in the IC, and the illegality detection data is determined in advance. If the two match, it is determined that "illegal operation has occurred" and the operation or function of the electronic device is stopped, or data stored in the IC may be erased in some cases. Extremely confidential ICs with protection mechanisms are also available. In consideration of the operation efficiency and the like of the IC, the number of constituent bits of the fraud detection data used here cannot be so large, and is usually set to a small number of bits of at most about 3 bits.
[0004]
[Problems to be solved by the invention]
However, there are many memories with built-in ICs whose contents are indeterminate at the stage when the IC is manufactured. Therefore, when the power is turned on, the contents of the memory address where the fraud detection data is set happen to be compared. In some cases, it coincides with the data, and the occurrence probability is not necessarily low. For example, if the fraud detection data has a 3-bit configuration as described above, the probability that both data match is 1/8. If the IC is operated in such a state, it is determined that an unused IC having no unauthorized operation has been subjected to the unauthorized operation, and the function is stopped (or stored data is erased) at the same time when the power is turned on. Occurs. When such inconvenience occurs, a huge number of man-hours are required for the repair work.
[0005]
The present invention has been made in view of the above-mentioned conventional inconveniences, and aims to improve the productivity of highly integrated circuits by minimizing the rate of occurrence of operations and function stoppages caused by erroneous determination of memory contents. It is an object of the invention to provide a device for preventing unauthorized operation of a highly integrated circuit.
[0006]
[Means for Solving the Problems]
That is, the unauthorized operation preventing device for a highly integrated circuit according to claim 1 has a writable memory (8), and when unauthorized access is detected, unauthorized operation determination data (8) set at a predetermined address of the memory (8). In the tamper-proof device for a highly integrated circuit in which the function of the highly integrated circuit (1) is stopped based on 2), the preset comparison data and the set data in the memory (8) are used. When the power is turned on, when it is determined from the comparison result of the comparison circuit (6) that the memory (8) is used for the first time, the memory (8) includes: At least the unauthorized operation determination data (2) is initialized.
[0007]
In the above-described configuration, there is a disadvantage that an unused high-integration circuit, which has not been subjected to unauthorized operation or the like, is erroneously determined to have been subjected to unauthorized operation, and the function or operation is stopped (or stored data is erased) at power-on. Can be avoided.
[0008]
Further, in the unauthorized operation prevention device for a highly integrated circuit according to claim 2, the first use determination is based on unused determination data (3) set at a predetermined address of the memory (8); In addition, the number of constituent bits of the unused determination data (3) is larger than the number of constituent bits of the unauthorized operation determination data (2).
[0009]
Further, the unauthorized operation prevention device for a highly integrated circuit according to claim 3, wherein the unused operation determination data (3) does not match the predetermined unused determination comparison data (4), the unauthorized operation determination data (4). 2) is initialized, and after initialization, the content of the unused determination data (3) is made the same as the unused determination comparison data (4).
[0010]
In the present configuration, if the unused judgment data has a multi-bit structure of, for example, 32 bits, the probability that the memory content (unused judgment data) at power-on matches the content of the predetermined unused judgment comparison data is In most cases, the memory is unused and the illegal operation determination data is initialized, and the unused high-integration circuits that have not been illegally operated have been illegally operated. There is almost no possibility of misjudgment. After the initialization, the content of the unused determination data is rewritten to the same content as the unused determination comparison data, so that the re-initialization of the unauthorized operation determination data when the power is turned on again is prohibited.
[0011]
In the tamper-proof device for a highly integrated circuit according to claim 4, the illicit detection includes buffering the internal signal (S0) of the highly integrated circuit (1) and the internal signal (S0) (15). This is characterized by monitoring an exclusive OR with an output signal (S1) sent to the outside via an external device.
[0012]
According to a fifth aspect of the present invention, there is provided a device for preventing unauthorized operation of a high-integration circuit, wherein the unauthorized detection detects disturbance light when the storage case (10) of the high-integration circuit (1) is opened. It is characterized by being performed.
[0013]
Further, in the device for preventing unauthorized operation of a highly integrated circuit according to claim 6, the unauthorized access is detected when the storage case (10) of the highly integrated circuit (1) is opened. And a change in capacitance between the internal circuit and the internal circuit is detected.
[0014]
Further, in the tamper-proof device for a highly integrated circuit according to claim 7, the fraud detection is performed when the storage case (10) of the highly integrated circuit (1) is opened. And detection of conduction interruption of the internal circuit.
[0015]
Further, in the tamper-proof device for a highly integrated circuit according to claim 8, the illicit detection is performed by an electromagnetic wave detector (12) provided inside or outside a storage case (10) of the highly integrated circuit (1). ) To detect external electromagnetic waves.
[0016]
As described above, since the tendency of unauthorized operation can be grasped from the detected contents of the various unauthorized detection mechanisms described in claims 4 to 8, security can be further improved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a device for preventing unauthorized operation of a highly integrated circuit according to the present invention will be described with reference to FIGS.
[0018]
FIG. 1 is a block diagram showing an embodiment of an IC (for example, an ASIC) having a high degree of integration provided with an unauthorized operation preventing device, FIG. 2 is an operation flowchart thereof, and FIG. FIG. 4 and FIG. 5 are views showing the mounting state of the IC.
[0019]
As shown in FIG. 1, an IC 1 according to the present embodiment includes a control unit 7 for performing control according to a specific application such as a game machine or an IC card or performing control for preventing unauthorized operation thereof, and a writable unit such as a nonvolatile RAM or an EEPROM. The storage unit 8 includes a memory, an unauthorized operation detection circuit 9 that detects an unauthorized operation on the IC 1, and a comparison circuit 6.
[0020]
Here, the storage unit 8 stores various control data, and is also used for unauthorized operations detected by the unauthorized operation detection circuit 9 (such as opening of a product described below, irradiation of strong electromagnetic waves, removal of an IC for an unauthorized purpose, etc.). Predetermined addresses are provided for storing corresponding detection data (illegal operation determination data 2) and for storing data indicating unused / used IC 1 (unused determination data 3). The illegal operation determination data 2 has the same 3-bit configuration as in the prior art. The unused judgment data 3 is newly added data according to the present invention, and 32 bits having a larger number of constituent bits than the unauthorized operation judgment data 2 are secured.
[0021]
The comparison circuit 6 includes a preset unauthorized operation comparison data 5 for comparison of the unauthorized operation determination data 2, and a preset unused determination data for comparison of the unused determination data 3. The comparison data 4 is input.
[0022]
Next, an unauthorized operation prevention operation at the time of turning on the power in the above configuration will be described based on an operation flowchart of FIG.
[0023]
When the power of the IC 1 is turned on, first, in step (1), the unused judgment data 3 (the contents of the memory are undefined at the time of the first power-on) in the storage unit 8 are read out to the comparison circuit 6. It is compared with the unused judgment comparison data 4. If the two data do not match, it is determined that the IC 1 is not used, and the unauthorized operation determination data 2 in the storage unit 8 is initialized to “no unauthorized operation” in step (2). After initialization, in step (3), data indicating that the unused determination data 3 is "used", that is, the same data as the unused determination comparison data 4 is written. As a result, when the power is turned on from the next use, it is determined in step (1) that “there is use”, so that the storage unit 8 is not initialized, and the unauthorized operation monitoring process in step (4) is executed. Become. In step (4), the unauthorized operation determination data 2 in the storage unit 8 is read out to the comparison circuit 6 and compared with the unauthorized operation comparison data 5. If it is determined that "illegal operation is present", the IC1 is determined in step (5). Is stopped, and the confidential data stored in the storage unit 8 is deleted depending on the contents of the fraud.
[0024]
As described above, in the present embodiment, when it is determined that the IC 1 is unused, regardless of whether the unauthorized operation determination data 2 matches the unauthorized operation comparison data 5, Will be initialized. As a result, it is possible to avoid the inconvenience that an unused IC 1 that has not undergone unauthorized operation or the like is erroneously determined to have been subjected to unauthorized operation, and its function or operation is stopped (or stored data is erased) when the power is turned on.
[0025]
Here, as described above, the number of constituent bits of the unused judgment data 3 (that is, the unused judgment comparison data 4) is set to as large as 32 bits, and the probability that they match when the power is turned on is low. Since it is extremely low, in most cases, the unauthorized operation determination data 2 will be initialized. In addition, even if it is assumed that the two match, the probability that the unauthorized operation determination data 2 is determined to be "illegal" is 1/8 of that, so that an unauthorized operation is performed. It can be said that there is almost no possibility that an unused IC 1 that has not been performed is erroneously determined to have received an illegal operation and stops functioning.
[0026]
In the present embodiment, the unused judgment data 3 has a 32-bit configuration. However, it is needless to say that the present invention is not limited to this. Incidentally, if the bit configuration of the unused determination data 3 to 64 bits, the probability of misjudgment occurs it is approximately 1/10 ^19. Even if the number of constituent bits is increased in this way, the data is accessed only once at the time of power-on, so that there is no hindrance in terms of IC operation efficiency. In addition, since the bit configuration of the illicit operation determination data 2 (ie, the illicit operation comparison data 5) having a high access frequency is 3 bits as in the related art, the good operation efficiency of the IC is maintained and continued.
[0027]
Next, various unauthorized operation detection mechanisms mounted to enhance security will be described.
[0028]
The circuit shown in FIG. 3 monitors a malfunction or an improper operation due to an external factor on the output terminal side of the IC 1 and includes a buffer 15 and an exclusive OR circuit 16 (Exclusive OR or Exclusive NOR). In this configuration, when there is an illegal operation outside the IC 1 and there is a difference between the signal SO from the inside of the IC and the signal S 1 at the output terminal, the exclusive OR of the two is detected and the illegal detection signal S 2 is generated. Can be sent. According to the monitoring circuit, even if an external terminal is touched or a special circuit is connected to the external terminal for an unauthorized purpose, the illegal operation is immediately detected.
[0029]
In addition, as shown in FIG. 4, the IC 1 is housed in the housing case 10 and the light receiving element 11 is provided inside, so that the disturbance light when the housing case 10 is illegally opened is illegally operated by the light receiving element 11. Can be detected as
[0030]
If the electromagnetic wave detector 12 is provided near the IC 1 on the printed circuit board 14, when a strong electromagnetic wave or the like is radiated for an unauthorized purpose, it can be detected as an unauthorized operation. In this case, the electromagnetic wave detector 12 may be stored in the storage case 10 similarly to the IC 1.
[0031]
As shown in FIG. 5, a metal plate 13 such as a copper plate is embedded in a printed circuit board 14, and a change in capacitance between the storage case 10 and the metal plate 13 is monitored. Can also detect unauthorized opening of the.
[0032]
Further, although not shown, unauthorized opening can be detected by cutting the electrical wiring by opening the storage case 10.
[0033]
As described above, the present embodiment is provided with a mechanism for detecting various types of unauthorized operations that can be anticipated, and it is possible to grasp the tendency of unauthorized operations based on the detected contents, which is extremely effective in improving security.
[0034]
【The invention's effect】
As described above, according to the present invention, when the power is turned on, when the memory is determined to be used for the first time, the unauthorized operation determination data of the memory is initialized. It is possible to avoid the inconvenience that an unused high-integration circuit, which has not been subjected to unauthorized operation at power-on, is erroneously determined to have been subjected to unauthorized operation and stops its function or operation (or erases stored data). The enormous number of man-hours for such malfunction restoration can be reduced, and the productivity of highly integrated circuits can be improved.
[0035]
Also, in the present invention according to the second and third aspects, the first use determination is made based on unused determination data having a larger number of constituent bits than the unauthorized operation determination data. The above-mentioned inconvenience can be reliably avoided without impairing the operation efficiency of the device.
[0036]
Further, according to the present invention as set forth in claims 4 to 8, since a mechanism for detecting various unauthorized operations is provided, the tendency of unauthorized operation can be grasped from the detected contents, which is extremely effective for improving security.
[Brief description of the drawings]
FIG. 1 is a block diagram of an IC provided with an unauthorized operation prevention device of the present invention.
FIG. 2 is an operation flowchart of the unauthorized operation prevention device.
FIG. 3 is a circuit diagram showing an example of a fraud detection mechanism.
FIG. 4 is an external perspective view showing a mounted state of the IC.
FIG. 5 is a cross-sectional view showing a mounted state of the IC.
[Explanation of symbols]
1 Highly integrated circuits (ICs)
2 Unauthorized operation judgment data 3 Unused judgment data 4 Unused judgment comparison data 8 Memory (storage unit)
10 Storage case 12 Electromagnetic wave detector 15 Buffer

Claims (8)

It has a writable memory (8), and stops the function of the high-integration circuit (1) based on unauthorized operation determination data (2) set at a predetermined address of the memory (8) upon detection of unauthorized operation. Tamper prevention device for highly integrated circuits
A comparison circuit (6) for comparing preset comparison data with set data in the memory (8) is provided. When the power is turned on, the comparison result of the comparison circuit (6) indicates that the memory (8) An unauthorized operation prevention device for a highly integrated circuit, wherein at least the unauthorized operation determination data (2) in the memory (8) is initialized when it is determined that it is the first use. The first use judgment is based on the unused judgment data (3) set at a predetermined address of the memory (8), and the number of constituent bits of the unused judgment data (3) is determined by the illegal operation judgment. 2. The device according to claim 1, wherein the number of bits is larger than the number of constituent bits of the data. When the unused judgment data (3) does not match the predetermined unused judgment comparison data (4), the unauthorized operation judgment data (2) is initialized, and after the initialization, the unused judgment data (3) is initialized. 3. The apparatus for preventing unauthorized operation of a highly integrated circuit according to claim 2, wherein the contents of (i) are the same as the unused judgment comparison data (4). The fraud detection is performed by performing an exclusive OR operation on the internal signal (S0) of the high-integration circuit (1) and the output signal (S1) that sends the internal signal (S0) to the outside via the buffer (15). 4. An apparatus for preventing unauthorized operation of a highly integrated circuit according to claim 1, wherein the apparatus is monitored. 4. The device according to claim 1, wherein the fraud detection is performed by detecting disturbance light when the storage case of the highly integrated circuit is opened. 5. 3. The unauthorized operation prevention device for a highly integrated circuit according to claim 1. The fraud detection is performed by detecting a change in capacitance between the storage case (10) and the internal circuit when the storage case (10) of the highly integrated circuit (1) is opened. 4. An apparatus for preventing unauthorized operation of a highly integrated circuit according to claim 1, wherein The said fraud detection is performed by detecting conduction interruption between the storage case (10) and the internal circuit when the storage case (10) of the high-integration circuit (1) is opened. 4. An apparatus for preventing unauthorized operation of a highly integrated circuit according to any one of claims 1 to 3. The fraud detection is performed by detecting an external electromagnetic wave by an electromagnetic wave detector (12) provided inside or outside a storage case (10) of the highly integrated circuit (1). 4. An apparatus for preventing unauthorized operation of a highly integrated circuit according to claim 3.

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