Abstract:
A mobile terminal device includes biometric information detecting means for detecting biometric information; encryption key generating means for generating an encryption key on the basis of the biometric information in registration; encrypting means for encrypting a predetermined personal identification number with the encryption key to generate a biometric encrypted personal identification number in the registration; encrypted personal-identification-number storing means for storing the biometric encrypted personal identification number in the registration; decryption key generating means for generating a decryption key on the basis of the detected biometric information in verification; decrypting means for decrypting the biometric encrypted personal identification number with the decryption key to reproduce the personal identification number in the verification; and personal identification number verifying means for comparing the reproduced personal identification number with the stored biometric encrypted personal identification number to perform the personal-identification-number verification.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]     The present invention contains subject matter related to Japanese Patent Application JP 2005-196063 filed in the Japanese Patent Office on Jul. 5, 2005, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a mobile terminal device, a personal identification number (hereinafter referred to as a PIN) verification program, and a method of verifying a PIN, which are preferably applicable to, for example, a mobile telephone, a personal handyphone system (PHS), a personal digital assistant (PDA) with a wireless communication function, or a laptop personal computer, having a PIN verification function and a biometric information detecting function.  
         [0004]     2. Description of the Related Art  
         [0005]     Mobile telephones including ones adopting a global system for mobile communications (GSM) are known nowadays, which perform user authentication with subscriber identity module (SIM) cards detachable from the telephones. Specifically, each SIM card has information concerning a subscriber and a PIN stored therein. A user operates an operational unit of the mobile telephone to input the own PIN. The PIN input by the user is compared with the PIN stored in the SIM card. Use of the mobile telephone is permitted only if the PIN input by the user coincides with the one stored in the SIM card.  
         [0006]     Meanwhile, user authentication using biometric information including the fingerprints, irises, or vein patterns of users comes into practical use in recent years. For example, an electronic device and an authentication method using such user authentication are disclosed in Japanese Unexamined Patent Application Publication No. 2002-512409.  
       SUMMARY OF THE INVENTION  
       [0007]     Mobile telephones adopting PIN verification are in widespread use these days and, at the same time, there is a move to adopt biometric authentication in the mobile telephones. Only adding the biometric authentication to the mobile telephones adopting the PIN verification undesirably forces users to keep the PIN verification and the biometric authentication separate or to use both the PIN verification and the biometric authentication.  
         [0008]     It is desirable to provide a mobile terminal device, a PIN verification program, and a method of verifying a PIN, which ensure the compatibility between the widespread PIN verification and the biometric authentication growing popular to provide a new, simple, and inexpensive authentication method ensuring higher security and having greater convenience.  
         [0009]     According to an embodiment of the present invention, there is provided a mobile terminal device including biometric information detecting means for detecting biometric information; encryption key generating means for generating an encryption key on the basis of the biometric information detected by the biometric information detecting means, in personal-identification-number registration; encrypting means for encrypting a predetermined personal identification number with the encryption key generated by the encryption key generating means to generate a biometric encrypted personal identification number, in the personal-identification-number registration; encrypted personal-identification-number storing means for storing the biometric encrypted personal identification number generated by the encrypting means, in the personal-identification-number registration; decryption key generating means for generating a decryption key on the basis of the biometric information detected by the biometric information detecting means, in personal-identification-number verification; decrypting means for decrypting the biometric encrypted personal identification number stored in the encrypted personal-identification-number storing means with the decryption key generated by the decryption key generating means to reproduce the personal identification number, in the personal-identification-number verification; and personal identification number verifying means for comparing the personal identification number reproduced by the decrypting means with the biometric encrypted personal identification number stored in advance in the encrypted personal-identification-number storing means to perform the personal-identification-number verification for enabling a predetermined function.  
         [0010]     According to another embodiment of the present invention, there is provided a personal identification number verification program causing a computer to function as encryption-key generating and controlling means for controlling encryption key generating means so as to generate an encryption key on the basis of biometric information detected by biometric information detecting means, in personal-identification-number registration; encryption controlling means for encrypting a predetermined personal identification number with the encryption key generated by the encryption key generating means by causing the computer to function as the encryption-key generating and controlling means to generate a biometric encrypted personal identification number and controlling encrypting means so as to store the biometric encrypted personal identification number in encrypted personal-identification-number storing means, in the personal-identification-number registration; decryption-key generating and controlling means for controlling decryption key generating means so as to generate a decryption key on the basis of the biometric information detected by the biometric information detecting means, in personal-identification-number verification; decryption controlling means for controlling decrypting means so as to decrypt the biometric encrypted personal identification number stored in the encrypted personal-identification-number storing means with the decryption key generated by the decryption key generating means by causing the computer to function as the decryption-key generating and controlling means to reproduce the personal identification number, in the personal-identification-number verification; and personal-identification-number verifying and controlling means for comparing the personal identification number reproduced by causing the computer to function as the decryption controlling means with the personal identification number stored in advance in the encrypted personal-identification-number storing means to control personal identification number verifying means so as to perform the personal-identification-number verification for enabling a predetermined function, in the personal-identification-number verification.  
         [0011]     According to yet another embodiment of the present invention, there is provided a method of verifying a personal identification number including the steps of generating, by encryption key generating means, an encryption key on the basis of biometric information detected by biometric information detecting means, in personal-identification-number registration; encrypting, by encrypting means, a predetermined personal identification number with the generated encryption key to generate a biometric encrypted personal identification number and storing the biometric encrypted personal identification number in encrypted personal-identification-number storing means, in the personal-identification-number registration; generating, by decryption key generating means, a decryption key on the basis of the biometric information detected by the biometric information detecting means, in personal-identification-number verification; decrypting, by decrypting means, the biometric encrypted personal identification number stored in the encrypted personal-identification-number storing means with the generated decryption key to reproduce the personal identification number, in the personal-identification-number verification; and comparing, by personal identification number verifying means, the personal identification number reproduced by the decrypting means with the personal identification number stored in the encrypted personal-identification-number storing means in the personal-identification-number registration to perform the personal-identification-number verification for enabling a predetermined function, in the personal-identification-number verification.  
         [0012]     According to the embodiments of the present invention, in the registration of the personal identification number, the encryption key is generated on the basis of the biometric information detected by the biometric information detecting means, a predetermined personal identification number is encrypted with the encryption key to generate the biometric encrypted personal identification number, and the biometric encrypted personal identification number is stored in the encrypted personal-identification-number storing means.  
         [0013]     In the verification of the personal identification number, the biometric encrypted personal identification number stored in the encrypted personal-identification-number storing means is decrypted with the decryption key generated on the basis of the biometric information detected by the biometric information detecting means to reproduce the personal identification number and the reproduced personal identification number is supplied to the personal identification number verifying means. The personal identification number verifying means compares the personal identification number that is decrypted and reproduced with the personal identification number stored in advance in the encrypted personal-identification-number storing means to perform the personal-identification-number verification for enabling a predetermined function.  
         [0014]     According to the present invention, it is possible to realize the inexpensive mobile terminal device adopting the new and simple authentication method ensuring higher security and having greater convenience.  
         [0015]     According to the present invention, it is also possible to realize the new, simple and inexpensive authentication system ensuring higher security and having greater convenience. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a block diagram showing an example of the structure of a mobile telephone according to an embodiment of the present invention;  
         [0017]      FIG. 2  is a flowchart showing a process of registering a PIN encrypted with biometric information in the mobile telephone according to the embodiment of the present invention; and  
         [0018]      FIG. 3  is a functional block diagram of the CPU of the mobile telephone according to the embodiment of the present invention, showing how to decrypt the PIN encrypted with the biometric information. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     The present invention is applicable to a mobile telephone that compares a PIN stored in an SIM card with a PIN input by a user and, if the PIN stored in the SIM card coincides with the PIN input by the user, enables predetermined functions to perform PIN verification.  
         [0000]     Structure of Mobile Telephone and General Operation Thereof  
         [0020]      FIG. 1  is a block diagram showing an example of the structure of a mobile telephone according to an embodiment of the present invention. In signal reception, a reception signal, which an antenna  1  has received from a base station, is supplied to a radio-frequency receiver  3  through a selector  2 . The radio-frequency receiver  3  amplifies the reception signal to a level necessary for frequency conversion and supplies the amplified reception signal to a mixer  4 . The mixer  4  converts the reception signal into an intermediate-frequency signal on the basis of an intermediate-frequency conversion signal supplied from a local oscillator  11  and supplies the converted reception signal to a reception interface  5 .  
         [0021]     The reception interface  5  performs analog-to-digital (A/D) conversion to the intermediate-frequency reception signal to digitize the reception signal and supplies the digital signal to a reception demodulator  6  as a sample signal having a predetermined bit rate. The reception demodulator  6  performs, for example, error correction to the sample signal to divide the sample signal into audio data and communication data. The reception demodulator  6  supplies the audio data to an audio decoder  7  and the communication data to a communication data decoder  10 .  
         [0022]     The audio decoder  7  performs decompression etc. to the audio data to change the bit rate of the audio data and performs digital-to-analog (D/A) conversion to the audio data. The audio decoder  7  then supplies the analog audio signal to a speaker  9  through a speaker amplifier  8 . The speaker  9  outputs a sound power corresponding to the reception signal received by the antenna  1 .  
         [0023]     The communication data decoder  10  performs a predetermined demodulation process to the supplied communication data to demodulate the communication data. The demodulated communication data is stored in and controlled by, for example, a random access memory (RAM)  22  or is displayed in a display unit  30 .  
         [0024]     In contrast, in signal transmission, a sound collected by a microphone  18  is amplified by a microphone amplifier  17  with a predetermined gain and the amplified audio signal is supplied to an audio encoder  16 . The audio encoder  16  performs the A/D conversion to the audio signal and performs compression to the audio signal to change the bit rate of the audio signal. The audio encoder  16  then supplies the audio data to a transmission modulator  15 . The audio data can also be supplied to a central processing unit (CPU)  24  through a CPU bus line  25 .  
         [0025]     The communication data, excluding the audio data, is subjected to the compression in a communication data encoder  19  and is supplied to a transmission modulator  15  with an error correction code being added.  
         [0026]     The transmission modulator  15  performs a predetermined modulation and encoding process and the D/A conversion to the audio data or the communication data and supplies the modulated analog data to a transmission interface  14 . The transmission interface  14  converts the analog audio or communication signal into an intermediate-frequency audio or communication signal, amplifies the audio or communication signal to a required level, and supplies the amplified audio or communication signal to a mixer  13 .  
         [0027]     The mixer  13  converts the audio or communication signal into a transmission-frequency audio or communication signal on the basis of a transmission-frequency conversion signal supplied from the local oscillator  11 , and supplies the converted audio or communication signal to a radio-frequency transmitter  12 . The radio-frequency transmitter  12  amplifies the transmission-frequency audio or communication signal with a predetermined gain and supplies the amplified audio or communication signal to the antenna  1  through the selector  2 . The audio or communication signal is transmitted to the base station through the antenna  1 .  
         [0028]     In the mobile telephone having the above structure, the display unit  30 , an operational unit  31 , and a data interface (data I/F)  32  are connected to the CPU  24  via an input-output unit (I/O)  20  and the CPU bus line  25 .  
         [0029]     A read only memory (ROM)  21 , the RAM  22 , and an electrically erasable and programmable read only memory (EEPROM)  23  are connected to the CPU  24  via the CPU bus line  25 . In addition, a timer (real time clock (RTC))  26 , a high-capacity hard disk drive (HDD)  27 , a SIM card  28  detachable from the mobile telephone, and a biometric information detector  29  are also connected to the CPU  24  via the CPU bus line  25 .  
         [0030]     The timer  26  measures the current time and supplies the timing information to the CPU  24 . The non-volatile ROM  21  has a PIN verification program, in addition to a communication program etc., stored therein. The CPU  24  executes and controls user authentication, described below, on the basis of the PIN verification program stored in the ROM  21 . The readable and writable RAM  22  has data temporarily generated during data processing by the CPU  24 .  
         [0031]     The EEPROM  23  has setting conditions etc. of the mobile telephone, stored therein. The setting conditions etc. are set by a user who operates the operational unit  31 . The EEPROM  23  also has biometric parameters used for the user authentication, selected authentication information, and a biometric encrypted PIN stored therein. The selected authentication information, which is selected and set in advance by the user, indicates whether the PIN verification is used in the authentication and indicates whether biometric authentication is combined with the PIN verification if the PIN verification is used. The biometric encrypted PIN is encrypted with an encryption key generated on the basis of the biometric parameters of the user in registration of the PIN.  
         [0032]     The biometric information detector  29  detects biometric information including the fingerprint, iris, or vein pattern of the user and outputs the detected biometric information. The biometric parameters stored in the EEPROM  23  are generated on the basis of the biometric information detected by the biometric information detector  29 .  
         [0033]     The SIM card  28  has the contractual coverage presented to the user (subscriber) by a communication organization, who is an issuer of the SIM card  28 , information necessary for the communication, a telephone directory, and so on stored thereon. The SIM card  28  has the own CPU and a PIN memory having the PIN. The CPU of the SIM card  28  communicates with the CPU  24  of the mobile telephone according to the embodiment of the present invention to compare the PIN input by the user with the PIN stored in the PIN memory. If the PIN input by the user coincides with the PIN stored in the PIN memory (the user authentication authenticates the user as the authorized user), the SIM card  28  permits access to a variety of information stored in the SIM card  28 . The access permission allows the telephone function and the like of the mobile telephone according to the embodiment of the present invention to be used.  
         [0000]     Authentication Modes  
         [0034]     The mobile telephone according to the embodiment of the present invention determines in advance whether the user authentication with the PIN is performed and sets the determination. If the mobile telephone determines and sets the user authentication with the PIN, the mobile telephone determines whether the user authentication is performed only with the PIN or whether the user authentication with the PIN is combined with the user authentication with the biometric information and sets the determination.  
         [0035]     The information that is determined and set here is stored in the EEPROM  23  as the “selected authentication information”. The CPU  24  confirms the selected authentication information stored in the EEPROM  23  in the user authentication. If the selected authentication information indicates that the user authentication with the PIN is not performed, the CPU  24  accesses the SIM card  28  without performing the user authentication.  
         [0036]     In contrast, if the selected authentication information stored in the EEPROM  23  indicates that the user authentication only with the PIN is performed, the CPU  24  moves to a “manual authentication mode” in the user authentication and displays a screen in which the PIN is input in the display unit  30 . After the user inputs the PIN with the operational unit  31 , the CPU  24  supplies the input PIN to the SIM card  28 .  
         [0037]     The CPU of the SIM card  28  compares the PIN input by the user with the PIN stored in the PIN memory. If the PIN input by the user coincides with the PIN stored in the PIN memory, the CPU of the SIM card  28  authenticates the user who has input the PIN as the authorized user and supplies access enabling information indicating permission of an access to the SIM card  28  to the CPU  24  of the mobile telephone. The CPU  24  of the mobile telephone accesses the SIM card  28  in response to the access enabling information. The above process allows use of various functions of the mobile telephone on the basis of information concerning the subscriber, stored in the SIM card  28 .  
         [0038]     In contrast, if the selected authentication information stored in the EEPROM  23  indicates that the user authentication with the PIN is combined with the user authentication with the biometric information, the CPU  24  moves to an “automatic authentication mode” in the user authentication to perform new user authentication in which the user authentication with the PIN is combined with the user authentication with the biometric information, on the basis of the PIN verification program stored in the ROM  21 .  
         [0039]     In order to enable the new user authentication, it is necessary to register in advance the biometric parameters of the user and to register the PIN that coincides with the PIN stored in the SIM card  28 .  
         [0000]     Registration of Biometric Parameters  
         [0040]     When the user selects the user authentication in which the user authentication with the PIN is combined with the user authentication with the biometric information, the CPU  24  displays a message prompting the user to input the biometric information in the display unit  30 , on the basis of the PIN verification program stored in the ROM  21 .  
         [0041]     If the biometric information detector  29  is a fingerprint sensor, the user holds a finger over the fingerprint sensor to provide the fingerprint information when the message prompting the user to input the biometric information is displayed in the display unit  30 . Alternatively, if the biometric information detector  29  is an iris sensor, the user shots his iris by a camera to provide the iris information.  
         [0042]     After the biometric information is detected in the biometric information detector  29  in the above manner, the CPU  24  generates the biometric parameters of the user on the basis of the biometric information and registers the generated biometric parameters in the EEPROM  23 . The registration of the biometric parameters is completed.  
         [0000]     Registration of PIN (Biometric Encrypted PIN)  
         [0043]     After the biometric parameters are registered in the above manner, the CPU  24  registers the PIN coinciding with the PIN that is input by the user and is stored in the SIM card  28  in the mobile telephone on the basis of the PIN verification program stored in the ROM  21 .  FIG. 2  is a flowchart showing a process of registering the PIN.  
         [0044]     After the biometric parameters are registered, in Step S 1 , the CPU  24  of the mobile telephone displays a message prompting the user to input the biometric information in the display unit  30 . The user provides the biometric information through the biometric information detector  29  in response to the message in the manner described above.  
         [0045]     After the biometric information about the user is detected, in Step S 2 , the CPU  24  generates a biometric parameter on the basis of the biometric information provided by the user. The CPU  24  compares the generated biometric parameter with the biometric parameter registered in advance in the EEPROM  23  in the registration of the biometric parameter to determine whether the generated biometric parameter coincides with the biometric parameter registered in advance in the EEPROM  23 .  
         [0046]     If the generated biometric parameter does not coincide with the biometric parameter registered in advance in the EEPROM  23 , the CPU  24  determines that the user who provides the biometric information is not authorized as the user of the mobile telephone and the process proceeds to Step S 14 . In Step S 14 , the CPU  24  displays a message to deny use of the mobile telephone by the user who provides the biometric information in the display unit  30  and terminates the process in  FIG. 2 .  
         [0047]     If the CPU  24  determines in Step S 2  that the generated biometric parameter coincides with the biometric parameter registered in advance in the EEPROM  23 , the CPU  24  determines that the user who provides the biometric information is authorized as the user of the mobile telephone and the process proceeds to Step S 3 . In Step S 3 , the CPU  24  determines whether the user authentication with the PIN is set on the basis of the selected authentication information stored in the EEPROM  23 .  
         [0048]     When the user authentication with the PIN is not set, the user authentication is performed only on the basis of the biometric information. Hence, if the CPU  24  determines in Step S 3  that the user authentication with the PIN is not set, the CPU  24  terminates the process in  FIG. 2 .  
         [0049]     If the CPU  24  determines in Step S 3  that the user authentication with the PIN is set, the process proceeds to Step S 4 . In Step S 4 , the CPU  24  determines whether the user authentication with the PIN is set so as to be combined with the user authentication with the biometric information on the basis of the selected authentication information stored in the EEPROM  23 . If the CPU  24  determines that the user authentication with the PIN is not set so as to be combined with the user authentication with the biometric information, the CPU  24  terminates the process in  FIG. 2 . If the CPU  24  determines that the user authentication with the PIN is set so as to be combined with the user authentication with the biometric information, the process proceeds to Step S 5 .  
         [0050]     As described below, in the mobile telephone according to the embodiment of the present invention, after the user inputs the PIN coinciding with the PIN stored in the SIM card  28 , the PIN input by the user is encrypted with the biometric parameter to generate the biometric encrypted PIN that is stored in the EEPROM  23 . Accordingly, in Step S 5 , the CPU  24  determines whether the biometric encrypted PIN has been already registered in the EEPROM  23 . If the biometric encrypted PIN has already been registered in the EEPROM  23 , the CPU- 24  terminates the process in  FIG. 2 .  
         [0051]     If the biometric encrypted PIN has not been registered in the EEPROM  23 , the process proceeds to Step S 6 . In Step S 6 , the CPU  24  displays a message prompting the user to input the PIN coinciding with the PIN stored in the SIM card  28  in the display unit  30  and the process proceeds to Step S 7 .  
         [0052]     The user inputs the PIN coinciding with the PIN stored in the SIM card  28  with the operational unit  31  in response to the message. In Step S 7 , the CPU  24  monitors input of the PIN by the user to determine whether the PIN is input by the user. If the CPU  24  determines that the PIN is input by the user, the process proceeds to Step S 8 .  
         [0053]     The CPU  24  transfers the PIN input by the user to the SIM card  28 . The CPU of the SIM card  28  compares the transferred PIN (the PIN input by the user) with the PIN (authorized PIN) stored in the PIN memory of the SIM card  28 . The CPU of the SIM card  28  transmits the result of this comparison to the CPU  24  of the mobile telephone. In Step S 8 , the CPU  24  of the mobile telephone receives the result from the SIM card  28  to determine whether the PIN input by the user coincides with the authorized PIN stored in the PIN memory. If the CPU  24  determines that the PIN input by the user does not coincide with the authorized PIN stored in the PIN memory, the process proceeds to Step S 12 . If the CPU  24  determines that the PIN input by the user coincides with the authorized PIN stored in the PIN memory, the process proceeds to Step S 9 .  
         [0054]     In Step S 12 , the CPU  24  displays a message indicating that an unauthorized PIN is input in the display unit  30  and the process proceeds to Step S 13 .  
         [0055]     In the mobile telephone according to the embodiment of the present invention, if at least one unauthorized PIN is input a predetermined number of times, for example, three times, the CPU  24  inhibits subsequent accesses to the SIM card  28  to block use of the functions of the mobile telephone. In this case, after displaying the message indicating that an unauthorized PIN is input in the display unit  30  in Step S 12 , then in Step S 13 , the CPU  24  determines whether at least one unauthorized PIN is input the predetermined number of times or more (three times or more in this example) and an access to the SIM card  28  is inhibited. If an access to the SIM card  28  is not inhibited, the CPU  24  goes back to Step S 6 . If an access to the SIM card  28  is inhibited, that is, if the user inputs at least one unauthorized PIN the predetermined number of times or more, the process proceeds to Step S 14 . In Step S 14 , the CPU  24  displays the message to deny use of the functions of the mobile telephone by the user in the display unit  30  and terminates the process in  FIG. 2 .  
         [0056]     If the CPU  24  determines in Step S 8  that the PIN input by the user coincides with the authorized PIN stored in the PIN memory, then in Step S 9 , the CPU  24  displays a message indicating that the user authentication with the PIN is normally terminated in the display unit  30  and the process proceeds to Step S 10 .  
         [0057]     Since the PIN input by the user coincides with the PIN stored in the SIM card  28 , then in Step S 10 , the CPU  24  encrypts the PIN input by the user with the biometric parameter stored in the EEPROM  23  to generate the “biometric encrypted PIN”.  
         [0058]     Specifically, in the encryption of the PIN, the biometric parameter stored in the EEPROM  23  is used as the encryption key to encrypt the PIN input by the user.  
         [0059]     After the PIN is encrypted, then in Step S 11 , the CPU  24  stores the “biometric encrypted PIN” in the EEPROM  23  and terminates the process in  FIG. 2 . The registration of the PIN is completed.  
         [0000]     User Authentication with Biometric Authentication Being Combined with PIN Verification  
         [0060]     After the biometric encrypted PIN is registered in the EEPROM  23  in the above manner, it is possible to realize the new user authentication in which the user authentication with the biometric information is combined with the user authentication with the PIN.  
         [0061]     Specifically, after an operation of any key on the mobile telephone is detected, the CPU  24  determines whether the user authentication in which the user authentication with the biometric information is combined with the user authentication with the PIN is set, on the basis of the selected authentication information stored in the EEPROM  23 . If the user authentication in which the user authentication with the biometric information is combined with the user authentication with the PIN is set, the CPU  24  displays a message prompting the user to input the biometric information in the display unit  30  on the basis of the PIN verification program stored in the ROM  21 . The user provides the own biometric information through the biometric information detector  29  in response to the message.  
         [0062]      FIG. 3  is a functional block diagram of the CPU  24 , showing how to decrypt the biometric encrypted PIN stored in the EEPROM  23  on the basis of the biometric information provided by the user to transfer the decrypted biometric encrypted PIN to the SIM card  28 . Components from an analyzer  41  to a decryptor  45 , excluding the EEPROM  23  and the biometric information detector  29 , form the functional block diagram of the CPU  24  operating on the basis of the PIN verification program.  
         [0063]     Referring to  FIG. 3 , after the biometric information about the user is detected in the biometric information detector  29 , the CPU  24  functions as the analyzer  41  to analyze the biometric information detected in the biometric information detector  29  and generate the biometric parameter.  
         [0064]     Next, the CPU  24  functions as a comparer  42  to compare the biometric parameter generated by the CPU  24  functioning as the analyzer  41  with the biometric parameter stored in the EEPROM  23  in the registration of the biometric parameter.  
         [0065]     Next, the CPU  24  functions as a determiner  43  to determine whether the biometric parameter corresponding to the biometric information provided by the user coincides with the biometric parameter stored in advance in the EEPROM  23  on the basis of the comparison result achieved when the CPU  24  functions as the comparer  42 .  
         [0066]     If the CPU  24  determines that the biometric parameter corresponding to the biometric information provided by the user does not coincide with the biometric parameter stored in advance in the EEPROM  23 , the CPU  24  displays a message indicating that the functions of the mobile telephone are disabled in the display unit  30 . If the CPU  24  determines that the biometric parameter corresponding to the biometric information provided by the user coincides with the biometric parameter stored in advance in the EEPROM  23 , the CPU  24  functions as a decryption key generator  44  to set the biometric parameter corresponding to the biometric information about the user as a decryption key.  
         [0067]     Next, the CPU  24  functions as the decryptor  45  to decrypt and reproduce the encrypted PIN by decrypting the biometric encrypted PIN stored in the EEPROM  23  by using the biometric parameter, set by the CPU  24  functioning as the decryption key generator  44 , as the decryption key and supplies the decrypted and reproduced PIN to the SIM card  28 .  
         [0000]     Deletion of Decryption Key  
         [0068]     After the decryption process is terminated, the CPU  24  deletes the decryption key used in the decryption process. In other words, the mobile telephone generates a decryption key each time the user authentication is performed. Accordingly, since the decryption key is not left in the mobile telephone, it is possible to improve the security in the user authentication.  
         [0069]     The CPU of the SIM card  28  compares the PIN that is decrypted and reproduced on the basis of the biometric information provided by the user with the PIN stored in the PIN memory of the SIM card  28 . If the decrypted and reproduced PIN coincides with the PIN stored in the PIN memory of the SIM card  28 , the CPU of the SIM card  28  authenticates the user who inputs the PIN as the authorized user of the mobile telephone and supplies the access enabling information indicating permission of an access to the SIM card  28  to the CPU  24  of the mobile telephone. The CPU  24  of the mobile telephone accesses the variety of information stored in the SIM card  28  in response to the access enabling information that is received. As a result, it is possible to use the various functions of the mobile telephone on the basis of the information concerning the subscriber, stored in the SIM card  28 .  
         [0070]     In the above example, the biometric parameter is used as the encryption key to encrypt the PIN input by the user and the biometric parameter generated on the basis of the biometric information provided by the user is used as the decryption key to decrypt the encrypted PIN. However, a predetermined encryption key may be generated on the basis of the biometric parameter, the generated encryption key may be used to encrypt the PIN input by the user, the decryption key corresponding to the encryption key may be generated on the basis of the biometric parameter corresponding to the biometric information provided by the user, and the generated decryption key may be used to decrypt the encrypted PIN.  
         [0071]     Although the CPU  24  generates the decryption key if the CPU  24  determines that the biometric parameter corresponding to the biometric information provided by the user coincides with the biometric parameter stored in advance in the EEPROM  23 , the CPU  24  may generate the decryption key on the basis of the biometric parameter analyzed by the CPU  24  functioning as the analyzer  41  and, if the CPU  24  determines that the both of the biometric parameters are coinciding with each other, the CPU  24  may use the decryption key generated by the CPU  24  functioning as the analyzer  41  to decrypt the biometric encrypted PIN.  
         [0072]     As described above, the mobile telephone according to the embodiment of the present invention has the following features.  
         [0000]     Improved Security  
         [0073]     It is sufficient to input the PIN only at the beginning (only in the registration) and the user authentication with the biometric information is performed after the PIN is registered. Accordingly, it is possible to prevent a third person from stealing a glance at the PIN that is being input, thereby improving the security of the mobile telephone.  
         [0074]     Since the encrypted PIN is not decrypted unless the user is authenticated as the authorized user in the biometric authentication, it is possible to prevent unauthorized use of the mobile telephone by a malicious third person due to theft or loss of the mobile telephone. Hence, the security of the mobile telephone is improved.  
         [0075]     An access to the SIM card is permitted and the functions of the mobile telephone are used only after the user is authenticated as the authorized user in the biometric authentication. Accordingly, it is possible to prevent falsification of the SIM card or the mobile telephone, thereby improving the security of the mobile telephone.  
         [0076]     The PIN stored in the mobile telephone is encrypted on the basis of the biometric authentication information about the user. In addition, since the decryption key used in the decryption is generated on the basis of the biometric authentication information each time the user authentication is performed, the decryption key is not stored in the mobile telephone. Hence, the encrypted PIN cannot not be decrypted even if a third person has stolen a glance at the encrypted PIN. Furthermore, the decryption key used in the decryption of the encrypted PIN is deleted after the decryption of the PIN is terminated, thus improving the security of the mobile telephone.  
         [0000]     Greater Convenience and Simplicity  
         [0077]     Since the user authentication with the PIN is performed on the basis of the biometric authentication information, it is not necessary for the user to store the PIN and, therefore, it is possible to prevent an inconvenience of the mobile telephone that is made unusable because the user has forgotten the PIN.  
         [0078]     The encrypted PIN is decrypted on the basis of the biometric authentication information about the user, so that it is not necessary to provide a special decryption key for the decryption of the encrypted PIN. As a result, the mobile telephone adopting the simple authentication system having greater convenience can be realized.  
         [0000]     Inexpensiveness  
         [0079]     Since the biometric authentication function and the support of the SIM card can be achieved only with software including the PIN verification program without special hardware, the inexpensive mobile telephone can be realized.  
         [0000]     Modifications  
         [0080]     Although the present invention is applied to the mobile telephone in the above description, the present invention is applicable to other terminal devices including a PHS, a PDA, a laptop personal computer, and a desktop personal computer to achieve advantages similar to the ones described above.  
         [0081]     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.