JPS62118471A - Accounting device - Google Patents

Abstract

PURPOSE:To have no contradiction in an accounting processing between an IC card and an accounting device by providing a random number generating means for generating a random number in the accounting device for performing a finance transaction with a portable type device. CONSTITUTION:When the IC 107 card is inserted into the accounting device, a microprocessor 102 generates the random number KW in a random number generator 103, enciphers an amount of a charge F and the random number KW as a key in a cipher/decoder 104 and feeds to the IC card 107 through a card interface 101. Herein, the card 107 enciphers the amount of a payment and an error and alteration detection code CC by the random number KW and feeds. The microprocessor 102 decodes the received data in the decoder 104 by making the random number KW the key. If the code CC is correct, from the amount of the charge F, the amount of the payment F' is subtracted, and information A in which the the amount of the payment F' is subtracted or not and the code CC are enciphered in the decoder 104 according to the random number KW and fed to the card 107.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a billing device that performs billing processing with a card having an arithmetic function (hereinafter referred to as an IC card).

(Prior Art) As a charging method using an IC card, there is the following method using the authentication function of the IC card. The IC card and the billing device share a secret code KM.

The charging device generates a random number RN and sends it to the IC card together with the charge amount F encrypted with KM. The IC card decrypts the encrypted fee amount using KM to obtain the fee amount F, and subtracts F from the remaining amount stored in the IC card. KM more RN
is encrypted and sent back to the billing device. The billing device decodes it using KM, and if it matches the RN, it is assumed that no tampering has been done, and the charge amount F is settled.

(Problems to be Solved by the Invention) According to the conventional system, when the billing device determines that there has been tampering, the charge amount F is not settled, but the IC card reduces the remaining balance. have A situation where the RN does not appear when the KM decodes what is returned by the billing device may be due to tampering, or it may be a simple error that is not malicious. If a malicious IC card holder falsifies a message, it is his fault even if only the IC card is deducted, but there are many other cases, so if the billing device does not clear the charge, it is better not to deduct the IC card as well. desirable.

The aim of the invention is to eliminate this drawback.

(Means for solving the problems) In order to solve the above problems, the present invention employs the following means. That is, in a billing device that performs financial transactions with a monthly general device, a random number generating means that generates a random number, and a charge amount and the random number KW that are notified to the portable device.
a first code conversion means that converts the code depending on a predetermined pattern; an inverse conversion means for performing inverse conversion; a determination means for determining whether the received error/tampering detection code is correct; and an operation for changing the charge amount only when the determination means makes a positive determination. and second code converting means for code converting the error/tampering detection pattern to be notified to the portable device and the determination result of the determining means depending on the random number KW. be.

(effect) Figure 2 is used to illustrate how the invention works.

201 is a billing device, 202 is an IC card, and both share a secret key KM. Let F be the amount of charge that the billing device wants the IC card to pay, and C8 be the amount of money owned by the IC card, that is, the remaining balance. First, the charging device 201 generates a random number KW, encrypts it together with the fee amount F using KM, and
Send to C card. IC card is EK encrypted with KM
It receives M(F, KW) and decodes it with KM. Then, subtract F' from the remaining amount C8. F' should originally match F, but it is the amount that is actually paid in cases where O8<F, such as when paying even a portion of the amount. This F' and the error/tampering detection code CC are encrypted with the key KW and sent to the billing device.

Specifically, CC is an arbitrarily determined pattern.

The billing device decrypts the sent message, and if a correct CC appears, it determines that there is no error or tampering, and then F
′ from F, otherwise leave F as is,
Whether CC is correct or not, information A and CC are encrypted with KW and sent to the IC card. The IC card decodes it,
If a correct CC appears, it is determined that there is no error or tampering, and if information A indicates that the billing device has not deducted F' from F, it adds F' to C8 and returns the original F.
′ is returned to the state before the reduction.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention. The present invention relates to the billing device 201 shown in FIG. In the figure, a card interface 101 interfaces with an IC card. The microprocessor 102 controls various data and performs four arithmetic operations, and its programs are stored in the ROM 105. RAM
106 is a storage area for the charge amount F and a work area for the microprocessor. In addition, at least the charge amount is non-volatile R.
I need to put it on AM. A random number generator 103 generates random numbers, and an encoder/decryptor 104 performs encryption and decryption.

The operations of the microprocessor 102 are shown in a flowchart in FIG. When the IC card is inserted into the billing device, the microprocessor sends a random number K to the random number generator 103.
W is generated and encrypted using KW as a key along with the fee amount F.
The card interface 10 is encrypted by the decryptor 104.
1 to the IC card 107. Here, the IC card is configured to encrypt the payment amount and the error/tampering detection code CC with KW and send it. The microprocessor 102 sends the received data to the encoder/decryptor 104.
Decrypt using the key. If the error/tampering detection code is correct CC, the payment amount F' is subtracted from the fee amount F, and the information A indicating whether or not the amount has been reduced and the error/tampering detection code CC are encrypted by KW and decrypted by the decoder 104. Send to IC card.

In this embodiment, it is desirable that the key KM is built into the encryption/decryption device. Further, the random number generator ]-03 may be a commercially available natural random number generator. The encoder/decoder 04 must be the same as that used in the IC card. It can also be executed by the microprocessor 102, but in this case the KM is stored in an area that cannot be accessed from the outside.

In this embodiment, the billing device may not reduce the fee due to reasons such as the payment amount F' notified from the IC card being too small. At this time A
If = NO, then 1; Yes. This modification is within the scope of the invention.

In this embodiment, if the IC card first notifies the user of the reduction, there is no need to notify the payment amount F' later.

Further, in this embodiment, the data that the billing device first sends to the IC card is the charge amount F and the random number KW encrypted with KM, but an error/tampering detection code can be added. At this time, if the IC card decodes and a correct error/tampering detection code does not appear, the IC card will notify the billing device of termination.

(Effects of the Invention) As described above in detail, the present invention has great effects because it is possible to prevent inconsistency in billing processing between the IC card and the billing device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the operation of the present invention, and FIG. 3 is a flow chart of the work to be performed by the microprocessor. In the figure, 101 is a card interface, 102 is a microprocessor, 1103 is a random number generator, and 104 is a cryptographic controller.
Decoder, J-05 is ROM, 106 is RAM, 201
107 and 202 indicate a billing device and an IC card, respectively.

Claims (1)

[Claims] In a billing device that performs financial transactions with a portable device, a random number generating means generates a random number, and a charge amount notified to the portable device and the random number KW are code-converted depending on a predetermined pattern. a first code conversion means;
The portable device receives an error/tampering detection code code-converted depending on the random number KW, and receives the random number K.
an inverse conversion means that performs inverse conversion depending on W; a determination means that determines whether or not the received error/tampering detection code is correct; and a second code converting means that converts the error/tampering detection pattern to be notified to the portable device and the judgment result of the judging means depending on the random number KW. billing device.