JP2880709B2 - Memory control method for IC card - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to, for example, a nonvolatile data memory and
The present invention relates to a memory control method for a so-called IC card incorporating an IC (integrated circuit) chip having a control element such as a CPU. (Prior Art) Recently, as a new portable data storage medium, a non-volatile data memory and a control device such as a CPU have been developed.
An IC card with a built-in C chip has been developed. This type of IC card accesses a built-in data memory by a built-in control element, and inputs and outputs necessary data in response to a request from an external device. When reading data from such an IC card, the external device sets the address where the data is stored and the data length so that the data is output from the IC card, and when the data is written, In this method, the address and data to be stored are input to an IC card and written. Further, in the case of collation of the personal identification number, the collation of the personal identification number is performed by inputting the address where the personal identification number exists and the collation data into the IC card. That is, the method of accessing the normal data and the data to be kept secret is the same. For data that should be kept confidential, such as a personal identification number, a mark indicating that the data is confidential is added to the write data when the data is written to the data memory, and the data is stored as a record. When the read / write request of the external device is requested, the control element recognizes whether or not the area which the external device desires to access is an area where the data is written as confidential data by reading the record data of the area. In the area where the confidential data is written, the inaccessibility is output to the external device, and in the accessible area, the read / write operation is performed and the result of the operation is output to the external device. Has become. However, in such a conventional method, it is known where confidential data is located by repeatedly performing random access, and there is a serious problem in security management. (Problems to be Solved by the Invention) As described above, by repeatedly performing random access, it is known where confidential data is, and there is a major problem in security management. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a memory control method for an IC card in which there is no possibility of knowing where confidential data is located and a great effect is obtained in security management. [Structure of the Invention] (Means for Solving the Problems) A memory control method in an IC card according to the present invention is a memory control method in an IC card having a program memory storing a program and a data memory storing data. A program for converting an address in the data memory into a specific address is stored in the program memory in advance, and basic data satisfying a card function at the time of manufacture of an IC card is designated by an arbitrary address in a first area of the data memory Writing to the
When writing data at the time of issuance of an IC card, the program in the program memory is converted into a specific address system in which the start address of the data memory to be written is set to address 0 by the program in the program memory. Sequentially writing data to a second area of the memory; and, when accessing the data memory after issuance of an IC card, a specific address system in which a start address of the second area is set to address 0. Second
And accessing the first area after conversion to the specific address system depending on the system. (Operation) By storing the confidential data in an area (area) that cannot be accessed from the outside, even if a random access is repeatedly performed, there is no possibility of knowing where the confidential data is. A great effect on security management can be obtained. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 schematically shows a configuration of an IC card as an IC card according to the present invention, in which a control element (for example, a CPU) 11 as a control unit, a nonvolatile data memory 12 whose storage contents can be erased, a program It comprises a memory 13 and a contact portion 14 for obtaining electrical contact with a card reader / writer (not shown). Of these, the portions within the broken lines (control element 11, data memory 12, program memory 13) are 1 It consists of two IC chips. The program memory 13 is composed of, for example, a mask ROM, and has read / write, password setting / password collation, encryption /
It stores a control program of the control element 11 having a function program for realizing basic functions such as decoding.
The data memory 12 stores various data required when the IC card performs an operation process.
It is composed of PROM. The data memory 12 is divided into a plurality of areas as shown in FIG.
An area (A) 21 for storing functions required for controlling the IC card during the manufacture of the IC card, an area (B) 22 for storing data required for issuing the IC card, and the user of the IC card himself / herself. Three areas (C) 23 for storing necessary data are defined. Next, writing of data to the data memory 12 will be described with reference to FIG. First, at the time of manufacturing an IC card, a basic area that satisfies the card function (A)
Define 21. After that, the defined area (A) 21 of 20
Write data a from address 0 to address 2FF, and
Write data a 'from address to address 9FF. These data a, a 'are an arbitrary address designation. After the data writing to the area (A) 21 is completed, an area (B) 22 to be written when an IC card is issued is defined. After that, 4 from 300 address of defined area (B) 22
Write data b to address FF. Here, when writing the data b in this area (B) 22, the start address 300 of the data memory 12 to be written from now on is set to address 0 by the control program stored in advance in the program memory 13. To a specific address system
Data b is sequentially written from address 0 to address 1FF of this specific address system. It should be noted that such an address conversion method is realized by employing a method known in, for example, Japanese Patent Application Laid-Open No. 59-63097. Next, an area (C) 23 in which data necessary when a user of the IC card is used is defined. Thereafter, the data c is stored in the defined area (C) 23 from address A00 to address AFF.
Write. Here, when writing the data c, similarly to the writing in the area (B) 22, the data is converted into a specific address system by the address conversion, so that the data c is written next to the last address of the area (B) 22. Addresses, that is, addresses 200 to 2FF are sequentially written. Next, data reading from the data memory 12 will be described. From data a written as described above to data c
Reading is performed for each area up to. Here, at the time of data writing in area (B) 22, the above-described address conversion is performed, writing is performed in a specific address system with reference to the head address of this area, and thereafter, writing is sequentially performed up to a writable area. . Therefore, data is read out from the area converted into the specific address system. In the above-described example, the address can be arbitrarily designated from address 0 of the area (B) 22 and the data can be read. However, in the area (A) 21, the address is converted in the area (B) 22 as described above, and the head address is used as the reference address, so that the data cannot be read. Therefore, even if data is read at addresses 200 to 2FF or 700 to 9FF in the area (A) 21, data cannot be read from the area (A) 21. Thus, in an area, in the example of FIG.
Is stored in the program memory 13 in advance, and when the areas B and C of the data memory 12 are accessed, the data memory 12 is controlled by the control program in the program memory 13.
Are converted to the specific address system. Therefore, once converted to a specific address system, access is made uniquely in the specific address system, and an area other than specified by the specific address system (area A in the example of FIG. 1) cannot be accessed. Thus, when accessing data in the data memory 12, for example, if the card user area is defined as accessible, other confidential data and the like are not accessed, and the contents thereof can be protected. [Effects of the Invention] As described above in detail, according to the present invention, it is possible to provide a memory control method in an IC card which has a great effect on security management without fear of knowing where confidential data is.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is for explaining an embodiment of the present invention. FIG. 1 is a diagram showing a configuration of a data memory, and FIG. 2 is a block diagram schematically showing a configuration of an IC card. It is. 11 ... Control element (control unit), 12 ... Data memory, 13 ...
... program memory, 14 ... contact part, 21, 22, 23 ...
…area.

Claims (1)

(57) [Claims] In a memory control method for an IC card having a program memory storing a program and a data memory storing data, a program for converting an address in the data memory to a specific address is stored in the program memory in advance, and Writing basic data that satisfies the card function at the time of manufacture into the first area of the data memory by designating an arbitrary address; and when writing data at the time of issuing an IC card, the program in the program memory will Converting the first address of the data memory to be written to a specific address system with address 0, and sequentially writing data to the second area of the data memory using the specific address system; When accessing the data memory Accessing the second area of the data memory using a specific address system in which the start address of the second area is set to address 0, and after the conversion to the specific address system, the A memory control method for an IC card, wherein access to the first area is not possible.