JPH0771070B2 - Interface device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an interface device particularly suitable for a POS system.

(Prior Art) A POS system connects a data input device for inputting sales data (hereinafter referred to as a POS device) and an external computer for collecting and inquiring data through a public telephone line,
Sales data such as daily sales for each product and credit data for credit sales are sent to an external computer on the central side via a public telephone line, and the sales data can be called from an external computer. Accordingly, the data stored in the POS device is sent out periodically, and the credit data is sent out at every selling point.

By the way, the sales data usually does not require a high degree of confidentiality, so the raw data is directly output, while the credit data is directly related to the personal property and privacy of the person. Is encrypted once by the interface device and sent to the external computer, and the data related to the inquiry result is also encrypted and sent back by the telephone line, decrypted by the interface device and output to the POS device.

However, since the raw data is communicated between the POS device and the interface device, the data may be stolen from here.

(Object) The present invention has been made in view of such a problem, and an object of the present invention is to provide an interface device capable of consistently protecting from a POS device to an external computer. .

(Summary of the Invention) That is, a feature of the present invention is that an interfering wave generating means for outputting an interfering wave signal to a data input line, and an interference by receiving a signal from the input line and a signal from the interfering wave generating means. The point is that an interfering wave removing means for removing the wave and outputting to the encryption means is provided.

(Examples) Therefore, the details of the present invention will be described below based on illustrated examples.

FIG. 1 shows an embodiment of the present invention, in which reference numeral 10 denotes an interface device characterized by the present invention.
For example, a card reader 21 for reading data stored in a credit card or the like, and an output terminal 23 and an input terminal 11 of a POS device 20 having a PIN pad 22 for a card holder to input a personal identification number are connected by a cable 30, The interfering wave removing means 15 including a circuit for outputting the difference between the two signals, such as a differential amplifier, has the data from the POS device 20 placed on the interfering wave via the data input line 31 and the interfering wave described later. Generating means 1
The data from the POS device 20 that has been input from the interference wave from 6 and has the interference wave removed by the interference wave removal means 15 is encrypted by the encryption means 1
It is encrypted by 4, and is transmitted to the central computer through the modem 13 and the public telephone line C.

The data sent from the central computer via the public telephone line C and the modem 13 is decrypted by the decrypting means 17 and sent to the POS device 20 via the data output line 32. Has been done.

Reference numeral 16 is the above-mentioned interfering wave generating means, which is, for example, an oscillator for generating a sine wave having an extremely large amplitude as compared with the amplitude of the data signal, the output end of which is the data input line 31 and the above-mentioned interfering wave removing means 15 Is connected to the other input terminal of. Reference numeral 40 in the figure denotes a telephone connected to the modem 13, and 18 denotes a case for protecting the interface device 10.

In this embodiment, when the data is read from the credit card by the card reader 21 and the personal identification number is entered by the PIN pad 22, the POS device 20 operates the data input line 3
A data signal is input to the interface device 10 via 1 (FIG. 2I). By the way, this data transmission line 31
Since the interfering wave from the interfering wave generating means 16 is applied (II), the data signal input from the data input line 31 has a waveform which is largely deviated from the original data signal due to the superposition of the interfering wave ( III). The interfering wave removing means 15 receives the data signal on which the interfering wave is superposed and the interfering wave (I) from the interfering wave generating means 16 and takes the difference between them to cancel only the interfering wave (I). Restore the original data signal (I). The data from the restored POS device 20 is encrypted by means 1
After being encrypted by 4, the modem 13 and public telephone line C
Via, is sent to an external computer while maintaining confidentiality.

On the other hand, when a signal is taken out from the cable 30 connecting the POS device 20 and the interface device 10, the interfering wave from the interfering wave generating means 16 is superimposed on the data input line 31 (II
I), because the data is greatly distorted, it cannot be deciphered and abuse is prevented.

In this way, when the inquiry is completed by the external computer,
The inquiry result is encrypted on the sending side, input via the telephone line C and the modem 13, decrypted by the decrypting means 17, and then transmitted to the POS device 20 via the data output line 32.

In this embodiment, the sine wave is used as the interfering wave for the sake of simplification of the description, but it is apparent that the random wave as shown in FIG. In addition, according to this, it is possible to more surely prevent the theft of data.

(Effect) As described above, according to the present invention, the interfering wave generating means for outputting the interfering wave signal to the data input line for receiving the data from the POS device, the signal from the data input line and the interfering wave generating means are used. Since an interfering wave removing means for removing the interfering wave by receiving the signal of is provided, it is difficult to steal data from the data line connecting the data input terminal device such as the POS device and the interface device, and the encrypting means is used. Together, it can consistently protect theft of data from the transmission line connecting the POS device to the external computer.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention, FIG. 2 is an explanatory view showing the operation of the same apparatus, and FIG. 3 is a waveform diagram showing another embodiment of an interfering wave. 10 …… Interface device 11 …… Terminal 12 …… Terminal 20 …… POS device 30 …… Connection cable 31 …… Data input line

Claims (1)

[Claims] 1. An interface device for encrypting input data by an encryption means and outputting the encrypted data, an interference wave generating means for outputting an interference wave signal to a data input line, a signal from the data input line and an interference wave generating means. An interface device comprising an interfering wave removing means for receiving the signal from the interfering wave and removing the interfering wave to output to the encryption means.