Patent Publication Number: US-2009221264-A1

Title: Storage system of mobile terminal and access control method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a storage system of a mobile terminal and an access control method for restricting access to storage data stored in a storage medium attachable and detachable to and from the mobile terminal provided with a radio communication function. 
     2. Description of the Related Art 
     Along with recent developments in function, mobile terminals each provided with a radio communication function, such as mobile telephone terminals, can store a large amount of data including personal information, such as telephone books, short mails (SMS) and user certificates. 
     For example, in the third generation mobile telephone system (3GPP) using the W-CDMA system, the above-described personal information can be stored in a storage medium, specifically a universal subscriber identity module (USIM), which is attached and detached to and from a card slot provided in a mobile terminal. 
     Such a mobile terminal having a card slot for a USIM includes so-called “a lock function,” a function of restricting access to data stored in the USIM (see, for example, page 14 and FIGS. 4 and 5 of Japanese Patent Translation Publication No. 2001-08253). 
     Specifically, in response to a request made by an external device to activate the lock function, the mobile terminal sets a function of a controller to control access to the USIM to a lock mode. When the function of the controller is set to the lock mode, the access to the data stored in the USIM inserted into the card slot of the mobile terminal is restricted. 
     However, the above-described conventional method for restricting access to data stored in an USIM (storage medium) has the following problem. That is, even when a mobile terminal is set to the lock mode, if a USIM inserted into the mobile terminal is taken out from a card slot thereof and is inserted into a card slot of another mobile terminal that is set to the lock mode, the data stored in the USIM is made accessible. For this reason, if important data, such as personal information, is stored in the USIM, the conventional method might allow an unauthorized access to the important data. 
     SUMMARY OF INVENTION 
     The present invention has been made in view of the above problem. Accordingly, an object of the present invention is to provide a storage system of a mobile terminal and an access control method that more securely prevent unauthorized access to data stored in a storage medium attachable and detachable to and from the mobile terminal. 
     To solve the above-described problem, the present invention has the following aspects. Firstly, a first aspect of the present invention provides a storage system of a mobile terminal, which includes a mobile terminal (mobile terminal  100 ) having a radio communication function and a storage medium (USIM  150 ) attachable and detachable to and from the mobile terminal. The mobile terminal includes a control signal receiver (SMS receiver  101 ) configured to receive a control signal (SMS message M 1 ) from an external device of the mobile terminal and a relay unit (SMS relay unit  105 ) configured to relay, to the storage medium, the control signal including an access restriction request (access restriction request R 1 ) requesting restriction of access to storage data (user data D 1 ) stored in the storage medium. The storage medium includes an access controller (access controller  151 ) configured to set the storage medium to an access restriction state in which access from the outside of the mobile terminal to the storage data is restricted, based on the access restriction request included in the control signal relayed by the relay unit. 
     In such a storage system of a mobile terminal, the storage medium is set to an access restriction state in which access from the outside of the mobile terminal to the storage data is restricted, based on the access restriction request included in the control signal relayed by the mobile terminal. In other words, the storage medium itself is set to the access restriction state not by the mobile terminal but by the access controller operating on the storage medium. 
     For this reason, even if the storage medium inserted into the mobile terminal is taken out from the card slot thereof and then the taken-out storage medium is inserted into a card slot of another mobile terminal, the storage data stored in the storage medium, such as telephone books, short mails (SMS), and user certificates is inaccessible. 
     In short, such a storage system of a mobile terminal makes it possible to more securely prevent unauthorized access to the data stored in the storage medium attachable and detachable to and from the mobile terminal. 
     A second aspect of the present invention relates to the first aspect of the invention, in which: the mobile terminal includes a request determination unit (request determination unit  103 ) determining if the control signal received by the control signal receiver includes the access restriction request; and the relay unit relays the control signal including the access restriction request to the storage medium, in a case where the request determination unit determines that the control signal includes the access control request. 
     A third aspect of the present invention relates to the first aspect of the invention, in which: the mobile terminal includes a transmitter (access request transmitter  107 ) transmitting an access request (access request R 2 ) to the storage data to the storage medium; the storage medium includes an access request receiver (access request receiver  153 ) receiving the access request, and a state determination unit (state determination unit  155 ) determining if the storage medium is set to the access restriction state; and the access controller rejects the access request, in a case where the state determination unit determines that the storage medium is set to the access restriction state. 
     A fourth aspect of the present invention relates to the third aspect of the invention, in which: the storage medium has a control file (control file F 1 ) showing if the storage medium is in the access restriction state; the access controller rewrites a content of the control file into the access restriction state based on the access restriction request; and the state determination unit determines if the storage medium is set to the access restriction state based on the content of the control file. 
     A fifth aspect of the present invention provides an access control method which restricts access to storage data stored in a storage medium attachable and detachable to and from a mobile terminal provided with a radio communication function. The access control method includes the steps of: receiving a control signal from the outside of the mobile terminal; relaying, to the storage medium, the control signal including an access restriction request requesting restriction of access to the storage data; and setting the storage medium to an access restriction state in which access from the outside of the mobile terminal to the storage data is restricted, based on the access restriction request included in the relayed control signal. 
     According to the aspects of the present invention, it is possible to provide a storage system of a mobile terminal and an access control method thereof that more securely prevent unauthorized access to storage data stored in the storage medium attachable and detachable to and from the mobile terminal. 
     Note that the entire contents of the Japanese Patent Application No. 2008-040629, filed on Feb. 21, 2008, are incorporated herein by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration view of an overall communication system including a mobile terminal  100  according to an embodiment of the present invention; 
         FIG. 2  is a schematic block diagram of the mobile terminal  100  and a USIM  150  according to the embodiment of the present invention; 
         FIG. 3  is a functional block diagram of the mobile terminal  100  according to the embodiment of the present invention; 
         FIG. 4  is a functional block diagram of the USIM  150  according to the embodiment of the present invention; 
         FIG. 5  is an operational sequence diagram of the mobile terminal  100  and the USIM  150  that restrict access to storage data of the USIM  150  according to the embodiment of the present invention; and 
         FIGS. 6A and 6B  are an image view of an SMS message M 1  according to the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described below. Specifically, the description will be given in the following order: (1) Schematic Configuration of Overall Communication System including Mobile Terminal, (2) Configuration of Storage System of Mobile Terminal, (3) Operation of Storage System of Mobile Terminal, (4) Advantageous Effects, and (5) Other Embodiments. 
     In the following description of the drawings, the same or similar reference numerals are given to denote the same or similar portions. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. 
     Therefore, specific dimensions and the like should be determined by taking into consideration the following description. Moreover, as a matter of course, also among the drawings, there are included portions in which dimensional relationships and ratios are different from each other.
     (1) Schematic Configuration of Overall Communication System including Mobile Terminal   

       FIG. 1  is a schematic configuration view of an overall communication system including a mobile terminal  100  according to the present embodiment. As shown in  FIG. 1 , the communication system according to the present embodiment includes a communication network  10 , a radio base station  20 , an Over The Air server  30  (hereinafter, OTA server  30 ), and the mobile terminal  100 . The communication system according to the present embodiment is the third generation mobile telephone system adopting the W-CDMA system. 
     The radio base station  20  and the OTA server  30  are connected to the communication network  10 . The radio base station  20  executes radio communications with the mobile terminal  100  according to the W-CDMA system. In addition, according to a short message service (SMS), the mobile terminal  100  can transmit/receive an SMS message M 1  through the radio base station  20 . 
     The OTA server  30  performs transmission/reception of the SMS message M 1  with the mobile terminal  100 . In particular, in the present embodiment, the OTA server  30  transmits to the mobile terminal  100  an SMS message M 1  including an access restriction request R 1  (unillustrated in  FIG. 1  and see  FIG. 6A ) requesting restriction of access to storage data stored in a universal subscriber identity module (USIM)  150  (hereinafter, USIM  150 ) inserted into the mobile terminal  100 . In the present embodiment, the SMS message M 1  constitutes a control signal. 
     The OTA server  30  (OTA platform) performs encryption or the like on the SMS message M 1  including the access control request R 1 , and then transmits the SMS message to the mobile terminal  100  as a secure packet. 
     The mobile terminal  100  is a mobile telephone terminal provided with a radio communication function executing radio communications with the radio base station  20 . The mobile terminal  100  has a card slot (unillustrated) into which the USIM  150  is inserted. 
     The USIM  150  is a storage medium attachable and detachable to and from the mobile terminal  100 . The USIM  150  stores files relating to telephone books, short mails (SMS), and user certificates, which are used by the mobile terminal  100 . In the present embodiment, the mobile terminal  100  and the USIM  150  constitute a storage system of the mobile terminal.
     (2) Configuration of Storage System of Mobile Terminal   

     Next, the description will be given of the configurations of the mobile terminal  100  and the USIM  150  which constitute the storage system of the mobile terminal in the present embodiment. Specifically, the description will be given in the following order: (2.1) Schematic Block Configurations of Mobile Terminal and Storage Medium, (2.2) Functional Block Configuration of Mobile Terminal and (2.3) Functional Block Configuration of Storage Medium.
     (2.1) Schematic Block Configurations of Mobile Terminal and Storage Medium   

       FIG. 2  is a schematic block configuration view of the mobile terminal  100  and the USIM  150 . As shown in  FIG. 2 , the mobile terminal  100  includes a mobile equipment/USIM interface  110  (hereinafter, ME/USIM interface  110 ) and a USIM application toolkit  120  (hereinafter, USAT  120 ). 
     The ME/USIM interface  110  provides various interfaces between the mobile terminal  100  (ME) and the USIM  150 . The USAT  120  is configured of an application using the USAT function. The USAT  120  provides a function to control the USIM  150 , such as readout and update of the storage data stored in the USIM  150 . 
     Similar to the mobile terminal  100 , the USIM  150  includes an ME/USIM interface  160  and a USAT  170 . 
     The USAT  170  has a USAT framework  171 , a remote file management  172  (hereinafter, RFM  172 ), and an applet  173 . 
     The USAT framework  171  provides a framework of the USAT. The RFM  172  provides a function to remotely manage the various files stored in the USIM  150 . The applet  173  is a small application which is executed on the USIM  150 . In particular, in the present embodiment, the applet  173  provides a function to restrict access to the storage data stored in the USIM  150 . 
     Note that contents of the storage data stored in the USIM  150  and a control file F 1  (unillustrated in  FIG. 2  and see  FIG. 4 ) may be updated by using a personal computer  40  provided with a card slot (reader/writer) into which the USIM  150  can be inserted.
     (2.2) Functional Block Configuration of Mobile Terminal   

       FIG. 3  is a functional block diagram of the mobile terminal  100 . As shown in  FIG. 3 , the mobile terminal  100  includes an SMS receiver  101 , a request determination unit  103 , an SMS relay unit  105 , and an access request transmitter  107 . Note that portions relating to the present invention will be mainly described below. Accordingly, it should be noted that the mobile terminal  100  may include a block (such as baseband processor) which is necessary for achieving a function as the mobile terminal  100  but is unillustrated or is not described. 
     The SMS receiver  101  receives an SMS message M 1  from an external device of the mobile terminal  100 , specifically from the OTA server  30 . In the present embodiment, the SMS receiver  101  constitutes a control signal receiver. 
     The request determination unit  103  determines if the SMS message M 1  received by the SMS receiver  101  is an SMS message M 1  for OTA. Specifically, the request determination unit  103  determines if the SMS message received by the SMS receiver  101  includes an access restriction request R 1 . 
       FIG. 6A  shows an image view of the SMS message M 1  including the access restriction request R 1 . The access restriction request R 1  requests restriction of access to storage data, specifically user data D 1 , stored in the USIM  150 . 
     The SMS relay unit  105  relays the SMS message M 1  including the access restriction request R 1  to the USIM  150 . In the present embodiment, the SMS relay unit  105  constitutes a relay unit. The SMS relay unit  105  relays the SMS message M 1  including the access control request R 1  to the USIM  150  in a case where the request determination unit  103  determines that the SMS message M 1  includes the access restriction request R 1 . In addition, the SMS relay unit  105  can also relay an SMS message M 1  including an access request R 2  (see,  FIG. 6B ) to the USIM  150 .  FIG. 6B  shows an image view of the SMS message M 1  including the access request R 2 . 
     The access request transmitter  107  transmits, to the USIM  150 , the access request R 2  to the storage data (user data D 1 ) stored in the USIM  150 . In the present embodiment, the access request transmitter  107  constitutes a transmitter. 
     The access request transmitter  107  requests the SMS relay unit  105  to relay the SMS message M 1  to the USIM  150  in a case where the SMS message M 1  received from the OTA server  30  by the SMS receiver  101  includes the access request R 2 . The access request transmitter  107  can also transmit the SMS message M 1  including the access request R 2  to the USIM  150 , based on an operation of the mobile terminal  100 .
     (2.3) Functional Block Configuration of Storage Medium   

       FIG. 4  is a functional block diagram of the USIM  150 . As shown in  FIG. 4 , the USIM  150  includes an access controller  151 , an access request receiver  153 , a state determination unit  155 , a control file storage unit  157 , and a user data storage unit  159 . 
     The access controller  151  restricts access from the outside to storage data, based on the access restriction request R 1  included in the SMS message M 1  relayed by the SMS relay unit  105  of the mobile terminal  100 . Specifically, the access controller  151  sets the USIM  150  to an access restriction state (that is, a locked state) in which access from the outside to the user data D 1  is restricted, based on the access restriction request R 1  received from the mobile terminal  100 . 
     When the access restriction state is set, authorization to execute readout or update of a specific file included in the user data D 1  is restricted. The specific file includes information relating to telephone books, short mails (SMS), and user certificates. 
     Specifically, the access controller  151  sets the USIM  150  to the access restriction state by executing a command script shown in a data portion of the SMS message M 1 , after authenticating the SMS message M 1  relayed by the SMS relay unit  105  of the mobile terminal  100 . More specifically, the access controller  151  rewrites the content of the control file F 1  into an access restriction state, based on the received access restriction request R 1 . 
     In addition, the access controller  151  rejects the access request to the user data D 1  if the state determination unit  155  determines that the USIM  150  is set to the access restriction state. 
     Specifically, if the access request such as a readout request or an update request for a specific file included in the user data D 1  is acquired while the USIM  150  is set to the access restriction state, the access controller  151  sends an error response to the mobile terminal  100  and does not execute the readout or update of the specific file. Note that the content displayed on a display unit (unillustrated) of the mobile terminal  100  (for example, display of an error message) depends on functions provided for the mobile terminal  100 . 
     In addition, the access controller  151  rewrites the content of the control file F 1  into a normal state (that is, an unlocked state) if the SMS message M 1  which releases the access restriction state is received. If an access request is acquired while the USIM  150  is set to the normal state, the access controller  151  executes the access request. 
     The access request receiver  153  receives an access request from the mobile terminal  100 . Specifically, the access request receiver  153  receives the SMS message M 1  including the access request R 2  which is relayed by the SMS relay unit  105  of the mobile terminal  100 . The access request receiver  153  notifies the state determination unit  155  of the access request R 2  included in the received SMS message M 1 . 
     The state determination unit  155  determines if the USIM  150  is set to the access restriction state. Specifically, if the access request R 2  is notified from the access request receiver  153 , the state determination unit  155  determines, based on the content of the control file F 1 , if the USIM  150  is set to the access restriction state. The state determination unit  155  notifies the access controller  151  if the USIM  150  is set to the access restriction state. 
     The control file storage unit  157  stores the control file F 1 . The control file F 1  shows if the USIM  150  is in the access restriction state. 
     The user data storage unit  159  stores the user data D 1  including files relating to telephone books, short mails (SMS), and user certificates.
     (3) Operation of Storage System of Mobile Terminal   

     Next, the description will be given of operations of the mobile terminal  100  and the USIM  150  which constitute the storage system of the mobile terminal in the present embodiment. Specifically, the operation of restricting access to storage data stored in the USIM  150  will be described. 
       FIG. 5  is an operational sequence diagram of the mobile terminal  100  and the USIM  150 , which restricts access to storage data stored in the USIM  150 . As shown in  FIG. 5 , at step S 10 , power is supplied to the mobile terminal  100  (and the USIM  150 ). Then, the mobile terminal  100  and the USIM  150  start up. 
     At step S 20 , the mobile terminal  100  notifies the USIM  150  of a terminal profile of the mobile terminal  100 . 
     At step S 30 , the USIM  150  notifies the mobile terminal  100  of a response to the acquisition of the terminal profile. 
     At step S 40 , the USAT  120  of the mobile terminal  100  and the USAT  170  of the USIM  150  are set to an idle state. 
     At step S 50 , the OTA server  30  transmits the SMS message M 1  including the access restriction request R 1  to the mobile terminal  100 . The access restriction request R 1  includes a group of commands (SELECT command and UPDATE BINARY command) to the USIM  150  to update EF_LOCK. 
     At step S 60 , the mobile terminal  100  determines that the access restriction request R 1  is included in the SMS message M 1  received from the OTA server  30 , and relays the SMS message M 1  to the USIM  150 . 
     At step S 70 , the USIM  150  executes command processing, based on the access restriction request R 1  included in the received SMS message M 1 . Specifically, the USIM  150  executes the command script displayed on the data portion of the SMS is message M 1 , so that the USIM  150  is set to the access restriction state. 
     At step S 80 , the USIM  150  notifies the mobile terminal  100  of a response to the received SMS message M 1 . 
     At step S 90 , the mobile terminal  100  transmits, to the OTA server  30 , an SMS reception notification showing that the SMS message M 1  is received. 
     At step S 100 , the mobile terminal  100  requests the USIM  150  to execute the command script. Specifically, the mobile terminal  100  instructs the USIM  150  to fetch the command script. 
     At step S 110 , the USIM  150  executes SEND SMS, based on the fetch instruction from the mobile terminal  100 . With the command script being executed, the USIM  150  notifies the mobile terminal  100  of an execution result of the command script. 
     At step S 120 , the mobile terminal  100  transmits, to the OTA server  30 , a command execution result notification showing that the command to set the USIM  150  to the access restriction state is executed, based on the information (SEND SMS) notified from the USIM  150 . 
     Subsequently, at step S 130 , the mobile terminal  100  transmits, to the USIM  150 , an access request to the user data D 1  stored in the USIM  150 . The access request is transmitted to the USIM  150  when a user of the mobile terminal  100  operates the mobile terminal  100 . In addition, the mobile terminal  100  can receive the SMS message M 1  (see  FIG. 6B ) including the access request R 2  from the OTA server  30 , and transmit the received SMS message M 1  to the USIM  150 . 
     At step  140 , the USIM  150  determines if the USIM  150  is set to the access restriction state. Specifically, in a case where the access request is acquired, the USIM  150  determines based on the content of the control file F 1  if the USIM  150  is set to the access restriction state. 
     Since the USIM  150  is set to the access restriction state in the processing at step S 70 , the USIM  150  rejects the access request to the user data D 1  and executes error processing. 
     At step S 150 , the USIM  150  notifies the mobile terminal  100  of an error response to the access request. That is, the USIM  150  notifies the mobile terminal  100  that the access request to the user data D 1  is rejected and the error processing is executed.
     (4) Advantageous Effects   

     In the storage system of the mobile terminal according to the present embodiment, the USIM  150  is set to the access restriction state in which access from the outside to the user data D 1  is restricted according to the access restriction request R 1  included in the SMS message M 1  relayed by the mobile terminal  100 . That is, not the mobile terminal  100  but the USIM  150  itself is set to the access restriction state by the access controller  151  operating on the USIM  150 . In addition, the access controller  151  rejects the acquired access request to the user data D 1 , in a case where the state determination unit  155  determines that the USIM  150  is set to the access restriction state. 
     For this reason, even if the USIM  150  is taken out from the card slot of the mobile terminal  100  and the taken-out USIM  150  is inserted into a card slot of another mobile terminal, the user data D 1  stored in the USIM  150 , such as telephone books, short mails (SMS), and user certificates is inaccessible. 
     In other words, such a storage system of the mobile terminal makes it possible to more securely prevent unauthorized access to the data stored in the USIM  150  attachable and detachable to and from the mobile terminal  100 . 
     In the present embodiment, the SMS relay unit  105  relays the SMS message M 1  including the access restriction request R 1  to the USIM  150 , in a case where the request determination unit  103  determines that the SMS message M 1  includes the access restriction request R 1 . For this reason, the SMS message M 1  which does not relate to the USIM  150  can be prevented from being relayed. 
     In the present embodiment, the state determination unit  155  determines based on the content of the control file F 1  if the USIM  150  is set to the access restriction state. Accordingly, it can be quickly determined if the USIM  150  is set to the access restriction state by using the control file F 1  having a simple configuration. 
     In the present embodiment, the SMS message M 1  including the access request R 2  can also be received from the OTA server  30 . Accordingly, even when the mobile terminal  100  is stolen or lost, the mobile terminal  100  can be remotely set to the access restriction state.
     (5) Other Embodiments   

     As described above, the content of the present invention has been disclosed by using one embodiment of the present invention. However, it should not be understood that the description and drawings which constitute one part of this disclosure limit the present invention. From this disclosure, various alternative embodiments will be apparent to a person skilled in the art. 
     For example, in the above-described embodiment of the present invention, it is determined based on the control file F 1  if the USIM  150  is set to the access restriction state. However, the control file F 1  does not always have to be used. For example, every time an access request to the user data D 1  is acquired, the access request is tested. Then, when access to user data D 1  which is set to the access restriction state is rejected, it may be determined that the user data D 1  is set to the access restriction state. 
     In the above-described embodiment, when the request determination unit  103  determines that the access restriction request R 1  is included in the SMS message M 1 , the SMS message M 1  including the access restriction request R 1  is relayed to the USIM  150 . However, it is also possible that all the SMS messages M 1  are relayed to the USIM  150  and then only the SMS message M 1  necessary for the USIM  150  is acquired. 
     In the above-described embodiment, the user data D 1  is set to the access restriction state by using the entire user data D 1  as a target. However, for example, it is also possible that the user data D 1  is set to the access restriction state only by using files relating to personal information as a target. 
     In the above-described embodiment, the SMS message M 1  is used as a control signal. However, it is also possible that the access restriction request R 1  and the access request R 2  are transmitted by using not the SMS message M 1  but, for example, general e-mails or dedicated control signals. 
     In the above-described embodiment, the description has been given by using the third generation mobile telephone system adopting the W-CDMA system as an example. However, the radio communication system to which the present invention is applied is not limited to the third generation mobile telephone system adopting the W-CDMA system. 
     As described above, the present invention includes, as a matter of course, various embodiments which are not described herein. Accordingly, the technical scope of the present invention is defined only by the particular matters included in the scope of claims which are appropriate from this disclosure.