JP5052878B2 - Storage device and user authentication method - Google Patents

Description

  The present invention relates to a user authentication technique using encryption means.

  In recent years, with the development of IT technology, various storage media such as flash memory, hard disk, MO, and DVD have become widespread. In order to store information that is not desired to be known by a third party, such as confidential information for duties, in such a storage medium, a device for performing user authentication using a password and a device for storing data encrypted are being developed. For example, Patent Document 1 below discloses a portable storage device that performs usage authentication using a password input by a user.

Special table 2003-524842 gazette

  On the other hand, in such a storage device, there are cases where an administrator and a user want to use them properly from a plurality of standpoints. For example, when used by an administrator, it is possible to access a storage medium connected to a storage device and perform various settings related to the storage medium, and when used by a user without administrator authority. Is a case where it is desired to perform an operation in which only the storage medium connected to the storage device can be accessed.

  However, if the technique described in Patent Document 1 is used in such a case, the administrator and the user must manage the same password, and if one of them changes the password, Each time, it was necessary to convey the fact to the other party, which was cumbersome to operate. Alternatively, in order to avoid such a situation, it is necessary to set two types of passwords for the administrator and for the user, resulting in a problem that the security strength is lowered.

  In view of the above-described problems, the problem to be solved by the present invention is to provide a storage device that can ensure convenience and high security even when use authentication is performed from a plurality of standpoints.

The storage device of the present invention that solves the above problems is as follows.
A storage device capable of authenticating a user using an encryption means,
Public key encryption means for generating a predetermined public key and private key, performing encryption with the public key, and decrypting with the private key;
User identification information receiving means for receiving identification information for the user of the storage device input by a user of the storage device;
As an initial setting for authenticating the user, the public key encryption unit is used to generate a public key for the user, a public key and a secret key for the administrator of the storage device , and A first key is generated based on the user identification information received by the user identification information receiving means in response to the administrator input, and the first key is encrypted with the user public key. A second key that is encrypted, and a third key encrypted with the public key for the administrator, the public key for the user, the public key for the administrator, the second key, and the An initial setting means for storing a third key in a first storage medium provided in or connected to the storage device and for storing desired data;
A fourth key is generated based on the user identification information received by the user identification information receiving means in response to the user input, and the fourth key is generated using the public key encryption means. Is encrypted with the stored public key for the user, a fifth key is generated, the fifth key is compared with the stored second key, and the user checks at least the first key User authentication means for authenticating a user for enabling access to a storage medium;
An administrator private key receiving means for receiving the administrator private key in response to the operation of the administrator;
Using the public key encryption means to decrypt the stored third key with the administrator private key received by the administrator private key receiving means to generate a sixth key, A sixth key is encrypted with the stored user public key to generate a seventh key, the seventh key is compared with the stored second key, and the administrator The gist of the present invention is that it further comprises administrator authentication means for performing administrator authentication for enabling access to the first storage medium and setting various settings relating to the first storage medium.

  The storage device configured as described above performs user authentication based on the user identification information, and performs administrator authentication based on the administrator private key generated by the public key encryption unit. That is, since different methods are used for user and administrator authentication, a plurality of users can be authenticated without lowering the security strength.

  In this application, the storage device is a device that is integrally provided with a storage medium and a storage medium control device that writes data to the storage medium, such as a USB flash memory, an external hard disk drive, a computer, etc. Various devices and control devices that can be detachably connected to a storage medium and write data to the storage medium, for example, various devices such as a CD drive, a DVD drive, an MO drive, a Blu-ray drive, and a memory card reader Is a collective term.

  Further, in such a storage device, the first storage medium includes a hidden area that can be accessed only by a predetermined program, and the initial setting means includes a public key for the user, a public key for the administrator, and a second key. The third key may be stored in the hidden area.

  The storage device having such a configuration stores information related to the authentication of the administrator and the user in the hidden area of the storage medium connected to the storage device, so that the storage device should be in the hands of a third party. However, this information cannot be easily accessed. Therefore, the security of the storage medium connected to the storage device can be increased.

  Further, in such a storage device, the initial setting means further stores the secret key for the administrator in a second storage medium connected to the storage device, and the secret key reception means for the administrator The administrator secret key may be received in accordance with an operation for designating the location where the administrator secret key is stored.

  The storage device having such a configuration stores a secret key for the administrator used as an authentication key for administrator authentication in a second storage medium different from the first storage medium for storing desired data. Even when the first storage medium storing the data is lost or transferred to a third party, the authentication key information necessary for user authentication is not stored in the first storage medium. In addition, the third party is not easily authenticated by the user. Further, the administrator does not need to memorize the authentication key or record and store it on paper or the like. Therefore, security can be ensured and secret key information can be managed easily and reliably.

  Further, in such a storage device, after user authentication is performed, new user identification information is received in response to a user input in order to change the user identification information. When the means and the new user identification information accepting means accept the new user identification information, the initial setting means is used to create at least the first to third items based on the new user identification information. An initial setting changing unit that regenerates a key, stores the newly generated second key and the new third key in the first storage medium, and changes the initial setting. Also good.

  When the user changes the identification information for the user, the storage device having such a configuration also changes the information necessary for the administrator authentication stored in the storage medium. Even when the identification information is changed, the administrator authentication can be performed in the same manner as before the change.

  Further, in such a storage device, the initial setting changing means uses the initial setting means when the new user identification information accepting means accepts new user identification information, based on the new user identification information. In addition, the first to third keys and the public key for the user are regenerated, and the regenerated second key, the new third key, and the new public key for the user are generated. The initial setting may be changed by being stored in the first storage medium.

  Since the storage device configured as described above changes the user public key when the user changes the user identification information, the security can be improved.

  Further, in such a storage device, a common key encryption unit that generates a predetermined common key and encrypts or decrypts it with the common key, and a desired data and a first key as a common key encryption unit The data input means for encrypting and using the first key as the common key, and the desired data input after being encrypted by the data input means, and the first key as the common key encryption means It may be a device provided with data output means for decrypting using the common key and outputting from the first storage medium.

  The storage device configured as described above encrypts a common key for encrypting desired data stored in the first storage medium by a common key encryption method with a high processing speed by using a public key encryption method with high security. Since the encrypted common key is stored in the storage medium, both the writing speed to the storage medium and the security of the storage medium can be achieved. Further, since two types of encryption methods are used, security is improved as compared with the case where one type of encryption method is used.

  The present invention can be configured as a user authentication method in addition to the configuration as the storage device described above.

Examples of the present invention will be described in the following order.
(1) Schematic configuration of USB flash memory:
(2) Initial setting method for user authentication:
(3) User authentication method:
(4) User password change method:
(5) Administrator authentication method:
(6) Data encryption storage method:

(1) Schematic configuration of USB flash memory:
FIG. 1 is an explanatory diagram showing a schematic configuration of a USB flash memory 10 as an embodiment of the present application. The USB flash memory 10 includes a general-purpose input / output port 110, a CPU 120, a ROM 130, an SRAM 140, an encryption circuit 150, an internal interface 160, a flash memory 170, a USB connector 190, and a voltage control unit 200, which are connected via an internal bus. Has been.

  The general-purpose input / output port 110 is a parallel interface used when an additional device such as a fingerprint authentication device (not shown) is connected to the USB flash memory 10.

  The CPU 120 operates as a functional unit such as user authentication and data writing to the flash memory 170 by developing a program related to the control of the USB flash memory 10 stored in the flash memory 170 or the ROM 130 in the SRAM 140 and executing the program. To do.

  The ROM 130 is a nonvolatile memory, and stores firmware for starting up the USB flash memory 10 when the USB flash memory 10 is connected to the computer PC.

  The SRAM 140 is a buffer used when the CPU 120 performs various processes. In the present embodiment, a single buffer is shown for simplification, but a configuration comprising, for example, a buffer for the flash memory 170 and a buffer for the encryption circuit 150 for speeding up each process. It is good.

  The encryption circuit 150 is a circuit for encrypting / decrypting data input / output to / from the flash memory 170, a password for performing user authentication for enabling the USB flash memory 10, and the like. Both key encryption and common key encryption circuits are provided. In the present embodiment, the public key cryptosystem employs the RSA system, and the common key system employs the AES system. In this embodiment, the encryption circuit 150 is used as the encryption means, but another method such as encryption software may be used.

  The internal interface 160 includes an interface for exchanging data with the flash memory 170.

  The flash memory 170 is a non-volatile memory that erases data in block units. In this embodiment, the flash memory 170 is a NAND flash memory suitable for increasing the capacity.

  The USB connector 190 is a serial interface that can use a bus-powered power source, and is connected to a host computer PC having a USB port.

  The voltage control unit 200 adjusts the 5V bus-powered power supplied from the host computer PC connected via the USB connector 190 to, for example, 3.3V and supplies it to each unit.

  FIG. 2 is an explanatory diagram showing an internal area of the flash memory 170 shown in FIG. The flash memory 170 includes a hidden area 171, a free area 172, and a secure area 174. The free area 172 and the secure area 174 are a master boot record area, a partition information area, a file system information area, and a data information area (181 to 184 and 186 to 189 in the figure) for the free area or the secure area, respectively. ).

  The hidden area 171 is an area for storing programs used by the CPU 120 and information related to user authentication (to be described later) and data encryption stored in the flash memory 170. The free area 172 is an area that can be accessed without performing user authentication. The secure area 174 is an area that can be accessed only when the user authentication is successful.

  The master boot record areas 181 and 186 are areas that are read first when the USB flash memory 10 is started up, and are areas for storing information for starting up the driver of the USB flash memory 10. The partition information areas 182 and 187 are areas for storing a partition table in which the position and size of the internal area described above are recorded. The file system information areas 183 and 188 are areas for storing information for managing files and directories. The data information areas 184 and 189 are areas for storing data to be stored in the flash memory 170.

  The hidden area 171 described above is an area that can only be viewed using a dedicated program. Therefore, it cannot normally be seen on the OS of the host computer PC to which the USB flash memory 10 is connected. On the other hand, the free area 172 is an area that can be viewed on the OS of the host computer PC just by connecting the USB flash memory 10 to the host computer PC. The secure area 174 is an area that can be viewed after successful user authentication.

  The USB flash memory 10 includes an encryption function and a user authentication function as security functions for storing information that is not desired to be known by others in the secure area data information area 189 of the flash memory 170. The encryption function uses the encryption circuit 150 described above to encrypt data stored in the host computer PC connected to the USB flash memory 10 and store it in the secure area data information area 189. This function decrypts the encrypted data stored in the data information area 189 and outputs it to the host computer PC. When the user uses the USB flash memory 10, the user authentication function allows the user to input information such as a password, confirms whether or not the user is permitted in advance, and uses it in advance. This is a function that permits use of the secure area 174 of the USB flash memory 10 only when it is confirmed that the user is permitted.

  The USB flash memory 10 has two usage modes called a user mode and an administrator mode. In the user mode, the USB flash memory 10 is connected to the host computer PC, and data stored in the host computer PC is stored in the free area data information area 184 or the secure area data information area 189, or free area data is stored. Data stored in the information area 184 and the secure area data information area 189 can be output to the host computer PC. In the administrator mode, in addition to the operation in the user mode described above, various settings of the USB flash memory 10, for example, the setting for limiting the allowable number of inputs when the user password is entered incorrectly and the free area 172 cannot be changed. You can make settings. Therefore, the user authentication function described above is prepared for user mode authentication and administrator mode authentication.

(2) Initial setting method for user authentication:
FIG. 3 is a flowchart showing an initial setting procedure for user authentication of the USB flash memory 10. Only the above-mentioned administrator has the authority to perform this initial setting. The series of processing shown in the figure is started when the administrator connects the USB flash memory 10 to the computer PCm for the administrator and selects “initial setting” from the selection screen displayed on the monitor of the computer PCm. The When this process is started, the CPU 120 receives the user temporary password PW0 from the administrator who performs the initial setting (step S100). This temporary user password PW0 is determined as a default password at the time of shipment, and can be changed to the user password PW1 when the user uses the USB flash memory 10 (details are given below) Later).

  Next, the CPU 120 generates a key A0 from the received user temporary password PW0 (step S110). In this embodiment, the key A0 is obtained by converting the character string of the received user temporary password PW0 by UNICODE. However, the present invention is not limited to this, and the key A0 is uniquely obtained from the input password. Any method that can generate a key may be used. For example, another method may be used such as generating a salt using a pseudo-random number generator and generating a key A0 using the one-way hash function from the salt and the user temporary password PW0.

  When the key A0 is generated, the CPU 120 uses the encryption circuit 150 to generate the user public key B0 and the user private key C0, which are RSA encryption key pairs (step S120).

  Then, the CPU 120 encrypts the key A0 generated in step S110 with the user public key B0 generated in step S120 to generate a key A0B0 (step S130). The key A0B0 and the user public key B0 Is stored in the hidden area 171 of the flash memory 170 (steps S140 and S150), and the key A0 is stored in the RAM of the computer PCm connected to the USB flash memory 1 (step S160). The key A0B0 and the user public key B0 are information used for user authentication to be described later. If such information is stored in the hidden area 171 as described above, the USB flash memory 10 should be lost. Thus, even when the data is transferred to a third party, user authentication cannot be easily performed, and the confidentiality of the data stored in the USB memory 10 can be ensured.

  Next, the CPU 120 uses the encryption circuit 150 to generate an administrator public key D0 and an administrator private key E0, which are RSA encryption key pairs (step S170).

  The CPU 120 reads and encrypts the key A0 stored in the RAM of the computer PCm in step S160 with the administrator public key D0 generated in step S170, and generates the key A0D0 (step S180). A0D0 and the administrator public key D0 are stored in the hidden area 171 of the flash memory 170 (steps S190 and S200).

  Then, the CPU 120 displays an input instruction screen for the storage location of the administrator private key E0 on the monitor of the computer PCm, accepts the administrator input, and assigns the administrator private key E0 to the administrator computer PCm. Is stored in the designated location of the hard disk (step S210).

  With the above process, the initial setting for user authentication by the administrator is completed. As a result, the USB flash memory 10 is removed from the connected computer PCm and is used by the user. The above-described key A0, key A0B0, and key A0B0 are examples of the first key, the second key, and the third key, respectively, in the claims.

(3) User authentication method:
FIG. 4 is a flowchart showing a user authentication procedure when the user uses the secure area 174 of the USB flash memory 10 in the user mode. In the series of processes shown in the figure, the user connects the USB flash memory 10 for which the above-described initial setting has been completed to the user computer PCu, and performs “user mode authentication” from a selection screen displayed on the monitor of the computer PCu. Start by selecting. In order to use the secure area 174 of the USB flash memory 10, the user must undergo user authentication described below. When this process is started, the CPU 120 of the USB flash memory 10 receives the user temporary password PW0 from the user (step S300). In step S300, the temporary user password PW0 is accepted before the user password to be described later is changed. When the user changes the temporary user password PW0 to the desired user password PW1. The user password PW1 is accepted.

  Next, the CPU 120 generates a key A0 from the received user temporary password PW0 (step S300). This process is the same process as step S110.

  When the key A0 is generated, the CPU 120 reads the user public key B0 stored in step S150 from the hidden area 171 of the flash memory 170, and uses the user public key B0 to generate the key A0 generated in step S300. Is encrypted to generate a key A0B0 (step S320).

  When the key A0B0 is generated, the CPU 120 collates the key A0B0 generated in step S320 with the key A0B0 stored in the hidden area 171 of the flash memory 170 in step S140 (step 330).

  As a result, if the two keys do not match (step S330: NO), it means that the user temporary password input in step S300 is incorrect, and the CPU 120 displays the screen of the computer PCu to which the USB flash memory 10 is connected. Display an error (step S340), and return to step S300.

  On the other hand, if both keys match (step S330: YES), it means that the user temporary password input in step S300 is correct, and the CPU 120 stores the key A0 in the RAM of the computer PCu (step S350). Then, the user operation mode is entered (step S360), and the user authentication in the user mode is completed. In this user operation mode, in addition to inputting / outputting data to / from the free area data information area 184 and secure area data information area 189, the ratio between the free area 172 and the secure area 174 is changed, and a user password to be described later is changed. Is possible. Note that the key A0 is stored in the RAM of the computer PCu in the step S350 so that the key A0 is not left in the USB flash memory 10 from the viewpoint of security when the USB flash memory 10 is removed from the computer PCu. For this purpose, it may be stored in the SRAM 140 of the USB flash memory 10. In this embodiment, the key A0 is used as an encryption key when data is encrypted and stored in the secure area data information area 189 (details will be described later).

  The key A0 generated in step S310 is an example of the fourth key in the claims, and the key A0B0 generated in step S320 is an example of the fifth key in the claims.

(4) User password change method:
FIG. 5 is a flowchart illustrating a procedure when the user changes the user password of the USB flash memory 10 in the user mode. When the user authentication is successful, the user has the authority to change the user password in addition to accessing the secure area 174 in the flash memory 170. The series of processes shown in the figure is a selection that is displayed on the monitor of the computer PCu after the user connects the USB flash memory 10 to the user computer PCu, performs the above-described user mode authentication and shifts to the user operation mode. Start by selecting "Change User Password" from the screen. When this process is started, the CPU 120 of the USB flash memory 10 receives a new user password PW1 from the user (step S400).

  Next, the CPU 120 generates a key A1 from the received new user password PW1 (step S110). The method for generating the key A1 is the same as that in step S110.

  When the key A1 is generated, the CPU 120 uses the encryption circuit 150 to generate a user public key B1 and a user private key C1 that are a new RSA encryption key pair (step S420).

  Next, the CPU 120 determines that the user public key B1 generated in step S420 is not the same as the user public key B0 generated in step S120, and the administrator public key generated in step S170. It is determined whether it is not the same as D0 (step S430). As a result, when it is determined that the user public key B1 is the same as the user public key B0 or the administrator public key D0 (step S430: NO), the CPU 120 returns the process to step S420. The user public key and the user private key are generated again.

  On the other hand, if it is determined that the user public key B1 is not the same as the user public key B0 and not the same as the administrator public key D0 (step S430: YES), the CPU 120 generates in step S420. The user public key B1 is used to encrypt the key A1 generated in step S410 to generate a key A1B1 (step S440). The key A1B1 and the user public key B1 are stored in the hidden area 171 of the flash memory 170. (Steps S450 and S460).

  Next, the CPU 120 encrypts the key A1 generated in step S410 with the administrator public key D0 generated in step S170 to generate a key A1D0 (step S470). The key A1D0 is stored in the flash memory 170. Saving in the hidden area 171 (step S480).

  Thus, the setting of the user password by the user is completed, and thereafter, the user can perform user authentication using a new password desired by the user.

  In this embodiment, the user public key B1 and the user private key C1 are newly generated in the above step S420. This is a change of the user password rather than continuing to use the same key pair. This is because it is considered that security can be improved by changing to a new key pair by using an opportunity, and this is not necessarily performed. Instead of the newly generated user public key B1, the user public key B0 generated in the initial setting step S120 shown in FIG. 3 may be used as it is. In that case, the steps S420 and S430 are not necessary, and the key A1B0 is generated instead of the key A1B1 in the step 440. The steps S440 to S490 correspond to the change of the initial setting shown in FIG. 3, and the keys A1B1 and A1D0 are examples of new second and third keys in the claims.

(5) Administrator authentication method:
FIG. 6 is a flowchart showing the procedure of administrator authentication when the administrator uses the secure area 174 of the USB flash memory 10 or makes various settings in the administrator mode. The series of processes shown in the figure starts when the administrator connects the USB flash memory 10 to the administrator computer PCm and selects “administrator mode authentication” from the selection screen displayed on the monitor of the computer PCm. Is done. In order to use the secure area 174 of the USB flash memory 10, the administrator must perform administrator authentication described below. In the example shown in the figure, the above-described user password is changed prior to this processing. When this process is started, the CPU 120 of the USB flash memory 10 receives an administrator private key E0, which is an administrator authentication key, from the administrator (step S600).

  In this embodiment, in accordance with the instruction screen displayed on the monitor of the computer PCm by the CPU 120 in this embodiment, the administrator saves the administrator private key E0 (in this embodiment, the initial setting step S210 in FIG. 3). The CPU 120 reads and accepts the administrator private key E0 stored in the designated location. However, the present invention is not limited to this. . For example, in response to an operation in which the administrator copies the contents of the administrator private key E0 stored in a predetermined location on the hard disk of the computer PCm and pastes it on the instruction screen displayed on the screen of the computer PCm, the CPU 120 Various methods such as a method for accepting the administrator private key E0 and a method for the CPU 120 to accept the administrator private key E0 by inputting the contents of the administrator private key E0 recorded in advance on the paper by the administrator. Can be considered.

  When the administrator private key E0 is received, the CPU 120 reads the key A1D0 stored in step S480 from the hidden area 171 of the flash memory 170, and this key A1D0 is received in step S600. Decrypted with E0 to generate a key A1 as a sixth key (step S610).

  When the key A1 is generated, the CPU 120 reads out the user public key B1 stored in step S460 from the hidden area 171 of the flash memory 170, and uses the user public key B1 to generate the key A1 generated in step S610. Is encrypted to generate a key A1B1, which is a seventh key (step S620).

  When the key A1B1 is generated, the CPU 120 collates the key A0B0 generated in step S620 with the key A1B1 stored in the hidden area 171 of the flash memory 170 in step S450 (step S630).

  As a result, if the two keys do not match (step S630: NO), the manager private key E0 (administrator authentication key) received in step S600 is incorrect, and the CPU 120 stores the USB flash memory. An error is displayed on the screen of the computer PCm to which 10 is connected (step S640), and the process returns to step S600.

  On the other hand, if the two keys match (step S630: YES), it means that the administrator private key E0 received in step S600 is correct, and the CPU 120 stores the key A1 in the RAM of the computer PCm (step S600). In step S650, the process shifts to the administrator operation mode (step S660), and the user authentication in the administrator mode is completed. In this administrator operation mode, various settings related to the USB flash memory 10 can be made in addition to the operations possible in the user operation mode. The reason why the key A1 is stored in the RAM of the computer PCm is to prevent the key A1 from being left in the USB flash memory 10 when the USB flash memory 10 is removed from the computer PCm. It may be stored in the SRAM 140. The key A1 may be used as an encryption key when data is encrypted and stored in the flash memory 170 (details will be described later).

  In the above example, it is assumed that the user password is changed according to FIG. 5 and the user password PW1 is set before performing the administrator authentication. In step S610, the flash in step S480 is performed. Reads the key A1D0 stored in the memory 170, decrypts it to generate the key A1, encrypts it to generate A1B1, and collates it with the key A1B1 stored in the flash memory 170 in step S450 above If the user authentication is performed but the user does not change the user password shown in FIG. 5 and the default user temporary password PW0 is used and the USB flash memory 10 is used, the process proceeds to step S190. The key A0D0 stored in the flash memory 170 is read and decrypted to obtain the key A0. Form, which generates an A0B0 by encrypting, by matching the key A0B0 stored in the flash memory 170 in which the above step S140, it is of course to perform the administrator authentication.

  Note that the key A1 generated in step S610 is an example of a sixth key in the claims, and the key A1B1 generated in step S620 is an example of the seventh key in the claims.

  Since the USB flash memory 10 having such a configuration uses different methods for user and administrator authentication, it is possible to authenticate a plurality of users without lowering the security strength. In addition, even after the administrator makes initial settings, the administrator uses the administrator's private key stored in his / her computer PCm even if the user sets a new password desired by himself / herself. Administrator authentication can be performed using E0. Therefore, the operation of the USB flash memory 10 is facilitated.

(6) Data encryption storage method:
FIG. 7 is a flowchart showing a procedure in which the user encrypts predetermined data D stored in the user computer PCu and stores it in the secure area data information area 189 of the flash memory 170 included in the USB flash memory 10. . The series of processes shown in the figure shows a predetermined instruction, for example, an encryption area displayed on the monitor of the computer PCu after the user succeeds in the authentication in the user mode of FIG. 4 and shifts to the user operation mode. This is started by dragging a file to be saved in the flash memory 170 to the window. When this process is started, the CPU 120 of the USB flash memory 10 reads the key A0 stored in step S350 of FIG. 4 from the RAM of the user computer PCu (step S700).

  When the key A0 is read, the CPU 120 receives the data D of the file to be stored in the flash memory 170 from the user computer PCu via the USB connector 180, and stores it in the SRAM 140 (step S710).

  When the data to be stored is received, the CPU 120 encrypts the data using the SRAM 140 and the encryption circuit 150 using the key A0 read in step S700 as a common key for the common key encryption method (step S720). In the present embodiment, the key A0 generated from the user password PW0 is used as the above-mentioned common key. However, the present invention is not limited to this, and a key not related to the user password PW0 or the key A0 may be used. Good.

  Then, the CPU 120 stores the data D encrypted in step S720 in the secure area data information area 189 of the flash memory 170 (step S730).

  Through the above processing, predetermined data stored in the user computer PCu is encrypted and stored in the secure area data information area 189 of the flash memory 170 included in the USB flash memory 10. In the above example, it is assumed that the user password shown in FIG. 5 has not been changed, and the key A0 is used as the common key. A1 will be used. The same applies to the case where the administrator succeeds in authentication in the administrator mode and shifts to the administrator operation mode. Furthermore, when the data D encrypted and stored by the procedure of FIG. 7 is decrypted and stored in the user computer PCu, the common key A0 is read, the encrypted data is read and decrypted in the same flow. The computer PCu is stored in a predetermined location.

  Since the USB flash memory 10 having such a configuration uses two types of encryption methods, a public key method and a common key method, for user authentication and encryption of stored data, one type of encryption method is used. Compared with security. In addition, by using a common key encryption method with a high processing speed for data encryption and using a public key encryption method with high security for user authentication, both the processing speed and the security of the storage medium can be achieved.

  As mentioned above, although the Example of this invention was described, this invention is not limited to such an Example, Of course, in the range which does not deviate from the summary of this invention, it can implement in a various aspect. For example, the storage device of the present invention is not limited to the USB flash memory shown in the embodiment, but can be applied to various storage devices such as an external hard disk drive, a CD drive, a DVD drive, an MO drive, a Blu-ray drive, and a memory card reader. be able to. Also, it can be realized in the form of a user authentication method. For example, it is applied to user authentication of a notebook computer, and an administrator private key E0 is stored in a USB flash memory, or a mobile phone is used. Various modes are conceivable, such as a mode in which the administrator private key E0 is stored in an SD card or miniSD by applying to the user authentication.

It is explanatory drawing which shows schematic structure of the USB flash memory 10 as an Example. 3 is an explanatory diagram showing an internal area of a flash memory 170. FIG. 4 is a flowchart showing a procedure of initial setting for performing user authentication of the USB flash memory 10; It is a flowchart which shows the user authentication procedure when a user uses the secure area 174 of the USB flash memory 10 in the user mode. It is a flowchart which shows the procedure at the time of a user changing the user password of the USB flash memory 10 in user mode. 4 is a flowchart showing a procedure for administrator authentication when the administrator uses the secure area 174 of the USB flash memory 10 or makes various settings in the administrator mode. 4 is a flowchart showing a procedure in which a user encrypts predetermined data D stored in a user computer PCu and stores it in a secure area data information area 189 of the USB flash memory 10.

Explanation of symbols

10 ... USB flash memory 110 ... General-purpose input / output port 120 ... CPU
130 ... ROM
140 ... SRAM
DESCRIPTION OF SYMBOLS 150 ... Circuit for encryption 160 ... Internal interface 170 ... Flash memory 171 ... Hidden area 172 ... Free area 174 ... Secure area 181 ... Master boot record area for free area 182 ... Partition information area for free area 183 ... File system information for free area Area 184 ... Free area data information area 186 ... Secure area master boot record area 187 ... Secure area partition information area 188 ... Secure area file system information area 189 ... Secure area data information area 190 ... USB connector 200 ... Voltage Control unit

Claims (9)

A storage device capable of authenticating a user using an encryption means,
Public key encryption means for generating a predetermined public key and private key, performing encryption with the public key, and decrypting with the private key;
User identification information receiving means for receiving identification information for the user of the storage device input by a user of the storage device;
As an initial setting for authenticating the user, the public key encryption unit is used to generate a public key for the user, a public key and a secret key for the administrator of the storage device , and A first key is generated based on the user identification information received by the user identification information receiving means in response to the administrator input, and the first key is encrypted with the user public key. A second key that is encrypted, and a third key encrypted with the public key for the administrator, the public key for the user, the public key for the administrator, the second key, and the An initial setting means for storing a third key in a first storage medium provided in or connected to the storage device and for storing desired data;
A fourth key is generated based on the user identification information received by the user identification information receiving means in response to the user input, and the fourth key is generated using the public key encryption means. Is encrypted with the stored public key for the user, a fifth key is generated, the fifth key is compared with the stored second key, and the user checks at least the first key User authentication means for authenticating a user for enabling access to a storage medium;
An administrator private key receiving means for receiving the administrator private key in response to the operation of the administrator;
Using the public key encryption means to decrypt the stored third key with the administrator private key received by the administrator private key receiving means to generate a sixth key, A sixth key is encrypted with the stored user public key to generate a seventh key, the seventh key is compared with the stored second key, and the administrator A storage device comprising: administrator authentication means for performing administrator authentication for enabling access to the first storage medium and setting various settings relating to the first storage medium. The storage device according to claim 1,
The first storage medium includes a hidden area that can be accessed only by a predetermined program,
The initial setting means stores the public key for the user, the public key for the administrator, the second key, and the third key in the hidden area. The storage device according to claim 1 or 2,
The initial setting means further stores the secret key for the administrator in a second storage medium connected to the storage device,
The manager private key accepting unit accepts the manager secret key in response to an operation of the manager specifying a location where the manager secret key is stored. A storage device according to any one of claims 1 to 3,
Further, after the user authentication is performed, in order to change the user identification information, new user identification information receiving means for receiving new user identification information in response to the user input;
When the new user identification information accepting means accepts the new user identification information, the initial setting means is used to at least the first to third based on the new user identification information. And an initial setting changing means for changing the initial setting by storing the newly generated second key and the new third key in the first storage medium. Storage device. The storage device according to claim 4,
When the new user identification information receiving means receives the new user identification information, the initial setting changing means uses the initial setting means based on the new user identification information. The first to third keys and the public key for the user are regenerated, and the regenerated new second key, the new third key, and the new public key for the user are generated. A storage device that stores the first storage medium and changes an initial setting. A storage device according to any one of claims 1 to 5,
And a common key encryption means for generating a predetermined common key and performing encryption and decryption using the common key;
Data input means for encrypting the desired data using the first key as a common key of the common key encryption means and inputting the desired data to the first storage medium;
Data output that is decrypted by using the first key as a common key of the common key encryption unit and is output from the first storage medium after being encrypted and input by the data input unit And a storage device. The storage device according to claim 1, wherein:
The first storage medium includes a storage area that is accessible before the user authentication or the administrator authentication. The storage device according to any one of claims 1 to 7,
The first storage medium includes a storage area that can be accessed only after the user authentication or the administrator authentication is performed. A user authentication method for authenticating a user so that the user can use a predetermined device by using public key encryption means,
As an initial setting for authenticating the user, the device generates a public key for the user of the device, a public key and a secret key for the administrator, and inputs to the administrator of the device. In response, the user identification information is received, a first key is generated based on the user identification information, and the first key is encrypted with the user public key. And a third key encrypted with the public key for the administrator, and the public key for the user, the public key for the administrator, the second key, and the third key , before KiSo location is provided, or is stored in the connected storage medium before KiSo location,
When performing user authentication so that the user can use at least part of the functions of the device, the user identification information is received in response to the user input, and the user identification information is A fourth key is generated, and the fourth key is encrypted with the stored public key for the user to generate a fifth key, and the fifth key and the stored second key are generated. Verify against the key of 2
When the administrator authenticates the administrator so that the functions of the device can be used, the administrator accepts a secret key for the administrator according to the operation of the administrator, and uses the secret key for the administrator. Decrypting the stored third key to generate a sixth key; encrypting the sixth key with the stored user public key to generate a seventh key; and A user authentication method for performing authentication by comparing a key with the stored second key.

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