JP3756241B2 - Memory card - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a technical field related to a prepaid card system using an IC memory. In particular, the present invention relates to a memory card that has a remaining number counter composed of a plurality of memory bits and a mutual authentication function, can be refilled and reused, and omits a random number generation circuit required for mutual authentication. is there.
[0002]
[Prior art]
In an IC memory prepaid card used for a telephone card or the like, a counter for storing the remaining number can always be subtracted and cannot be increased. For this reason, prepaid cards must be thrown away when all the counter values have been subtracted and the purchased card has been used up. That is, it was in a “disposable” state.
[0003]
[Problems to be solved by the invention]
Japanese Patent Laid-Open No. 3-8090 “Reusable Prepaid Memory Card” describes that a memory card refilling machine checks the validity of a card. However, the described method cannot prevent the counter from being reused by increasing the remaining number of counters using an illegal card filling machine.
[0004]
On the other hand, there has been proposed a method of refilling a counter when mutual authentication is performed between a card and a terminal and it is confirmed that each card is valid. However, there is a possibility that the refill key is stolen by continuous unauthorized access.
Further, in order for the card to output a random number necessary for executing the terminal authentication, it is necessary to provide a special random number generation circuit area in the prepaid card.
[0005]
[Means for Solving the Problems]
In order to solve these problems, the memory card according to the present invention uses a terminal authentication key calculated based on a card ID and a master key when executing terminal authentication, and also uses a random number (third By calculating a random number) from a random number (second random number) input when the terminal device performs card authentication and a random number (first random number) stored in the memory, a complex random number generation circuit Without being installed, a different random number (third random number) can be easily generated every time terminal authentication is executed.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a diagram showing a configuration of an information processing mechanism in a memory card of the present invention. In FIG. 1, 1 is a memory card of the present invention, 2 is a storage means comprising an IC memory, 3 is an arithmetic means comprising a logic circuit or a CPU (central processing unit), and 4 is for transmitting and receiving data to and from a terminal device. Interface.
[0007]
The storage means 2 is further configured in detail, 5 is an IC identification area for storing data for identifying an IC memory card such as a card ID, and 6 is a user area for storing data for identifying a user such as a user ID. , 7 is an issuer area for storing data set on the issuer side such as the number of refills and its upper limit value, and 8 is a counter area for storing the remaining number of prepaid cards. Here, the remaining frequency is a numerical value indicating the remainder of the prepaid card, and is a numerical value such as the actual amount of money, the frequency of telephone calls, the number of times of use of vehicles, and the like.
9 is a first random number stored originally, 10 is a second random number input from a terminal device (not shown), 11 is a third random number calculated from the first random number 9 and the second random number 10. It is a random number.
[0008]
Further, the calculation means 3 is configured in more detail, 12 is a terminal authentication means for performing processing on the memory card side when the memory card 1 authenticates whether or not the terminal apparatus is authentic, and 13 is a memory card by the terminal apparatus. A card authenticating means for performing processing on the memory card side when authenticating whether or not 1 is authentic; and 14 for inputting a second random number output when the terminal device performs card authentication to the memory card 1 The random number input means 15 is a random number calculation means for calculating the third random number 11 from the first random number 9 and the second random number 10.
[0009]
The operation of the memory card 1 in the above configuration will be described. When the memory card 1 is set in the terminal device for normal use or refilling processing, the memory card 1 performs authentication processing as to whether or not the terminal device is authorized by the terminal authentication means 12. At that time, the third random number 11 stored in the storage unit 2 is used.
The third random number 11 is a random number calculated by the random number calculation means 15 based on the first random number 9 and the second random number 10. Here, the first random number 9 is a random number stored in the storage unit 2 in advance. The second random number 10 is a random number generated when the terminal device performed the card authentication process last time, and is a random number input by the random number input unit 14 and stored in the storage unit 2.
[0010]
The calculation performed by the random number calculation means 15 is as follows. (1) A specific digit from the first random number 9 and the second random number 10 is extracted from that digit of the specific random number, and the third random number 11 is assembled. The third random number 11 is assembled by switching the arrangement order of each digit of the first random number 9 and the second random number 10. (3) The third random number is shifted by shifting the digits of the first random number 9 and the second random number 10. 11 is assembled. (4) A numerical operation or a logical operation is performed between the first random number 9 and the second random number 10 to assemble a third random number 11. (5) The first random number 9 and the second random number 10 And an arithmetic process such as assembling the third random number 11 by performing a numerical operation or a logical operation with a predetermined numerical value. The actual calculation is performed by combining one or more of these.
Depending on any of the above random number generation methods or combinations, different random numbers can be generated each time execution is performed, and unauthorized use of a memory card, such as refill processing using an unauthorized terminal, can be prevented. it can.
[0011]
As described above, in the memory card of the present invention, since the terminal authentication process is performed using the random number (third random number 11) calculated based on the random number generated by the terminal device, a chip area is required with a complicated configuration. Therefore, the memory card is inexpensive.
[0012]
In the present invention, a specific area of the storage means 2 of the memory card 1 is configured to be readable from the inside but not from the outside. For example, the user area 6, the issuer area 7, the first random number 9 and the second random number 10 except the IC identification area 5, the counter area 8 and the third random number 11 can be read from the inside, but the external It is configured to be unreadable from. Such a configuration is realized by making it possible to set the reading mode independently for each area and setting the reading mode from the inside but not setting the reading mode from the outside. it can.
In addition, the mutual authentication process is performed first by performing the terminal authentication process for determining whether or not the terminal device using the memory card is legitimate, and whether or not the memory card by the terminal apparatus is legitimate only when it is determined to be legitimate. Card authentication processing is performed.
As a result, the data stored in the memory card is not read unnecessarily, and security against unauthorized refilling or the like is improved.
[0013]
【Example】
Next, an example explains the present invention. First, the refilling process will be described. FIG. 2 is a flowchart showing a process of performing mutual authentication and refilling (counter recharge) in the memory card of the present invention. As shown in FIG. 2, in the refilling process, terminal authentication is first executed by the memory card (S1), and if it is not a regular terminal device (S2), the refilling process is interrupted (S3). In the case of a regular terminal device (S2), card authentication is executed by the terminal device. At this time, a second random number is generated by the terminal device and input to the memory card (S4). If the memory card is not authorized as a result of the card authentication (S5), the refilling process is interrupted (S3). In the case of a regular memory card (S5), a refill command is executed (S6). After the execution, the refilling process is terminated.
[0014]
Next, terminal authentication processing which is one of mutual authentication processing will be described. FIG. 3 is a flowchart showing the process of terminal authentication. In steps S <b> 101 to S <b> 104, the terminal device outputs a “card ID transmission request” to the memory card 1, and the memory card 1 that receives this outputs “card ID” to the terminal device. The terminal device reads the “card ID” from the memory card 1. Next, the terminal device generates a “terminal authentication key f (ID, M)” from the stored “master key M” and “card ID” using the function f.
[0015]
Next, in steps S105 to S106, the memory card 1 stores the "terminal authentication key f (ID, M)" when it is issued. The terminal device outputs a “random number transmission request” to the memory card 1, and the memory card 1 that has input this outputs the third random number 11 (RNA ′) stored in the storage unit 2 in the previous card authentication (described later) to the terminal. The terminal device reads the random number “RNA ′”.
Next, in steps S107 to S110, both the memory card 1 and the terminal device have a function g () for authentication, and calculate a function g (f (ID, M), RNA ′).
[0016]
Next, in step S111, the terminal device outputs the calculation result to the memory card 1, and the memory card 1 reads it and confirms that both the calculation results are equal. If the calculation results are equal, the terminal device is a regular terminal device, and if the calculation results are not equal, the terminal device is not a regular terminal device.
[0017]
Next, card authentication processing which is the other authentication processing of mutual authentication will be described. FIG. 4 is a flowchart showing the card authentication process. In steps S201 to S204, the terminal device outputs a “card ID transmission request” to the memory card 1, and the memory card 1 receiving this outputs “card ID” to the terminal device. The terminal device reads the “card ID” from the memory card 1. Next, the terminal device generates a “card authentication key h (ID, M)” from the stored “master key M” and “card ID” using the function h.
[0018]
Next, in steps S205 to S206, the memory card 1 stores the “card authentication key h (ID, M)” when it is issued. The terminal device generates a random number “RNB”. The terminal device outputs the random number “RNB” to the memory card 1, and the memory card 1 reads the random number “RNB” and stores it in the storage unit 2 as the second random number 10.
Next, in steps S207 to S210, both the memory card 1 and the terminal device have a function g () for authentication, and calculate a function g (h (ID, M), RNB).
[0019]
Next, in step S211, the memory card 1 outputs the calculation result to the terminal device, and the terminal device confirms that both calculation results are equal. If the calculation results are equal, the memory card 1 is a regular memory card, and if the calculation results are not equal, the memory card 1 is not a regular memory card.
On the other hand, in step S212, the memory card 1 has a function x (), and the random number calculation means 15 calculates x from the second random number 10 (RNB) and the first random number 9 (RNA) stored in the memory card 1. (RNA, RNB) is calculated and stored in the storage means 2 as the third random number 11 (RNA ′).
[0020]
In order to prevent unauthorized use, “RNA ′” and “RNB” need to be transmitted and received with different values for each authentication. The random number “RNB” is a value generated by the terminal, and may be considered to be a sufficiently dispersed value because the calculation is performed using a microcomputer or the like. On the other hand, in order to set the random number “RNA ′” to a sufficiently dispersed value, it is essential in the prior art that the memory card 1 has a similar random number generation circuit. However, as described above, in the present invention, the random number “RNB” (stored in the storage unit 2 of the memory card 1 and becomes the second random number 10) transmitted from the terminal device at the time of card authentication, and the storage unit of the memory card 1 2 is used to calculate a new random number “RNA ′” to be used for the next mutual authentication. Therefore, the memory card 1 can generate sufficiently distributed random numbers only by having the simple random number calculation means 15.
[0021]
【The invention's effect】
As described above, according to the memory card of the present invention, it is possible to prevent unauthorized use such as refilling the remaining frequency counter due to unauthorized access. Further, the memory card can output a random number required for executing the terminal authentication without providing a special random number generation circuit area in the prepaid card.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an information processing mechanism in a memory card of the present invention.
FIG. 2 is a flowchart showing a process of performing mutual authentication and refilling (counter recharge) in the memory card of the present invention.
FIG. 3 is a flowchart showing a process of terminal authentication.
FIG. 4 is a flowchart showing a card authentication process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Memory card 2 Memory | storage means 3 Calculation means 4 Interface 5 IC identification area 6 User area 7 Issuer area 8 Counter area 9 1st random number 10 2nd random number 11 3rd random number 12 Terminal authentication means 13 Card authentication means 14 Random number Input means 15 Random number calculation means

Claims (3)

A memory card having storage means, terminal authentication means, card authentication means, random number input means, and random number calculation means,
The storage means stores a terminal authentication key, a card authentication key, a card ID, a first random number, and a third random number,
The terminal authentication means calculates terminal authentication data using the terminal authentication key and the third random number,
The terminal authentication means inputs from the terminal device terminal authentication data calculated by the terminal device using the card ID input from the memory card by the terminal device and the third random number,
Further, the terminal authentication means performs terminal authentication by comparing the two terminal authentication data,
The random number input means inputs a second random number from the terminal device when the terminal device performs card authentication,
The card authentication means outputs card authentication data calculated using the card authentication key and the second random number to the terminal device,
The random number calculating means calculates a third random number used in the next execution of the terminal authentication from the first random number and the second random number, and calculates a third random number stored in the storage means. Update,
A memory card characterized by that. 2. The memory card according to claim 1, wherein the first random number stored in the storage means is a random number that cannot be read from the outside. 4. The memory card according to claim 2, wherein the terminal authentication is executed before the card authentication in the mutual authentication when the memory card is used.

Images