JPH0827828B2 - Code generation card - Google Patents

Description

The present invention relates to a cryptographic card used for data communication between a host computer and a terminal computer and composed of a semiconductor or the like.

[Conventional technology]

Conventionally, as a so-called IC card composed of semiconductors etc. used for data communication, the IC card stores a unique encryption code, and it is possible to determine whether the used card is issued by the issuer or not. When the computer confirms, and when the computer determines that it was issued by the issuer, it opens a data communication line between the host computer and the terminal computer, and each individual supplies the personal identification number etc. memorized to the host computer. If there is a match between the registered number and the personal identification number, the host computer may judge that it is the true cardholder and exchange information thereafter.

In addition, a personal identification number that identifies the user is written on each of the issued cards, this card is inserted into the card slot of the terminal computer, and the personal identification number stored in the card by the terminal computer and the individual are supplied to the terminal computer. If the personal identification numbers match, it is judged that the user is a true cardholder and opens a data communication line between the terminal computer and the host computer.

Among the above, the one that the issuer has uniquely set the encryption to be stored in the card is the simplest card, but even if the card is stolen, the personal identification number will be on the card Since it is not written, there is no danger of being read. However, even with this card, the personal identification number may be stolen by a third party intervening on the data communication line to eavesdrop. To prevent this eavesdropping, the user's personal identification number is complicated. However, it is appropriate to use a personal identification number of about 4 digits, and a complicated personal identification number is inconvenient.

Also, if the user's personal identification number is written in the card, the personal identification number in the card can be easily read by using a card reader or the like, and a third party can easily forge the card. There was also a problem that I could do it.

The technology disclosed in Japanese Patent Laid-Open No. 61-157989 by the same applicant has solved the problems of the card used for transactions using the data communication line. This technology stores multiple ciphers in the IC card, and also incorporates a clock element in the IC card, and automatically selects the cipher to be used from the plurality of cipher groups based on the date and time engraved by this clock element. is there. A mechanism is also provided on the host computer side to determine the cipher to be used with the same algorithm as the IC card, and when the card is issued, the clock element in the card is reset and activated, and the reset date and time is also stored in the host computer. By recording,
To confirm the authenticity of the card by making it possible for the host computer to identify the same cipher used by the IC card and by comparing and verifying the cipher sent from the IC card via the communication line with the cipher specified by the host computer. Is.

[Problems to be solved by the invention]

According to this technology, the code used by the IC card changes over time, so even if the code is eavesdropped on the data communication line, this code cannot be used next time.
Therefore, eavesdropping on the data communication line can be made meaningless, and the IC card can significantly improve the security of data communication between host computers.

However, even this technology does not provide sufficient security. For example, the logic for generating the code needs to be known to the system manufacturer, the person in charge of maintenance, and internal parties, but it cannot be asserted that the information is leaked from these people. Also, if you have a high level of technology, you can list the ciphers generated in the IC card and all the ciphers stored in advance in the IC card by analyzing the actual IC card acquired. It doesn't have to be the case that information is not leaked from various people.

In the technique disclosed in JP-A-61-157989, a method of determining a cipher to be used is a method of sequentially selecting ciphers to be used at that time from a group of ciphers arranged in order corresponding to the time ticked by a clock element. . Therefore, if the order in which the ciphers are lined up is clarified, anyone who understands the logic of the IC card can use the cipher code used at that time on the data communication line without knowing the reset date and time of the clock element. By knowing, it is possible to predict the next cipher that will be used, and a third party can impersonate the cardholder and gain unauthorized access to the host computer any number of times. Although it is necessary to obtain high-level technology and to obtain technical information from insiders in order to make illegal contact by such a method, it cannot be said that this is completely impossible. The emergence of IC cards with higher security that can handle such situations is awaited. Especially for financial data and data related to privacy, there is no limitation that this security is sufficient, and it is expected that IC cards with higher security will appear.

[Means for solving problems]

The present invention has been made in view of the above problems, and when a card is issued to each card, stores a plurality of ciphers in the card and activates a clock mechanism for managing time,
Each time the card is used, the execution address used at that time is stored and retained. On the other hand, the host computer stores the time when the card was issued and the code. The execution address used is stored and held. Then, when a new card is used, the IC card calculates a new execution address by modifying the execution address used last time with the address created by the clock mechanism, and determines the cipher to be used based on the execution address d. On the other hand, the host computer also identifies the cipher used with the same algorithm as the IC card,
It is intended to provide a code generation card which can verify the authenticity of the card user by verifying the consistency between this code and the code supplied from the card side through the data line.

As means for achieving the above object, the cipher generation card according to the present invention, as shown in the block diagram of FIG. 1, generates a clock signal at regular time intervals, and receives a clock signal input to a designated shift register. A clock element 1 for sequentially generating a plurality of time series addresses by shifting one stored address, and one time series address among the plurality of time series addresses sequentially output from the clock element 1. And a modification means 5 for modifying the execution address when the card is used last time, and an execution address storage means 7 for storing the execution address modified by the modification means 5 until the next time the card is used.
And a cipher storage means 10 for storing ciphers at a plurality of addresses called by the execution addresses modified by the modification means 5, and the execution addresses stored in the execution address storage means 7 are modified by the modification means. The means 5 modifies, and the modified execution address is newly added to the execution address storage means 7.
(EN) A cryptographic card that makes it meaningless to use data that has been wiretapped on a communication line by storing and updating the data.

[Action]

The algorithm having the above-described configuration is configured such that one address stored in a shift register designated by receiving a clock signal generated by the clock element 1 is shifted to sequentially generate a plurality of time-series addresses and execution addresses. The execution address at the time of previous use stored in the storage means 7 is input to the modifying means 5, and the modifying means 5 modifies the input signal by performing an exclusive OR of the two inputs, and the modifying means 5 The output signal of is processed into an execution address that cannot be predicted. This unexpected execution address is supplied to the encryption storage means 10, and the execution address causes the encryption storage means 10 to read one address from a plurality of addresses, and the encryption stored in the address is sent to the host computer. Supply. As described above, although the ciphers are stored in the cipher storage means 10 in order, the order of taking out the ciphers is not in order.

The host computer manages the time from the time when the cryptographic card is supplied to the user, and with this time as a parameter, a predetermined cipher is taken out from the address storing the cipher with the same algorithm as the cryptographic card. If this code matches the code supplied from the code generating card, the data communication line will be opened.

Even if a third party intervenes on the data communication line and tries to decipher the code, even if he / she eavesdrops on the data communication line unless he / she knows the date and time when the cryptographic card was issued, the algorithm on the card and the complete cipher list. It is meaningless. Even if the IC card logic is clarified by obtaining technical information from insiders or by analyzing the actual card by a person having advanced technology, and even if the cipher currently used on the data communication line can be eavesdropped, Since the order of taking out the used ciphers from the cipher group is not related to the order in which the ciphers are stored, it is impossible to predict the cipher to be used next time. Therefore, even in this case, the sniffing of ciphers on the data communication line is still possible. It is meaningless.

〔Example〕

An embodiment of a cryptographic generation card according to the present invention will be described in detail with reference to the drawings.

Reference numeral 1 in FIG. 2 denotes a timepiece element which is driven from the time a card is issued to an individual. An oscillation circuit 2 composed of a crystal oscillator, a semiconductor or the like generates a reference clock pulse having a constant repetition period, and this oscillation circuit Reference numeral 2 is connected to a frequency dividing circuit 3 having flip-flops in multiple stages. The frequency dividing circuit 3 divides a reference clock pulse and outputs a 1-bit clock signal at regular time intervals. This clock signal is supplied to the input terminal of the shift register 4, and the shift register 4 generates time-series addresses each consisting of an 8-bit pulse train every time the clock signal is input. Here, the time-series address is the same as the address of the cipher storage means described later, and the fixed period set by the timepiece element 1 is determined in consideration of the error between the host computer and the oscillation circuit 2, and the oscillation circuit. The period may be shortened by using a high-precision crystal oscillator circuit or the like as 2.

Numeral 5 is a modifying means, which inputs an exclusive OR 6,6, ...
This exclusive logical division 6,6,… is configured by connecting in parallel.
Generates a random number, and uses the time-series address and the execution address at the time of previous use to create the execution address to be used this time using the algorithm shown below.

Xn: Output of nth exclusive OR Yn, t: Output of nth shift register after clock signal is input t times Xn = Xn-1 (EXOR) Yn-1, t Xo = X ₇ ( EXOR) Y ₇ , t However, (EXOR) is an exclusive OR.

The execution address is supplied to the encryption storage means 10 and the execution address storage means 7.

The execution address storage means 7 uses the execution address modified by the modification means 5 as an input signal and stores the execution address until the next use of the card, and the output line of the modification means 5 is a latch circuit 8. Of the latch circuit 8, the first output side of the latch circuit 8 is connected to the inverter 9, and the signal inverted by the inverter 9 is supplied as the eighth input of the latch circuit 8. Here, the inverter 9 logically inverts the execution address so as to make it impossible to read the execution address stored in the latch circuit 8 and supplies it to the latch circuit 9. However, the embodiment is a simple example, and various logic circuits other than those used here can be adopted,
Shifting the logically inverted signal for further encryption is also considered. It should be noted that the confidentiality of this card can be maintained now and in the future without the inverter 9 and the logic circuit connected to the input side of the latch circuit 8.

Reference numeral 10 denotes a cryptographic storage means such as a ROM or a RAM backed up by a battery, which stores cryptographic codes given by the host computer and unknown to the cardholder in the same number (256 kinds) of addresses as the time series address. Stores personal identification numbers, such as personal names, for communicating with the terminal computer. This encryption storage means 10
Is connected to the output of the modifying means 5 via the buffer circuit 11 and stores the execution address supplied from the modifying means 5 in each address of the cipher storage means 10 to call the cipher. The storage elements used here have 256 types of addresses, but the storage capacity of the encryption storage means 10 is not limited to this, and may be increased or decreased. Further, if this card makes meaningless the intervention of a third party on the data communication line, the personal identification number or the like stored in the cryptographic storage means 10 for interacting with the terminal computer is the minimum necessary limit. You may

However, in the above cryptographic generation card, the card holder must always communicate with the terminal computer by using the personal identification number of the cryptographic storage means 10 to open the communication line with the host computer, and the card can directly communicate with the host computer via the terminal computer. Interact. The process of this exchange is as follows. The exclusive OR of the time series address generated by the time element 1 in the card and the execution address stored in the execution address storage means 7 at the time of the previous use 6 ...
The modified execution address is stored in the latch circuit 8 directly or via the inverter 9 or the like, and the execution address is also supplied to the encryption storage means 10 via the buffer circuit 11. The execution address stored in the address storage means 7 becomes a modification execution address for the next use, while the execution address supplied to the encryption storage means 10 is a predetermined one from among a plurality of addresses in the encryption storage means 10. The cipher used to call the address and stored in the called address is provided to the host computer. The time when the card was issued and the time when the card was used are stored in the host computer, a new execution address is calculated using the execution address and the time series address when the card was used last time, and the new execution address is stored in the address. It is checked whether or not the existing code and the code supplied from the card match, and if they match, it is determined that the card is a genuine card and the subsequent exchange of information is permitted.

As described above, the cipher called by the execution address is one of 256 addresses, so even if a third party forges or duplicates the card and uses it, the execution address does not match 1 /. If the content of the encryption is composed of 64 bytes, for example, it is possible to secure 256 × 64 types of encryption stored in one address.
It becomes one of x64 = 4194,304 times, and it is practically impossible to match the execution address. In addition, if you try to match addresses and ciphers further, you need to repeat the test nearly infinitely, and even if a third party makes a hand, the card cannot be forged, and the forgery of the card itself is completely meaningless. You can do it. Further, if a well-known card is read three times and this method does not agree with this method, a method such as checking with a host computer is also used for more complete security. Further, since the time-series signal modified by the modifying means 5 is stored in the latch circuit 8 by logically inverting it by the inverter 9 or the logic circuit, even if a third party eavesdrops the communication data on the data communication line, Since there is no way to know the next time-series signal, the next transaction cannot be performed by impersonating a genuine user based on the wiretapped signal.

〔The invention's effect〕

As described above, the code generation card according to the present invention stores a plurality of codes in each card at the time of card issuance and activates a clock mechanism for managing time, and uses each time the card is used. The stored execution address is stored, and when a new card is used, the IC card calculates the new execution address by modifying the execution address used last time with the address at that time created by the clock mechanism, and based on this execution address Since it decides which cipher to use, the IC card and the host computer will exchange different ciphers each time, and the cipher used at each exchange will be the order of the addresses stored in the cipher storage means. Since it is selected regardless of
When a third party intervenes on the data communication line and steals the cipher used at that time, the cipher to be used next cannot be specified from the cipher. Further, the present invention can prevent the intervention of a person who has a technique of merely eavesdropping the cipher on the data communication line, and can eavesdrop the cipher on the data communication line, for example, by a person having a more advanced technique. Even a person who has the technology and who can obtain the information about the entire contents and arrangement of the cipher from the insider can prevent the intervention. As described above, according to the present invention, the act of eavesdropping the currently used cipher by a third party on the data communication line can be made meaningless, and the security at the time of communication between the IC card and the host computer can be significantly enhanced.

[Brief description of drawings]

FIG. 1 is a block diagram of a cryptographic generation card according to the present invention, and FIG. 2 is a block diagram showing an embodiment of a cryptographic generation card according to the present invention. 1: clock element, 5: modifying means, 7: execution address storing means, 10: cipher storing means.

Claims (2)

[Claims] 1. A clock signal is generated at regular intervals, and one address stored in a designated shift register is shifted in response to the input of this clock signal to sequentially generate a plurality of time series addresses. The timepiece element 1, the modification means 5 that modifies the execution address when the card is used last time by one time series address among the plurality of time series addresses that are sequentially output from the timepiece element 1, and the modification means 5. Execution address storage means 7 for storing the modified execution address until the next time the card is used, and cipher memory for storing ciphers at a plurality of addresses called by the execution address modified by the modification means 5, respectively. The modification means 5 modifies the execution address stored in the execution address storage means 7, and the modified execution address is newly implemented. By storing changes in the address storage unit 7, the encryption generation card meaningless to use are eavesdropped on communications line data. 2. A cryptographic generation card according to claim 1, wherein the modifying means 5 is an exclusive OR of a clock signal and the execution address at the time of use.