JP2010231458A - Electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electronic equipment which prevents information stored in an external storage device from being illegally browsed and allows a specific person to browse the information. <P>SOLUTION: The electronic equipment includes: a self-identification information storage part which stores self-identification information; an identification information storage part which stores other identification information; an encoding part which encodes writing information to which encryption keys are written as decoding keys, generates a plurality of decoding keys from the self-identification information and the other identification information, and encodes the encryption keys by using the keys; a writing part which writes the encoded writing information to the storage part of an external storage device and writes the encoded encryption keys to a secret area of the external storage device; a reading part which reads the encoded writing information from the external storage device;and a decoding part which collates the self-identification information with the encoded encryption keys, decodes the encoded encryption keys on the basis of the self-identification information when the self-identification information match the encoded encryption keys, and decodes information encoded by the decoded encryption keys. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic device that exchanges information with a removable external storage device.

  As an electronic device such as a cellular phone, an electronic device having a function for preventing personal information such as an address, an e-mail, a photograph, and a transmission / reception history stored in the electronic device and secret information from leaking has been proposed. .

  For example, in Patent Document 1 and Patent Document 2, a passphrase such as a personal identification number and a password is set, and a communication information terminal (that is, an electronic device) capable of setting a secret mode in which secret information is not displayed unless a passphrase is input. Is described. Patent Document 1 further describes that when a pass phrase is input, designated secret information is displayed while maintaining the secret mode.

  Patent Documents 3 and 4 describe a system that extracts information stored in a portable electronic device by communication via a base station or disables the portable electronic device.

  In Patent Document 5 and Patent Document 6, when data is moved between a portable electronic device and another device for the purpose of using the content without limitation, the encrypted content data is not included. A system is described that can be used with other devices only when the portable electronic device is connected to the device. Patent Documents 5 and 6 also describe a system that deletes content on the transmission side after sending encrypted content data to another device. Patent Document 6 describes that an encryption key is generated based on a telephone number or device unique ID assigned to a portable electronic terminal that sends data.

Japanese Patent Laid-Open No. 11-308322 JP-A-11-355417 JP 2004-32402 A JP 2006-148431 A JP 2006-303697 A JP 2007-174658 A

  Here, some electronic devices are provided with a removable external storage device such as an SD card, and such information is written and stored in the external storage device, thereby backing up personal information, copyrighted content, and secret information. In addition, personal information, copyrighted content, and secret information may be passed to another person or another terminal using this external storage device.

  On the other hand, the portable electronic devices and systems described in Patent Literature 1 to Patent Literature 4 are intended to protect information stored in the portable electronic device, and protect information stored in the external recording device. There is no mention of what to do. Moreover, after setting and encrypting a passphrase as described in Patent Document 1 and Patent Document 2, it is stored in an external storage device, thereby preventing browsing by an unspecified third party. Although it is possible, it is necessary to notify the passphrase to the target person who wants to browse the information, which places a burden on the operator. If the passphrase is known, it may be viewed by an unintended third party. If information that is not encrypted with a passphrase or the like is stored in the external storage device, the third party who has acquired the external storage device can freely browse the information, and thus confidentiality cannot be maintained.

  In addition, in the portable electronic devices described in Patent Literature 5 and Patent Literature 6, in order to view the information even when the information is moved to another terminal, the transmitted portable electronic device is connected by some means. There is a need. For this reason, the information cannot be freely viewed on other terminals simply by moving the information.

  The present invention has been made in view of the above, and an electronic device that can be browsed by a specific target person while suppressing unauthorized browsing of information stored in an external storage device. The purpose is to provide.

  The present invention relates to an electronic device in which an external storage device composed of a storage area in which information is stored and a secret area in which confidential information is stored is detachable, and information is written to and extracted from the external storage device. A self-specific information storage unit for storing self-specific information for specifying the self, a specific information storage unit for storing other specific information for specifying other operators, and the external storage using an encryption key as a decryption key. An encryption unit that encrypts write information to be written to the device, further creates a plurality of decryption keys from the self-specific information and the other specific information, and encrypts the encryption key using each of the keys; A writing unit that writes the encrypted write information by the encryption unit to the storage unit of the external storage device, and writes an encrypted encryption key to a secret area of the external storage device; and the external storage device A read unit that reads the encrypted write information from, and the self-identifying information and the encrypted encryption key are collated, and if they match, the encryption key is decrypted based on the self-identifying information, and the decrypted encryption key And the decryption unit for decrypting the encrypted information.

  Here, the self-specific information and the other specific information are preferably configured by telephone numbers.

  Further, it is preferable that the self-specific information and the other specific information are configured by mail addresses.

  The self-specific information and the other specific information are preferably configured with terminal information for specifying a terminal.

  The specific information storage unit is preferably an address book.

The address book stores a plurality of the other specific information as a group,
The encryption unit preferably uses the other specific information included in the designated group as a decryption key.

  Further, it is preferable that the encryption unit encrypts the encryption key based on other specific information selected from a plurality of specific information.

  In addition, the encryption unit further encrypts using a passphrase as a decryption key, and the decryption unit collates the input phrase and the passphrase, and if they match, the self-identifying information and the encryption It is preferable to verify the encrypted encryption key.

  Further, it is preferable that the decoding unit switches the write information to be decoded according to the degree of coincidence of the decoding process.

  Further, the present invention is an electronic device in which an external storage device composed of a storage area in which information is stored and a secret area in which confidential information is stored is detachable, and an electronic device that writes information to and extracts information from the external storage device. A self-identifying information storage unit that stores self-identifying information that can identify the device; a reading unit that reads encrypted writing information from the external storage device; and the cipher encrypted with the self-identifying information And a decryption unit that decrypts the encryption key based on the self-identifying information when the key is matched, and decrypts the encrypted information with the decrypted encryption key.

  The electronic device according to the present invention has an effect that the information stored in the external storage device can be browsed by a specific target person while suppressing unauthorized browsing.

FIG. 1 is a block diagram showing a schematic configuration of a mobile phone which is an embodiment of the electronic apparatus of the present invention. FIG. 2 is an explanatory diagram showing a schematic configuration of the external memory. FIG. 3 is a flowchart showing an example of the processing operation of the mobile phone. FIG. 4A is an explanatory diagram for explaining the operation of the mobile phone. FIG. 4B is an explanatory diagram for explaining the operation of the mobile phone. FIG. 4C is an explanatory diagram for explaining the operation of the mobile phone. FIG. 4-4 is an explanatory diagram for explaining the operation of the mobile phone. FIG. 5A is an explanatory diagram for explaining the operation of the mobile phone. FIG. 5B is an explanatory diagram for explaining the operation of the mobile phone. FIG. 5C is an explanatory diagram for explaining the operation of the mobile phone. FIG. 6A is an explanatory diagram of an example of the encryption process. FIG. 6B is an explanatory diagram for explaining an example of the encryption process. FIG. 6C is an explanatory diagram for explaining an example of the encryption process. FIG. 6-4 is an explanatory diagram for explaining an example of the encryption process. FIG. 7 is a flowchart showing an example of the processing operation of the mobile phone. FIG. 8A is an explanatory diagram for explaining an example of the decoding process. FIG. 8-2 is an explanatory diagram for explaining an example of the decoding process. FIG. 8C is an explanatory diagram for explaining an example of the decoding process. FIG. 9 is an explanatory diagram for explaining the operation of the mobile phone. FIG. 10 is an explanatory diagram for explaining the operation of the mobile phone. FIG. 11 is an explanatory diagram for explaining another operation of the mobile phone.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description. In addition, constituent elements in the following description include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. In the following, a mobile phone will be described as an example of an electronic device, but the application target of the present invention is not limited to a mobile phone. For example, a PHS (Personal Handyphone System), a PDA, a portable navigation device, a game machine, The present invention can also be applied to a personal computer or the like. That is, it can be used for various electronic devices including a stationary electronic device in addition to a portable electronic device (that is, a portable electronic device).

  FIG. 1 is a block diagram showing a schematic configuration of a mobile phone which is an embodiment of an electronic apparatus according to the invention. As shown in FIG. 1, the cellular phone 10 basically includes a housing 12, a CPU (Central Processing Unit) 22, a memory 24, a communication unit 26, an operation unit 28, an audio processing unit 30, and a display. The unit 32, the connection terminal 34, and the external memory 60 are included. The mobile phone 10 has various configurations as a mobile phone, such as an imaging unit and various terminals, in addition to the above configuration.

  The housing 12 is an exterior that accommodates each part of the mobile phone 10. Here, as the housing | casing 12, it is comprised by the two members connected with the hinge, the housing | casing which can be folded, the housing | casing which slides two members, one box-shaped housing | casing, etc. are illustrated. .

  The CPU 22 is a processing unit that comprehensively controls the overall operation of the mobile phone 10. That is, the power supply control unit 20 and the communication unit 26 are executed so that various processes of the mobile phone 10 are executed according to an operation of the operation unit 28 and software stored in the memory 24 of the mobile phone 10. In addition, it controls the operation of the display unit 32 and the like. Various processes of the mobile phone 10 include, for example, a voice call performed via a circuit switching network, creation and transmission / reception of an e-mail, browsing of a Web (World Wide Web) site on the Internet, and the like. The operations of the communication unit 26, the audio processing unit 30, the display unit 32, and the like include, for example, transmission / reception of signals by the communication unit 26, input / output of audio by the audio processing unit 30, display of images by the display unit 32, and the like. .

  The CPU 22 executes processing based on programs (for example, operating system programs, application programs, etc.) stored in the memory 24. The CPU 22 is configured by, for example, a microprocessor unit (MPU: Micro Processor Unit), and executes various processes of the mobile phone 10 described above according to the procedure instructed by the software. That is, the CPU 22 sequentially reads instruction codes from an operating system program, application program, or the like stored in the memory 24 and executes processing.

  The CPU 22 has a function of executing a plurality of application programs. Examples of application programs executed by the CPU 22 include a write application program that performs a process of writing information (data) to the external memory 60, a read application program that reads information stored in the external memory 60, and target information. There are a plurality of application programs such as an encryption application program that encrypts the encrypted object information, a decryption application program that decrypts the encrypted target information, and a game application program that operates various games.

  The memory 24 stores software and data used for processing in the CPU 22, and the above-described write task 40 for operating the write application program, read task 42 for operating the read application program, and encryption application program An encryption task 44 for operating the decryption task 46 and a decryption task 46 for operating the decryption application program are stored. Each task will be described in detail later. In addition to these tasks, the memory 24 stores the telephone number and mail address of the communication partner, and manages the address book 48, the telephone number, mail address, and operator's address assigned to the mobile phone 10. And a profile 49 in which personal information such as a birthday is entered.

  In addition to these, in the memory 24, for example, communication, downloaded image data, audio data, software used by the CPU 22 to control the memory 24, audio files such as dial tone and ringtone, software processing process Temporary data used in is stored. Note that computer programs and temporary data used in the software processing process are temporarily stored in a work area allocated to the memory 24 by the CPU 22. The memory 24 is, for example, a nonvolatile storage device (nonvolatile semiconductor memory such as ROM: Read Only Memory, a hard disk device, etc.), a readable / writable storage device (eg, SRAM: Static Random Access Memory, DRAM: Dynamic Random Access). Memory) and the like.

  The communication unit 26 establishes a radio signal line by a CDMA system or the like with a base station via a channel assigned by the base station, and performs telephone communication and information communication with the base station.

  The operation unit 28 is configured with keys assigned with various functions such as a power key, a call key, a numeric key, a character key, a direction key, a determination key, and a call key, and these keys are input by a user operation. Then, a signal corresponding to the operation content is generated. The generated signal is input to the CPU 22 as a user instruction.

  The audio processing unit 30 performs processing of an audio signal input to the microphone 50 and an audio signal output from the speaker 52. That is, the sound processing unit 30 amplifies the sound input from the microphone 50, performs AD conversion (Analog Digital conversion), and then performs signal processing such as encoding to convert the sound into digital sound data to be converted into the CPU 22 Output to. Further, the audio data sent from the CPU 22 is subjected to processing such as decoding, DA conversion (Digital Analog conversion), amplification, etc. to convert it into an analog audio signal, which is then output to the speaker 52.

  The display unit 32 includes a display panel such as a liquid crystal display (LCD, Liquid Crystal Monitor) or an organic EL (Organic Electro-Luminescence) panel, and a video corresponding to video data supplied from the CPU 22 and an image corresponding to the image data. Is displayed on the display panel.

  The connection terminal 34 is a terminal connected to the external memory 60. The connection terminal 34 is connected to the CPU 22 and connects the CPU 22 and the external memory 60 by wire. The CPU 22 and the external memory 60 transmit and receive information (data) via the connection terminal 34.

The external memory 60 is a storage device that is detachably attached to the connection terminal 34. Note that various storage devices having a fixed capacity storage area can be used, for example, ROM, RAM, E ² PROM, nonvolatile RAM, flash memory, HDD (Hard Disk Drive), and the like. Specifically, an SD memory card, a memory stick, or the like can be used.

  The external memory 60 will be described in more detail. Here, FIG. 2 is an explanatory diagram showing a schematic configuration of the external memory. As shown in FIG. 2, the external memory 60 includes three storage areas: a system area 62, a secret area 64, and a normal area 66. The system area 62 is an area in which the ID of the external memory 60 is stored. The system area 62 is an area that cannot be written by the mobile phone 10 (CPU 22 thereof), that is, an area that is read-only. The secret area 64 is an area that cannot be viewed by an operator, but is writable by the CPU 22 of the mobile phone 10. The secret area 64 cannot write arbitrary information (data) selected by the operator, and the CPU 22 writes and reads information necessary for the system. The normal area 66 is an area where arbitrary information selected by the operator, for example, image data, music files, backup data, and the like can be written and read by the CPU 22. Note that the external memory 60 exchanges information with the CPU 22 when connected to the connection terminal 34. Specifically, the CPU 22 acquires the media ID stored in the system area 62, performs mutual authentication, and determines whether the external memory 60 connected via the connection terminal 34 is an accessible external memory 60. judge. When the CPU 22 determines that the external memory 60 is accessible, the CPU 22 exchanges information between the secret area 64 and the normal area 66. If the CPU 22 performs mutual authentication and determines that the external memory 60 is inaccessible, the CPU 22 does not exchange information between the CPU 22 and the external memory 60. The mobile phone 10 is basically configured as described above.

  Next, the operation of the mobile phone 10 will be described. First, the operations of the writing application program and the encryption application program will be described with reference to FIGS. Here, FIG. 3 is a flowchart showing an example of the processing operation of the mobile phone. FIGS. 4-1 to 4-4 are explanatory diagrams for explaining the operation of the mobile phone, and FIGS. 5-1 to 5-3 are explanatory diagrams for explaining the operation of the mobile phone. FIGS. 6A to 6D are explanatory diagrams for explaining an example of the encryption process. In this embodiment, data (information) is written to the external memory 60 by a writing application program operated by the CPU 22, and encryption is performed by an encryption application program operated by the CPU 22.

  First, the operator inputs an instruction to copy or move data stored in the memory 24 of the mobile phone 10 (hereinafter referred to as “target data”) to the external memory 60. When an instruction to copy or move the target data is input, the mobile phone 10 reads the write task 40 and the encryption task 44 from the memory 24, starts the write application program and the encryption application program, and performs the following processing. Is called.

  The CPU 22 of the mobile phone 10 determines whether or not to protect the target data as step S12. Specifically, an inquiry as to whether or not to protect the target data is displayed on the display unit 32, an instruction to protect or not protect the target data input by the operator is detected, and based on the detection result judge. If it is determined in step S12 that the target data is not protected (No), that is, if it is detected that an instruction not to protect the target data is input by the operator, the CPU 22 moves the target data to the external memory 30 in step S30. To finish the process.

  If it is determined in step S12 that the target data is to be protected (Yes), that is, if it is detected that an instruction to protect the target data is input by the operator, the CPU 22 generates an encryption parameter in step S14, The target data is encrypted using the generated encryption parameter (encryption key). When the target data is encrypted in step S14, the CPU 22 moves the encrypted target data to the external memory 60 in step S15. That is, the CPU 22 writes the encrypted target data in the normal area 66 of the external memory 60.

  If CPU22 moves object data by step S15, it will add an own telephone number to a key ring as step S16. Here, the key ring is a list in which one or more telephone numbers are input. Specifically, as step S16, the CPU 22 reads the telephone number assigned to the mobile phone 10 from the profile 49, and writes the read telephone number in the key bundle.

  If CPU22 adds an own telephone number to a key ring at step S16, it will determine whether an object person is added as step S18. Specifically, an inquiry as to whether or not to add a target person is displayed on the display unit 32, an instruction to add or not add the target person input by the operator is detected, and based on the detection result Judgment. Here, the target person is a person or terminal that sets the target data written in the external memory 60 to be in a viewable state.

  If it is determined in step S18 that the target person is to be added (Yes), that is, if it is detected that an instruction to add the target person has been input by the operator, the CPU 22 proceeds to step S20. In step S20, the CPU 22 acquires the telephone number of the target person to be added from the address book, and adds the acquired telephone number to the key ring. Here, the target person to be added is determined based on the operator's input, and the CPU 22 selects the person selected and determined by the operator's operation as the target person. Specifically, the CPU 22 reads the address book 48 from the memory 24, displays a name (person, company, store), causes the operator to select it, and causes the name to be selected by the operator. CPU22 reads the telephone number registered as the thing of the selected name, and adds the read telephone number to the list | wrist of a key ring as a telephone number of an object person. Note that the method of selecting the target person by the operator is not particularly limited, and even if names (persons, companies, stores) stored in the address book are selected one by one, they are set in the address book. A group may be selected. After adding the subject person's telephone number to the key ring in step S20, the CPU 22 proceeds to step S18. That is, the CPU 22 repeats step S18 and step S20 until it is determined not to add the subject person, and continues to add the subject person's telephone number to the key ring.

  If it is determined in step S18 that the target person is not added (No), that is, if the CPU 22 detects that an instruction not to add the target person is input by the operator, the process proceeds to step S22. As step S22, the CPU 22 encrypts the encryption parameter with the key ring created in steps S16 and S20. Specifically, the CPU 22 encrypts the encryption parameter by setting each telephone number registered in the key ring as a decryption key.

  When the encryption parameter is encrypted in step S22, the CPU 22 determines whether or not to set a passphrase in step S24. Specifically, an inquiry as to whether or not to set a passphrase is displayed on the display unit 32, an instruction to set or not to set a passphrase input by the operator is detected, and based on the detection result Judgment. The passphrase is a number string or character string set with numbers, alphabets, or the like.

  If the CPU 22 determines in step S24 that a passphrase is not set (No), that is, if it is detected that an instruction not to set a passphrase is input by the operator, the process proceeds to step S28. If it is determined in step S24 that a passphrase is to be set (Yes), that is, if it is detected that an instruction to set a passphrase is input by the operator, the CPU 22 uses the passphrase as step S26. Re-encrypt cryptographic parameters. That is, the encryption parameter encrypted using the key ring with the passphrase set as the decryption key is further encrypted. If CPU22 encrypts a passphrase, it will progress to step S28.

  The CPU 22 stores the encrypted encryption parameter in the secret area 64 of the external memory 60 as step S28. That is, the CPU 22 writes the encryption parameter encrypted in step S22 or the encryption parameter re-encrypted in step S26 in the secret area 64 of the external memory 60. Further, the CPU 22 writes a key bundle (list of telephone numbers) that is a key for decryption together with the encryption parameter in the secret area 64. If a passphrase is set, the passphrase is also written in the secret area 64. After writing the encryption parameter in the secret area 64, the CPU 22 terminates the encryption application program and the write application program, and terminates the process, assuming that the encryption and write processing has ended.

  Next, the processing in the CPU 22 shown in FIG. 3 will be described together with the operation by the operator. First, as shown in FIG. 4A, the operator determines data (that is, target data) to be written (stored) in the external memory 60, and further selects to protect (encrypt) the target data. (Step S12). Based on the operator's decision, the CPU 22 encrypts the target data as shown in FIG. 5A and writes the encrypted target data to the external memory 60.

  Next, as shown in FIG. 4B, the operator determines whether to set a target person who can browse other than himself / herself for the target data (step S18). When the operator selects to set the target person, as shown in FIG. 4-3, the operator determines the target person to be added (step S20). Specifically, a target person is selected from names registered in the address book, or names in the group are selected as target persons at once by selecting a group registered in the address book. Based on the operator's decision, the CPU 22 creates a key ring of the target person who is set to be viewable, and encrypts the encryption parameter by the created key ring, that is, a viewable (mobile) telephone number (see FIG. 5-2).

  Thereafter, when a passphrase is also set, the operator sets a passphrase as shown in FIG. 4-4 (steps S24 and S26). As shown in FIG. 5-3, the CPU 22 re-encrypts the encryption parameter with the set passphrase. The operator can write the data in the external memory 60 in a protected state by performing the above operations.

  Next, the processing in the CPU 22 shown in FIG. 3, specifically, the processing in the CPU 22 in step S22 will be described together with the encryption and data flow. First, as shown in FIG. 6A, the target data (content A) selected by the operator is encrypted with the encryption parameter (content key) arbitrarily created by the encryption application program, and the encrypted target data (content A ′) is created. The CPU 22 writes the content A ′ in the normal area 66 of the external memory 60 by the writing application program.

  After writing the content A ′ in the external memory 60, the CPU 22 creates a key for decrypting the content key by the encryption application program. First, the CPU 22 creates a key for the mobile phone 10 so that the mobile phone 10 that has written the target data can decrypt it. Specifically, as shown in FIG. 6B, the information on the telephone number assigned to the mobile phone 10 is read from the information on the mobile phone 10 stored in the profile 49, and the information on the telephone number is read out. Create a key (user key). For example, the user key “e4g1An” is created from the information of the telephone number “090-1234-5678”.

  Next, as shown in FIG. 6-3, the CPU 22 calculates a checksum (error detection code) from the content key used for encrypting the content A ′, and creates a data string composed of the content key and the checksum. create. Further, the CPU 22 creates a data string in which the user key and an arbitrary random number are connected, and calculates a message digest (MD5, hash value) from the created data string. Thereafter, the CPU 22 creates an encrypted content key obtained by encrypting the data string composed of the content key and the checksum with a message digest.

  Further, as shown in FIG. 6-4, the CPU 22 generates a data string formed by concatenating the encrypted content key and the random number used when generating the encrypted content key (the random number used for creating the message digest). It is created, this data string is encrypted with a constant C, and an encrypted unique key is created. The CPU 22 writes the encrypted unique key thus created in the secret area 64 of the external memory 60 by the writing application program in step S28. Further, the CPU 22 repeatedly creates an encrypted unique key for each selected target person, that is, for each telephone number of the target person added to the key ring, and creates an encrypted unique key corresponding to each telephone number. The CPU 22 creates an encrypted unique key as described above.

  Next, the operations of the reading application program and the decrypting application program will be described with reference to FIGS. Here, FIG. 7 is a flowchart showing an example of the processing operation of the mobile phone. FIGS. 8A to 8C are explanatory diagrams for explaining an example of the decoding process. In the present embodiment, reading of data from the external memory 60 is performed by a reading application program operated by the CPU 22, and decoding is performed by a decoding application program operated by the CPU 22.

  First, the operator inputs an instruction to view or reproduce arbitrary data (hereinafter referred to as “target data”) from the data stored in the external memory 60. Note that the target data stored in the external memory 60 may be the same data as the target data described with reference to FIG. When an instruction to view or play back the target data is input, the mobile phone 10 reads the reading task 42 and the decrypting task 46 from the memory 24, and the reading application program and the decrypting application program are activated, and the following processing is performed. Is called.

  In step S50, the CPU 22 of the mobile phone 10 determines whether the target data is protected data. Specifically, it is determined whether or not the target data is encrypted data. If the CPU 22 determines in step S50 that the target data is not protected (No), the CPU 22 proceeds to step S62.

  If it is determined in step S50 that the target data is protected (Yes), the CPU 22 acquires the encrypted encryption parameter from the secret area 64 in the external memory 60 in step S52. When the CPU 22 acquires the encryption parameter encrypted in step S52, the CPU 22 decrypts the encrypted encryption parameter using its own mobile phone number in step S54. The decoding process will be described later.

  After decrypting the encryption parameter in step S54, the CPU 22 decrypts the encrypted target data using the decrypted encryption parameter in step S56. When the target data is decoded in step S56, the CPU 22 determines whether the target data has been successfully decoded in step S58. That is, the CPU 22 determines whether the target data is in a viewable or reproducible state. If the CPU 22 determines in step S58 that the data decoding has succeeded (Yes), the CPU 22 proceeds to step S62.

  If the data decryption is not successful in step S58 (No), that is, the CPU 22 determines that the target data is not in a state that can be reproduced and viewed, the encryption parameter encrypted with the input passphrase is obtained in step S60. Is decrypted. The passphrase is input by the operator. Specifically, the CPU 22 displays an image requesting the operator to input a passphrase on the display unit 32 so that the passphrase can be input, and the passphrase input by the operator in this state is displayed. To detect. If CPU22 decodes object data with the input passphrase, it will progress to step S54 and will repeat the said operation.

  If the CPU 22 determines that the target data is not protected in step S50 and if it is determined in step S58 that the target data has been successfully decrypted, the CPU 22 can reproduce or view the target data in step S62. And the process ends.

  In the flowchart shown in FIG. 7, the processing from step S54 to step S60 is repeated until it is half-determined that the decoding of the target data is successful in step S58, but the present invention is not limited to this. If the process is repeated a certain number of times, the process may be terminated as a decoding failure. If it is determined that there is no phone number in the key ring with the encrypted encryption parameter, it is possible to display that the data cannot be decrypted without displaying the passphrase input screen. Good.

  Next, the processing in the CPU 22 shown in FIG. 7, specifically, the processing in the CPU 22 in step S54 will be described together with the flow of encryption and data. First, as shown in FIG. 8A, the CPU 22 acquires one encrypted unique key from the secret area 64 of the external memory 60, decrypts the encrypted unique key using the constant C, and encrypts the encrypted content. A data string composed of a key and a random number is calculated. The random number is a random number used when generating the encrypted content key (a random number used for creating a message digest).

  Next, as shown in FIG. 8B, the CPU 22 is assigned to the mobile phone 10 from the information of the mobile phone 10 stored in the profile 49 as in FIG. The telephone number information is read out, and a key (user key) is created from the telephone number information. Further, the CPU 22 creates a data string obtained by connecting the user key and an arbitrary random number, and calculates a message digest from the created data string. Thereafter, the CPU 22 decrypts the encrypted content key using the message digest, and calculates a content key (encryption parameter) and a checksum. Thereafter, a checksum value is calculated from the decrypted content key, compared with the checksum acquired when decrypted, and if both match, it is determined that the decryption is successful. If the two checksums have different values and the decryption fails, the process returns to the process of FIG. 8A and the same process is repeated using different encrypted unique keys stored in the secret area 64. Note that if decryption is not successful even after collation with all encrypted unique keys stored in the secret area 64, the data is not decrypted by the terminal in use.

  Next, when the decryption is successful and the content key is acquired, the CPU 22 reads the encrypted target data (content A ′) written in the external memory 60 as shown in FIG. 8C. Thereafter, the CPU 22 decrypts the read target data (content A ′) with the content key, and acquires the decrypted target data (content A). CPU22 displays the acquired content A on the display part 32, and is made to reproduce | regenerate or browse. The CPU 22 decrypts the target data encrypted as described above to make it in a viewable state.

  As described above, the mobile phone 10 encrypts the target data to be written in the external memory 60 using its own terminal and the telephone number of the target person's terminal that is set to be viewable. Even when the target data is stored, the possibility that the target data is browsed and reproduced by an unspecified third party can be reduced. Specifically, as shown in FIG. 9, a group A terminal (viewer) that is set to be viewable can view target data, and a group B terminal that is not set to be viewable is You can make the data invisible. FIG. 9 is an explanatory diagram for explaining the operation of the mobile phone.

  This makes it easy to exchange with others who want to be able to browse, and the phone number that is not assigned the same number and is difficult to duplicate is used as a key for encryption. By the operation, it is possible to suppress the possibility that the target data is browsed on an unintended terminal.

  Further, since the CPU 22 performs the decryption process based on the information stored as the telephone number of its own terminal, it can be decrypted without the operator performing an operation such as inputting a passphrase. As a result, the viewer can decrypt the data simply by inputting an instruction to reproduce and browse the target data. This eliminates the need for notifying the viewer of information such as a passphrase for decryption, thereby increasing the usefulness. Also, there is no need to worry about leaking passphrases.

  Further, by storing the decryption key in the secret area of the external memory, the general user can encrypt the target data without knowing that the key exists. As a result, a third party who browses the external memory can recognize that the data is broken or data that cannot be viewed on his / her own terminal. Thereby, the confidentiality of object data can be made higher.

  Furthermore, by setting a passphrase as in this embodiment, the confidentiality can be further increased. Here, FIG. 10 is an explanatory diagram for explaining the operation of the mobile phone. As shown in Fig. 10, even when the group name set in the address book is used to set the passphrase and the group name is specified as the target person, the passphrase is set and By notifying the passphrase to only some of the target persons, it is possible to prevent a person with a name in the group or a person who does not know the passphrase even from the terminal from solving the passphrase. Moreover, even if the portable terminal device 10 is lost by setting a passphrase, it is possible to reduce the possibility of being viewed by the acquirer. In this case, it is necessary to notify the passphrase, but even if the passphrase is leaked, the target data can be viewed and reproduced by a third party whose name or phone number is not listed in the address book Can be reduced. That is, it can only be played back by the terminal having the telephone number registered in the target decryption key.

  Further, by using the group setting of the address book as in the present embodiment, the operator can select a plurality of target users who can easily browse.

  Here, it is preferable that the mobile phone 10 increases or decreases the number of viewers who can browse the target data, that is, can update the key ring list as needed even after the target data is written in the external memory. . FIG. 11 is an explanatory diagram for explaining another operation of the mobile phone. For example, as shown in FIG. 11, the settings can be changed so that Mr. A and Mr. D can browse, but Mr. A can browse as it is and Mr. D cannot view. It is preferable to do. By making the key ring list updatable, operability can be improved. Furthermore, it is preferable that whether or not to set a passphrase can be reset. The operability can also be improved by enabling resetting in this way.

  In addition, as in the above embodiment, a key corresponding to each telephone number is individually created even when the key bundle list is updated by further encrypting the key (content key) obtained by encrypting the target data. It is possible to update the decryption key simply by deleting or deleting. Therefore, the decryption key can be changed without once decrypting the target data, changing the setting of the encryption key, and re-encrypting the data, thereby reducing the amount of processing by the CPU.

  In this embodiment, a telephone number is used as a key used for encryption and decryption. However, the present invention is not limited to this, and an e-mail address or a terminal number may be used. Here, the information that can be used as the key of the present invention is the information that can identify the target person, the information that the target person and the target person have in common, that is, the information that can be exchanged, and is difficult to duplicate. It needs to be information. Since telephone numbers, mail addresses, and terminal numbers are numbers that need to be identified, they are suitable because they are basically not duplicated. When terminal numbers are used, they may be actively exchanged, or may be exchanged and stored in the address book when communicating between terminals such as during a call. Here, it is preferable to use a mail address and a telephone number as the decryption key, and it is more preferable to use a telephone number. By using the e-mail address and telephone number, even if the terminal is replaced, if the e-mail address and telephone number remain as they are, they can be used without being changed. In addition, depending on the user, the e-mail address is more likely to be changed, so it is more preferable to use a telephone number.

  In the present embodiment, the operator selects the viewer, but the present invention is not limited to this. For example, when writing the transmitted / received e-mail in the external memory 60, the target person who has an address in the e-mail to be stored may be set to be viewable. Specifically, an e-mail address is extracted from the stored e-mail, the extracted e-mail address is compared with address book information, a telephone number is extracted, and encryption is performed using the extracted telephone number as a decryption key. You may do it. The mail address may be used as a decryption key.

  In the above embodiment, only whether or not the target data can be browsed and reproduced is selected. However, the present invention is not limited to this, and the number and types of information that can be browsed can be set for the target person. You may do it. For example, the information that can be browsed may be changed depending on whether or not the passphrase can be input, or the telephone number of the viewer, that is, the information that can be browsed by the viewer may be changed. Specifically, it may be set so that a closer viewer can browse and reproduce more information.

  Further, in the above embodiment, the encrypted terminal is encrypted based on the telephone number or the like as in the case of other viewers, but the key for decryption by the encrypted terminal needs to be the telephone number. Instead, it may be created by a one-way function. For example, a message digest may be used.

  In the above embodiment, the electronic device has a write task, a read task, an encryption task, and a decryption task. However, the present invention is not limited to this, and the electronic device is a write-only or read-only electronic device. Also good. That is, an electronic device having a writing task and an encryption task may be used, or an electronic device having a reading task and a decryption task. Each of the above effects can be obtained even when only the writing and encryption functions and only the reading and decryption functions are provided.

  As described above, the electronic device according to the present invention is useful for writing and / or reading information to / from an external memory, and when writing information that is intended to be viewed only by a specific target person to the external memory. It is suitable for use when reading information.

10 mobile phone 12 housing 22 CPU
24 memory 26 communication unit 28 operation unit 30 audio processing unit 32 display unit 34 connection terminal 40 write task 42 read task 44 encryption task 46 decryption task 48 address book 49 profile 50 microphone 52 speaker 60 external memory 62 system area 64 secret area 66 Normal area

Claims (10)

An external storage device composed of a storage area in which information is stored and a secret area in which confidential information is stored is detachable, and is an electronic device that writes information to and extracts information from the external storage device,
A self-identifying information storage unit for storing self-identifying information capable of identifying the self;
A specific information storage unit for storing other specific information capable of specifying other operators;
Encrypt write information to be written to the external storage device using an encryption key as a decryption key, and further create a plurality of decryption keys from the self-specific information and the other specific information, using each of the keys, An encryption unit for encrypting the encryption key;
A write unit for writing the encrypted write information in the encryption unit to the storage unit of the external storage device, and writing the encrypted encryption key to a secret area of the external storage device;
A reading unit that reads encrypted write information from the external storage device;
The decryption that collates the self-identifying information with the encrypted encryption key, decrypts the encryption key based on the self-identifying information if they match, and decrypts the encrypted information with the decrypted encryption key And an electronic device.   The electronic device according to claim 1, wherein the self-specific information and the other specific information include a telephone number.   The electronic device according to claim 1, wherein the self-specific information and the other specific information are configured by mail addresses.   The electronic device according to any one of claims 1 to 3, wherein the self-specific information and the other specific information include terminal information for specifying a terminal.   The electronic device according to claim 2, wherein the specific information storage unit is an address book. The address book stores a plurality of the other specific information as a group,
The electronic device according to claim 5, wherein the encryption unit uses the other specific information included in the designated group as a decryption key.   The electronic device according to claim 1, wherein the encryption unit encrypts the encryption key based on other specific information selected from a plurality of specific information. The encryption unit further encrypts using a passphrase as a decryption key,
The decryption unit collates the input phrase and the passphrase, and collates the self-identifying information with the encrypted encryption key when they match. The electronic device according to any one of the above.   The electronic device according to claim 1, wherein the decryption unit switches the write information to be decrypted according to a degree of coincidence of decryption processing. An external storage device composed of a storage area in which information is stored and a secret area in which confidential information is stored is detachable, and is an electronic device that writes information to and extracts information from the external storage device,
A self-identifying information storage unit for storing self-identifying information capable of identifying the self;
A reading unit that reads encrypted write information from the external storage device;
The decryption that collates the self-identifying information with the encrypted encryption key, decrypts the encryption key based on the self-identifying information if they match, and decrypts the encrypted information with the decrypted encryption key And an electronic device.

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