JPH046990B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field The present invention is used in transaction processing devices such as automatic teller machines (CDs) and automated teller machines (ATMs), and is used to detect secret numbers of magnetic cards based on a cryptographic system. The present invention relates to a secret number determination device that determines whether a secret number and a secret number input during a transaction match or do not match.

(b) Conventional technology and its drawbacks Currently, in terminals such as CDs and ATMs, the secret number is checked by reading the encrypted secret number from the magnetic card and decrypting it with the encryption key fixed to the terminal. However, encryption keys are often changed to prevent encryption keys from being stolen. Generally, the encryption key is set using a setting switch provided at the end of the device. However, this setting switch is usually sealed so that once the encryption key is set, the value cannot be read out, and even if it is read out by some means, there is nothing to compare it to, so it is difficult to know whether the read value is correct. I don't know. In this way, the encryption key is set by the above setting switch so that it cannot be read from the outside in order to maintain confidentiality, but on the other hand, it is not possible to determine whether the set encryption key is correct or not, and therefore, if the encryption key is different. Even when the secret number of the magnetic card and the input number match, there is an inconvenience in that it is determined that the secret numbers do not match.

(c) Purpose of the invention In view of the above-mentioned circumstances, the present invention sets an encryption key determination code together with an encryption key in advance, decrypts the encrypted data of the encryption key determination code of the magnetic card with the set encryption key, and decrypts the magnetic card. The purpose of the present invention is to provide a secret number determination device that can verify a cryptographic key by comparing a cryptographic key determination code with a set cryptographic key determination code.

(d) Structure and Effects of the Invention To summarize, the present invention includes an encryption key and encryption key determination code storage means for storing a preset encryption key and an encryption key determination code, and a cryptographic key determination code storage means for storing a preset encryption key and an encryption key determination code. reading the encrypted data of the encryption key determination code from the magnetic card recorded in the encoded form, decrypting the data with the encryption key stored in the storage means, and storing the decrypted encryption key determination code and the data in the storage means. a cryptographic key determination code comparing means for comparing the cryptographic key determination code stored in the magnetic card with the cryptographic key determination code stored in the storage means; and a secret number verification processing means that executes a secret number verification process when the determination is made, decrypts the encrypted data of the encryption key determination code of the magnetic card, and extracts the decrypted encryption key determination code and a preset encryption key. The encryption key is verified by comparing it with the determination code, and if the encryption keys are different, the secret number check is not performed.

According to this invention, since the encryption key can be verified using a magnetic card, it is possible to reliably cancel a transaction using a CD or an ATM when the encryption key is different. Transactions such as CDs can be processed smoothly without mistakenly determining that the correct secret number is incorrect even though the secret number is incorrect. In addition, even if the encryption key is sealed in a configuration switch to ensure its confidentiality, the validity of the encryption key can be accurately determined, so the encryption system can be completely closed to prevent leakage of the encryption key. ,
Moreover, the encryption key can be changed safely.

(e) Embodiment FIG. 1 is a control block diagram of a CD to which the secret number determination device of the present invention is applied.

In addition to the memory 2 for storing programs, the CPU 1 of the CD is connected with 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. a line control circuit 12 connected through a line;
DES (DaTa Encription Standard) chip 13,
A constant setting circuit 14 is connected. The keyboard control circuit 3 performs operation guidance on the CRT 7 and display control of input data such as the amount to be paid specified using 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 a card reader/writer 10 that reads or writes the recorded contents of a magnetic card issued to each customer. The slip issuing control circuit 6 controls the issuing of slips by the slip issuing machine 11.

The DES chip 13 is an LSI that has the function of encrypting and decoding in a DES encryption system. In this DES encryption system, plaintext P is converted into ciphertext C(=f(P,k)) using encryption key k.
On the receiving side of the ciphertext C, the same encryption key k is used to decrypt the ciphertext C and the plaintext P(=
f′(C,k)). The encryption key used in this encryption system is set in the constant setting circuit 14 by the setting switch 15. Also, constant setting circuit 1
4, an encryption key determination code (hereinafter referred to as ID) for checking the validity of the set encryption key is also set by the setting switch 15. The setting switch 15 has a switch structure that is sealed after the encryption key and ID are set. Once sealed, the setting state cannot be changed without destroying the switch, and the encryption key set from the setting switch 15 cannot be changed. It also becomes impossible to read the ID.

FIG. 2 shows the card recording format of a magnetic card issued to each customer by a card issuing machine (not shown) for use in the CD payment transaction. As shown in the figure, the magnetic card includes the system mark representing the CD system, bank/branch number, account number, as well as a CD-specific ID encrypted with the encryption key set on the CD and a customer-specific secret number. is recorded. Data is recorded on the magnetic card by encrypting the same ID as the CD-specific ID set on the CD with the CD-specific encryption key set on the CD. In other words, as shown in Figure 3, when opening an account, a customer enters, for example, a customer-specific secret number (1234).
A magnetic card is issued containing encrypted data (A36b) encrypted with a CD-specific encryption key and encrypted data (3Q7F) in which a CD-specific ID (abcd) is encrypted with the same encryption key K. . These encrypted data (A36b, 3Q7F) are decrypted using the encryption key K into a secret number (1234) and ID (abcd).

In the above configuration, the CD constant setting circuit 14
corresponds to the encryption key and encryption key determination code storage means of the secret number determination device according to the present invention.

Hereinafter, payment transaction processing using a magnetic card in the CD will be explained with reference to the flowchart shown in FIG.

At step n1 (hereinafter referred to simply as ni), the customer inserts the CD into the card slot (not shown).
When a magnetic card is inserted into the magnetic card, the contents recorded on the magnetic card are read by the card reader/writer 10 (n2). The data read from the magnetic card is stored in memory 2, and the system code and bank branch number code are checked at n3. If the code check result is not OK, indicate that the card cannot be used on the CRT7, return the magnetic card, and exit (n3,
n14, n15).

If the codes such as the system code match (n3), read the encrypted data of the ID and secret number read from the magnetic card.
Send to DES chip 13 (n4). Subsequently, the encryption key data set in the constant setting circuit 14 is sent to the DES chip 13, and the DES chip 13 decrypts the code (n5, n6). After the magnetic card ID and secret number have been decoded, the CD-specific ID data set in the constant setting circuit 14 is read, and the ID decoded from the magnetic card is compared with the CD-specific ID ( n7, n8). This ID check result is OK
If so, it means that the encryption key used when issuing the magnetic card matches the encryption key set on the CD, and it is determined that the encryption key on the CD is set correctly. Accept number input. At n9, a message is displayed on the CRT 7 to prompt the secret number to be input, and the secret number is input by operating the ten keys on the keyboard 8 and stored in the memory 2 (n10).
Once the secret number has been entered, the encrypted data of the secret number read from the magnetic card is decrypted using the encryption key set on the CD, and the decrypted secret number is compared with the entered secret number (n11 ). If the entered secret number and the secret number decoded from the magnetic card match (n11), it is determined that the magnetic card is being used legitimately, and the billing amount specified by the customer is transmitted to the center. When the payment is possible, the banknotes corresponding to the billed amount are discharged through the bill dispensing machine 9, and a slip with the withdrawal amount, balance, etc. printed is issued, and the payment process is completed. After completing the payment process (n12), the magnetic card is returned and the CD payment transaction is completed (n13). In the secret number check of n11, if the entered secret number and the secret number decoded from the magnetic card do not match, it is determined that the card is not being used legitimately, and a message indicating that the secret number is different is displayed on the CRT7. (n19) and return the magnetic card without performing a CD payment transaction (n13).

As mentioned above, when the ID check result is OK, it is determined that the encryption key is correct and the secret number check is performed, but if both IDs do not match, n8→
Proceed to n16. In this case, the encryption key set on the CD is different from the encryption key used to decrypt the ID on the magnetic card, or the ID set on the CD is different from the ID on the magnetic card, so the encryption key or
It is determined that the ID is not set correctly and normal processing of the CD is impossible. Therefore, at this time
Display the standby status for staff processing on the CRT7,
Transactions using CDs will be discontinued and magnetic cards will be returned (n16-n18). While the transaction is suspended, the staff member re-checks the encryption key and ID using a test card with the ID encrypted with the correct encryption key. In addition,
The above n8 is the cryptographic key determination code comparison means of this invention,
Further, the above n11 corresponds to the secret number verification processing means of the present invention.

By the above operation, when processing a CD payment transaction, the validity of the encryption key and ID set in the CD is checked. Therefore, by fixing the ID for operational purposes of the CD system, it is possible to determine whether only the encryption key set for the CD is correct or not. As a result, it is possible to determine whether or not to execute a payment transaction depending on whether the set encryption key is correct or not, allowing smooth operation of the CD system. Moreover, even if the setting switch 15 is sealed and the encryption key is set to be unreadable, as long as the ID is set correctly, the validity of the encryption key can be determined reliably by ID check, so it is not necessary to change the settings of the encryption key. It is possible to reliably verify the settings even if the settings are correct, and prevent setting errors.

[Brief explanation of drawings]

Fig. 1 is a control block diagram of an automated teller machine (CD) to which the secret number determining device of the present invention is applied, Fig. 2 is a diagram showing the card recording format of a magnetic card used in the CD, and Fig. 3 is the same. Diagram to explain the encryption system in CD, Figure 4 is the same CD
2 is a flowchart showing the operational procedure of payment transaction processing by.

Claims (1)

[Claims] 1. A device that reads encrypted secret number data from a magnetic card, decrypts it with an encryption key, and determines whether the decrypted secret number and the secret number input by input operation match or disagree. reading the encrypted data of the encryption key determination code from an encryption key and encryption key determination code storage means for storing the encryption key and the encryption key determination code; and a magnetic card on which the encryption key determination code is encrypted and recorded together with the secret number; Encryption key determination code comparing means for decoding the data with an encryption key stored in the storage means and comparing the decrypted encryption key determination code with the encryption key determination code stored in the storage means; secret number verification processing means for executing a secret number verification process when it is determined by the comparison by the comparison means that the encryption key determination code of the magnetic card matches the encryption key determination code stored in the storage means; A secret number determination device comprising: