JPH0638278B2 - 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 recognition function. IC card and billing device are secret codes
Share 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. The billing device decrypts it with KM, and if it matches RN, considers that tampering has not been made and clears the fee F.

(Problems to be Solved by the Invention) According to the conventional method, there is a drawback that the remaining amount is reduced by the IC card, even though the billing device does not settle the fee amount F when it is determined that there is tampering. . The situation in which the RN does not appear after decrypting the one returned by the billing device with KM may be due to tampering, or it may be a simple error that is not malicious. If the malicious IC card owner falsifies the message, even if only the IC card is reduced, it is self-employed, but in many other cases, it is better not to subtract the IC card unless the billing device clears. desirable.

The object of the invention is to eliminate this drawback.

(Means for Solving Problems) In order to solve the above problems, the present invention employs the following means. That is, in a cash card that has an amount of money equivalent to cash and conducts a financial transaction with a billing device, the charge amount and the random number VR that are code-converted depending on a predetermined pattern KM sent from the billing device are inversely converted. a first inverse transform unit, and a code converting means for code conversion of VR ₁ obtained by modifying the random number VR for notifying the charging device in dependence on the pattern KM, or the apparatus has been reduced in the charging device not to Information indicating whether or not and the second inverse transforming means for inversely transforming the data transmitted after being code-transformed depending on the pattern KM of VR ₂ obtained by transforming the random number VR, and the second inverse transforming means. A reduction means for reducing the payment amount from the amount equivalent to the cash except when the information indicating that the VR ₂ included in the output is correct and the charging device has not been reduced is transmitted. Characteristic cash car It is.

(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 key KM
To share. Let F be the amount of money that the billing device wants the IC card to pay, and CS be the amount that the IC card possesses at this point, that is, the balance. First, the billing device 201 generates a random number VR and encrypts it with the key amount KM together with the fee amount F, and then the IC card 20.
Send to 2. The IC card 202 decrypts it with the key KM, and the remaining money
Subtract F'from CS. Here, F'should be the same as F originally, but it is the actual amount to be paid in case of partial payment when CS <F. VR ₁ This was F 'and a portion of predetermined random numbers VR bit-reversed
Is encrypted with the key KM and sent to the billing device. The billing device 201 decrypts the sent message with the key KM, and if the correct VR
_{If 1} is obtained, it is judged that there is no error tampering, F'is subtracted from F, otherwise it is left as it is and information A as to whether VR ₁ was correct and a part of VR are bit-inverted VR ₂
Is encrypted with the key KM and sent to the IC card 202. Each IC card is decrypted, and if VR ₂ is correct, it is determined that there is no error or tampering, and if the information A indicates that the billing device does not reduce F'to F ', add F'to CS. Return to the original CS.

From the above, it was shown that the drawbacks of the conventional method can be eliminated.

(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 the figure, when the fee amount F encrypted with the key KM and the random number VR are received from the billing device, they are decrypted by the encryption / decryption device 103. If the balance CS of the IC card is F or more, F = F ',
If not, F '= CS and F'is subtracted from the balance. Further, F 'and the VR ₁ that bit inversion part predetermined of VR is encrypted by the encryption and decryption unit 103 KM as a key, and sends the charging apparatus. On the other hand, when the information A indicating whether or not the bill is reduced by the billing device and the data obtained by encrypting VR _{2 in} which a part of VR is bit-inverted by KM are received from the billing device, the processor 102 causes the encryption / decryption device 103 to transmit the data. Decrypt, if VR
_{If 2} 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. In this embodiment, I
If the C card first notifies the balance, it is not necessary to notify the payment amount F ′ later. Further, the VR is first encrypted and sent from the billing device, but if it is sent without being encrypted, VR ₁ = VR may be set. These are included in the scope of the present invention.

(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.

Claims (1)

[Claims] 1. A cash card having an amount of money equivalent to cash and performing a financial transaction with a billing device, the charge amount and a random number code-converted depending on a predetermined pattern KM sent from the billing device. The first reverse conversion means for reverse conversion of VR and the random number VR for notifying the charging device are modified.
Code conversion means for performing a code conversion of VR ₁ depending on the pattern KM, information indicating whether or not the charging device has reduced the price, and VR ₂ obtained by transforming the random number VR with the pattern K.
Second inverse conversion means for inversely converting the data that has been code-converted and sent depending on M, and VR ₂ included in the output of the second inverse conversion means is correct and the billing device does not reduce the amount. Reducing means for reducing the payment amount from the amount equivalent to the cash except when the information indicating that it has been sent,
A cash card, which consists of: