JPH09185691A - System and method for inspecting program in ic card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect the normality of program in an IC card without reading the program outside. SOLUTION: In addition to an IC card 10 of an inspecting object, a normal IC card 1 and a terminal 7 for inspection are prepared. The proper program to be built in the IC card 10 of inspecting object is built in the normal IC card 1. This proper program contains a hash function and a calculation program for outputting the calculated result by performing calculation while substituting any relevant program into this hash function. The terminal 7 for inspection has functions for executing this calculation by transmitting a parameter for hash function arbitrarily selected by an inspecting person to both the regular IC card 1 and the inspecting object card 10, receiving the calculated result and comparing the calculated results of both the cards. When both the card are coincident as a result of this comparison, the program of inspecting object IC card 10 is judged proper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for checking the validity of a program in an IC card.

[0002]

2. Description of the Related Art Conventionally, as a method for inspecting whether a program written in an IC card is a legitimate one approved by an IC card issuer or a service provider of various electronic commerce, Japanese Patent Application No. Method relating to No. 147086 and Japanese Patent Application No. Sho 63
A method related to No. 56743 is known.

The inspection method according to Japanese Patent Application No. 3-147086 checks the validity of the thumb code before executing the processing program by means of calculating a program check code (sum code) provided in the IC card together with the processing program. Is to do. As a result of the check, if the thumb code is valid, the processing program is executed.

In the inspection method according to Japanese Patent Application No. 63-56743, the match / mismatch of both programs is checked by means of a built-in (processing) program provided in the IC card and a valid program from the outside. It is a thing.
If there is a mismatch as a result of the check, the fact is notified to the outside, and the existence of the garbled program is notified.

[0005]

Generally, it is said that an IC card has high security because various information stored therein is protected by a program built in the IC card.

By the way, since the above-mentioned two inspection methods are for inspecting the garbled program of the legitimate processing program in the IC card, the processing program itself written in the IC card is not the garbled program. When is a malicious program, it may be difficult to detect it.

[0007] For example, in the inspection method according to Japanese Patent Application No. 63-56743, even if the illegal program written in the IC card is actually judged to be inconsistent with the legitimate program by the comparing means in the IC card. As long as it has the function of issuing a notification that the two match (it is a legitimate program), it cannot be detected as an unauthorized program. Therefore, if an IC card manufacturer betrays a trust relationship with an IC card issuer or the like and writes an unauthorized program having the above function in the IC card instead of the regular program, or writes the above-mentioned illegal program in the regular program. There is no way to know this even if additional malicious programs are written.

[0008] Also, a third party who attempts fraud may
Obtain a special command (illegal command) from the C card manufacturer, issue this to the IC card through a terminal equipped with an IC card reader / writer, etc., and then use the information (encryption / authentication key, prepaid frequency) in the IC card. There is no means to know this even if the electronic money balance amount is tampered with.

Further, the above-mentioned third party issues an illegal command obtained from the IC card manufacturer to the IC card to read secret information in the IC card such as a key for encryption / authentication and forge the IC card. There is no way to know this, even if you do or get fraudulent electronic money.

Therefore, in order to deal with such a problem, a method of inspecting the processing program written in the IC card by reading all the processing programs in the IC card has been studied. However, in this method, not only the parties but also the third party are notified of the processing program in the IC card, so that the security of the IC card is deteriorated, which causes many problems and is not practical. .

Therefore, an object of the present invention is to provide an inspection method and method for a program in an IC card, which can inspect the validity of the program written in the IC card without reading the program to the outside. Especially.

[0012]

According to the method and method of the present invention, a legitimate IC card containing a legitimate program is prepared in addition to the IC card to be inspected. Each IC card has a built-in predetermined inspection function and calculation means for inputting the program in the own card to the function to perform calculation. This inspection function and calculation means are preferably incorporated in the program itself of each IC card. In addition to the IC cards, a device for instructing the IC cards to execute the calculation by the calculating means and a device for receiving the calculation results from the IC cards and collating the two are provided. . These devices can be realized by, for example, one computer.

At the time of inspection, the IC card to be inspected and the legal I
The calculation by the above-mentioned function is instructed to each of the C cards, and each IC card inputs each program into each function to execute the calculation. Next, the calculation result is read out from each IC card and both calculation results are compared.
As a result, if both calculation results match, the IC to be inspected
The program on the card is judged to be valid.

As the above-mentioned function, a one-way function having a property that the calculation result is compressed more than the original program and the calculation result is different when the parameters are different is desirable. Furthermore, a function that is as difficult as possible to derive different programs that produce the same calculation result is desirable. As a function having such a property, for example, a hash function can be cited, but the function is not limited to this, and an appropriate cryptographic function may be used.

It is desirable that the parameters of the function are variable rather than fixed. In particular, it is desirable that the inspector can arbitrarily select and input it to the IC card at the time of inspection. As a result, it is virtually impossible to prepare an unauthorized program that produces the same calculation result as the regular program in advance and keep it in the IC card.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the background behind the principle of the present invention will be described in detail.

In the present invention, a calculation function for inputting the entire processing program in the IC card or the entire contents of the program memory (usually a mask ROM) to a certain function in the IC card and outputting the calculation result is generally used. , Have by program. When the IC card receives a specific inspection request command from the outside, this calculation function executes the calculation using the above function and returns the calculation result to the sender of the inspection request command.

An IC card (hereinafter referred to as a legitimate IC card) containing a legitimate processing program which should be contained in the IC card to be inspected is specially prepared. Further, a collation device for collating the calculation result output from the legitimate IC card with the calculation result output from the IC card to be inspected is provided outside the IC card. For this collation device, for example, the inspection device that is the transmission source of the inspection request command also serves as this.

Here, by using an appropriate kind of function as the above-mentioned function, when the program contained in the IC card to be inspected is different from the regular program, the calculation result transmitted from each IC card. Therefore, it is possible to detect that the program contained in the IC card to be inspected is an unauthorized program. The above function is preferably a one-way function having the following properties.

The calculation result can be compressed to some extent, and the calculation result does not become too long.

Since it is a one-way function, it cannot be calculated in the reverse direction, and therefore the original program is unknown.

It is extremely difficult to find a program different from the original program that produces the same calculation result.

When the function key (parameter) is changed, the calculation result is completely different.

As a function having such a property, for example, see the hash function (for details of the hash function, see "Modern Cryptography", page 224, published by the Institute of Electronics and Communication Engineers, September 1, 1986). ), It is desirable to use this, but other functions may be used.

Further, the key (parameter) of the function used for the calculation is arbitrarily determined by the inspector (or the above-mentioned inspection apparatus) and given to the IC card to be inspected from the outside. That is, the key can be freely changed by the inspector. By making the key variable like this,
Since the calculation result for the regular program is not constant, it becomes impossible to pre-store the "illegal program" having the function of outputting the same calculation result as the regular program in the IC card to be inspected. as a result,
It is possible to detect fraudulent activity reliably, and eventually prevent it. If the key is fixed, the calculation result for the regular program will be constant, so an "illegal program" that has the function of outputting the same calculation result as the inspection target I
It can be built in the C card beforehand (however, it is considerably difficult).

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an inspection terminal in one embodiment of the inspection system of the present invention.

The inspection terminal is, as shown in the figure, a personal computer (hereinafter abbreviated as PC) 7 and this PC.
IC card reader / writer (hereinafter referred to as IC
Card R / W) 3. IC card R / W3
Is an IC card 10 to be inspected or a legal I prepared in advance.
It provides an interface for the PC 7 to access the C card 1.

The calculation result matching program 5 is installed in the PC 7. By executing this collation program, the PC 7 gives the above-mentioned keys to the legitimate IC card 1 and the IC card 10 to be inspected via the IC card R / W 3, and causes the calculation by the hash function to be performed. The calculation results output from the IC cards 1 and 10 are received and compared, and it is determined that the regular program is incorporated in the IC card 10 only when both match.

FIG. 2 shows the structure of the legitimate IC card 1.
The IC card 10 to be inspected has exactly the same configuration.

As shown, the legitimate IC card 1 is provided with a rectangular card-shaped card body 11 and an IC module 25 incorporated in the card body 11. The IC module 25 is a whole processing program 1 in which the inspection calculation program 17 including the CPU 13 and the hash function 15 is incorporated.
Program memory (mask ROM) 2 in which 9 is stored
1 and a data memory 23 for storing various data necessary for business processing.

Next, the processing operation of the inspection terminal by executing the calculation result collation program 5 will be described with reference to the flowchart of FIG.

After the calculation result collation program 5 is started, first, the inspector inserts the legitimate IC card 1 into the IC card R / W3, and the IC card R / W3 drives the legitimate IC card 1 with the necessary drive voltage and drive command signal. Is applied, and thereby the IC card 1 is activated (that is, activated) (step S101).

Next, the inspector selects an arbitrary value (this is called a key value) as a parameter (key) for the hash function, and inputs this key value into the PC 7 (step S10).
2). The PC 7 sets the input key value in the inspection request command, and the inspection request command is sent to the valid IC card 1
(Step S103). Here, the inspection request command is a kind of data for making the legitimate IC card 1 recognize that the legitimacy inspection request regarding the processing program in the card 1 is issued.

Upon receipt of the inspection request command, the legitimate IC card 1 sets the key value in this command and all the programs 19 in the program memory 21 in the hash function 15 and executes the calculation of the hash function 15. . For example, when DES encryption is used as the calculation of this hash function, the DES encryption is represented by y = f (x, k), and k
Is the key value, x is the input information, and y is the calculation result, all programs 19 in the program memory 21 are regarded as plain text and set to the input information x, and the key value received from the inspection request command is set to k. Then, the above function y = f (x, k) is converted into C
Calculate in BC mode. As a result, all programs 19
The calculation result y of the hash function for is obtained. For details of DES encryption and CBC mode, see, for example, "Modern Cryptography" (September 1, 1986,
Published by The Institute of Electronics and Communication Engineers).

The legitimate IC card 1 uses the above calculation result as P
Reply to C7. The PC 7 receives the calculation result and stores it in the built-in memory (step S104).

Next, the inspector deactivates the legitimate IC card 1 and removes it from the IC card R / W 3 while leaving the calculation result in the built-in memory of the PC 7, and instead, I
The C card 10 is inserted into the IC card R / W3 and activated (step S105).

Subsequently, the inspector selects the same key value as the key value selected above and inputs it to the PC 7 (step S10).
6). The PC 7 sets this same key value in the inspection request command and sends it to the IC card 10 (step S10).
7).

When the IC card 10 receives the inspection request command, it inputs the key value in the command and all the programs 19 in the program memory 21 of the card 10 into the hash function in the program 19 for calculation. It executes and returns the calculation result to the PC 7. Upon receipt of this calculation result, the PC 7 stores it in the internal memory (step S
108).

Next, the PC 7 reads the valid IC from the built-in memory.
The calculation result from the card 1 and the calculation result from the IC card to be inspected 10 are read out and the two are compared (step S109). As a result, if the two calculation results are the same (step S110), the program in the inspection target IC card 10 is recognized as a regular program (step S110).
111), on the other hand, if they are different, it is recognized as an unauthorized program (step S112), and the recognition result is output.

As described above, according to the embodiment of the present invention, since the hash function having the above-mentioned property is used for the inspection, it is possible to check the normal program with respect to the normal program. It is very difficult to get the same calculation result as the calculation result for the program. Therefore, if an unauthorized program is built into the IC card,
It is possible to detect this with high accuracy. Therefore,
It is very difficult to sneak an illegal program that operates to illegally read or tamper various information in the IC card according to a command from the outside into the IC card, and it is very safe for electronic transactions using the IC card. The property is improved.

Further, in the above-mentioned embodiment, the key value of the function is made variable by the examiner's discretion, so that it is practically impossible to make an illegal program that produces the same calculation result as the regular program, which is safe. The property is further improved.
As a key value, if a program on the inspection terminal side prepares a plurality of kinds of values in advance (excluding values that are particularly easy to estimate), the inspector can select from among them. Easy to use.

It should be noted that the above description is only related to one embodiment of the present invention, and the present invention is not meant to be limited to the above description.

For example, a function other than the hash function, for example, an appropriate cryptographic function may be used as the calculation function.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an inspection terminal according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an IC card according to the same embodiment.

FIG. 3 is a flowchart showing a processing operation of the inspection terminal of the embodiment.

[Explanation of symbols]

 1 Legitimate IC card 3 IC card reader / writer 5 Hash function calculation result collation program 7 Personal computer 10 IC card to be inspected 11 Card body 13 CPU 15 Hash function 17 Inspection calculation program 19 Overall processing program 21 Program memory 23 Memory 25 IC module

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Kimihiro Kato 3-3-3 Toyosu, Koto-ku, Tokyo NTT Data Communications Corp.

Claims (7)

[Claims] 1. A method for inspecting whether or not a program in an IC card is a legitimate program, wherein an IC card to be inspected that has a program whose authenticity is unknown and a legitimate IC card that has a legitimate program in it are provided. Each of the IC card to be inspected and the legitimate IC card has a predetermined inspection function and a calculation means for inputting the program in the own card to the function to perform calculation; Inspection command means for instructing each of the target IC card and the legitimate IC card to execute calculation by the calculation means; and receiving the calculation result of the calculation means from each of the inspection target IC card and the legitimate IC card, It is provided with a collating means for collating the calculation results from the both cards and determining whether the program in the IC card to be inspected is authentic or not. Inspection system of the IC card in the program to be. 2. The IC card program inspection method according to claim 1, wherein the parameter of the function is variable.
C card program inspection method. 3. The IC card program inspection method according to claim 2, wherein the inspection instruction unit commands execution of the calculation unit,
A method for inspecting a program in an IC card, characterized in that the parameters are designated. 4. The IC card program inspection method according to claim 2, wherein the function is: The calculation result is compressed in a data amount more than the program input to the function, and B. A method of inspecting a program in an IC card, which is a one-way function having a property that the calculation result differs if the parameters differ. 5. The inspection method for the program in the IC card according to claim 4, wherein the function is a hash function or a cryptographic function. 6. The IC card program inspection method according to claim 1, wherein in each of the inspection target IC card and the legitimate IC card, the program includes the inspection function and the calculation means. IC card program inspection method. 7. A method of inspecting whether or not a program in an IC card is a legitimate program, which comprises an IC card to be inspected that has a program whose authenticity is unknown and a legitimate IC card that has a legitimate program in it. A process of preparing two IC cards each having a predetermined inspection function and a calculating means for performing calculation by inputting the program in the own card to the function, and the inspection target IC card, A process of instructing each of the valid IC cards to execute calculation by the calculating means, and receiving the calculation result of the calculating means from each of the valid IC card and the IC card to be inspected, and calculating from both of the cards. A program in an IC card, which comprises a process of collating results and determining whether the program in the IC card to be inspected is authentic or not. Inspection method.