JP3400480B2 - Program analysis prevention device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a program analysis prevention device for preventing illegal analysis of an operation program of a terminal device in a system such as a POS system in which a host device and a terminal device are connected by a communication line. .

[0002]

2. Description of the Related Art Conventionally, as a program analysis prevention device of this type, a terminal device has been disconnected by disconnecting a communication line between a host device and the terminal device or by cutting off power supply to the terminal device. There is a device that electrically deletes the operation program of the terminal device and a device that mechanically destroys the memory storing the program when the theft is detected.

[0003]

However, the above-described conventional program analysis prevention device may not fully function due to the backup function of the power supply in the terminal device. That is, the terminal device usually has a function of backing up the supply of electricity for a certain period of time even when the supply of electricity is cut off in order to cope with a power outage, etc., and even when the supply of electricity is cut off due to theft of the terminal device, The backup function works. Therefore, if you turn on the power within a certain time when the backup function is working or finish the analysis of the program,
There is a drawback that it is possible to perform illegal program analysis.

Further, particularly in the case of a device that mechanically destroys the memory, if the device itself becomes large and the memory is destroyed due to a malfunction or the like, it is necessary to replace the memory in order to restore it, which is troublesome for the recovery work. There was a drawback that it cost.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional drawbacks, to provide an apparatus which is not affected by the backup function of the power source, is easy to restore, and reliably prevents unauthorized program analysis. To do.

[0006]

In order to achieve the above object, a program analysis prevention device of the present invention comprises a host device,
The host device comprises a terminal device connected to the host device via a communication line, and the host device includes a key input unit for inputting an encryption key used for encrypting a program according to a predetermined rule, and the key input. Encryption key storage unit that stores and holds the encryption key input from the unit, and an instruction to decrypt the program encrypted according to the encryption key
A program editing unit that stores an editing program consisting of a sentence , the key input unit, the encryption key storage unit, and the program editing unit are controlled and stored in the program editing unit.
Decoding process of operation program according to editing program
Becomes a control unit which performs management, the terminal device, a program storage unit for holding and storing the operating program, an encryption key storage unit for holding and storing the encryption key is downloaded from the host apparatus , A program editing unit that stores an editing program that includes an instruction sentence that encrypts the program according to the encryption key, and the host device by controlling the program storage unit, the encryption key storage unit, and the program editing unit. If the editing program stored in the above program editing section is
Performs encryption processing of the operation program I, and with then erasing the editing program of the program editing unit uploads the operating program connection between the host device and the encrypted when restored to the host device And a control unit.

[0007] To achieve the above object, consists of a host device, a terminal device connected via a communication line to said upper apparatus, said host device, for encrypting a program according to a predetermined rule A key input section for inputting an encryption key used for a key, an encryption key storage section for storing and holding the encryption key input from the key input section, and a control for controlling the key input section and the encryption key storage section The terminal device includes a program storage unit that stores and holds an operation program, an encryption key storage unit that stores and holds the encryption key downloaded from the host device, and the encryption unit. a program editing section that stores an editing program of statement to encrypt and decrypt the operation program according to the key, the program storage unit, the encryption key Symbol And controls the parts and program editing section performs encryption processing on <br/> Symbol operation program in accordance with the host device and if the connection is broken in the program editing portion stored editing program, and After that, while deleting the editing program of the program editing section,
When the connection with the above host device is restored, is it the above host device?
Download the editing program from the above program
The encrypted operation program stored in the collection section is changed to the editing program stored in the program editing section.
And a control unit for performing a decoding process .

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a program analysis prevention device according to an embodiment of the present invention. As shown in the figure, the program analysis prevention device of the present embodiment is a higher-level device 1
0 and a terminal device 20 connected to the higher-level device 10 via a communication line. This embodiment is used in a system such as a POS system in which a host device and a terminal device are connected by a communication line. The host device 10 is installed in a host device of a system such as a central computer, and a terminal device. 20 is mounted on a terminal device of a system such as a reader / writer device of a prepaid card or a register. The communication line connecting the host device 10 and the terminal device 20 may be wired or wireless.

The host device 10 has a key input unit 11 for inputting an encryption key for encrypting the operation program of the terminal device 20 according to a predetermined rule, and an encryption key storage unit 12a for storing and holding the encryption key. And a program editing unit 12b that stores a decryption editing program that decrypts the operation program of the terminal device 20 encrypted according to the encryption key, and a ROM 13 that stores the operation program of the higher-level device 10 and universal data. It comprises a communication unit 14 for connecting to the terminal device 20, and a control unit 15 for controlling the operation of each of these units.

The key input unit 11 has an encryption key table 11a as shown in FIG. 2, and selects an appropriate encryption key from the encryption key table 11a based on an external input command. The encryption key storage unit 12a and the program editing unit 12b are provided in the RAM 12. RA
M12 stores an operation program of the terminal device 20 and an editing program for encrypting the operation program. The RAM 12 is backed up by the battery 16.

The control unit 15 is composed of a CPU,
It controls the operation of each unit, controls the sending and receiving of commands and data, sends the encryption key to the encryption key storage unit 12a and the terminal device 20, and sends the operation program and the editing program to the terminal device 20. Moreover, the connection state with the terminal device 20 is monitored. Further, the control unit 15 has a RAM 12
It is backed up by the battery 16 similarly to. The control unit 15 may also serve as an operation control unit on the system of the device in which the higher-level device 10 is mounted,
It may be provided separately from the operation control unit.

The terminal device 20 has a program storage unit 21a that stores and holds an operation program, an encryption key storage unit 21b that stores and holds an encryption key, and an encryption that encrypts the operation program according to the encryption key. A program editing unit 21c that stores a computerized editing program, a ROM 22 that stores universal programs and data, a communication unit 23 for connecting to the higher-level device 10, and a control unit 24 that controls these units are provided. Become.

The program storage unit 21a, the encryption key storage unit 21b, and the program editing unit 21c are provided in the RAM 21. The RAM 21 is backed up by the battery 25. The control unit 24 is composed of a CPU, controls the operation of each unit, controls the transmission and reception of commands and data, and stores the encryption key, the operation program, the editing program, etc. downloaded from the higher-level device 10 in the RAM 21.
Or sends the encrypted operation program to the host device 10
To send. Also, the connection state with the host device 10 is monitored. Further, the control unit 24 is backed up by the battery 25 like the RAM 21.

Next, the operation of this embodiment will be described with reference to the flowcharts of FIGS. 3, 4 and 5. 3 is a flowchart showing the operation of the host device 10 until the communication with the terminal device 20 is cut off, and FIG. 4 is a flowchart showing the operation of the terminal device 20 until the communication with the host device 10 is cut off. Is a flow chart showing the operations of both devices 10 and 20 after the communication between the host device 10 and the terminal device 20 is restored.

First, the operation of the host device 10 will be described with reference to FIG. In the initial state, the control unit 15 monitors the connection state of the communication line with the terminal device 20 (step S1). When the communication state is normal, the control unit 15 controls the key input unit 1
It is checked whether or not it is necessary to transmit data to the terminal device 20, such as input of a new encryption key from 1 or update of the operation program of the terminal device 20 (step S2). Then, if transmission is necessary, the processing content of the transmission data is determined (step S3), and the terminal device 2 is transmitted via the communication unit 14.
The encryption key input to 0 or predetermined data to be transmitted and the encryption key stored in the encryption key storage unit 12a of the RAM 12 are transmitted (step S4). That is,
When data is transmitted from the host device 10 to the terminal device 20, the latest encryption key is always transmitted. Then, after the transmission of all data is completed, the process returns to the initial state (steps S5 and S1).

When the state of communication with the terminal device 20 becomes abnormal, the control unit 15 holds the encryption key stored in the encryption key storage unit 12a of the RAM 12 at that time (step S6). , Wait for the connection of the communication line with the terminal device 20 to be restored (step S7).

Next, the operation of the terminal device 20 will be described with reference to FIG. In the initial state, the control unit 24 sets the host device 10
The connection state of the communication line with is monitored (step S1).
When the communication state is normal, the control unit 24 determines that the host device 1
It is checked whether or not the transmission data from 0 is received (step S2). And when the data is received,
First, the encryption key is extracted from the received data and stored in the encryption key storage unit 21b of the RAM 21 (step S3). Then, if there is data other than the encryption key, the processing content is determined (step S4), and the processing is executed. Execute (Step S
5) If necessary, the processing result is transmitted to the host device (step S6). After these operations are completed, the process returns to the initial state (step S1).

When the state of communication with the higher-level device 10 becomes abnormal, the control unit 24 encrypts the operation program according to the encrypted editing program stored in the program editing unit 21c of the RAM 21 (steps S7-). S11)
Do. First, with reference to the encryption key stored in the encryption key storage unit 21b, a command before encryption and a command after encryption in the operation program are searched (step S).
7). Next, the operation program stored in the program storage unit 21 of the RAM 21 is analyzed for each statement (step S8). Then, the command text that matches the unencrypted command text retrieved in step S7 is encrypted according to the encryption key (steps S9 and S10). The above analysis and conversion are repeated until all the relevant command statements of the operation program are completed (step S11).

After the above-described program encryption processing is completed, the control section 24 erases the encrypted editing program of the program editing section (step S12). Therefore, even if only the programs stored in the RAM 21 and the ROM 22 of the terminal device 20 are analyzed, it becomes impossible to decrypt the encrypted operation program. After this, the control unit 24
Waits for the connection of the communication line with the host device 10 to be restored (step S13).

Next, according to FIG. 5, both devices 10 when the connection of the communication line between the host device 10 and the terminal device 20 is restored,
The recovery operation of 20 will be described. The control unit 24 of the terminal device 20 uploads the encrypted operation program to the higher-level device 10 when the connection is restored after the connection of the communication line with the higher-level device 10 is disconnected (steps S1 and S2) (step S3). ).

On the other hand, the control unit 15 of the host device 10 receives the operation program uploaded from the terminal device 20 after the connection is restored after the connection of the communication line with the terminal device 20 is cut off (step S11, S12, S13),
The operation program is decrypted according to the decryption editing program stored in the program editing unit 12b of the RAM 12 (step S14). The decryption procedure is the same as the encryption of the operation program in the terminal device 20, and the pre-encryption and post-encryption instructions are searched for based on the encryption key stored in the encryption key storage unit 12a, and the operation program is searched. Is analyzed for each statement and the encrypted statement is sequentially decrypted.

Here, since the encryption key stored in the encryption key storage unit 12a is the one at the time when the connection with the terminal device 20 was cut off, the operation program is encrypted in the terminal device 20. It is the same as that used for conversion. After the decryption of the operation program is completed, the control unit 15 downloads the decrypted operation program and the encrypted editing program stored in the program editing unit 21c of the RAM 21 of the terminal device 20 (steps S15 and S16). Since the encrypted edit program is deleted after the operation program is encrypted in the terminal device 20, it is necessary to download it when the communication line is restored.

The control unit 24 of the terminal device 20 is connected to the host device 1
The operation program and the encrypted editing program downloaded from 0 are stored in the program storage unit 21a and the program editing unit 21c of the RAM 21 (steps S4 and S5).

Next, another embodiment of the present invention will be described with reference to FIG. The host device 10 of this embodiment is a RAM
12 does not include a program editing unit that stores a decryption editing program that decrypts the encrypted operation program. Further, the program editing unit 21c provided in the RAM 21 of the terminal device 20 stores a decrypted edit program for decrypting the encrypted operation program, in addition to the encrypted edit program for encrypting the operation program.
Therefore, when the terminal device 20 recovers after the connection of the communication line with the host device 10 is disconnected, the terminal device 20 decrypts the operation program without transmitting the encrypted operation program to the host device 10. Can be converted. The configurations of the host device 10 and the terminal device 20 other than the above are the same as those shown in the embodiment of FIG.

Next, the operation of this embodiment will be described.
In the present embodiment, the host device 10 and the terminal device 20
Both devices 10 and 20 until the connection of the communication line with
1 is the same as the operation shown in the flowcharts of FIGS. 3 and 4 according to the embodiment of FIG. 1, and is omitted, and the operation after the connection of the communication line is restored will be described with reference to the flowchart of FIG.

First, when the connection of the communication line is restored (steps S1 and S2), the control unit 15 of the higher-level device 10 makes RA
An encryption key stored in the encryption key storage unit 12a of M12, an encryption key table 26 as shown in FIG.
The encrypted editing program stored in the program editing unit 21c is downloaded to the terminal device 20 (step S
3). To download the encryption editing program,
Similar to the embodiment of FIG. 1, after the operation program is encrypted,
This is because the encrypted editing program is erased for security.

On the other hand, when the communication line is restored (steps S11 and S12) and the control unit 24 of the terminal device 20 receives the downloaded encryption key, the encryption key table 26 and the encrypted editing program (step S13). ), Referring to the encryption key and the encryption key table 26,
The operation program is decrypted according to the decryption editing program of the program editing unit 21c (step S14).

The encryption key is the RAM of the terminal device 20.
21 is stored in the encryption key storage unit 21b of the host device 10, and the encryption key storage unit 12a of the RAM 12 of the host device 10 holds the encryption key when the communication line is disconnected. You do not have to download the encryption key. Also, the encryption key table 26
Is for decrypting the operation program, the contents of the instructions before and after the conversion are reversed as compared with the encryption key table 11a in FIG. Furthermore, when the encrypted editing program is erased after the operation program is encrypted, the decrypting editing program is also erased, and both editing programs may be downloaded after the communication line is restored.

[0029]

As described above, the program analysis prevention device of the present invention mutually monitors the communication state between the host device and the terminal device, and immediately encrypts the operation program when an abnormality occurs. By deleting the editing program, even if the terminal device is stolen, the normal operation program cannot be analyzed from the terminal device, and an illegal program analysis can be prevented. Further, after the connection of the communication line is restored, the encrypted operation program is decrypted by the host device and downloaded to the terminal device so that the terminal device can operate normally, so that the recovery operation is easy. .

Further, since the program analysis prevention apparatus of claim 2 decides that the terminal device decrypts the encrypted program by itself after the connection of the communication line is restored,
Since it is not necessary to send and receive the operation program to and from the host device, there is an effect that the recovery work can be performed safely and promptly by reducing the communication amount.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a program analysis prevention device according to an embodiment of the present invention.

FIG. 2 is a chart showing an encryption key table provided in the key input unit of FIG.

FIG. 3 is a flowchart showing the operation of the host device in FIG.

FIG. 4 is a flowchart showing an operation of the terminal device of FIG.

5 is a flowchart showing operations of the host device and the terminal device of FIG. 1. FIG.

FIG. 6 is a block diagram showing another embodiment of the present invention.

7 is a flowchart showing the operation of the host device and the terminal device of FIG.

FIG. 8 is a chart showing an encryption key table downloaded to the terminal device of FIG.

[Explanation of symbols]

10 Upper device 11 Key input section 12a Encryption key storage unit 12b Program editor 15 Control unit 20 terminal devices 21a Program storage section 21b Encryption key storage unit 21c Program editor 24 Control unit

Claims (2)

(57) [Claims] 1. An upper device and a terminal device connected to the upper device via a communication line, wherein the upper device inputs an encryption key used for encrypting a program according to a predetermined rule. From the key input unit, the encryption key storage unit that stores and holds the encryption key input from the key input unit, and the command statement that decrypts the program encrypted according to the encryption key.
A program editing section for storing a composed editing program, the key input unit, and controls the encryption key storing unit and the program editing section, the editing flop stored in the program editing portion
The operation program is decrypted according to the program.
It and a Cormorant controller, the terminal device, a program storage unit for holding and storing the operating program, an encryption key storage unit for holding and storing the encryption key is downloaded from the host device,
A program editing unit that stores an editing program that includes an instruction sentence that encrypts the program according to the encryption key, and controls the program storage unit, the encryption key storage unit, and the program editing unit to operate with the host device. The edition stored in the program editor when the connection is lost.
Encryption of the above operation program according to the collection program
And a control unit for performing the processing and thereafter deleting the editing program of the program editing unit and uploading the encrypted operation program to the upper device when the connection with the upper device is restored. Program analysis prevention device characterized by. 2. A host device and a terminal device connected to the host device via a communication line, wherein the host device inputs an encryption key used to encrypt a program according to a predetermined rule. A key input unit, an encryption key storage unit that stores and holds the encryption key input from the key input unit, and a control unit that controls the key input unit and the encryption key storage unit. The terminal device includes a program storage unit that stores and holds an operation program, an encryption key storage unit that stores and holds the encryption key downloaded from the host device,
By controlling a program editing unit that stores an editing program including command statements for encrypting and decrypting the operation program according to the encryption key, the program storage unit, the encryption key storage unit, and the program editing unit, performs encryption processing of the operation program in accordance with the program editing portion stored editing program if the connection to the host device is interrupted, and with then erasing the editing program of the program editing portion, the higher-level device professional editing from the higher-level device when the connection is restored and
Download the program and store it in the program editor
And decrypts the encrypted operation program according to the editing program stored in the program editing unit.
A program analysis prevention device comprising a control unit for processing .