Patent Publication Number: US-2007115494-A1

Title: Image processing system, information processing device, computer readable recording medium, and information processing method

Description:
PRIORITY INFORMATION  
      This application claims priority to Japanese Patent Application No. 2005-333720, filed on Nov. 18, 2005, which is incorporated herein by reference in its entirety.  
     BACKGROUND  
      1. Technical Field  
      The present invention relates to an image processing system.  
      2. Related Art  
      There has been known an image processing system that includes image processing devices, such as a printer, a facsimile, and a multi-function (MF) apparatus, and a personal computer (PC) that issues a job to those image processing devices.  
      In one known image processing system, the image processing device identifies a user on the basis of a user ID/password to perform output management or accounting for each user. A PC in this image processing system issues a job with a user ID/password attached. The image processing device authenticates the user by means of the user ID/password attached to the job and performs accounting for the authenticated user. In this system, although in some cases the user is requested to enter a user ID/password each time the user issues a job, most PCs hold a once-entered user ID/password in the internal non-volatile storage area to thereby eliminate the need for re-entry by the user.  
      In another known image processing system, the image processing device has a so-called “direct fax function”; that is, the image processing device does not print data but sends data directly to a facsimile in accordance with an instruction from the PC. In this system, although in some cases the user is requested to enter a destination number each time the user uses the direct fax function, most PCs hold the fax transmission destination information in an internal non-volatile storage area in advance and simply specify the destination number by reference to the fax destination information.  
     SUMMARY  
      According to an aspect of the invention, there is provided an image processing system including: an image processing device that processes an image; an information registration unit that transmits confidential information, included in setting information used for issuing a job, to the image processing device and registers the confidential information therein; an information acquisition unit that, before issuing a job, requests the image processing device to send the registered confidential information and acquires the confidential information; and a job issuing unit that issues the job to the image processing device using the acquired confidential information. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Embodiments of this invention will be described in detail by reference to the following figures, wherein;  
       FIG. 1  is a diagram showing the general configuration of an image processing system in an embodiment;  
       FIG. 2  is a block diagram showing the functional configuration of an MF apparatus and a PC;  
       FIG. 3  is a diagram showing an operating procedure of the image processing system when information is registered;  
       FIG. 4  is a diagram showing an operating procedure of the image processing system when information is registered;  
       FIG. 5  is a diagram showing an operating procedure of the image processing system when account printing is performed;  
       FIG. 6  is a diagram showing an operating procedure of the image processing system when direct fax transmission is performed; and  
       FIG. 7  is a diagram showing an operating procedure of the image processing system when information is updated. 
    
    
     DETAILED DESCRIPTION  
      Exemplary embodiments of this invention will be described hereinafter with reference to the attached drawings.  
       FIG. 1  is a diagram showing the general configuration of an image processing system  1  of this embodiment. As shown in  FIG. 1 , the image processing system  1  includes an image processing device  10 , and one or more information processing devices  20  connected to the image processing device  10  via a network N. In this embodiment, the image processing device  10  has a printer function or a facsimile function. For example, the image processing device  10  is a multi-function (MF) apparatus having two or more of the printer function, a scanner function, a copy function, and the facsimile function. In this example, each of the information processing devices  20 , which is a device issuing a job to the image processing device  10 , is a PC. In the description below, the image processing device  10  is described as an MF apparatus  10 , and each of the information processing devices  20  as a PC  20 .  
       FIG. 2  is a block diagram showing the functional configuration of the MF apparatus  10  and that of the PC  20 . The following describes the configuration of the MF apparatus  10  and that of the PC  20  with reference to  FIG. 2 .  
      The PC  20  is implementing by the combination of software and the hardware resources. In this embodiment, the software resources of the PC  20  include an operating system (OS), device drivers, and various application software programs; and the hardware resources of the PC  20  include a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), a hard disk, input devices such as a keyboard and a mouse, and output devices such as a display.  
      The PC  20  has a PC storage unit  21  and a device driver unit  22 . The PC storage unit  21  includes a volatile storage area allocated in the RAM, and a non-volatile storage area allocated on a hard disk. The device driver unit  22  is implemented by a computer program (a device driver in this example) executed by the CPU. The device driver unit  22  has a setting information acceptance unit  22   a , a user certificate registration unit  22   b , an MF public key registration unit  22   c , an information registration unit  22   d , an information acquisition unit  22   e , and a job issuing unit  22   f . To implement the functional blocks  22   a - 22   f  described above, it is of course possible for the device driver to use other software functions such as the OS. The computer program for implementing the functional blocks  22   a - 22   f  described above is not limited to the device driver, but other programs may also be used.  
      The setting information acceptance unit  22   a  accepts setting information used for issuing a job. More specifically, the setting information acceptance unit  22   a  accepts setting information for issuing a print job or a direct fax transmission job, on the basis of the user operation on the screen. The setting information includes confidential information such as personal management security information; for example, account-authentication user ID/password or fax transmission destination information, and other general information (IP address of the MF apparatus  10 , device configuration information, etc.).  
      The user certificate registration unit  22   b  registers a user&#39;s public key certificate (hereinafter called “user certificate”) and a private key (hereinafter called a user private key). More specifically, on the basis of the user operation on the screen, the user certificate registration unit  22   b  registers a user certificate, issued by a certificate authority (for example, an official certificate authority), and a user private key, which forms a key pair with the user public key included in the user certificate, into the non-volatile storage area of the PC storage unit  21 . Instead, the user certificate registration unit  22   b  may also store the certificate file and the private key file into the non-volatile storage area for the device driver or record information identifying the OS-managed certificate file and the private key file (for example, paths and file names of the files).  
      The MF public key registration unit  22   c  registers the public key of the MF apparatus  10  (hereinafter called “MF public key”). In this embodiment, the MF public key registration unit  22   c  communicates with the MF apparatus  10  via the network N to exchange the user certificate, which is registered by the user certificate registration unit  22   b , and the MF public key, which is registered in the MF apparatus  10 , and stores the MF public key, acquired through the exchange, into the non-volatile storage area of the PC storage unit  21 . Note that the MF public key registration unit  22   c  can acquire the MF public key by some other method.  
      The information registration unit  22   d  associates the confidential information, included in the setting information accepted by the setting information acceptance unit  22   a , with the user certificate, registered by the user certificate registration unit  22   b , and transmits the associated confidential information to the MF apparatus  10  for registration. Before the transmission, the information registration unit  22   d  encrypts the confidential information by means of the MF public key, registered by the MF public key registration unit  22   c , to prevent leakage of the confidential information. Transmitting the confidential information and the user certificate, which are associated with each other, means not only that the user certificate is transmitted with the confidential information, but also that the user certificate identifying information (hereinafter called “user certificate identification information”) is transmitted with the confidential information. In this embodiment, because the user certificate is already transmitted to the MF apparatus  10  by the MF public key registration unit  22   c , the information registration unit  22   d  transmits the user certificate identification information with the confidential information. The user certificate identification information is, for example, a certificate serial number described in the user certificate.  
      Before issuing a job, the information acquisition unit  22   e  specifies a user certificate, registered by the user certificate registration unit  22   b , to request the MF apparatus  10  to supply the confidential information registered as an entry associated with the user certificate. The user certificate is specified, for example, by providing the user certificate identification information. As will be described later, in response to the request from the information acquisition unit  22   e  to supply confidential information specified in conjunction with the user certificate, the MF apparatus  10  encrypts the confidential information, registered as an entry associated with the user certificate, by means of the user public key included in the user certificate and returns the encrypted confidential information to the information acquisition unit  22   e . Therefore, the information acquisition unit  22   e  acquires the confidential information encrypted by means of the user public key included in the specified user certificate.  
      The job issuing unit  22   f  decrypts the encrypted confidential information, acquired by the information acquisition unit  22   e , by means of the user private key, registered by the user certificate registration unit  22   b , and by means of the decrypted confidential information issues a job to the MF apparatus  10 . For example, the job issuing unit  22   f  transmits a print job to the MF apparatus  10  with the decrypted account-authentication user ID/password attached to the print job. Alternatively, the job issuing unit  22   f  displays the decrypted fax transmission destination information on the display screen, accepts the specification of a destination number from the user on the display screen, and transmits a direct fax transmission job to the MF apparatus  10  with the specified destination number attached to the direct fax transmission job. To prevent leakage of the confidential information, the job issuing unit  22   f  encrypts the account-authentication user ID/password or the destination number with the MF public key registered by the MF public key registration unit  22   c.    
      Meanwhile, the MF apparatus  10  has a print engine  11 , a facsimile device  12 , an MF apparatus storage unit  13 , and a controller  14 . The print engine  11  is a device that prints an image on a print medium such as paper by means of the xerography method or the ink jet method. The facsimile device  12  is a device that sends or receives image data to or from other facsimile devices. The MF apparatus storage unit  13  includes a volatile storage area allocated in RAM, and a non-volatile storage area allocated on a hard disk. In this embodiment, the non-volatile storage area of the MF apparatus storage unit  13  stores in advance a key pair consisting of the MF public key and the MF private key. The controller  14  controls the entirety of the MF apparatus  10  and manages confidential information. The function of the controller  14  can be configured in one of several ways; in the description below, the function is implemented by executing the predetermined programs on the CPU. The controller  14  has a user certificate registration unit  14   a , an information saving unit  14   b , an information transmission unit  14   c , and a job execution unit  14   d.    
      The user certificate registration unit  14   a  registers a user certificate. More specifically, the user certificate registration unit  14   a  receives a user certificate from the PC  20  via the network N and stores the received user certificate in a non-volatile storage area of the MF apparatus storage unit  13 . In this embodiment, the user certificate registration unit  14   a  exchanges a user certificate and an MF public key with the MF public key registration unit  22   c  of the PC  20 .  
      The information saving unit  14   b  receives confidential information, transmitted from the information registration unit  22   d  of the PC  20  in conjunction with the user certificate, and saves the received confidential information and the user certificate in the non-volatile storage area of the MF apparatus storage unit  13  in association with each other. As described above, in this embodiment the confidential information is encrypted by means of the MF public key. The information saving unit  14   b  may decrypt the encrypted confidential information by means of the MF private key before saving; in this embodiment, the information saving unit  14   b  stores the encrypted confidential information to thereby ensure security.  
      In response to a confidential information request, which specifies a user certificate, from the information acquisition unit  22   e  of the PC  20 , the information transmission unit  14   c  passes the confidential information, saved in the MF apparatus storage unit  13  as an entry associated with the user certificate, to the information acquisition unit  22   e . In this embodiment, because the confidential information is saved in a form encrypted by means of the MF public key, the information transmission unit  14   c  that receives the request decrypts the confidential information, requested by means of the request, by means of the MF private key. Subsequently, the information transmission unit  14   c  encrypts the decrypted confidential information by means of the user public key included in the specified user certificate and transmits the encrypted confidential information to the information acquisition unit  22   e.    
      In response to a job from the job issuing unit  22   f  of the PC  20 , the job execution unit  14   d  executes the job. For example, when a print job is received, the job execution unit  14   d  performs user authentication on the basis of the account-authentication user ID/password and, if the user is authenticated successfully, causes the print engine  11  to execute the job and executes account processing for the user ID; for example, counts the number of prints. Alternatively, in response to a direct fax transmission job, the job execution unit  14   d  causes the facsimile device  12  to transmit a direct fax to the specified destination number. Because the confidential information, such as the user ID/password or the destination number, is encrypted by means of the MF public key, the job execution unit  14   d  decrypts the encrypted confidential information by means of the MF private key before executing the job.  
      The following describes the detailed operation of the image processing system  1  having the above-described configuration. The description is divided into operations performed at the four following times: at the time of information registration, at the time of normal operation (account printing time), at the time of normal operation (direct fax transmission time), and at the time of information update.  
      A. Processing at Information Registration Time  
       FIGS. 3 and 4  are diagrams showing the operation procedure of the image processing system  1  at the time of information registration. The following describes the operation of the image processing system  1  at the time of information registration with reference to  FIGS. 3 and 4 . In the description below, note that the device driver is not installed in the PC  20  before the operation is started.  
      As shown in  FIG. 3 , in step S 11  the device driver corresponding to the MF apparatus  10  is installed in the PC  20 .  
      In step S 12 , the PC  20  displays a screen for setting the setting information on the basis of the user operation. More specifically, the PC  20  displays the properties screen of the device driver when “Properties” is selected from the right-click menu of the icon of the device driver on the screen.  
      In step S 13 , when the properties screen is displayed, the device driver unit  22  creates, in the PC storage unit  21 , the data structure of the device driver for storing the setting information. Subsequently, the device driver unit  22  accepts the input of setting information on the basis of the user operation on the properties screen and stores the received setting information in the data structure. The setting information includes general information and confidential information as described above. The confidential information includes account-authentication user ID/password and fax transmission destination information.  
      In step S 14 , when a “Register user certificate and MF public key” button is pressed by the user on the properties screen, the device driver unit  22  displays a dialog box for registering the MF public key of the MF apparatus  10  to be associated with the device driver and the user certificate of the user. On the basis of the user operation in the dialog box, the device driver unit  22  registers the user certificate of the user, who uses the device driver and the MF apparatus  10 , and the user private key into the PC storage unit  21 . Simultaneously, the device driver unit  22  exchanges the user certificate registered as described above and the MF public key with the MF apparatus  10  and registers the MF public key, acquired through the exchange, into the PC storage unit  21 . The MF apparatus  10  registers the user certificate, acquired through the exchange described above, into the MF apparatus storage unit  13 .  
      In step S 15  in  FIG. 4 , when the properties screen of the device driver is closed with the user certificate and the MF public key registered in the PC  20 , the device driver unit  22  encrypts a part of the data structure of the device driver, created in step S 13 , that must be made kept secret, by means of the MF public key registered in step S 14  described above. That is, the device driver unit  22  encrypts the confidential information by means of the MF public key.  
      In step S 16 , the device driver unit  22  transmits to the MF apparatus  10  the confidential information encrypted in step S 15  described above, as well as the information (user certificate identification information) identifying the user certificate registered in step S 14  described above.  
      In step S 17 , when the user certificate identification information and the encrypted confidential information are received from the device driver unit  22 , the MF apparatus  10  saves the encrypted confidential information in the MF apparatus storage unit  13  in association with the user certificate identified by the user certificate identification information. Meanwhile, the device driver unit  22  deletes the confidential information from the PC  20  after transmitting the confidential information with the other information (general information) retained in the non-volatile storage area in the PC storage unit  21 .  
      B. Processing at the Time of Normal Operation (Processing at the Time of Account Printing)  
       FIG. 5  is a diagram showing the operation procedure of the image processing system  1  at the time of account printing. The following describes the operation of the image processing system  1  at the time of account printing with reference to  FIG. 5 .  
      In step S 21 , when a print instruction is accepted from an application software program, the device driver unit  22  transmits to the MF apparatus  10  a confidential information transmission request, as well as user certificate identification information that identifies a user certificate registered in the PC storage unit  21 .  
      In step S 22 , upon receipt of the transmission request and the user certificate identification information from the device driver unit  22 , the MF apparatus  10  checks if the user certificate identified by the user certificate identification information is registered in the MF apparatus storage unit  13 . If the user certificate is found to be registered, the MF apparatus  10  uses the user public key included in the user certificate to encrypt the confidential information, saved as an entry associated with the user certificate identified by the user certificate identification information described above, and returns the encrypted confidential information to the device driver unit  22 . If the user certificate is found not to be registered, the MF apparatus  10  returns a message to the device driver unit  22  indicating that the information is not found.  
      In step S 23 , the device driver unit  22  receives the encrypted confidential information from the MF apparatus  10  and uses the user private key, registered in the PC storage unit  21 , to decrypt the encrypted confidential information in the volatile storage area to thereby make the account-authentication user ID/password available for use.  
      At this time, if the properties screen of the device driver is open, the device driver unit  22  displays the decrypted confidential information on the properties screen. If the decrypted confidential information contains multiple account-authentication user IDs (that is, multiple account-authentication user IDs are registered for one user), the device driver unit  22  displays the user ID selection dialog box to prompt the user to specify the specification of a user ID which is to be used. If the decrypted confidential information includes only one user ID, the device driver unit  22  may or may not display the confirmation dialog box.  
      In step S 24 , the device driver unit  22  attaches the account-authentication user ID/password, determined in step S 23  described above, to a print job and transmits the print job to the MF apparatus  10 . In this case, before the transmission the device driver unit  22  encrypts at least the account-authentication user ID/password by means of the MF public key registered in the PC storage unit  21 .  
      In step S 25 , upon receipt of the print job to which the encrypted account-authentication user ID/password is attached, the MF apparatus  10  decrypts the encrypted user ID/password by means of the MF private key registered in the MF apparatus storage unit  13  and authenticates the user on the basis of the decrypted user ID/password. If the user is authenticated successfully, the MF apparatus  10  executes the received print job by means of the print engine  11  and performs account processing for the user ID; for example, counts up the number of prints. If the user authentication fails, the MF apparatus  10  discards the print job and does not execute the printing. In this case, the MF apparatus  10  may send to the device driver unit  22  a message which indicates the failure of user authentication. Meanwhile, after transmitting the print job the device driver unit  22  does not record the confidential information, which was decrypted, expanded, and processed in the volatile storage area of the PC  20 , into a non-volatile storage area such as a hard disk, but discards the confidential information from the PC  20 .  
      C. Processing at the Time of Normal Operation (Processing at the Time of Direct Fax Transmission)  
       FIG. 6  is a diagram showing the operation procedure of the image processing system  1  at the time of direct fax transmission. The following describes the operation of the image processing system  1  at the time of direct fax transmission.  
      In step S 31 , upon acceptance of a direct fax transmission instruction from an application software program, the device driver unit  22  transmits to the MF apparatus  10  a confidential information transmission request, as well as user certificate identification information that identifies the user certificate registered in the PC storage unit  21 .  
      In step S 32 , upon receipt of the transmission request and the user certificate identification information from the device driver unit  22 , the MF apparatus  10  checks if the user certificate identified by the user certificate identification information is registered in the MF apparatus storage unit  13 . If the user certificate is found to be registered, the MF apparatus  10  uses the user public key included in the user certificate to encrypt the confidential information, saved as an entry associated with the user certificate identified by the user certificate identification information described above, and returns the encrypted confidential information to the device driver unit  22 . If the user certificate is found not to be registered, the MF apparatus  10  returns a message to the device driver unit  22  indicating that the information is not found.  
      In step S 33 , the device driver unit  22  receives the encrypted confidential information from the MF apparatus  10  and uses the user private key, registered in the PC storage unit  21 , to decrypt the encrypted confidential information in the volatile storage area to thereby make the account-authentication user ID/password and the fax transmission destination information available for use. At this time, if the properties screen of the device driver is open, the device driver unit  22  displays the decrypted confidential information on the properties screen. The device driver unit  22  performs the same account authentication information processing as in step S 23  described above.  
      In step S 34 , the device driver unit  22  displays a dialog box for specifying a fax transmission destination number and accepts the specification of a destination number from the user through the dialog box. In this dialog box, a list of the destination numbers included in the decrypted fax transmission destination information is displayed so as to allow the user to list and reference the registered destination numbers and specify a desired destination number in the dialog box. In this case, the device driver unit  22  may either limit the specification of a destination number to the numbers included in the decrypted fax transmission destination information and inhibit the user from specifying other destination numbers, or allow the user to specify other destination numbers.  
      In step S 35 , the device driver unit  22  attaches to a direct fax transmission job the account-authentication user ID/password, determined in step S 33  described above, and the destination number specified in step S 34  described above, and transmits the job to the MF apparatus  10 . In this case, before the transmission the device driver unit  22  encrypts at least the account-authentication user ID/password and the destination number by means of the MF public key registered in the PC storage unit  21 .  
      In step S 36 , upon receipt of the direct fax transmission job to which the encrypted account-authentication user ID/password and the destination number are attached, the MF apparatus  10  uses the MF private key registered in the MF apparatus storage unit  13  to decrypt the encrypted user ID/password and the destination number and authenticates the user on the basis of the decrypted user ID/password. If the user is authenticated successfully, the MF apparatus  10  executes the direct fax transmission job by the facsimile device  12  on the basis of the decrypted destination number and performs account processing for the user ID regarding the facsimile transmission. If the user authentication fails, the MF apparatus  10  discards the direct fax transmission job and does not execute the direct fax transmission. In this case, the MF apparatus  10  may send, to the device driver unit  22 , a message which indicates the failure of user authentication. Meanwhile, the device driver unit  22  does not record the confidential information, which was decrypted, expanded, and processed in the volatile storage area of the PC  20 , into a non-volatile storage area such as a hard disk, but discards the confidential information from the PC  20  after transmitting the job.  
      D. Processing at the Time of Information Update  
       FIG. 7  is a diagram showing the operation procedure of the image processing system  1  at the time of information update. The following describes the operation of the image processing system  1  at the time of information update. Although the following describes only the update of an account-authentication user ID/password, the same operation is used to update other confidential information such as fax transmission destination information.  
      In step S 41 , when the user presses the “Add/update account-authentication user ID/password” button on the properties screen of the device driver, the device driver unit  22  displays a dialog box to prompt the user to enter an account-authentication user ID/password. Simultaneously, the device driver unit  22  transmits to the MF apparatus  10  a confidential information transmission request, as well as user certificate identification information that identifies the user certificate registered in the PC storage unit  21 .  
      In step  42 , upon receipt of the transmission request and the user certificate identification information from the device driver unit  22 , the MF apparatus  10  uses the user public key included in the user certificate to encrypt the confidential information, saved as an entry associated with the user certificate identified by the user certificate identification information described above, and returns the encrypted confidential information to the device driver unit  22 .  
      In step S 43 , the device driver unit  22  receives the encrypted confidential information from the MF apparatus  10 , decrypts the encrypted confidential information in the volatile storage area by means of the user private key registered in the PC storage unit  21 , and displays the decrypted account-authentication user ID/password in the dialog box.  
      In step S 44 , the device driver unit  22  accepts editing (addition or change) of the account-authentication user ID/password in the dialog box described above and, when the “OK” button is pressed, closes the dialog box.  
      In step S 45 , at the same time the dialog box is closed, the device driver unit  22  encrypts the updated account-authentication user ID/password by means of the MF public key registered in the PC storage unit  21  and transmits to the MF apparatus  10  the encrypted account-authentication user ID/password, as well as the user certificate identification information that identifies the user certificate registered in the PC storage unit  21 .  
      In step S 46 , upon receipt of the user certificate identification information and the encrypted updated account-authentication user ID/password from the device driver unit  22 , the MF apparatus  10  writes the encrypted updated account-authentication user ID/password over the confidential information saved as an entry associated with the user certificate identified by the user certificate identification information. Meanwhile, the device driver unit  22  does not record the confidential information, which was decrypted, expanded, and processed in the volatile storage area of the PC  20 , into a non-volatile storage area such as a hard disk, but discards the confidential information from the PC  20  after the transmission of the user ID/password.  
      The image processing system  1  described above may also be configured as described in (a)-(o).  
      (a) The device driver unit  22  transmits the confidential information to the MF apparatus  10  in step S 16  and, subsequently, records information, which indicates that the confidential information is saved in the MF apparatus  10 , in the non-volatile storage area of the PC storage unit  21 . This information helps the device driver unit  22  to check if the confidential information is registered.  
      (b) When the user certificate identification information and the encrypted confidential information are received in step S 17 , the MF apparatus  10  checks if the user certificate identified by the user certificate identification information is already registered in the MF apparatus storage unit  13 . If the user certificate is already registered, the MF apparatus  10  saves the encrypted confidential information; if the user certificate is yet not saved, the MF apparatus  10  discards the confidential information and sends a message to the device driver unit  22  to indicate that the user certificate is not saved.  
      (c) In the PC  20 , the device driver unit  22  uses the OS or the application software function supplied with the OS to manage a public key, a private key, and a certificate, or encrypt/decrypt. That is, the OS and the application software supplied with the OS perform key management and encryption/decryption processing, whereas the device driver unit  22  simply calls up the processing.  
      (d) The device driver unit  22  is configured in such a way that the priority specification of the user ID is accepted on the properties screen. Even if the decrypted confidential information includes multiple account-authentication user IDs/passwords in step S 23  but a particular user ID is assigned priority, the device driver unit  22  does not open the user ID selection dialog box but decides to use the priority-assigned user ID.  
      (e) The device driver unit  22  writes other code over the information when discarding the information from the volatile storage area.  
      (f) If no user certificate is present in the PC  20  or the public key of the MF apparatus  10  cannot be acquired, the device driver unit  22  does not hold the confidential information, such as a user ID/password, in the non-volatile storage area of the PC  20 , but requests the user to enter the confidential information whenever it is required.  
      (g) If an addition or change to the decrypted confidential information is accepted after transmitting a job, the device driver unit  22  transmits the updated confidential information to the MF apparatus  10  and, after the transmission, discards the confidential information from the volatile storage area as in steps S 45 -S 46 .  
      (h) The device driver unit  22  can acquire confidential information, registered into the MF apparatus  10  by some other PC  20 , from the MF apparatus  10  and use the confidential information. For example, the device driver unit  22  has a user interface (UI) that accepts an instruction to use confidential information already registered in the MF apparatus  10  and, if the instruction is accepted, does not register new confidential information. Alternatively, before registering new confidential information, the device driver unit  22  checks if the confidential information associated with the user certificate, registered in the PC storage unit  21 , is already registered in the MF apparatus  10 . If the confidential information is not yet registered, the device driver unit  22  registers the new confidential information; if the confidential information is already registered, the device driver unit  22  does not register the new confidential information.  
      (i) When a response indicating that no information is present is received from the MF apparatus  10  in step S 22  or S 32  described above, the device driver unit  22  notifies the user that the information is not present or is lost. The information is reported, for example, by displaying a confirmation dialog box or by displaying characters or an icon, which indicates that the information is lost, when the properties screen of the device driver is opened.  
      (j) Upon receipt of a response indicating that the information is not present from the MF apparatus  10  in step S 22  or S 32  described above, the device driver unit  22  initializes the information, registered in step S 14  described above. In this case, the device driver unit  22  may inform the user that the information is initialized.  
      (k) Upon receipt of a response indicating that the information is not present is received from the MF apparatus  10  in step S 22  or S 32  described above, the device driver unit  22  does not transmit the job to the MF apparatus  10  but terminates the print processing or the direct fax transmission processing.  
      (l) Upon receipt of a response indicating that the information is not present from the MF apparatus  10  in step S 22  or S 32  described above, the device driver unit  22  displays a dialog box, which requests the user to enter confidential information such as an account-authentication user ID/password or fax transmission destination information, and transmits the job to the MF apparatus  10  on the basis of the information entered through the dialog box. In this case, the device driver unit  22  may transmit the entered confidential information to the MF apparatus  10  for registration therein.  
      (m) The MF apparatus  10  identifies the PC  20  that first registered confidential information and rejects and discards update information received from a PC other than that PC  20 .  
      (n) The ME apparatus  10  validates a user on the basis of a user certificate upon receipt of the user certificate from the device driver unit  22  in step S 14 .  
      (o) The MF apparatus  10  transmits an MF certificate, which includes the MF public key, to the device driver unit  22  in step S 14 . The device driver unit  22  validates the MF apparatus  10  on the basis of the MF certificate when the MF certificate is received from the MF apparatus  10 .  
      Although embodiments of the present invention have been described with a certain degree of particularity using specific examples, it is to be understood that the invention is not limited thereto. It is further understood by those skilled in the art that various changes and modifications may be made to the invention without departing from the spirit and scope thereof.  
      For example, the confidential information may be other information such as confidential-print (security-print) user ID/password. The following briefly describes confidential printing. To perform confidential printing, the device driver unit  22  transmits a confidential-print job to the MF apparatus  10  in accordance with an instruction from the user. In this case, a confidential-print user ID/password is attached to the confidential-print job. The MF apparatus  10  receives the job and temporarily saves it therein. Subsequently, the MF apparatus  10  receives a user ID/password from the user and, if a confidential-print job to which the received user ID/password is attached is saved, executes the confidential-print job.  
      Although in the above embodiment the device driver unit  22  transmits a confidential information transmission request to the MF apparatus  10  upon receipt of a print instruction or a direct fax transmission instruction, the device driver unit  22  may transmit a transmission request at some other time. For example, the device driver unit  22  may transmit a transmission request at one of the following times: when device driver information is referenced, when power is turned on, when the PC  20  is reset, when a user logs on, when the mode is returned from power-saving mode or sleep mode, or when a user directly specifies an instruction to acquire information.