JP2014160383A - Portable terminal equipment and decryption processing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it difficult for a third person to decrypt the application software of portable terminal equipment by a highly convenient method.SOLUTION: Portable terminal equipment for storing application software in a non-volatile memory, and for developing a program in an RAM for execution is configured to repeat following processing of receiving the application software whose core portion is divided into a plurality of programs, and encrypted by a secret key making a pair with a public key, and executing a decryption processing program to successively decrypt a plurality of core modules of the application software by using the public key, and overwriting the decrypted programs on the previous programs in the same storage region as the RAM for execution. Thus, it is possible to allow the portable terminal equipment to execute the core portion of the application software.

Description

  The present invention relates to a mobile terminal device that executes application software, and has a function of preventing application software for the mobile terminal device from being analyzed and falsified from the outside, and encrypted application software The present invention relates to a decryption processing program for decrypting a mobile terminal device.

  In recent years, various types of mobile terminal devices such as smart phones and electronic tablets have become widespread, and various types of application software are used in these various mobile terminal devices. In particular, application software that allows users to enjoy various moving images and sounds using these portable terminal devices has become widespread. Using a mobile terminal device as a moving image / sound playback device has the advantage that it can easily play back moving images and sounds because it does not require fixed mobile terminal device hardware.

  However, when distributing image / sound data to a portable terminal device through a communication line, there is a problem of how to protect the copyright of the image / sound. In Patent Document 1 and the like, data of copyrighted works of images and music are encrypted in order to protect them from unauthorized copying, and the encrypted data is decrypted by application software that operates on the mobile terminal device. However, if the application software program is illegally analyzed and illegally modified, there is a problem that unauthorized copying of the copyrighted work becomes possible.

  Similarly, other types of application software have the same weakness that the program may be illegally analyzed and altered illegally, hindering the application of advanced information services through mobile terminal devices. .

  In order to solve this problem, Patent Document 2 discloses a technique for preventing software from being decrypted and falsified by encrypting the software. This technology is called tamper resistant software technology (DavidAucsmith et.al; “Tamper Resistant Software: An Implementation”, Proceeding of the 1996 Intel Software Developer's Conference).

  Tamper-resistant software technology analyzes the parts of application software that require protection at the start of execution, decrypts them before execution, and re-encrypts them after execution. It is a technology that makes analysis with tools difficult.

JP-A-9-307545 JP 2004-280678 A

The above-described tamper-resistant software technology is an advanced software security technology. However, when various application software is supplied to a user of a mobile terminal device such as a smart phone or an electronic tablet while providing high usability and convenience. In addition, if the software obfuscation function is excessive, there is a problem that the convenience of distribution of application software is impaired.

  The present invention has been proposed in view of such circumstances, and provides convenience for distribution of application software by providing application software with obfuscation and increased security in a highly convenient method with simplified processing. The purpose is to improve sex.

  In order to solve the above problems, the present invention is a portable terminal device that stores application software in a non-volatile memory, and develops and executes a program in a RAM. The core part is divided into a plurality of programs and a public key The application software encrypted with the paired secret key is received, and the decryption program is executed to sequentially decrypt the plurality of programs in the core part of the application software using the public key, and The portable terminal device is characterized in that the core part of the application software is executed by repeating the process of overwriting, writing, and executing the previous program in the same storage area.

  As a result, the mobile terminal device of the present invention is not decrypted by the cracker because the core part of the application software stored in the non-volatile memory is encrypted, and a plurality of programs of the decrypted core part are stored on the RAM. Since the same storage area is sequentially overwritten and executed, there is only a short time on the RAM, so that the application software can be used with high security, reducing the risk of the application software being decrypted and altered by a cracker. .

  In addition, the present invention is the portable terminal device described above, further comprising a communication unit that receives the public key from a certificate authority via a communication network.

  As a result, the mobile terminal device of the present invention receives the public key from the certificate authority, and the altered application software is encrypted using an illegal public key and disguised as legitimate application software for distribution. Can be prevented.

  Further, the present invention is the portable terminal device described above, wherein the core part is divided into a plurality of programs and encrypted together with the hash value of the divided part, and the decryption processing program is A mobile terminal device that decrypts the converted portion into a program and a hash value, calculates a hash value of the decrypted program, and collates the hash value with the decrypted hash value It is.

  Thereby, the portable terminal device of the present invention can find application software that has been tampered with illegally and use only legitimate application software.

  Further, the present invention is the mobile terminal device described above, wherein the decryption processing program repeats a process of overwriting and executing a previous program in the same storage area of the RAM. It is.

  In addition, the present invention is the mobile terminal device described above, wherein the application software is application software including the decryption program and the public key.

Further, the present invention is a decryption processing program for executing an application software program stored in a non-volatile memory in a portable terminal device by expanding the program on a RAM, and publishing the core portion of the application software divided into a plurality of programs Encrypted with a private key that is paired with the key, the plurality of programs encrypted in the core part are sequentially decrypted using the public key, and the previous program is overwritten in the same storage area of the RAM The decryption processing program is characterized in that the processing to be written and executed is repeated.

  Further, the present invention is the above decryption program, wherein the plurality of divided programs and the hash value of the program are encrypted together, and the decryption program is encrypted. A decryption processing program that decrypts a plurality of programs and hash values, calculates a hash value of the decrypted program, and collates the hash value with the decrypted hash value.

  In the present invention, since the core part of the application software stored in the nonvolatile memory by the mobile terminal device is encrypted, the application software is not decrypted by the cracker, and the core module is decrypted and expanded on the RAM. However, since the combined program is frequently overwritten in the same storage area in the RAM, the core module program exists in the RAM for only a short time, making it difficult for the cracker to decipher the application software. Application software can be used with high security in a portable terminal device with less risk of tampering. Thereby, it is highly convenient and has an effect of promoting the distribution of application software.

It is a block diagram which shows the structure of the information processing system of 1st Embodiment. (A) It is a block diagram which shows the structure of the application supply apparatus in the information processing system of 1st Embodiment. (B) It is a block diagram which shows the structure of the portable terminal device in the information processing system of 1st Embodiment. It is a figure which shows the data structure of the application software which the application supply apparatus of 1st Embodiment produces. It is a block diagram which shows the data flow which a portable terminal device expand | deploys the data of application software on the storage area of RAM in the information processing system of 1st Embodiment. It is a flowchart which shows operation | movement of the application supply apparatus in the information processing system of 1st Embodiment, and operation | movement of a portable terminal device.

Embodiments of the present invention will be described below.
[First Embodiment]
FIG. 1 is a block diagram showing a configuration of an information processing system 1 according to the first embodiment. The information processing system 1 includes an application supply device 10, a mobile terminal device 20, and a communication network 100. A certificate authority 200 is connected to the communication network 100. FIG. 2 shows configurations of the application supply device 10 and the mobile terminal device 20 in the information processing system 1.

(App supply device)
FIG. 2A shows the configuration of the application supply apparatus 10. The application supply device 10 includes a control unit 11 configured by a CPU (Central Processing Unit), a ROM 12 (Read Only Memory), a RAM (Random Access Memory) 13, a bus 14, an interface (I / F) 15, a communication unit 16, an input An output unit 17, a display 18, and a magnetic disk 19 are provided.

The control means 11, ROM 12, RAM 13, and interface 15 are connected to each other by a bus 14. The communication unit 16, the input / output unit 17, the display 18, and the magnetic disk 19 are connected to the bus 14 by the interface 15. The ROM 12 is a nonvolatile read-only memory. The ROM 12 stores basic software such as an operating system (hereinafter referred to as “OS”).

  The control unit 11 executes various processes in accordance with the OS stored in the ROM 12 and the program read from the magnetic disk 19 and developed in the RAM 13. The RAM 13 is a volatile memory capable of rewriting stored data, and stores programs necessary for the control means 11 to execute various processes.

  The interface 15 manages input / output of information among the communication unit 16, the input / output unit 17, the display 18 and the magnetic disk 19. The interface 15 exchanges data with the control unit 11, the ROM 12 and the RAM 13 via the bus 14. The communication unit 16 mediates communication with the certificate authority 200 and the mobile terminal device 20 via the communication network 100. The communication network 100 is not limited to wireless communication, and a wired communication line is also included in the communication network 100.

  The input / output unit 17 is, for example, a keyboard or a pointing device, and inputs various commands from the user and other necessary information in accordance with the user's operation. The display 18 is an LCD (Liquid Crystal Display), for example, and displays various information such as characters and images. The magnetic disk 19 stores an encryption / decryption program (for example, an encryption processing routine and a decryption processing routine), a program of the application software D10, a key Ko, attribute information of each key, and data necessary for executing the program. ing.

  The application supply device 10 divides the program of the application software D10 provided to the mobile terminal device 20 into a core portion of the program and the remaining program portions as in the data structure of FIG. The core part of the program is a program part that performs an important process in the program of the application software D10 and important data that is desired to prevent decryption. Next, the core part of the program is further divided into a plurality of divided program parts C of the core, and each program part is individually encrypted as follows, for example, an encrypted core module D11. , D12, D13, D14 data is created.

  The application supply apparatus 10 individually encrypts a plurality of core division program parts C created using a secret key Kg to create encrypted data E (C, Ko). That is, the encrypted core module D11 that is the encrypted data E (C, Ko) of the divided program part C of the first core and the encrypted data E (C, Ko) of the divided program part C of the second core. ), The encrypted core module D13 of the third core divided program part C, and the encrypted core module D14 of the fourth core divided program part C are created. To do.

  Then, the application supply apparatus 10 combines the data of the encrypted core modules D11, D12, D13, and D14, the application non-core program D15 of the remaining program portion of the application software D10, and the decryption processing program D16. Data of the application software D10 is created and passed to the mobile terminal device 20.

(Mobile terminal device)
FIG. 2B shows the configuration of the mobile terminal device 20. The portable terminal device 20 includes a control unit 21, a RAM 22, a ROM 23, a nonvolatile memory 24, and an interface 25 connected to a bus 26, and a communication unit 27, a wireless LAN communication unit 28, and a USB input / output unit 29 are connected to the interface 25. Prepare. The nonvolatile memory 24 can be configured by a flash memory. In addition, for the nonvolatile memory 24, a storage medium such as a hard disk built in the portable terminal device 20, a ROM in the form of a portable medium, a hard disk, a flexible disk, a magneto-optical disk, a CD-ROM, or the like is used. You can also.

  The control means 21 executes various processes in accordance with an OS stored in the ROM 23 and a program in which the application software D10 read from the nonvolatile memory 24 is linked to the RAM 22 and expanded. The RAM 22 is a volatile memory capable of rewriting stored data, and stores programs necessary for the control means 21 to execute various processes.

  The interface 25 exchanges data with the control means 21, ROM 23, and RAM 22 via the bus 26. The communication unit 27 mediates wireless communication between the application supply device 10 and the certificate authority 200 via the communication network 100.

  In the ROM 23, for example, a control program (for example, a decryption processing routine) of the control means 21 is stored. The nonvolatile memory 24 includes a program executed by the control means 21, data necessary for executing the program, a plurality of files, a key Ko for authentication or secure messaging (SM), and attribute information thereof (an encryption algorithm for the key Ko, Key size) is stored.

  The mobile terminal device 20 can correspond to the application software D10 in which a plurality of application supply devices 10 have encrypted the core part of the program. For each application software D10 encrypted by each application supply device 10, a certificate authority is provided. From 200, the public key certificate issued for the ID number of the application supply device 10 is received, and the public key Ko of the application supply device 10 stored in the public key certificate is stored in the RAM 22. That is, the mobile terminal device 20 acquires a plurality of keys Ko for each of the plurality of application supply devices 10 and stores them in the RAM 22.

(Data structure of application software for installation)
FIG. 3 shows a data structure of application software D10 created by the application supply device 10 and installed in the mobile terminal device 20. The application software D10 is sent from the application supply device 10 to the mobile terminal device 20, and is stored in the nonvolatile memory 24 of the mobile terminal device 20.

  The application software D10 for installation is obtained by disassembling a core part that the application supply apparatus 10 performs important processing into a plurality of core modules D11, D12, D13, and D14, and encrypting each core module. create.

  Then, the encrypted core module is combined with the plain text application non-core program D15, and the decryption processing program D16 is further added to constitute data of the application software D10 for installation. The decryption processing program D16 is a program that combines the encrypted core modules D11, D12, D13, and D14 and further links the programs. In this way, a plurality of encrypted core modules D11, D12, D13, D14 and a decryption processing program D16 are set as a set, and together with the non-core program D15 of the application, one application software D10 is configured.

  By making the application software D10 into this data structure, even if a cracker who wants to analyze the application software D10 reads the application software D10 from the nonvolatile memory 24 of the mobile terminal device 20, the program is encrypted. There is an effect that cannot be deciphered.

  Further, the mobile terminal device 20 executes the decryption processing program D16 to decrypt and carry one of the encrypted core modules D11, D12, D13, and D14 of the application software D10 as shown in FIG. The previous program is overwritten and expanded in the core area 22a of the application on the RAM 22 of the terminal device 20.

  Then, the decryption processing program D16 causes the mobile terminal device 20 to execute the overwritten program, decrypts the next encrypted core module, and again stores the previous program in the core area 22a of the application. Overwrite and expand.

  In this way, the mobile terminal device 20 performs dynamic link processing for overwriting the core module program one after another in the core area 22a of the same application on the RAM 22 in accordance with the program of the decryption processing program D16.

  It should be noted that the dynamic link function of overwriting the core module program 22a of the program of the decryption processing program D16 is incorporated into the encrypted program in each of the core modules D11, D12, D13, D14. It may be implemented with.

  That is, each decrypted core module is provided with a dynamic link function for performing a process of overwriting the program of the next core module on the core area 22 a of the application on the RAM 22. As a result, the program of the next core module is overwritten and expanded on the core area 22a of the application, and after execution of the previous program, execution of the next program overwritten on the core area 22a of the application is started. Next, the program of the next core module is overwritten on the core area 22a of the same application. Then, a plurality of programs are sequentially overwritten on the core area 22a of the same application on the RAM 22 and executed.

  As described above, a function for linking a program to be executed next may be incorporated in the program of each core module.

  The application supply apparatus 10 creates a plurality of encrypted core modules D11, D12, D13, and D14. That is, the application supply apparatus 10 divides the core part of the program of the application software D10 into a plurality of parts by using a public key cryptosystem, and creates the core modules D11, D12, D13, D14 by encrypting each part. To do.

  Then, the mobile terminal device 20 executes the decryption processing program D16 to dynamically decrypt the core modules D11, D12, D13, and D14 of the application software D10 for installation according to the operation of the application software D10. The program of the next core module is overwritten on the core area 22a of the application on the RAM 22 in which the previously executed program is written, and the overwritten program is executed.

(Overview of overall information processing system operation)
Below, the outline | summary of operation | movement of the information processing system 1 whole of this embodiment is demonstrated.
(Register electronic signature public key)
First, the application supply apparatus 10 previously executes a key generation algorithm to generate a public key Ko and a private key Kg for an electronic signature. Then, the public key Ko is disclosed through a third party organization.

(Created by encrypting the application software for installation)
As shown in the block diagram of FIG. 3, the application supply apparatus 10 divides the program of the application software D10 into a core part of the program and a non-core program D15 of the application, which is the remaining program part. Next, the core portion of the program is divided into a plurality of core modules, and the divided program portion C of each core is encrypted using the secret key Kg to create encrypted data E (C, Ko). . The encrypted data E (C, Ko) of the divided program portion C of each core is assumed to be core modules D11, D12, D13, and D14.

  And the application supply apparatus 10 produces the data which combined the core module D11, D12, D13, D14, the decryption processing program D16 containing the public key Ko, and the application non-core program D15 as application software D10. It is sent to the mobile terminal device 20.

(Decrypt application software for installation)
FIG. 4 shows a data flow in the portable terminal device 20 in which the application software D10 is stored in the nonvolatile memory 24 and then the program is expanded on the RAM 22 and executed. In particular, the core modules D 1, D 2, D 3, and D 4 decrypt them and sequentially overwrite the core areas of the apps in the same storage area of the RAM 22 for execution.

  The mobile terminal device 20 stores the application software D10 sent from the application supply device 10 in the nonvolatile memory 24. The application software D10 includes a decryption processing program D16 including the public key Ko, a plurality of encrypted core modules D11, D12, D13, and D14, and a non-core program D15 of the remaining application of the application software D10. Then, when the mobile terminal device 20 executes the application software D10, data of a program that is required to execute the function is expanded and stored on the RAM 22 whenever necessary.

  In particular, the core modules D 1, D 2, D 3, and D 4 that are encrypted data are stored in the core area 22 a of the application on the RAM 22 only in the divided program portion C of the core that is decrypted. When the execution of the program of the divided program part C of one core is finished, the encrypted data E (C, Ko) of the divided program part C of each next core is decrypted using the public key Ko, and the core is divided. A program part C is created, and the divided program part C of the core is overwritten on the core area 22a of the same application on the RAM 22 in which the divided program part C of the core executed previously is stored. Thereby, the memory of the program of the previous module is erased.

  In this way, there is an effect that the security of the application software D10 can be increased by overwriting and expanding the plurality of decrypted core divided program portions C on the core area 22a of the application on the same RAM 22.

  In addition, since the core part of the program of the application software D10 is divided into a plurality of divided program parts C of the core and overwritten on the core area 22a of the application which is the same area on the RAM 22, the program is executed. The storage area occupied by the RAM 22 can be reduced, and the storage capacity of the RAM 22 can be saved. In addition, regardless of the capacity of the storage area of the RAM 22 of the mobile terminal device 20, there is an effect that a long and large core program can be executed.

  Hereinafter, the operation of the application supply device 10 and the operation of the mobile terminal device 20 of the information processing system 1 according to the present embodiment will be described with reference to the flowchart of FIG.

(Operation of application supply device)
FIG. 5 shows a flowchart of an encryption processing routine in the application supply apparatus 10 in which the control means 11 disassembles the core portion of the program of the application software D10 into a plurality of modules and encrypts each module.

(Application software encryption processing)
The encryption processing routine encrypts the divided program part C of the core, which is one of a plurality of modules obtained by disassembling the core part of the program of the application software D10. FIG. 5 also shows a flowchart of a decryption processing routine in which the control means 21 of the mobile terminal device 20 decrypts the encrypted data E (C, Ko).

(Step S1: Program module division processing)
The control means 11 of the application supply apparatus 10 divides the program of the application software D10 into a core part of the program and the remaining program parts as shown in the block diagram of FIG. 3, and further, the core part is divided into a plurality of cores. Is divided into divided program parts C.

(Step S2: Encryption processing)
Next, the control means 11 performs the following encryption process for each divided program part C of each core obtained by dividing the core part into a plurality of parts. That is, the control means 11 calculates the hash value H1 by performing the irreversible conversion processing of the divided program part C of the core with the first program of the signature generation algorithm, for example, with a one-way hash function such as the SHA-1 function. Next, the control means 11 creates encrypted data E (C, Ko) by encrypting the divided program portion C of the core and its hash value using the secret key Kg with the program next to the signature generation algorithm.

  Thus, the encrypted data E (C, Ko) is created from the divided program portion C of each core divided into a plurality. The created encrypted data E (C, Ko) are set as core modules D11, D12, D13, and D14. When all the core modules D11, D12, D13, and D14 have been created, the process proceeds to step S3.

(Step S3)
The control means 11 includes application software D10 including a decryption processing program D16 including the public key Ko, encrypted core modules D11, D12, D13, and D14 of the core part of the application software, and a non-core program D15 of the application. Is created and sent to the mobile terminal device 20.

  As one method of sending the application software D10 from the application supply device 10 to the mobile terminal device 20, data can be transmitted from the Web server to the user's mobile terminal device 20 by communication via the communication network 100. The portable terminal device 20 receives the data through the communication unit 27 and the wireless LAN communication unit 28. Further, the data of the application software D10 can be stored in a physical medium such as a USB memory or the nonvolatile memory 24 and sent to the mobile terminal device 20. That is, the USB memory can be read by the USB input / output unit 29 of the mobile terminal device 20, or the nonvolatile memory 24 can be directly mounted on the mobile terminal device 20.

(Operation of mobile terminal device)
FIG. 5 shows a flowchart of a procedure in the mobile terminal device 20 in which the control means 21 decrypts the encrypted application software D10, develops it on the RAM 22, and executes the program.

(Step S31)
The control means 21 of the mobile terminal device 20 receives the public key certificate issued to the ID number of the application supply device 10 from the certificate authority 200, and uses the public key Ko stored in the public key certificate as R.
Store in AM22. This operation may be performed after the loading of the application software D10 in the next step S32.

(Step S32)
Next, the control means 21 stores the application software D10 transmitted from the application supply device 10 in the nonvolatile memory 24. That is, the decryption program D16 including the public key Ko of the application software D10, the encrypted core modules D11, D12, D13, and D14 of the core part of the application software, and the non-core program D15 of the application are nonvolatile. Store in the memory 24.

(Step S33)
Next, the control means 21 verifies the validity of the public key Ko included in the decryption processing program D16 by comparing it with the public key Ko read from the public key certificate received from the certificate authority 200 and stored in the RAM 22. If the authentication cannot be performed, the execution of the application software D10 is stopped. If the authentication is successful, the process proceeds to step S34.

(Step S34)
Upon receiving a command for starting the operation of the application software D10 from the user, the control unit 21 operates the program of the application software D10 as follows. First, the control means 21 reads the application non-core program D15 of the application software D10 to be executed from the nonvolatile memory 24, and dynamically expands it in the application non-core area 22b on the RAM 22.

(Step S35)
Next, the control means 21 executes the program of the application non-core program D15. When it becomes necessary to execute the core module during the execution of the program, the decoding processing routine after step S36 is executed.

(Step S36: Decoding processing routine)
When the execution request for the core module is generated, the control means 21 dynamically expands the program of the decryption processing program D16 in the non-core area 22b of the application on the RAM 22 and operates it.

  The program of the decryption processing program D16 reads the corresponding module from the encrypted core modules D11, D12, D13, and D14 from the nonvolatile memory 24, and the encrypted data E (C, Ko) is as follows: To decrypt.

  The program of the decryption processing program D16 decrypts the encrypted data E (C, Ko) using the public key Ko stored in the RAM 22 to obtain the core divided program portion C and the hash value H1. The obtained hash value H1 is stored in the register of the control means 21. Then, the divided program portion C of the core is overwritten and stored in the core area 22a of the application in the same area as the program of the core module previously executed on the RAM 22. Next, the process proceeds to step S37.

  In this way, by overwriting the core area 22a of the application on the RAM 22 that previously stored the core divided program part C with the next core divided program part C, the RAM 22 stores the core stored previously. The divided program part C is deleted.

(Step S37)
Next, the control unit 21 calculates a hash value H2 by applying a hash function to the divided program portion C of the core expanded in the core area 22a of the application. And the hash value H2
Is compared with the hash value H1 previously decrypted. If the hash values H1 and H2 match, it is determined that the divided program portion C of the core has not been tampered with, and the process proceeds to step S38. If the hash values H1 and H2 do not match, the execution of the application software D10 is stopped and the process returns to step S31.

(Step S38)
Next, the control means 21 executes the program of the divided program portion C of the core that has been expanded in the core area 22 a of the application on the RAM 22. After the execution of the program, the process returns to step S36, the decryption processing program D16 is executed, and any of the core modules D11, D12, D13, D14 to be executed next is read from the nonvolatile memory 24.

  Then, the encrypted data E (C, Ko) of the read module is decrypted using the public key Ko to obtain the core divided program part C and its hash value H1, and the core divided program part C Are overwritten and stored in the core area 22a of the application in the same area as the program of the core module previously executed on the RAM 22. Then, the process proceeds to next Step S37.

  Thus, the control unit 21 repeats the operations from step S36 to step S38, and executes the decryption processing routine up to the last module of the core modules D11, D12, D13, D14, thereby encrypting the core module. By deleting the decrypted program of D11, D12, D13, and D14 one after another in the core area 22a of the application, which is the same storage area on the RAM 22, the previous core module program is erased from the core area 22a of the application. To do.

  In this way, the core modules D11, D12, D13, D14 are sequentially decrypted and overwritten on the same storage area on the RAM 22 to erase the previous data, so the core modules D11, D12, The time for which the data of D13 and D14 exist in the RAM 22 is only a short time from the time when the execution of one core module is started to the time when the next core module is executed. . By doing so, there is an effect that it is extremely difficult to analyze the program by a cracker who is trying to analyze the application software D10.

  As described above, in the information processing system 1 according to the first embodiment, the application supply apparatus 10 divides the core part of the application software D10 into the divided program parts C of a plurality of cores using the secret key Kg, The divided program portion C of each core is converted into encrypted data E (C, Ko), the core modules D11, D12, D13, D14 of the encrypted data E (C, Ko), and the non-core program D15 of the application Then, the application software D10 including data including the public key Ko and the decryption processing program D16 is sent to the mobile terminal device 20.

  On the other hand, in the mobile terminal device 20, the control means 21 stores the application software D 10 received from the application supply device 10 in the nonvolatile memory 24.

  The control means 21 receives an operation start command for the application software D10 from the user, and dynamically expands the program of the application software D10 on the RAM and executes it. When it is necessary to execute the program of the divided program part C of the core of the application software D10, the decryption processing program D16 is executed and the encrypted data E (C of the corresponding core modules D11, D12, D13, D14 is executed. , Ko) using the public key Ko.

  The decrypted core divided program portion C is overwritten one after another on the same storage area in the application core area 22 a on the RAM 22, and the program of the immediately previous core module is deleted from the RAM 22. And the program of the division | segmentation program part C of the core of the core area | region 22a of an application is performed.

  In this way, the program of the divided program portion C of the core developed in the application core area 22a on the RAM 22 of the mobile terminal device 20 exists on the RAM 22 only for a period necessary for the operation of the application software D10.

  In addition, when the operation of the application software D10 is stopped (including a temporary stop operation), module data read restriction means for deleting the divided program portion C of the core from the core area 22a of the application on the RAM 22 is also provided. This module data read limiting means erases the data from the application core area 22a in an emergency, so that the core divided program portion C stored in the application core area 22a on the RAM 22 is also in the event of an emergency. There is an effect that it cannot be read from an external program other than the application software D10 that is the owner of the application.

  As described above, the present embodiment improves the convenience of distribution of the application software D10, and the mobile terminal device 20 provides the correct application software D10 that has not been tampered with high security quality to prevent eavesdropping and key leakage by a cracker. Since it can be discriminated and executed carefully, there is an effect of promoting the distribution of the application software D10.

[Second Embodiment]
As the second embodiment of the present invention, the decryption processing program D16 is sent as external library software to the mobile terminal device 20 separately from the application software D10, and the application software D10 not including the decryption processing program D16 is decrypted. It can be sent to the mobile terminal device 20 separately from the program D16. Then, the decryption processing program D16 as external library software is shared by a plurality of application software D10 and executed. Other than that, the configuration is the same as in the first embodiment.

(Modification 1)
As a first modification of the second embodiment, the public key Ko is not included in the decryption processing program D16 as external library software, and the mobile terminal device 20 encrypts the public key Ko by each application supply device 10. For each application software D10, it may be acquired from the certificate authority 200 and stored in the RAM 22 for use.

  Each application supply apparatus 10 divides the core part of the application software D10 into the divided program part C of the core, and uses the secret key Kg corresponding to the public key Ko to encrypt the divided program part C of each core. E (C, Ko) is converted, and as the core modules D11, D12, D13, and D14, application software D10 including data combined with the non-core program D15 of the application is sent to the mobile terminal device 20.

  In the portable terminal device 20, the control means 21 executes the decryption processing program D16 as external library software, and reads the public key Ko corresponding to the core modules D11, D12, D13, D14 of the application software D10 to be decrypted from the RAM 22 Then, the core modules D11, D12, D13, and D14 are sequentially decrypted and overwritten on the core area 22a of the application on the RAM 22 for expansion.

  In this way, the control means 21 of the mobile terminal device 20 reads the external library software decryption processing program D16 and causes the program to be executed, while obtaining the public key Ko associated with each application software D10 separately. Then, using the public key Ko, the core modules D11, D12, D13, D14 are sequentially decrypted and overwritten on the core area 22a of the application on the RAM 22 for expansion.

  As a result, the application software D10 created by the different application supply devices 10 shares the common decryption processing program D16, while the application software D10 core module D11 encrypted with a different secret key Kg for each application supply device 10, D12, D13, and D14 can be decrypted and executed with different public keys Ko corresponding to their secret keys Kg.

DESCRIPTION OF SYMBOLS 1 ... Information processing system 10 ... Application supply apparatus 11 ... Control means 12 ... ROM
13 ... RAM
14 ... bus 15 ... interface 16 ... communication unit 17 ... input / output unit 18 ... display 19 ... magnetic disk 20 ... portable terminal device 21 ... control means 22 ...・ RAM
22a: Application core area 22b: Application non-core area 23: ROM
24 ... Non-volatile memory 25 ... Interface 26 ... Bus 27 ... Communication unit 28 ... Wireless LAN communication unit 29 ... USB input / output unit 100 ... Communication network 200 ... Authentication Station C ... core division program part D10 ... application software D11, D12, D13, D14 ... encrypted core module D15 ... non-core program D16 of application ... decryption processing program E ( C, Ko) ... encrypted data Kg ... secret key Ko ... public key

Claims (7)

  A portable terminal device that stores application software in a non-volatile memory and executes the program by expanding it into a RAM, and the core part is divided into a plurality of programs and encrypted with a secret key paired with a public key By executing the decryption processing program, a plurality of programs in the core part of the application software are sequentially decrypted using the public key, and written over the previous program in the same storage area of the RAM. A mobile terminal device that executes a core part of the application software by repeating the process executed in step (b).   2. The portable terminal device according to claim 1, further comprising a communication unit that receives the public key from a certificate authority via a communication network.   3. The portable terminal device according to claim 1, wherein the core part is divided into a plurality of programs and encrypted together with a hash value of the divided parts, and the decryption processing program is stored in the encryption processing program. A mobile terminal device that decrypts the converted portion into a program and a hash value, calculates a hash value of the decrypted program, and collates the hash value with the decrypted hash value .   4. The mobile terminal device according to claim 1, wherein the decryption program repeats a process of overwriting a previous program in the same storage area of the RAM and executing the program. 5. A portable terminal device.   5. The portable terminal device according to claim 1, wherein the application software is application software including the decryption processing program and the public key. 6.   A decryption program for executing a program of application software stored in a non-volatile memory in a portable terminal device by developing the program on a RAM, wherein the secret is a core part of the application software divided into a plurality of programs and paired with a public key Encrypted by a key, the plurality of programs encrypted in the core portion are sequentially decrypted using the public key, written over the previous program in the same storage area of the RAM, and executed A decryption processing program characterized by repeating processing.   7. The decryption processing program according to claim 6, wherein the plurality of divided programs and a hash value of the program are encrypted together, and the decryption processing program is encrypted. And decrypting the hash value, calculating a hash value of the decrypted program, and comparing the hash value with the decrypted hash value.

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