JPS61228569A - Secret information memory device - Google Patents

Abstract

PURPOSE:To inhibit a case where the secret information can be read out of a stolen card by storing the entire part of a secret information memory means in a container and providing a photodetector at a place close to the opened/ closed part of the container to destroy the memory contents with photodetection. CONSTITUTION:An operator reads the data on a customer's credit card through a card reader 11 of a transaction device 10 and gives an password number input device 20 to the customer. Thus the customer supplies his/her password number through a keyboard 22 of the device 20. The device 20 stores the input password number into a RAM 26 according to a program of a ROM 25 via a CPU 21 and also coding the number with the coding data stored in the RAM 26 to transmit it to the device 10. A photodetecting part 27 detects the light sent from outside when the container of the device 20 is opened and delivers it to the CPU 21. The CPU 21 clears the data of the RAM 26 with the photodetection signal. As a result, the secret data stored in the RAM 26 is destroyed to disable the reading of the secret information in case a card is stolen.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a secret information storage device for storing encrypted data, a password, or other secret information in a credit card processing system, a handy terminal processing system, or the like.

(b) Prior art and its drawbacks Conventionally, for example, in a credit card system, a PIN input device encrypts the input PIN and sends it to a transaction processing device, etc., but the encryption data used for this encryption is , data that requires extremely confidentiality;
It is necessary to prevent it from being easily read. However, conventional secret information storage devices that store such secret information are vulnerable to theft. Therefore, this is a cause of lowering the reliability of the entire system.

(C) Purpose of the Invention The purpose of the present invention is to provide a secret information storage device that makes it impossible to read out the secret information stored in the device even if the device itself that stores the secret information is stolen. It is in.

(d1 Structure and effect of the invention) This invention comprises a storage means for storing secret information, a container for storing the entire storage means, a photodetector disposed near an opening/closing part of the container, and a photodetector for detecting light of the detector. and means for destroying the stored contents of the storage means.

According to this invention, when the container of a device that stores confidential information is opened, the light entering the container is detected and the confidential information is destroyed at that point, so it is virtually impossible to read out the confidential information. Can be prohibited.

TELE EMBODIMENT FIG. 1 is a block diagram of a credit card processing system which is an embodiment of the present invention.

10 is a transaction processing device, 20 is a password input device,
Re-equipment is connected by cable. Transaction processing device 10
is a device that performs transactions using credit cards. The operator causes the card reader 11 of the transaction processing device 10 to read the card data of the customer's credit card, and hands the password input device 20 to the customer. The customer inputs the password from the keyboard 22 of the password input device. The password input device 20 encrypts the input password and then transmits it to the transaction processing device IO. The transaction processing device 10 receives this encrypted personal identification number and transmits it to the center via the telephone line together with the previously read card data. This allows credit card verification.

FIG. 2 shows a block diagram of a password input device. The display 23 is an LED (light emitting diode), and when it is lit, it indicates that the password can be entered.

In this lighting state, the password entered from the keyboard 22 is stored in the RAM 26 by the CPU 21 according to the program in the ROM 25.
Encrypt using the encryption data stored in .

Next, when the customer operates the ENT key on the keyboard 22, the encrypted password is transferred to the serial transmission control unit 24.
is output to the transaction processing device 10 as serial data.

The light detection unit 27 detects light incident from the outside when the container of the PIN input device is opened, and sends the detection signal to the CPU.
This is for outputting to. The CPU executes a predetermined program stored in the ROM based on this detection signal, and clears the data in the RAM 26. This allows R
Destroy the secret data stored in AM26.

FIG. 3 shows a photodetector placed near the opening/closing part of the container of the password input device. In both figures, 29 is an upper cabinet, 30 is a lower cabinet, 28 is a wiring board, and 27 is a photodetector such as a photodiode. (
As shown in A), the upper cabinet and the lower cabinet are normally in a closed state, and the photodetector 27 is shielded from light from the outside. When the upper cabinet 29 is opened, external light enters from the gap with the lower cabinet as shown in (B), and the photodetector 27 indicates that the light has been detected if the illuminance of the external light is above a certain value. signal to CPU
Output to.

FIG. 4 is a diagram showing a memory map of the RAM.

Area M1 is encryption data for encrypting the password, the contents of which are already determined before using the password input device. Area M2 is an encrypted password entered from the keyboard 22. Area M3
is a working area used for processing various registers, flags, etc. for encryption and other processing.

FIGS. 5 and 6 are flowcharts showing the processing procedure of the personal identification number input device.

FIG. 5 shows the normal operation procedure. First, in step n1, it is determined whether there is any command from the transaction processing device. If there is any command, reception processing is performed at step n2, and corresponding processing is executed at step n3. At step n4, it is determined whether there is any key force on the keyboard 22. If there is human power for the key, processing for determining the key is performed in step n5. If the pressed key is a numeric key, this is determined in step n6, and the numeric code corresponding to the numeric key is input into the input buffer IB in step n7. Furthermore, the contents of the input buffer are encrypted and transferred to the area M in FIG.
Store in 2. By operating the numeric keys in this way, a multi-digit password is encrypted and stored. After that, E
If the NT key has been operated, this is determined in step nll, and the encrypted personal identification number is transmitted to the transaction processing device 10 in step n12. Furthermore step nl
o is a process corresponding to the operation of the clear key (CL key), and when the clear key is pressed, the password is cleared. Incidentally, step n13 is another process while waiting for reception from the transaction processing device or key input from the keyboard.

Figure 6 shows C when there is a detection output from the photodetector.
It is a flowchart about interrupt processing performed by PU. This interrupt processing is executed at any step of the processing shown in FIG. 5 above. First, in step n20, the RAM is stored in the address register AD.
Set the lowest address LA. At step n21, OO is written to the contents of the RAM indicated by address AD. At step n23, it is determined whether the currently designated address is the highest address register of the RAM. If it is less than that, the address register AD is incremented in step n22 and the process returns to n21. That is, by this process, the memory contents from the lowest address to the highest address of the RAM, that is, the entire contents of the RAM, are filled with data 0.
0 will be written. Thereafter, in step n24, a message indicating that all contents of the RAM have been cleared is transmitted to the transaction processing device. Of course, if the PIN input device is physically disconnected from transaction processing, outputting this message is meaningless, but reading out the secret information is definitely impossible.

<Other Embodiments> The above embodiment was a method of destroying the contents by writing some data to the RAM, but another method is to forcibly cut off the power supply to the RAM to destroy the stored contents. There is a way to destroy it. FIG. 7 shows an example of this. In the figure, 26 is a RAM, and vCC is its power input terminal. 31 is a switching P-channel MO3 transistor for supplying or cutting off the power supply voltage VCC. Signal S is CP
It is output from U and is normally at a low level, and normally the MO3) transistor 31 is turned on. 32 is an N-channel MO3, and the above 31 and C-M
It has an O3 configuration. That is, normally 32 is in an off state. 35 is a backup battery. diode 33
．． 34 is for backflow prevention. If the CPU determines the detection signal from the photodetector, it sets the signal S to High level. Therefore, 31 is turned off and 32 is turned on. As a result, the RAM power supply terminal VCC becomes GND level,
The stored contents will be destroyed.

Incidentally, no matter what state the address bus, data bus, chip select read/write signals are in, if the power supply voltage reaches the GND level, the stored contents will be destroyed.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of a credit card processing system that is an embodiment of the present invention, Fig. 2 is a block diagram of a PIN input device, and Fig. 3 is a sectional view of the vicinity of the opening/closing part of the container of the PIN input device. , FIG. 4 shows the RA in the PIN input device.
FIG. 5 is a flowchart showing the processing procedure of the PIN input device, FIG. 6 is a flowchart showing the interrupt processing procedure of the PIN input device, and FIG. 7 is another embodiment. It is a circuit diagram around a certain RAM.

Claims (4)

[Claims] (1) A storage means for storing secret information, a container for storing the entire storage means, a photodetector placed near the opening/closing part of the container, and the storage contents of the storage means are detected by light detection by the detector. A secret information storage device characterized by comprising a means for destroying the. (2) The secret information storage device according to claim 1, wherein the storage means stores encryption data for encrypting input information. (3) The secret information according to claim 1 or 2, wherein the storage means is constituted by a volatile memory, and the storage content destruction means cuts off the power supply to the volatile memory. Storage device. (4) The secret according to claim 1 or 2, wherein the storage means is constituted by a non-volatile memory, and the storage content destruction means is constituted by means for writing specific data into the non-volatile memory. Information storage device.