JPH06101015B2 - Cash card - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cash card for performing a charging process with a charging device.

(Prior Art) As a charging method using a card having an arithmetic function (hereinafter referred to as an IC card), there is the following method using an IC card authentication function. The IC card and the billing device share the secret code KM. The billing device generates a random number RN and sends it to the IC card together with the fee amount F encrypted with KM. The IC card decrypts the encrypted fee amount with KM to obtain F, and subtracts F from the balance stored in the IC card. Furthermore, RN is encrypted with KM and returned to the billing device. In billing devices it KM
Decryption is performed, and if it matches RN, it is considered that the tampering has not been performed, and the fee F is cleared.

(Problems to be Solved by the Invention) According to the conventional method, there is a drawback that the remaining amount is reduced with the IC card, even though the charging device determines that the tampering has not been performed and the fee amount F is not settled. . If the KM does not appear after decrypting what is returned by the billing device with KM, the situation may be tampering or it may be a simple error that is not malicious. If a malicious IC card owner falsifies the message, even if the IC card is reduced, it is self-profitable, but in many other cases, it is better not to subtract the IC card if the billing device does not settle. desirable.

The object of the invention is to eliminate this drawback.

(Means for Solving Problems) The cash card of the present invention has a balance CS equivalent to cash,
In a cash card which shares a predetermined pattern KM and an error / falsification detection code CC and conducts a financial transaction with a billing device, the amount of charge F code-converted depending on the predetermined pattern KM. And a random number KW are received from the billing device and then inversely converted, and the error / falsification detection code CC is coded depending on the random number KW included in the output of the first inverse converter. After conversion, the code conversion means for notifying the billing device, the information indicating whether or not the billing device has reduced the charge amount F and the error / falsification detection code CC depend on the random number KW. Second reverse conversion means for receiving and reverse conversion after receiving the code conversion, and determining whether or not the error / falsification detection code CC included in the output of the second reverse conversion means is shared. Means and the judgment hand Does not subtract the charge amount F from the balance CS corresponding to cash, when the positive determination is made and information indicating that the charging device did not reduce the charge amount F is sent. When the billing device has sent information in which the charge amount F has been reduced, it comprises subtraction means for subtracting the charge amount F from the balance CS.

(Operation) How the present invention works will be described with reference to FIG.
201 is a billing device and 202 is an IC card, both of which are secret keys
Share KM. Let F be the amount of money that the billing device wants the IC card to pay, and CS be the amount of money owned by the IC card, that is, the balance. First, the charging device 201 generates a random number KW, encrypts it with the fee amount F with KM, and sends it to the IC card. The IC card receives E _KM (F, KW) encrypted with KM and decrypts it with KM. Then subtract F'from the balance CS. Although F'should be the same as F originally, it is the actual amount to be paid in case of partial payment when CS <F.
This F'and the error / falsification detection code CC are encrypted with the key KW and sent to the billing device.

CC is a bit pattern preset between the charging device and the IC card. For example, CC with 111 …… 1 ALL "1"
Suppose At this time, the IC card encrypts F'and CC with KW and sends them to the billing device. The billing device uses the received ciphertext
Decode with KW, correct CC (bit pattern is ALL ″
If 1 ″) is detected, it is determined that there is no error or tampering, and F is subtracted from F ′. Otherwise, F is left as it is, and the information A indicating whether CC is correct and CC are encrypted with KW. And send it to the IC card, which decrypts it and
If CC comes out, it is judged that there is no error or tampering, and if the information A indicates that the charging device does not reduce F'from F ', CS is added with F'and the original F'is added. Return 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 IC card 202 shown in FIG. The interface 101 interfaces with the charging device 105. The encryption / decryption device 103 performs encryption and decryption. The processor 102 executes input / output management of data to and from the memory 104, four arithmetic operations and the like, which will be described in detail in the flowchart of FIG. In FIG. 3, when the charge amount F and the random number KW encrypted with the key KM are received from the billing device, they are decrypted by the encryption / decryption device 103, and F'is subtracted from the balance CS of the IC card. Although F'should be the same as F originally, it is the amount actually paid when a part is to be paid when CS <F. Further, F'and the error / falsification detection code CC are encrypted by the encryption / decryption device 103 using KW as a key and sent to the billing device. On the other hand, when the information A indicating whether or not the bill is reduced by the billing device and the data in which the error / falsification detection code CC is encrypted by KW is received from the billing device, the processor 102 causes the encryption / decryption device 103 to decrypt it. If the error / falsification detection code is correct and A indicates that the bill has not been reduced by the billing device, F'is added to the balance CS of the IC card to restore the balance.

In the present embodiment, the encryption / decryption device 103 has the same function as the encryption / decryption device of the billing device, but the processor
It is possible to substitute 102. Further, in this embodiment, if the IC card first notifies the balance, it is not necessary to notify the payment amount F'afterwards.

(Effects of the Invention) As described in detail above, the use of the present invention makes it possible to prevent a gap in the charging process between the IC card and the charging device, which is a great effect.

[Brief description of drawings]

FIG. 1 is a 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 flowchart of the work to be performed by the processor 102. In the figure, 101 is an interface, 102 is a processor, 103 is an encryption / decryptor, 104 is a memory, 105 and 201 are billing devices, and 202 is an IC card.

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Claims (1)

[Claims] 1. A cash card that has a balance CS equivalent to cash, shares a predetermined pattern KM and an error / falsification detection code CC, and performs a financial transaction with a billing device, wherein the predetermined amount is set. First inverse conversion means for performing inverse conversion after receiving the charge amount F and the random number KW code-converted depending on the received pattern KM from the charging device, and the error / falsification detection code CC for the first inverse conversion means. Code conversion means for notifying the charging device after code conversion depending on the random number KW included in the output of the inverse conversion means, and information indicating whether or not the charging amount F has been reduced by the device in the charging device. Second inverse conversion means for receiving and inversely converting the error / falsification detection code CC after the code conversion depending on the random number KW; and the error / error included in the output of the second inverse conversion means. The tampering detection code CC is shared In the case where the determination means for determining whether or not the information is sent and the information indicating that the determination means makes an affirmative determination and the charging device has not reduced the charge amount F, it corresponds to cash. When the billing device does not subtract the charge amount F from the balance CS and sends the information in which the charge amount F is reduced, the subtraction means subtracts the charge amount F from the balance CS. And a cash card.