JPH0447862B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical field This invention enables confirmation of a customer's secret number (PIN number, password) between a terminal device such as an automatic teller machine (CD) or an automatic teller machine (ATM) and a center. The present invention relates to a cryptographic system processing device for use in a system for performing and processing data transmission.

(b) Prior art and its disadvantages Currently, in CDs, ATMs, etc., the security of transactions is ensured by reading the customer's secret number from a magnetic card and comparing the secret number. As one measure to ensure security, we have introduced a cryptographic system that encrypts secret numbers. However, conventionally, when encrypted data recorded on a magnetic card is decrypted into a secret number at a center, there is a risk that the decrypted secret number may be stolen from the center. Furthermore, when decrypting with a terminal such as a CD or ATM, the encryption key is fixed to the terminal, but there is a possibility that the encryption key could be stolen and the private number easily decrypted. Moreover, when decrypting at a terminal, if the encryption keys are different, decoding cannot be performed, which limits the range of use of magnetic cards at terminals, which is an inconvenience that hinders networking.

(c) Purpose of the Invention In view of the above-mentioned circumstances, the present invention provides a cryptographic system processing device that can protect secret numbers in a cryptographic system and increase security by storing only customer-specific cryptographic keys in a center. With the goal.

(d) Structure and Effects of the Invention The present invention provides a system in which a terminal and a center are connected via a communication line, a customer's secret number is confirmed, and data is transmitted between the terminal and the center. An encryption key transmission means that generates an encryption key and sends it to a center file corresponding to the customer's account number; and a encryption key transmission means that encrypts the customer's secret number with the encryption key stored in the center file and sends the encrypted data to a magnetic card. a magnetic card issuing device including a means for writing encrypted data into a terminal; a card reader reads the recorded contents of the magnetic card entered into the terminal; and the customer-specific encryption key corresponding to the read account number is sent from the center. The present invention is characterized by comprising an encryption key transmission means for transmitting to a terminal, and a decryption means for decoding the encrypted data of the magnetic card into a secret number using the encryption key transmitted from the center.

According to this invention, only the encryption key for each customer is stored in the center file, so the secret number cannot be stolen from the center, and even if the encryption key is stolen from the center, the encrypted data on the magnetic card cannot be stolen. The secret number cannot be decrypted unless it is known, thereby ensuring the security of the secret number. That is, since the encryption key is transmitted from the center to the terminal for decoding, there is no need to transmit the encrypted data on the magnetic card to the center, and a closed system can be established. Furthermore, the security of the cryptographic system is increased by using customer-specific cryptographic keys instead of fixing a common cryptographic key to each terminal. Furthermore, by transferring the encryption key from the center to each terminal, the same magnetic card can be used on different terminals, expanding the range of terminal usage of magnetic cards.
Networking can be done smoothly. Moreover,
Changing the encryption key only changes the encrypted data, so even if your magnetic card is dropped or stolen, you can continue transactions using the same account number by changing only the encryption key without changing the secret number. be able to.

(e) Embodiment Applying the cryptographic system processing device of this invention
Figure 1 shows a control block diagram of the CD in the CD transaction processing system (hereinafter referred to as the CD system).

The CD is connected to the center via a telephone line, and the file processing of payment transaction data is performed at the center. Upon opening an account, a customer is issued a magnetic card to use when making deposits and withdrawals using CDs. Magnetic cards are issued using a card issuing device (not shown) installed at a bank or the like.

In addition to the memory 2 for storing programs, the CPU 1 of the CD is connected to a keyboard control circuit 3, a banknote release control circuit 4, a card mechanism control circuit 5, and a slip issuance control circuit 6 as I/O devices, as well as a telephone line. Line control circuit 1 that connects the CD to the center via
2. DES (Data
Encription Standard) chip 13 is connected. The keyboard control circuit 3 controls the display of operation guidance messages on the CRT 7 and the amount of payment specified on the keyboard 8. The banknote discharge control circuit 4 controls the banknote discharge operation of the banknote discharge machine 9. The card mechanism control circuit 5 controls reading and writing of the recorded contents of the magnetic card by the card reader/writer 10. The slip issuing control circuit 6 controls the issuing of slips by the slip issuing machine 11.
The DES chip 13 is an LSI having a function of performing encryption and decryption based on the DES encryption system. In this cryptographic system, a plaintext P is encrypted using an encryption key K, a ciphertext C (=f(P,K)) is transmitted, and the receiving side uses the same encryption key K to encrypt the ciphertext C.
is decoded into plaintext P(=f'(C,K). In this example, the 64-bit plaintext is decoded by DES chip 13.
Converts to 64-bit ciphertext using a 64-bit encryption key. The memory 2 includes a storage area for storing recorded contents read from a magnetic card by a card reader/writer 10.

FIG. 2 shows the card recording format of the magnetic card issued by the card issuing device. The magnetic card has a system mark representing the CD system,
In addition to the bank/branch number and account number, encrypted data that is an encrypted secret number is recorded. The card issuing device includes a DES chip, and when an encryption key is set by the customer, the entered secret number is encrypted with the encryption key, and a magnetic card with the encrypted data written thereon is issued. The magnetic card issuing process using the above-mentioned card issuing apparatus will be explained below with reference to the flowchart of FIG.

A customer goes to a bank where a card issuing device is installed and receives a magnetic card issued. step n10
(Hereinafter, step ni is simply referred to as ni.)
The secret number is input using the key input device of the card issuing device, and the encryption key is further input (n11). In this example, the card issuing device's DES chip encrypts and decrypts 8-digit plain text, and can input an 8-digit secret number, but treats 4 digits as a fixed code and uses the 4-digit secret number. may also be entered. Further, the encryption key is arbitrarily selected by the customer, but may also be determined using a random number generator or random number code book.

After entering the secret number and encryption key, enter the bank/branch number and account number (n12). n10～n12
When the input is completed, the card writer of the card issuing device forms the card recording format shown in FIG. 2 and records it on the magnetic card. Furthermore, the input encryption key is transmitted to the center along with the account number through a communication line, and the encryption key is filed in the center file for each account number (n13). After the centafail processing is completed, a magnetic card is issued that records encrypted data obtained by encrypting the customer's secret number using an encryption key determined by the customer (n14). As mentioned above, a card issuing device is used to issue a magnetic card that records encrypted data with a secret number encrypted, and an encryption key determined by the customer for encrypting the data is transmitted to the center. , and are filed by customer in the center file.

Next, the operation of payment transaction processing using the CD will be explained with reference to the flowchart shown in FIG.

The customer inserts a magnetic card into the CD's card slot (n1). The card reader/writer 10 reads data in the card recording format of the inserted magnetic card (n2).
Next, the read data is stored in memory 2 (n3). After storing the read data, check whether the stored system code and bank/branch number code data match the code of the CD system (n4). If these codes do not match, return the magnetic card (n13), and if the codes match, proceed to n4→n5.

At n5, data including the account number and for accessing the center file is transmitted to the center via the line control circuit 12. The center accesses based on the transmitted account number and transmits the encryption key corresponding to the account number to the CD (n6). The CD sends the received encryption key and the encrypted data stored in the memory 2 to the DES chip 13 to execute decryption (n7). Next, a message prompting you to enter the secret number key-in is displayed on the CRT7, and the secret number key-in is accepted (n8). When the secret number is input by operating the keyboard 8, the input secret number is compared with the secret number decoded at n7 (n9). When both secret numbers match (n9), it is determined that the operation was made using a legitimate card, and the payment transaction operation is accepted (n10). At n10, billing amount data specified by the customer is transmitted to the center and center inquiry processing is performed. In the case of a transaction that can be paid by center inquiry, the banknote dispensing machine 9 discharges banknotes for the billed amount. Note that if the result of the secret number check of n9 is inconsistent, key-in of the secret number is permitted again (n11). If the secret numbers match by keying in the secret number again, the above
Perform payment processing for n10. If the result of the second secret number check does not match, the magnetic card is returned (n11, n12).

The above operation allows you to use a magnetic card.
A CD payment transaction is processed. In this case, the secret number check is performed by decrypting the encrypted data recorded on the magnetic card using the encryption key transmitted from the center, and comparing the decrypted secret number with the secret number entered on the CD. It is carried out at the same time. Therefore, with CDs, the encryption key is not fixed, so there is no risk of the encryption key being stolen, and since the center stores only customer-specific encryption keys for each account number, there is a possibility that the secret number could be stolen from the center. There is no sex at all. Furthermore, the security of the cryptographic system is increased by using cryptographic keys for each customer. By storing only the encryption key in the center file in this way, it is possible to prevent theft from the center or the terminal and to protect the secret number. In addition, if the transmission line is encrypted by encrypting the encryption key and transmitting it to the center or terminal, the theft of the encryption key using the transmission line can be prevented and a more complete security system for the secret number can be obtained. be able to.

[Brief explanation of drawings]

Figure 1 shows a cash dispenser (CD) system to which the cryptographic system processing device of the present invention is applied.
Figure 2 is a control block diagram of the CD. Figure 2 is a diagram showing the card recording format of the magnetic card used in the CD system. Figure 3 is a flowchart showing the operational procedure of magnetic card issuing processing by the card issuing device used in the CD system. Figure 4 is a flowchart showing the operational procedure for CD payment transaction processing in the CD system.

Claims (1)

[Claims] 1. In a system in which a terminal and a center are connected via a communication line, a customer's secret number is confirmed, and data is transmitted between the terminal and the center, a customer-specific encryption key is generated. , an encryption key transmission means for transmitting to the center file corresponding to the customer's account number, and encrypted data for encrypting the customer's secret number with the encryption key stored in the center file and writing the encrypted data on the magnetic card. a magnetic card issuing device including a writing means; a cipher for reading the recorded contents of the magnetic card input into a terminal with a card reader and transmitting the customer-specific encryption key corresponding to the read account number from the center to the terminal; A cryptographic system processing device comprising: a key transmitting means; and a decoding means for decoding encrypted data on a magnetic card into a secret number using a cryptographic key transmitted from the center.