JP2012147506A - Encryption key setting method, network system, management device, information processing terminal, and encryption key setting program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an encryption key setting method having advanced security and an extremely low possibility of information leakage even if a PC is stolen.SOLUTION: A PC 20 creates a public key C1 and a secret key C1. When a management server 10 receives the public key C1 and a setting request packet from the PC 20, the management server 10 creates a public key S1 and a secret key S1 of the own server. The PC 20 receives the public key S1 and returns the own specific information by encrypting it. The management server 10 decrypts the encrypted information, creates a security key using the specific information, time information, etc., and encrypts the security key with the public key C1 to transmit the security key. The PC 20 decrypts the received encrypted information using the secret key C1, and encrypts predetermined data using the security key.

Description

  The present invention relates to a technique for collectively managing a security key for encrypting (decrypting) information stored in an information processing terminal using a management device.

  Data (personal information or the like) important for the user is stored in a storage device (for example, a hard disk) such as a personal computer (hereinafter referred to as a PC). Therefore, it is desired to prevent leakage of stored data. For example, it is desired to prohibit reading and writing of data. Therefore, the data protection device disclosed in Patent Document 1 discloses a configuration in which data encrypted using an encryption key is divided into a plurality of blocks, the arrangement is changed, and then stored in a hard disk. According to this configuration, even if the encryption key is leaked, it is difficult to decrypt the data.

  Further, in the apparatus of Patent Document 1, when a master key (for example, removable media) is not attached, the hard disk is not recognized by the PC, and therefore data cannot be read out by the PC alone, and the security is high. .

JP 2004-126745 A

  However, in recent years, with the spread of notebook PCs, there are many opportunities to carry PCs. If the user left the device with the master key set on the PC (stolen), there was a risk of information leakage. In addition, when a removable medium is used as a master key, it is easy to carry the master key, so there is a high possibility that the user will leave the master key or be stolen, and there is still a risk of information leakage.

  In view of the above problems, an object of the present invention is to provide an encryption key setting method having a high degree of security that is extremely unlikely to leak information even if a PC is stolen.

  An encryption key setting method of the present invention is an encryption key setting method for setting an encryption key used when encrypting information stored in a storage unit of an information processing terminal, wherein the information processing terminal encrypts information. A request transmission step of generating a terminal public key to be converted and a terminal secret key for decrypting information encrypted by the terminal public key, and transmitting the terminal public key and the encryption key setting request to the management device; When the management device receives the terminal public key and the encryption key setting request, the management public key that encrypts information and the management secret key that decrypts the information encrypted by the management public key A public key transmitting step for transmitting the management public key to the information processing terminal, and the information processing terminal generates encrypted information obtained by encrypting its own unique information with the management public key. Said An encryption information transmission step for transmitting to the physical device; and an encryption key for generating a decryption information by decrypting the encrypted information with the management secret key and generating a cipher key corresponding to the decryption information A generating step; an encryption key storing step in which the management device stores the encryption key together with the decryption information in a storage unit provided in the management device; and the management device encrypts the data using the terminal public key. An encryption key transmission step of transmitting an encryption key to the information processing terminal; and the information processing terminal decrypts the encrypted encryption key using the terminal private key, and uses the decrypted encryption key to transmit the information. An encryption step for encrypting predetermined information stored in the storage unit of the processing terminal, wherein the information processing terminal connects the encryption information to the information processing terminal in the encryption information transmission step. It is transmitted including device information of the removable media is, the management device, in the encryption key generating step, and generating the encryption key using the unique information and the device information.

  In this invention, the information processing terminal (PC) generates its own public key and private key. The terminal public key and the setting request packet are transmitted to the management apparatus. The management device (server) generates its own public key and secret key, and transmits this management public key when receiving the setting request packet. The public key and the private key may be generated only once, or may be generated for each encryption key setting. The information processing terminal encrypts its own unique information (PC configuration information or the like) using the management public key. Thereafter, the encrypted unique information is transmitted to the management apparatus. The management device decrypts the encrypted unique information using the management secret key. Thereafter, an encryption key (security key) paired with the unique information is generated and stored together with the unique information in a storage unit in the management apparatus. The encryption key may be created from the unique information, or may be randomly generated using other information such as time information at that time. The management device encrypts and transmits the encryption key using the terminal public key. The information processing terminal decrypts the encryption key by using the terminal secret key and encrypts predetermined data (folder). The information used for generating the security key includes device information of removable media (USB memory or the like). By including this device information, even if the release request packet and the unique information are transmitted to the management apparatus in a state where the removable medium is not connected, the unique information cannot be decrypted because the unique information is different from the key generation time.

  In the above invention, the information processing terminal takes in a second public key different from the management public key in advance, and the management apparatus decrypts information encrypted in advance with the second public key. 2 When the private key is captured and the encryption key setting request is received, response information is transmitted instead of the management public key, and when the response information is received, the information processing terminal transmits its own unique information. Encrypted information encrypted with the second public key is generated and transmitted to the management device, and the management device decrypts the encrypted information encrypted with the second public key with the second secret key. It is also possible to generate decryption information.

  In this invention, a public key (second public key) is set in advance in the information processing terminal. In order to set the public key in advance, any method may be used such as obtaining the public key by means other than a network connection such as a USB memory. The management apparatus sets a secret key (second secret key) that is paired with the second public key. When the management device receives the setting request packet from the information processing terminal, the management device does not transmit the public key and performs only a response. When the information processing terminal receives the response, the information processing terminal encrypts its own unique information using the second public key. Thereafter, the encrypted unique information is transmitted. The management device decrypts the encrypted unique information using the second secret key.

  In the above invention, the information processing terminal transmits a descrambling request together with a terminal public key to the management device, and the management device receives the descrambling request from the information processing terminal for management. The public key is transmitted, and the information processing terminal generates encrypted information obtained by encrypting its own unique information with the management public key, and transmits the encrypted information to the management device. Is decrypted with the management secret key to generate decryption information, the storage unit provided in the management device is referred to with the decryption information, the encryption key corresponding to the decryption information is read, and the encryption key is used for the terminal An encryption key encrypted using a public key is transmitted to the information processing terminal, and the information processing terminal decrypts the encrypted encryption key using the terminal private key and uses the decrypted encryption key The encrypted information. It is also possible to reduction.

  In the present invention, the information processing terminal transmits a descrambling request. When receiving the descrambling request, the management device transmits the management public key again. The information processing terminal encrypts the unique information using the received management public key and transmits the encrypted information to the management apparatus. The management device decrypts the unique information using the management secret key, and refers to the storage unit using this unique information. As a result, the encryption key paired with the unique information is read and encrypted using the terminal public key. The management device transmits the encrypted encryption key to the information processing terminal. The information processing terminal decrypts the encryption key by using the terminal secret key, and decrypts predetermined data (folder).

  In the above invention, the information processing terminal transmits a descrambling request together with a terminal public key to the management device, and the management device receives response information from the information processing terminal when the descrambling request is received. The information processing terminal generates encrypted information obtained by encrypting its own unique information with the second public key, and transmits the encrypted information to the management device. The management device uses the second public key. Decrypt the encrypted encryption information with the management secret key to generate decryption information, refer to the storage unit provided in the management device with the decryption information, read the encryption key corresponding to the decryption information, and An encryption key obtained by encrypting an encryption key using the terminal public key is transmitted to the information processing terminal, and the information processing terminal decrypts the encrypted encryption key using the terminal secret key, and Encrypted using the decrypted encryption key It is also possible to decode the predetermined information.

  In the present invention, the information processing terminal transmits a descrambling request. When receiving the descrambling request, the management device transmits response information again. The information processing terminal encrypts the unique information using the acquired second public key and transmits it to the management apparatus. The management device decrypts the unique information using the second secret key, and refers to the storage unit using this unique information. As a result, the encryption key paired with the unique information is read and encrypted using the terminal public key. The management device transmits the encrypted encryption key to the information processing terminal. The information processing terminal decrypts the encryption key by using the terminal secret key, and decrypts predetermined data (folder).

  Further, the network system of the present invention is a network system including an information processing terminal including a storage unit that stores predetermined information, and a management device connected to the information processing terminal, and the information processing terminal includes: A terminal public key for encrypting information, a terminal key generating means for generating a terminal private key for decrypting information encrypted with the terminal public key, the terminal public key, and an encryption key setting request Terminal transmitting means for transmitting information to the management device, the management device having a management public key for encrypting information and a management secret key for decrypting the information encrypted by the management public key A management key generating means for generating, and a management transmitting means for transmitting the management public key when an encryption key setting request is received from the information processing terminal. Generates encrypted information obtained by encrypting unique information of the information processing terminal with the management public key and transmits the encrypted information to the management device. The management device decrypts the encrypted information with the management secret key. An encryption key generating means for generating decryption information and generating an encryption key corresponding to the decryption information; and a management storage means for storing the encryption key together with the decryption information. An encryption key encrypted using a public key is transmitted to the information processing terminal, and the information processing terminal decrypts the encrypted encryption key using the terminal private key and uses the decrypted encryption key And a key setting means for encrypting predetermined information stored in the storage means of the information processing terminal, wherein the terminal transmission means is a removable media device connected to the information processing terminal in the encrypted information Include information Transmitted, the encryption key generation means, and generates the encryption key using the unique information and the device information.

  In the present invention, the information processing terminal includes public key fetching means for fetching a second public key different from the management public key in advance, and the management key generating means 2 captures a second secret key for decrypting information encrypted with the public key, and when the management transmission means receives the encryption key setting request, transmits the response information instead of the management public key, When the terminal transmission means receives the response information, it generates encrypted information obtained by encrypting its own unique information with the second public key, and transmits the encrypted information to the management apparatus. The encryption key generation means The decryption information is generated by decrypting the encrypted information encrypted with the second public key with the second secret key.

  Further, the present invention is the above invention, wherein the terminal transmitting means transmits a descrambling request together with a terminal public key to the management device, and the management transmitting means receives the descrambling request when the information is received. The management public key is transmitted to the processing terminal, and the terminal transmission unit generates encrypted information obtained by encrypting its own unique information with the management public key, and transmits the encrypted information to the management device, thereby generating the encryption key Means decrypts the encrypted information with the management secret key to generate decryption information, refers to the management storage means with the decryption information, reads an encryption key corresponding to the decryption information, and the management transmission means Transmits the encryption key encrypted using the terminal public key to the information processing terminal, and the key setting means decrypts the encrypted encryption key using the terminal secret key and performs the decryption. Encrypted using the specified encryption key. Characterized by decoding a predetermined information.

  Further, the present invention is the above invention, wherein the terminal transmitting means transmits a descrambling request together with a terminal public key to the management device, and the management transmitting means receives the descrambling request, Response information is transmitted to the information processing terminal, and the terminal transmission means generates encrypted information obtained by encrypting its own unique information with the second public key, and transmits the encrypted information to the management apparatus. Decrypts the encrypted information encrypted with the second public key with the management secret key, generates decryption information, refers to the management storage means with the decryption information, and corresponds to the decryption information The management transmission means transmits the encryption key encrypted using the terminal public key to the information processing terminal, and the key setting means uses the encrypted encryption key as the terminal secret key. Decrypted using the decrypted cipher Characterized by decoding a predetermined information encrypted with.

  A management apparatus of the present invention is a management apparatus that is connected to an information processing terminal including a storage unit that stores predetermined information and sets an encryption key for encrypting or decrypting the predetermined information. Generated by the information processing terminal and encrypted by the terminal public key for encrypting information and the terminal request receiving means for receiving the encryption key setting request, the management public key for encrypting the information, and the management public key A management key generating unit for generating a management secret key for decrypting the received information, a management transmitting unit for transmitting the management public key when receiving an encryption key setting request from the information processing terminal, and the information processing terminal Encrypted information receiving means for receiving encrypted information encrypted using the management public key, decrypting the encrypted information with the management private key, generating decrypted information, and corresponding to the decrypted information Encryption key Encryption key generation means for generating, and management storage means for storing the encryption key together with the decryption information, wherein the management transmission means transmits the encryption key encrypted using the terminal public key to the information processing terminal. And the encryption information includes information specific to the information processing terminal and device information of a removable medium connected to the information processing terminal, and the encryption key generation means includes the unique information and the information The encryption key is generated using device information.

  An information processing terminal of the present invention is an information processing terminal that includes storage means for storing predetermined information and is connected to a management device, and is encrypted by a terminal public key that encrypts information and the terminal public key A terminal key generating means for generating a terminal secret key for decrypting the converted information, a terminal public key, a terminal request transmitting means for transmitting an encryption key setting request to the management apparatus, and the management apparatus. Management public key receiving means for receiving a management public key for encrypting information, generating encrypted information obtained by encrypting unique information of the information processing terminal with the management public key, and transmitting the encrypted information to the management device Encrypted information transmitting means, receiving an encryption key corresponding to decryption information obtained by decrypting the encrypted information encrypted with the management public key and encrypted by the management device with the terminal public key Key setting means for decrypting the encrypted encryption key using the terminal private key and encrypting predetermined information stored in the storage means using the decrypted encryption key And the encryption information transmitting means transmits the encryption information including device information of a removable medium connected to the information processing terminal, and the encryption key includes the unique information and the device. It is generated using information.

  The encryption key setting program of the present invention causes the information processing terminal and a management apparatus connected to the information processing terminal to set an encryption key used when encrypting information stored in the storage unit of the information processing terminal. An encryption key setting program, wherein the information processing terminal generates a terminal public key for encrypting information, a terminal key generation procedure for generating a terminal secret key, and an encryption key setting request together with the terminal public key, A terminal transmission procedure for transmitting to the management device; a management public key for encrypting information to the management device; a management key generation procedure for generating a management secret key; and a management public key for the information processing terminal. A management key transmission procedure for transmission, and an encryption information transmission procedure for causing the information processing terminal to generate encrypted information obtained by encrypting its own unique information with the management public key and to transmit to the management device; An encryption key generation procedure for causing the management device to decrypt the encrypted information with the management secret key to generate decryption information and generate an encryption key corresponding to the decryption information, and a storage unit provided in the management device A storage procedure for storing the encryption key together with the decryption information, an encryption key transmission procedure for transmitting the encryption key encrypted using the terminal public key to the information processing terminal, and Key decryption procedure for decrypting the encrypted encryption key using the terminal private key, and encryption for encrypting predetermined information stored in the storage unit of the information processing terminal using the decrypted encryption key The encryption information transmission procedure includes a procedure for transmitting the encryption information including device information of a removable medium connected to the information processing terminal, and the encryption key generation procedure includes: Characterized in that it comprises the steps of generating the encryption key using the unique information and the device information.

  As described above, according to the present invention, since the predetermined data is encrypted and decrypted with the security key set by the management apparatus, even if the PC is carried away, the data content can be decrypted by a third party. There is very little possibility that

  Even if the release request packet and the unique information are transmitted to the management apparatus in a state where the removable medium is not connected, the unique information cannot be decrypted because the unique information is different from that at the time of key generation, so that security is improved.

The block diagram which shows the structure of the network system of this invention Block diagram showing the configuration of the management server 10 Block diagram showing the configuration of the PC 20 The flowchart which shows the security key setting process of the management server 10 and PC20 A flowchart showing the decryption processing of the management server 10 and the PC 20 The flowchart which shows the security key setting process of the management server 10 which concerns on an application example, and PC20 The flowchart which shows the decoding process of the management server 10 which concerns on an application example, and PC20

Hereinafter, a network system according to an embodiment of the present invention will be described in detail with reference to the drawings. In the network system of this embodiment, a management server installed in a company or the like centrally manages security keys for encrypting (decrypting) data (folders) stored in a plurality of connected PCs. To do.
FIG. 1 is a block diagram showing a configuration of a network system according to the present embodiment. This network system includes a management server 10 and a plurality of PCs 20 connected to the management server 10. FIG. 2 shows the configuration of the management server 10, and FIG. 3 shows the configuration of the PC 20.

  The management server 10 is a centralized management apparatus that is installed in a company or the like and manages each PC 20. The management server 10 includes a CPU 101, a RAM 102, a storage unit 103, a WAN port 104, a timer 105, a wired LAN port 106, a wireless interface 107, a display unit 108, and an operation unit 109. Each component is connected via a bus.

  The CPU 101 controls the management server 10 in an integrated manner. The storage unit 103 stores programs for performing various processes of the management server 10. The CPU 101 performs various processes by reading out the program stored in the storage unit 103 and developing it in the RAM 102.

  The storage unit 103 stores information (such as an assigned IP address) of each PC 20 connected to the management server 10, a security key set for each PC 20, and the like.

The WAN port 104 is an interface for connecting to the Internet.
The timer 105 measures the time when the CPU 101 executes various processes and the time elapsed since the execution of each process. The measurement result is temporarily stored in the RAM 102.

  The wired LAN port 106 is an interface for connecting to a wired LAN, and the management server 10 is connected to a PC or the like equipped with a wired LAN adapter via the wired LAN port 106 and a LAN cable.

  The wireless interface 107 is a transceiver that transmits and receives radio waves used in a wireless LAN. The management server 10 can send and receive data to and from the PC via the wireless interface 107.

  The display unit 108 is a general-purpose display (LCD or the like), and displays the processing contents of the management server 10. The user looks at the screen of the display unit 108 and operates the management server 10. Note that the display unit 108 is not limited to being built in as illustrated, but may be externally attached.

  The operation unit 109 is a user interface for a user to give an instruction to the management server 10 and includes, for example, a mouse or a keyboard.

  In FIG. 3, the PC 20 is a general-purpose personal computer, and includes a CPU 201, a RAM 202, a storage unit 203, a general-purpose interface 204, a wired LAN adapter 205, a wireless LAN adapter 206, a display unit 207, and an operation unit 208. Each component is connected via a bus.

  The CPU 201 controls the PC 20 in an integrated manner. The storage unit 203 stores programs for performing various processes of the PC 20. The CPU 101 performs various processes by reading out the program stored in the storage unit 203 and developing it in the RAM 202.

  The storage unit 203 stores important information (such as personal information) for each user.

  The general-purpose interface 204 is configured by a USB interface, for example, and is an interface for connecting various external peripheral devices of the PC 20. For example, a removable medium (USB memory) is connected to the general-purpose interface 204.

  The wired LAN adapter 205 is an interface connected to the wired LAN, and the PC 20 is connected to the management server 10 via the wired LAN adapter 205 and the LAN cable.

  The wireless interface 206 is a transceiver that transmits and receives radio waves used in a wireless LAN. The PC 20 can send and receive data to and from the management server 10 via the wireless interface 206.

  The display unit 207 is a general-purpose display (LCD or the like) and displays the processing content of the PC 20. The user operates the PC 20 while viewing the screen of the display unit 207. Note that the display unit 207 is not limited to being built in as illustrated, and may be externally attached.

  The operation unit 208 is a user interface for a user to give an instruction to the PC 20, and includes, for example, a mouse or a keyboard.

  As described above, the management server 10 manages the security key of each PC 20. When the user connects the PC 20 to the management server 10 (such as connecting a LAN cable to a wired LAN adapter), the management server 10 sets a security key for each PC 20 and transmits it. The PC 20 encrypts predetermined data (folder) in the storage unit 203 using the received security key. The encrypted data can be decrypted only with the security key that the management server 10 transmits again. The security key is a strong key using an arbitrary character string of 64 bits or 128 bits, and if this security key does not leak, there is very little possibility that the data content will be decrypted by a third party.

  The network system of the present embodiment is extremely unlikely to leak this security key, and the management server 10 can collectively manage the keys of the PCs 10. Hereinafter, processing for setting a security key for each PC 10 in the network system will be described. In this embodiment, programs for performing the following various processes are installed in the OS (Operating System) of the PC 10 and the OS of the management server 10. Of course, you may make it use PC which has already installed the program.

  FIG. 4 shows a flowchart of the security key setting process of the management server 10 and the PC 20. 4 to 7, the process described as the management server 10 side is a process performed by the CPU 101 of the management server 10, and the process described as the PC 20 side is a process performed by the CPU 201 of the PC 20. When the user of each PC 20 performs a security key issue request (connects the PC 20 to the LAN or instructs the operation unit 208 to encrypt a specific folder) (s101), the PC 20 has its own public key C1 and private key. C1 is generated (102). The public key C1 and the private key C1 are a pair, and data encrypted with the public key C1 can be decrypted only with the private key C1. The public key C1 and the secret key C1 are randomly generated. Thereafter, the generated public key C1 and the setting request packet are transmitted to the management server 10 (s103).

  When receiving the setting request packet and the public key C1 (s201), the management server 10 generates a public key S1 and a secret key S1 of the management server 10 itself (s202). The public key S1 and the secret key S1 are also randomly generated. Thereafter, the public key S1 is transmitted to the PC 20 that transmitted the setting request packet (s203).

  The PC 20 receives the public key S1 from the management server 10 (s104), and determines whether this public key S1 is transmitted from a single management server (s105). When the PC 20 is connected to the management server 10 via a wireless LAN, for example, if a third party has installed a server of the same type (having the same function) as the management server 10, a response may be made from this server. Yes. Therefore, the PC 20 interrupts the processing when there are a plurality of responses. This prevents connection to a third party server and prevents so-called server impersonation. Note that the PC 20 may transmit a packet for interrupting the processing to the management server 10 when there are a plurality of responses. Further, the user may be notified of cancellation by displaying information on processing interruption on the display unit 207 of the PC 20. Furthermore, when connected by a wireless LAN, after transmitting a packet for interrupting processing, the radio wave reception intensity may be lowered and the processing may be repeated from s101. In this case, the process from s101 is repeated until the response becomes single.

  When receiving from the single management server 10, the PC 20 encrypts its own unique information using the received public key S1 (s106). The unique information includes PC 20 configuration information, user information, and the like. Thereafter, the encrypted unique information is transmitted to the management server 10 (s107).

  The management server 10 receives the encrypted information (s204) and decrypts it using its own secret key S1 (s205). Further, using the decrypted unique information of the PC 20, a security key dedicated to the PC 20 (its user) is created (s 206). Note that the security key is randomly generated by combining the time information, random number, etc. at that time in addition to the unique information. Time information is read from the timer 105. Therefore, even if a third party intercepts the unique information, it is not used for security key estimation. Thereafter, the management server 10 stores the security key in the storage unit 103 in association with the unique information (s207). The management server 10 encrypts the security key using the public key C1 of the PC 20 (s208), and transmits it to the PC 20 (s209).

  The PC 20 receives the encrypted security key (s108) and decrypts it using its own secret key C1 (s109). Finally, predetermined data (folder) in the storage unit 203 is encrypted using the security key (s110). The security key may be deleted by the PC 20 after encryption, or may be deleted when the PC 20 is disconnected from the LAN. After being encrypted, the encrypted data content cannot be read out until the management server 10 transmits the decryption security key. That is, even if the PC 20 is carried outside in this state and a third party refers to the storage unit 203 of the PC 20, it is impossible to read the data contents.

  Next, FIG. 5 shows a flowchart of the decryption process of the management server 10 and the PC 20. First, the user of each PC 20 performs an operation for requesting decryption of the encrypted data (connecting the PC 20 to the LAN or specifying the encrypted data or folder using the operation unit 208) (s301). The PC 20 generates its own public key C1 and private key C1 (302). These public key C1 and secret key C1 may be the same as or different from the public key C1 and secret key C1 in the processing shown in FIG. Thereafter, the generated public key C1 and the release request packet are transmitted to the management server 10 (s303).

  When receiving the release request packet and the public key C1 (s401), the management server 10 generates the public key S1 and secret key S1 of the management server 10 itself (s402). The public key S1 and the secret key S1 may be the same as or different from the public key S1 and the secret key S1 in the processing shown in FIG. Thereafter, the public key S1 is transmitted to the PC 20 that has transmitted the release request packet (s403).

  The PC 20 receives the public key S1 from the management server 10 (s304), and determines whether the public key S1 is transmitted from a single management server (s305). This is also in order to prevent connection to a third party server. Similar to the processing in FIG. 4, when there are a plurality of responses, the PC 20 may transmit a packet for interrupting the processing to the management server 10, or the processing may be performed on the display unit 207 of the PC 20. The user may be notified of cancellation by displaying interruption information. Furthermore, when connected by a wireless LAN, after transmitting a packet for interrupting processing, the radio wave reception intensity may be lowered and the processing may be repeated from s301.

  When received from the single management server 10, the PC 20 encrypts its own unique information using the received public key S1 (s306). The unique information is the same as the unique information in the processing of FIG. 4 and is configured by configuration information, user information, and the like of the PC 20. Thereafter, the encrypted unique information is transmitted to the management server 10 (s307).

  The management server 10 receives the encrypted information (s404) and decrypts it using its own secret key S1 (s405). Further, using the decrypted unique information of the PC 20, the security key for the PC 20 stored in the storage unit 103 is collated (s406). Note that if the unique information of the PC 20 is not stored in the storage unit 103 or the security key corresponding to the unique information is not stored, a packet for interrupting the processing may be transmitted to the PC 20. Good.

  Thereafter, the management server 10 reads the security key associated with the unique information stored in the storage unit 103 (s407). The management server 10 encrypts the security key using the public key C1 of the PC 20 (s408), and transmits it to the PC 20 (s409).

  The PC 20 receives the encrypted security key (s308) and decrypts it using its own secret key C1 (s309). Finally, predetermined data (folder) in the storage unit 203 is decrypted using the security key (s310). As a result, the user can read out the encrypted data contents. This security key may be deleted by the PC 20 itself after decryption or when the PC 20 is disconnected from the LAN. In addition, the management server 10 transmits an encryption instruction packet at regular intervals, and the PC 20 performs the processing (s102 to s110) in FIG. 4 to automatically encrypt predetermined data (folders) at regular intervals. You may make it do. Since the data is encrypted every certain time, when the PC 20 is carried away, predetermined data is in an encrypted state.

  Further, the security key used at the time of decryption may be a common key used at the time of encryption or a corresponding (different) key. When a different key is used, when the management server 10 generates a security key during encryption (s207 in FIG. 4), a corresponding decryption security key is generated.

  As described above, since the predetermined data is encrypted and decrypted, even if the PC is carried away, there is very little possibility of the data content being decrypted by a third party. Further, since the security key is collectively managed by a management server installed in the company or the like, there is very little risk that the security key will be lost (stolen) on the go like a removable medium. The public key C1 (public key S1) and the secret key C1 (secret key S1) may be generated once and then used as the same key. From the second time onwards, the processing speed is improved by omitting the key generation processing.

  In the present invention, the following application examples are possible. FIG. 6 is a flowchart showing security key setting processing of the management server 10 and the PC 20 according to the application example. In this application example, each PC 20 has already acquired the public key S1 of the management server 10 in advance. In order to obtain the public key in advance, any method may be used, such as obtaining it by means other than a network connection such as a USB memory.

  When the user of each PC 20 performs a security key issue request operation (connects the PC 20 to a LAN or instructs the operation unit 208 to encrypt a specific folder) (s501), the PC 20 has its own public key C1 and private key. C1 is generated (502). These public key C1 and secret key C1 may be the same as or different from the public key C1 and secret key C1 in the processing shown in FIG. Thereafter, the generated public key C1, the setting request packet, and information indicating that the public key has been acquired (public key acquired packet) are transmitted to the management server 10 (s503).

  When receiving the setting request packet, the public key C1, and the public key acquired packet (s601), the management server 10 reads the secret key S2 corresponding to the public key S2 (s602). In this application example, the secret key S2 is stored in advance in the storage unit 103. Note that the secret key S2 may also be imported from the outside. The public key S2 and the secret key S2 are a pair, and data encrypted with the public key S2 can be decrypted only with the secret key S2. Thereafter, the response information is transmitted to the PC 20 that has transmitted the setting request packet (s603).

  The PC 20 receives the response information from the management server 10 (s504), and determines whether this response information is transmitted from a single management server (s505). This is also in order to prevent connection to a third party server. Similar to the processing in FIG. 4, when there are a plurality of responses, the PC 20 may transmit a packet for interrupting the processing to the management server 10, or the processing may be performed on the display unit 207 of the PC 20. The user may be notified of cancellation by displaying interruption information. Furthermore, when connected by a wireless LAN, after transmitting a packet for interrupting the process, the radio wave reception intensity may be lowered, and the process may be repeated from s501.

  When received from the single management server 10, the PC 20 encrypts its own unique information using the acquired public key S2 (s506). The unique information includes PC 20 configuration information, user information, and the like. Thereafter, the encrypted unique information is transmitted to the management server 10 (s507).

  The management server 10 receives the encrypted information (s604) and decrypts it using the secret key S2 (s605). Further, using the decrypted unique information of the PC 20, a security key dedicated to the PC 20 (its user) is created (s606). The security key is randomly generated by combining the unique time information and the time information and random number at that time. Thereafter, the management server 10 stores the security key in the storage unit 103 in association with the unique information (s607). The management server 10 encrypts the security key using the public key C1 of the PC 20 (s608), and transmits it to the PC 20 (s609).

  The PC 20 receives the encrypted security key (s508) and decrypts it using its own secret key C1 (s509). Finally, predetermined data (folder) in the storage unit 203 is encrypted using the security key (s510).

  Next, FIG. 7 shows a flowchart of the decryption processing of the management server 10 and the PC 20 in the application example. First, the user of each PC 20 performs an operation for requesting decryption of the encrypted data (connecting the PC 20 to the LAN or specifying the encrypted data or folder using the operation unit 208) (s701). The PC 20 generates its own public key C1 and private key C1 (702). These public key C1 and secret key C1 may be the same as or different from the public key C1 and secret key C1 in the processing shown in FIG. Thereafter, the generated public key C1, release request packet, and public key acquired packet are transmitted to the management server 10 (s703).

  When receiving the release request packet, the public key C1, and the public key acquired packet (s801), the management server 10 reads the secret key S2 corresponding to the public key S2 (s802). As described above, the secret key S2 is stored in the storage unit 103 in advance. Thereafter, response information is transmitted to the PC 20 that has transmitted the release request packet (s803).

  The PC 20 receives the response information from the management server 10 (s704), and determines whether or not this response information is transmitted from a single management server (s705). This is also in order to prevent connection to a third party server. Similar to the processing in FIG. 6, when there are a plurality of responses, the PC 20 may transmit a packet for interrupting the processing to the management server 10, or the processing may be performed on the display unit 207 of the PC 20. The user may be notified of cancellation by displaying interruption information. Furthermore, when connected by a wireless LAN, after transmitting a packet for interrupting the processing, the radio wave reception intensity may be lowered and the processing may be repeated again from s701.

  When received from the single management server 10, the PC 20 encrypts its own unique information using the acquired public key S2 (s706). The unique information is the same as the unique information in the processing of FIG. 6 and is configured by configuration information, user information, and the like of the PC 20. Thereafter, the encrypted unique information is transmitted to the management server 10 (s707).

  The management server 10 receives the encrypted information (s804) and decrypts it using the secret key S2 (s805). Further, the security information for the PC 20 stored in the storage unit 103 is collated using the decrypted unique information of the PC 20 (s806). Note that if the unique information of the PC 20 is not stored in the storage unit 103 or the security key corresponding to the unique information is not stored, a packet for interrupting the processing may be transmitted to the PC 20. Good.

  Thereafter, the management server 10 reads the security key associated with the unique information stored in the storage unit 103 (s807). The management server 10 encrypts the security key using the public key C1 of the PC 20 (s808), and transmits it to the PC 20 (s809).

  The PC 20 receives the encrypted security key (s708) and decrypts it using its own secret key C1 (s709). Finally, the predetermined data (folder) in the storage unit 203 is decrypted using the security key (s710). As a result, the user can read out the encrypted data contents.

  As described above, also in the application example, the security key is managed by the management server 10. In this application example, since the PC 20 has acquired the public key S2 in advance, and the public key is not transmitted and received between the management server 10 and the PC 20, the security is further improved.

  In the present embodiment, the PC 20 and the management server 10 communicate with each other on a one-to-one basis. However, when transmitting the setting request packet (cancellation request packet), the PC 20 transmits the setting request packet by broadcast. Also good. In this case, the management server 10 realizes a function of a DHCP (Dynamic Host Configuration Protocol) server that performs processing for assigning an IP address to a new PC 20 while performing normal network communication with other PCs 20.

  Note that, when generating the security key, the configuration information of the PC 20 is used as unique information of each PC 20, and this configuration information includes device information of a removable medium (such as a USB memory) connected to the general-purpose interface 204 of the PC 20. You may do it. By including this device information, even if the release request packet and the unique information are transmitted to the management server 10 in a state where the removable medium is not connected, the unique information cannot be decrypted because the unique information is different from that at the time of key generation. Therefore, it can be realized that the removable medium is used as the second key.

10-Management server 20-PC

Claims (11)

An encryption key setting method for setting an encryption key used when encrypting information stored in a storage unit of an information processing terminal,
The information processing terminal generates a terminal public key for encrypting information and a terminal secret key for decrypting information encrypted with the terminal public key, and sends the terminal public key and encryption key setting request. A request sending step to send to the management device;
When the management device receives the terminal public key and the encryption key setting request, a management public key for encrypting information and a management private key for decrypting information encrypted by the management public key Generating and transmitting the management public key to the information processing terminal;
The information processing terminal generates encrypted information obtained by encrypting its own unique information with the management public key and transmits the encrypted information to the management device; and
The management device generates decryption information by decrypting the encrypted information with the management secret key, and generates an encryption key corresponding to the decryption information; and
An encryption key storage step in which the management device stores the encryption key together with the decryption information in a storage unit provided in the management device;
An encryption key transmission step in which the management device transmits an encryption key encrypted with the terminal public key to the information processing terminal;
The information processing terminal decrypts the encrypted encryption key using the terminal secret key, and encrypts predetermined information stored in the storage unit of the information processing terminal using the decrypted encryption key An encryption step;
Consists of
In the encrypted information transmission step, the information processing terminal transmits the encrypted information including device information of a removable medium connected to the information processing terminal,
The management apparatus, in the encryption key generation step, generates the encryption key using the unique information and the device information. The information processing terminal takes in a second public key different from the management public key in advance,
The management device takes in a second secret key for decrypting information encrypted with the second public key in advance, and transmits response information instead of the management public key when receiving the encryption key setting request And
When the information processing terminal receives the response information, the information processing terminal generates encrypted information obtained by encrypting its own unique information with the second public key, and transmits the encrypted information to the management device. 2. The encryption key setting method according to claim 1, wherein decryption information is generated by decrypting the encrypted information encrypted with the two public keys with the second secret key. The information processing terminal sends a descrambling request together with a terminal public key to the management device,
The management device, when receiving the descrambling request, transmits a management public key to the information processing terminal,
The information processing terminal generates encrypted information obtained by encrypting its own unique information with the management public key, and transmits the encrypted information to the management device.
The management apparatus decrypts the encrypted information with the management secret key to generate decryption information, refers to a storage unit provided in the management apparatus with the decryption information, and obtains an encryption key corresponding to the decryption information. Read, send the encryption key encrypted using the terminal public key to the information processing terminal,
The encryption according to claim 1, wherein the information processing terminal decrypts the encrypted encryption key using the terminal private key, and decrypts the predetermined information encrypted using the decrypted encryption key. Key setting method. The information processing terminal sends a descrambling request together with a terminal public key to the management device,
When the management device receives the descrambling request, it sends response information to the information processing terminal,
The information processing terminal generates encrypted information obtained by encrypting its own unique information with the second public key, and transmits the encrypted information to the management device.
The management device generates decryption information by decrypting the encrypted information encrypted with the second public key with the management secret key, refers to a storage unit provided in the management device with the decryption information, and Read the encryption key corresponding to the decryption information, send the encryption key encrypted using the terminal public key to the information processing terminal,
The encryption according to claim 2, wherein the information processing terminal decrypts the encrypted encryption key using the terminal private key and decrypts the predetermined information encrypted using the decrypted encryption key. Key setting method. An information processing terminal comprising a storage means for storing predetermined information, and a network system comprising a management device connected to the information processing terminal,
The information processing terminal includes: a terminal public key for encrypting information; and a terminal key generating unit for generating a terminal private key for decrypting information encrypted with the terminal public key.
Terminal transmission means for transmitting the terminal public key and the encryption key setting request to the management device,
The management device includes a management public key that encrypts information, and a management key generation unit that generates a management private key that decrypts information encrypted with the management public key;
A management transmission means for transmitting the management public key when an encryption key setting request is received from the information processing terminal;
The terminal transmission means generates encrypted information obtained by encrypting information unique to the information processing terminal with the management public key, and transmits the encrypted information to the management device.
The management device decrypts the encrypted information with the management secret key to generate decryption information, and generates an encryption key corresponding to the decryption information;
Management storage means for storing the encryption key together with the decryption information,
The management transmission means transmits an encryption key encrypted using the terminal public key to the information processing terminal,
The information processing terminal decrypts the encrypted encryption key using the terminal secret key, and encrypts predetermined information stored in the storage unit of the information processing terminal using the decrypted encryption key Key setting means,
The terminal transmission means transmits the encryption information including device information of a removable medium connected to the information processing terminal,
The network system characterized in that the encryption key generation means generates the encryption key using the unique information and the device information. The information processing terminal includes a public key fetching unit that fetches a second public key different from the management public key in advance,
The management key generating means takes in a second secret key for decrypting information previously encrypted with the second public key,
The management transmission means, when receiving the encryption key setting request, transmits response information instead of the management public key,
The terminal transmission means, when receiving the response information, generates encrypted information obtained by encrypting its own unique information with the second public key, and transmits the encrypted information to the management device,
6. The network system according to claim 5, wherein the encryption key generation unit generates decryption information by decrypting the encrypted information encrypted with the second public key with the second secret key. The terminal transmission means transmits a descrambling request together with a terminal public key to the management device,
The management transmission means transmits a management public key to the information processing terminal when receiving the descrambling request,
The terminal transmission means generates encrypted information obtained by encrypting its own unique information with the management public key and transmits the encrypted information to the management device,
The encryption key generating means generates decryption information by decrypting the encrypted information with the management secret key, refers to the management storage means with the decryption information, and reads an encryption key corresponding to the decryption information,
The management transmission means transmits an encryption key encrypted using the terminal public key to the information processing terminal,
The network according to claim 5, wherein the key setting unit decrypts the encrypted encryption key using the terminal secret key, and decrypts predetermined information encrypted using the decrypted encryption key. system. The terminal transmission means transmits a descrambling request together with a terminal public key to the management device,
The management transmission means transmits response information to the information processing terminal when receiving the descrambling request,
The terminal transmission means generates encrypted information obtained by encrypting its own unique information with the second public key, and transmits the encrypted information to the management device.
The encryption key generation means generates decryption information by decrypting the encrypted information encrypted with the second public key with the management secret key, refers to the management storage means with the decryption information, and Read the encryption key corresponding to
The management transmission means transmits an encryption key encrypted using the terminal public key to the information processing terminal,
The network according to claim 6, wherein the key setting unit decrypts the encrypted encryption key using the terminal secret key, and decrypts predetermined information encrypted using the decrypted encryption key. system. A management device connected to an information processing terminal having storage means for storing predetermined information and setting an encryption key for encrypting or decrypting the predetermined information;
A terminal public key that is generated by the information processing terminal and encrypts information, and a terminal request receiving means for receiving an encryption key setting request;
A management public key for encrypting information, and a management key generating means for generating a management private key for decrypting the information encrypted by the management public key;
A management transmission means for transmitting the management public key when an encryption key setting request is received from the information processing terminal;
Encrypted information receiving means for receiving encrypted information encrypted using the management public key in the information processing terminal;
An encryption key generating means for generating decryption information by decrypting the encrypted information with the management secret key, and generating an encryption key corresponding to the decryption information;
Management storage means for storing the encryption key together with the decryption information,
The management transmission means transmits an encryption key encrypted using the terminal public key to the information processing terminal,
The encrypted information includes information specific to the information processing terminal, and device information of a removable medium connected to the information processing terminal,
The management apparatus characterized in that the encryption key generation means generates the encryption key using the unique information and the device information. An information processing terminal provided with storage means for storing predetermined information and connected to a management device,
A terminal public key for encrypting information, and a terminal key generating means for generating a terminal private key for decrypting information encrypted by the terminal public key,
A terminal request transmission means for transmitting the terminal public key and an encryption key setting request to the management device;
A management public key receiving means for receiving a management public key for encrypting information generated by the management device;
Encrypted information transmitting means for generating encrypted information obtained by encrypting unique information of the information processing terminal with the management public key and transmitting the encrypted information to the management device;
An encryption key receiving means for receiving an encryption key corresponding to decryption information obtained by decrypting encrypted information encrypted with the management public key, the encryption key being encrypted by the management device with the terminal public key;
Key setting means for decrypting the encrypted encryption key using the terminal private key and encrypting predetermined information stored in the storage means using the decrypted encryption key;
With
The encrypted information transmitting means transmits the encrypted information including device information of a removable medium connected to the information processing terminal,
The information processing terminal, wherein the encryption key is generated using the unique information and the device information. An encryption key setting program that causes the information processing terminal and a management device connected to the information processing terminal to set an encryption key used when encrypting information stored in a storage unit of the information processing terminal,
A terminal key generation procedure for causing the information processing terminal to generate a terminal public key for encrypting information and a terminal secret key;
A terminal transmission procedure for causing the management apparatus to transmit an encryption key setting request together with the terminal public key;
A management key generation procedure for causing the management device to generate a management public key for encrypting information and a management secret key;
A management key transmission procedure for causing the information processing terminal to transmit a management public key;
An encrypted information transmission procedure for causing the information processing terminal to generate encrypted information obtained by encrypting its own unique information with the management public key and transmitting the encrypted information to the management device;
An encryption key generation procedure for causing the management device to generate the decryption information by decrypting the encryption information with the management secret key, and to generate an encryption key corresponding to the decryption information;
A storage procedure for storing the encryption key together with the decryption information in a storage unit provided in the management device;
An encryption key transmission procedure for causing the information processing terminal to transmit an encryption key encrypted using the terminal public key;
An encryption key decryption procedure for causing the information processing terminal to decrypt the encrypted encryption key using the terminal private key;
An encryption procedure for encrypting predetermined information stored in the storage unit of the information processing terminal using the decrypted encryption key;
And execute
The encrypted information transmission procedure includes a procedure for transmitting the encrypted information including device information of a removable medium connected to the information processing terminal,
The encryption key generation program includes a procedure for generating the encryption key using the unique information and the device information.

Images