JPH04338823A - Detecting method for illicit alteration of soft module using ic card - Google Patents

Abstract

PURPOSE:To assure the safety of a computer system by detecting a soft module which is illicitly altered by infection of a virus, etc., by means of an IC card and then preventing the use of the detected module. CONSTITUTION:When a soft module is stored, a 1st electronic signature obtained based on an optional part of the soft module is added to this module by means of an IC card. When the soft module is used, a 2nd electronic signature is obtained based on the same optional part of the soft module by means of the same IC card. Then both electronic signatures are collated with each other for detection of the affection of a virus or the illicit alteration of the soft module.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for detecting unauthorized tampering of software modules stored in floppy disks, terminal devices, etc. The present invention relates to a method for detecting unauthorized tampering with a software module using an IC card, which is suitable for avoiding the use of software modules and highly efficiently preventing system destruction due to virus infection.

0002

[Prior Art] Programs that describe the operating order and contents of a computer, that is, software modules, can be easily accessed by third parties, and even software modules that have been developed at a huge cost can be easily accessed by copying, etc. It will be used illegally. Examples of conventional techniques aimed at preventing unauthorized use of software modules and protecting against passive attacks on software modules include, for example, Japanese Patent Application No. 2003-20002, filed by the inventor of the present application. 1045
99 specification and drawings. That is,
By encrypting part or all of the software module using an individual key and an IC card with encryption/decryption functions, users who do not have a valid IC card can start this software module. This makes it impossible to decrypt the data even if it is used, making it impossible to use it normally.

[0003] Furthermore, in protecting software modules, protection control against active attacks such as unauthorized tampering of software modules called computer viruses is also necessary. In particular, computer viruses (hereinafter simply referred to as viruses) have become a serious problem worldwide, and interest in virus countermeasures is gradually increasing in Japan. . Conventional antivirus countermeasures mainly involve providing countermeasure software programs. However, since such anti-virus programs are regular software modules, they have the disadvantage of becoming larger as the amount of viruses increases, and the processing time cannot be ignored, so frequent virus inspection is not recommended. Poor efficiency;
There is a lack of convenience. In addition, virus inspection of software modules stored on current floppy disks and terminal devices is not perfect, and those who use software modules may use them without realizing that they are infected with a virus, thereby increasing the risk of infection. There is a risk that the problem will be left unaddressed, and effective solutions are needed to stop this problem.

0004

The problem to be solved is that the conventional techniques for detecting unauthorized tampering with software modules cannot efficiently identify software modules that have been tampered with, such as computer viruses. The purpose of the present invention is to solve the problems of the prior art and efficiently detect software modules that have been tampered with by using an electronic signature generation function using an individual key of an IC card and its validity authentication function. An object of the present invention is to provide a method for detecting unauthorized tampering with a software module using an IC card, which avoids the use of IC cards, prevents system destruction, and improves system reliability.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the method of detecting unauthorized tampering of a software module using an IC card of the present invention uses an IC card that has a built-in microprocessor and has an individual key and a cryptographic unit. This is to detect unauthorized tampering by a third party to a software module that contains a computer virus.
A first electronic signature corresponding to the software module is generated using the individual key of the card and an arbitrary number of selected parts of the software module, and the generated first electronic signature is a cryptographic generation unit of an IC card that is added to the software module and stored in a storage medium, and used to generate a first electronic signature added to the software module when the software module stored in the storage medium is used; Alternatively, a cryptographic generation unit of another IC card that has a common individual key with this IC card uses this common individual key and the same selection part of the software module used to generate the first electronic signature. generates a second electronic signature corresponding to the software module to be used, compares this second electronic signature with the first electronic signature, and as a result of this verification,
The software module is characterized in that if the electronic signature of the first electronic signature and the second electronic signature do not match, the software module is detected as having been illegally tampered with.

[0006]

[Operation] In the present invention, an electronic signature (digital signature) generation function using an individual key of an IC card and an authentication function are utilized to detect unauthorized tampering of a software module such as a computer virus. That is, a first electronic signature is generated using an IC card based on a predetermined portion such as all or part of the software module, and this first electronic signature is added to the software module. Store it on a floppy disk, terminal device, etc. When using this software module, the IC card used to generate the first electronic signature or other
With the C card, a second electronic signature is generated again based on the part used to generate the first electronic signature, and this regenerated second electronic signature is combined with the first electronic signature added to the software module.
Verify with the electronic signature of If the soft module
If the software module has been tampered with illegally, each electronic signature will be different, so through this comparison, it is possible to detect illicit tampering with the software module. In this way, unauthorized tampering due to intrusion into a software module by a malicious third party or software modules infected with a computer virus can be quickly detected, and by prohibiting their use, it is possible to prevent the spread of infection. to prevent system destruction.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. FIG. 1 is a flowchart showing an embodiment of a method for detecting unauthorized tampering with a software module according to the present invention. Figure 1 (a) shows the procedure for generating and adding an electronic signature when storing a software module, and Figure 1 (b)
shows the procedure for generating an electronic signature and verifying it at the time of starting the software module. First, in FIG. 1A, when storing a software module (step 101), a predetermined portion or the entirety of the software module is selected (step 102). Then, using an IC card, a first electronic signature is generated based on a portion or the whole of the selected software module (step 103).
. When the generation of the first electronic signature using the IC card is completed (step 104), the first electronic signature is added to the software module (step 105), and then stored in a floppy disk, a terminal device, etc. (Step 1
06). Next, in FIG. 1(b), when the software module stored in this way is loaded (step 1
07), select the same part or the entire software module that was the target of the process in step 102 (step 108). Then, using the same IC card used for the process in step 103 or another IC card having the same individual key, an electronic signature of the loaded software module is created based on a portion or the whole of the selected software module, that is, Generate a second electronic signature (step 10)
9, 110). The second electronic signature generated in this way and the first electronic signature added to the loaded software module.
A comparison is made with the electronic signature of (step 111). If the first and second electronic signatures match (step 112), it is determined that it is a legitimate software module and is activated (step 113); however, if they do not match, this software module is Assuming that unauthorized tampering has been carried out by someone else, the system performs error processing such as displaying a warning without starting up (step 114).
). In this way, the use of software modules contaminated with viruses can be avoided.

Next, using FIGS. 2 to 5, I
A method for detecting unauthorized tampering with a software module using a C card will be explained in more detail. FIG. 2 is an explanatory diagram showing in detail the software module tampering detection method in FIG. 1. In particular, it shows the electronic signature generation and addition processing operations in FIG. 1(a).
First electronic signature (S) 2 generated using the C card 22
3 is added and this first electronic signature (S) 23 is added to the load module 24 (denoted as LM in the figure). That is, it corresponds to some parts of the load module 21, for example, a selected part (An) 25 (denoted as An in the figure) consisting of a plurality of parts (A1 to AN) selected according to an arbitrary rule (function f). do,
The IC card 22 has an individual key 26 that is a secret encryption key, and an electronic signature generation unit 27 that generates a unique electronic signature from arbitrary data using this individual key 26.
The procedure for generating an electronic signature (S) 23, adding it to the load module 24, and storing it in a terminal or the like is shown.

The procedure of the method for detecting unauthorized tampering with a software module according to the present invention will be explained in more detail below. The load module 21 is an arbitrary software module compiled into an executable state, and includes all the parts (A1 to AN) constituting the selected part (An) 25. When saving this load module 21, a first electronic signature (S) 23 for the load module 21 is generated based on the selection part (An) 25 using an IC card 22 that can generate a unique electronic signature. . That is, when the administrator or owner of the load module 21 uses the IC card 22 to save the load module 21, based on the selection part (An) 25,
An IC containing a cryptographic function (F) and a secret individual key (K)
Only the first electronic signature(s) 23 using the card 22
generate. At this time, the relationship between the load module (LM), the selection portion (An), and the secret individual key (K) can be expressed by the following equation. First, the function for selecting the selection part (An) is f(x), and An=f(LM)

...(1) Here, when n = 1, 2, 3, ..., N, the first electronic signature (S) 23 is S = F (Ak, K)
・
...(2) (Ak is a sentence made by arranging An in order, and Ak=ANAN-1AN-2...A1). The first electronic signature (S) 23 is the load module 2
This is the only disturbance code generated from the selected part (An) 25 of 1, and the selected part (An) used to generate the electronic signature.
25, if there is a change of one or more bits, the first electronic signature (S) 23 will be different. Here, an arbitrary function (f) for selecting the selection portion (An) 25 from the load module 21 is also used, similar to the individual key 26 for generating an electronic signature.
If it is stored in the IC card 22, the security will be higher. The first electronic signature (S) 23 generated in this way
is added to the load module 24 and saved. As explained in FIG. 3 below, when using this load module 24, the attached first electronic signature (S) 23 must be checked against the second electronic signature generated at startup. Let's do it.

FIG. 3 is an explanatory diagram showing in detail the software module tampering detection method in FIG. 1. In particular, the generation of the second electronic signature in FIG.
, shows the second electronic signature verification processing operation, and the load module 31 (denoted as LM' in the figure) used authenticates whether or not the load module 21 in FIG. 2 has not been tampered with. The load module 31 containing the first electronic signature (S) 23 is not activated as is, but is activated normally after a normal result is confirmed by the electronic signature verification unit 33 using the IC card 22. Activate it. That is, before starting the load module 31, the load module 31 sends the first electronic signature (S
) 23 was used to generate the selected part (An) 25 of FIG.
The selected part (An') 32 corresponding to
6(K), the second electronic signature (S') 34 is regenerated. Then, by the verification unit 33 of the IC card 22,
The first electronic signature (S) 23 added to the load module 31 is compared with the second electronic signature (S') 34 regenerated under exactly the same conditions, and if they match, the second electronic signature (S') 34 is verified. The validity of the electronic signature (S') 34, that is, the validity of the load module 31 is confirmed. Expressing this in the formula, An'=f(LM)
Formula (3
) Here, if n=1, 2, 3, ..., N, S'
=F(Ak',K)
Equation (4) (Ak' is a sentence made by arranging An' in order, Ak'=AN'AN-1'AN-2'...
A1'), and S=S'?

Equation (5) is obtained, and if S and S' match, the load module 31
start normally. In this way, by using an IC card that can generate and authenticate electronic signatures, the validity of the software module is checked when it is used. As a result, if the software module is infected with a virus or tampered with, for example, by intentional tampering, the verification result of the electronic signature will be incorrect. In such a case, by preventing the software module from starting, it is possible to protect against malicious mischief caused by viruses or the like in the software module.

[0011] Hereinafter, a method for actually operating the process of detecting unauthorized tampering of a software module using such an IC card will be explained. FIG. 4 is an explanatory diagram showing a first embodiment of an IC card operating method used in the software module tampering detection process in FIG. 1. This assumes that one software module 41 (denoted as LM in the figure) is used and managed by a group, and the number of members (1) to (N) in the group is
The number of issued IC cards 42 to 44 is limited, and all IC cards 42 to 44 in these groups have the same electronic signature 4.
5 (denoted as S1 in the diagram).
6 (a common individual key within a group, indicated as K1 in the figure) and the right to use it is given.

FIG. 5 shows a second method of operating an IC card used in the software module tampering detection process shown in FIG.
It is an explanatory diagram showing an example of. In the embodiment described using FIGS. 1 to 3, the IC card used is
We are proposing a system that is equipped with electronic signature generation for validity checking and authentication function for verifying its validity.
This shows an operational method in which the two functions are separated and a card for generating an electronic signature and a card for authenticating the signature are used separately. That is, a management IC card 53 (denoted as MASTER in the diagram) having an authentication function for a software module 52 (denoted as LM in the diagram) to which an electronic signature 51 (denoted as S1 in the diagram) is added, and a management IC card 53 (denoted as MASTER in the diagram) under which , user cards 55 to 5 for each member (1) to (N) having additional functions and generation of an electronic signature 51 using a common secret key 54;
It is applied to a system divided into seven parts. In this way, it is possible to flexibly support a system using the software module 52 or the software module 41 in FIG. 4.

As described above with reference to FIGS. 1 to 5, according to this embodiment, an IC card having an electronic signature generation function and an authentication function is used to store an electronic signature on a floppy disk or the like. Detects virus intrusion into software modules and intentional data tampering. If unauthorized tampering due to a mismatch in electronic signatures is detected, by preventing the software module from starting, for example, it is possible to protect against computer viruses that illegally invade from the outside, guaranteeing extremely high system security. can.

[0014]

[Effects of the Invention] According to the present invention, it is possible to check for unauthorized tampering of a software module every time it is started up in a short period of time, and to prevent the use of illegally tampered software modules and prevent computer viruses. This makes it possible to prevent the system from being destroyed due to this and improve the reliability of the system.

[0015]

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an embodiment of a software module unauthorized tampering detection method according to the present invention.

FIG. 2 is an explanatory diagram showing a more detailed embodiment of the software module unauthorized tampering detection method in FIG. 1;

FIG. 3 is an explanatory diagram showing a more detailed embodiment of the software module unauthorized tampering detection method in FIG. 1;

FIG. 4 is an explanatory diagram showing a first embodiment of an IC card operating method used for software module tampering detection processing in FIG. 1;

FIG. 5 is an explanatory diagram showing a second embodiment of an IC card operating method used for software module tampering detection processing in FIG. 1;

[Explanation of symbols]

21 Load module 22 IC card 23 First electronic signature (S) 24 Load module 25 Selection part (An) 26 Individual key 27 Electronic signature generation section 31 Load module 32 Selection part (An’) 33 Verification section 34 Second electronic signature (S’) 41 Soft module 42-44 IC card 45 Electronic signature 46 Common secret key 51 Electronic signature 52 Soft module 53 Management IC card 54 Common secret key 55-57 User card

Claims (1)

[Claims] [Claim 1] A software module unauthorized tampering detection method that detects unauthorized tampering by a third party to a software module containing a computer virus using an IC card that has a built-in microprocessor and has an individual key and encryption means. Yes, when the software module is stored, the cryptographic creation means of the IC card uses the individual key of the IC card and a selection part obtained by selecting an arbitrary number of arbitrary parts of the software module. generate a first electronic signature corresponding to the generated first electronic signature;
an electronic signature added to the software module, stored in a storage medium, and used to generate the first electronic signature added to the software module when the software module stored in the storage medium is used. A cryptographic creation means for an IC card or a cryptographic creation means for another IC card that has a common individual key with the IC card, and the common individual key.
A second electronic signature corresponding to the software module is generated using the same selected part of the software module used to generate the first electronic signature, and the second electronic signature and the selected part of the software module are If the first electronic signature and the second electronic signature do not match as a result of the verification, the software module is detected as having been fraudulently tampered with. A method for detecting unauthorized tampering of a software module using an IC card.