JP4070633B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus and can be applied to an image forming apparatus having storage means for storing input data.
[0002]
[Prior art]
For example, a copier or the like accumulates input data in a large-capacity storage device (HDD) in the copier, takes out the accumulated data from the accumulating means, and copies and outputs it on a sheet or the like based on the accumulated data.
[0003]
Therefore, the input data itself is stored in the storage means. For example, after stealing the storage means, there is a security problem that the stored data can be taken out maliciously using another device or the like. . In particular, leakage of confidential documents is a problem.
[0004]
Conventionally, in order to solve such problems, leakage of confidential documents has been prevented by performing the following means.
[0005]
First, the first confidential document leakage prevention means prevents leakage of confidential documents by, for example, prohibiting copying of a specific confidential document by a copying machine.
[0006]
Next, for example, when copying a document with a copying machine, when copying a document with a copying machine, only a user who is permitted to copy is given a password, and user authentication is performed based on the password. The image information stored in the copying machine cannot be accessed by copying by a person other than the authorized user, thereby preventing information leakage.
[0007]
[Patent Document 1]
JP 2002-50956 A
[0008]
[Patent Document 2]
JP 2001-325153 A
[0009]
[Problems to be solved by the invention]
However, the above-described confidential document leakage prevention means has the following problems.
[0010]
In the case of the above-mentioned first confidential document leakage prevention means, it is possible to prevent the copying of confidential documents by human hands in the company from leaking outside the company by prohibiting the copying of specific confidential documents. In this case, the original function of the copying machine is limited, and convenience is lost.
[0011]
The following confidential document leakage prevention means can prevent unauthorized access to the user authentication using a password or the like because the user authentication program is operating while the copying machine is energized, but the copying machine is powered off. If the internal storage device (HDD) is removed and the HDD is connected to another device (for example, a personal computer) and the internal information is analyzed, the internal information is easy because the authentication program does not work. May be deciphered.
[0012]
By the way, for example, in the field of information communication using a network such as a facsimile, when information communication is performed, information is encrypted and transmitted in order to prevent leakage of information on a transmission path.
[0013]
A general encryption method used in this case is that a common encryption key is determined in advance on the transmission side and the reception side, and on the transmission side, information related to transmission is encrypted based on the encryption key to transmit the transmission path. The reception side restores the received signal based on the encryption key. By doing so, the encryption key is not transmitted on the transmission line, and it cannot be decrypted even if the encryption information leaks illegally.
[0014]
Therefore, there is provided an image forming apparatus capable of preventing document leakage by accumulating image data encrypted by using an encryption key for input image data.
[0015]
[Means for Solving the Problems]
In order to solve such a problem, an image forming apparatus of the present invention is an image forming apparatus that forms an image based on input image data. (1) When the input image data is stored in the image storage means, the image data is always encrypted using the encryption key, and the encrypted image data stored in the image storage means is read out. Encrypting / restoring means to restore the encrypted image data And (2) encryption key compression / decompression processing means for compressing or decompressing the encryption key by a predetermined compression / decompression processing method, and (3) storing the compressed encryption key in the non-volatile storage means for storing the encryption key In addition, when the encryption key is used, the compressed encryption key is read out, and as the encryption key compression / decompression processing means, image compression / decompression processing means for performing compression / decompression processing of image data is applied. It is characterized by.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
(A) First embodiment
Hereinafter, a first embodiment of an image forming apparatus of the present invention will be described with reference to the drawings.
[0017]
In this embodiment, a digital copying apparatus (DPPC) will be described as an example of an image forming apparatus. However, an image forming apparatus (for example, a printer, a facsimile machine, a composite machine) having a storage unit that stores input images will be described. Widely applicable to machine etc.).
[0018]
(A-1) Configuration of the first embodiment
FIG. 1 is a schematic block diagram of a digital copying apparatus according to this embodiment.
[0019]
The image forming storage device according to the present embodiment includes a system control unit 1 that controls the entire apparatus, a scanner subsystem 2 that converts a document into a digital signal and outputs digital signal image data, and digital signal image data. A printer subsystem 4 that prints and outputs an image based on the paper, and a control panel 7 that displays the status of the image forming apparatus such as a paper jam and inputs various parameters and operation modes when the user performs copying. Is provided.
[0020]
The scanner subsystem 2, the printer subsystem 4, and the control panel 7 are equipped with CPUs 203, 43, and 74, respectively. These CPUs 203, 43, and 74 are serially connected to the system CPU 10 of the system control unit 1 that performs overall control. Control information is transmitted / received via the IF to control each block.
[0021]
As shown in FIG. 1, the system control unit 1 has two substrate configurations including a system control circuit 5 and an HDD block 80 that can store a plurality of image data. In other words, each unit is composed of different units.
[0022]
The system control circuit 5 includes a system CPU 10, a main memory 12, a ROM 11, an NVRAM 14, a page memory control circuit 30, and a LAN controller 60.
[0023]
The system CPU 10, the main memory 12, the ROM 11, and the NVRAM 14 are connected via a local bus 15. The system CPU 10, the HDD block 80, the page memory control circuit 30, and the LAN controller 60 are connected via the system bus 9.
[0024]
Hereinafter, each internal configuration of the system control circuit 5 will be described.
[0025]
The system CPU 10 controls the entire apparatus. A detailed internal configuration of the system CPU 10 will be described later.
[0026]
The ROM 11 stores a control program for controlling the entire apparatus. The ROM 11 reads a control program stored by the system CPU 10 in accordance with a predetermined rule when the power is turned on, and boot processing is performed by the control program.
[0027]
The main memory 12 is composed of a volatile DRAM, and stores a control program loaded from the ROM 11 by the system CPU 10 in a predetermined area when the power is turned on. The main memory 12 operates the stored control program while the power is on. Also, the main memory 12 performs random number generation according to a predetermined random number generation function when performing encryption processing of an encryption key used for encryption or restoration of image data (this encryption key encryption processing will be described later). Is stored as an encryption key.
[0028]
The NVRAM 14 backs up with a battery that stores setting values for each machine. The NVRAM 14 stores random numbers temporarily stored in the main memory 12 in a specific area.
[0029]
The page memory control circuit 30 temporarily stores image data (digital signal) in units of pages. The page memory control circuit 30 includes a page memory 300 that temporarily stores image data for each page, and a page memory control unit 301 that controls the page memory 300. Further, the page memory control circuit 30 performs image data compression processing and compression image data decompression processing, which will be described later, in response to a request. The internal configuration of the page memory 301 will be described later.
[0030]
The LAN controller 60 interfaces transmission and reception of image data between a terminal (for example, a personal computer or the like) connected on a network (not shown) and an image forming storage device.
[0031]
Next, the internal configuration of the HDD block 80 will be described.
[0032]
The HDD block 80 includes a mass storage device (hereinafter referred to as HDD) 830, an encryption / decryption circuit 810, an encryption key memory 820, and an IDE controller 800.
[0033]
The HDD 830 stores a plurality of image data encrypted by the encryption circuit 810.
[0034]
The encryption / decompression circuit 810 receives the image data compressed by the page memory control circuit 30 via the IDE controller 800, and encrypts the compressed image data based on the encryption key. The image data is stored in the HDD 830. The encryption / restoration circuit 810 reads the encrypted image data stored in the HDD 830, restores the encrypted image data based on the encryption key, and restores the restored image data (ie, the original image data). (Compressed image data) is provided to the IDE controller.
[0035]
Here, the encryption method performed by the encryption / restoration circuit 810 can be widely applied as long as it is an encryption / restoration method performed using an encryption key.
[0036]
The encryption key memory 820 is a volatile memory that stores an encryption key used for encrypting and restoring image data. When the image data is encrypted and restored by the encryption / restoration circuit 810, the encryption key stored in the encryption key memory 820 is read by the encryption / restoration circuit 810.
[0037]
The IDE controller 800 is an interface between the system bus 9, the HDD 830, the encryption circuit 810, the encryption key memory 820, and the system bus 9. The IDE controller 800 receives the compressed image data from the page memory control circuit 30 via the system bus 9 and supplies it to the encryption / decompression circuit 810. The IDE controller 800 supplies the image data restored by the encryption / restoration circuit 810 to the page control circuit 30 via the system bus 9.
[0038]
Next, the internal configuration of the system CPU 10 of the system control circuit 5 described above will be described. FIG. 2 is a block diagram showing the internal configuration of the system CPU 10.
[0039]
As shown in FIG. 2, the system CPU 10 includes a CPU core 100 that executes a control program of the ROM 11, a DRAM controller 101 that controls the main memory 12 (SDRAM) on the local bus 15, and a ROM 11 that is also on the local bus 15. The ROM controller 102 that controls the NVRAM 14, the local bus I / F 103 that interfaces the local bus 15, the SDRAM controller 101, and the ROM controller 102, and interrupts are input from each block on the device, and are based on a predetermined priority order. The interrupt controller 104 for notifying the CPU core 100 of only one interrupt, and the three channels serving as an interface for the scanner CPU 203, printer CPU 43, control panel CPU 74, and CPU core 100 to communicate with each other. Serial I / O (SIO) 105, a system bus controller 106 for interfacing each block on the system bus 9 and each block on the system control unit 1, a timer 107, a CPU core 100, and each of the system CPU 10 And an internal bus 108 for connecting blocks (DRAM controller 101, ROM controller 102, interrupt controller 104, 3-channel serial I / O (SIO) 105, system bus controller 106, timer 107).
[0040]
Next, the internal configuration of the page memory control unit 301 of the page memory control circuit 30 described above will be described. FIG. 3 shows the internal configuration of the page memory control unit 301.
[0041]
As shown in FIG. 3, the page memory control unit 301 includes a system bus interface (system bus IF) 32 for interfacing each internal block with the system bus 9, an LCD controller 33, an LED controller 34, and a page memory. 300, and between the page memory 300, a later-described device on the system bus 9, a scanner subunit 2 connected via a scanner image IF 92, and a printer subunit 4 connected via a printer image IF 91. And PM-CON 35 for controlling the transfer of image data.
[0042]
The PM-CON 35 arbitrates access requests from devices that access the page memory 300 in a predetermined priority order, and sequentially accesses the page memory 300 based on the access requests.
[0043]
The device that accesses the page memory 300 includes a scanner image processing unit 202 that writes image data to the page memory 300 via the scanner image IF 92 and a printer image processing unit that reads image data on the page memory 300 via the printer image IF 91. 41, the system CPU 10, the LCD controller 33, and an IDE controller 800 that stores image data on the page memory 300 in the HDD 830 or returns image data stored in the HDD 830 to the page memory 300.
[0044]
The page memory 300 is provided with a display data area for storing display data for display on the LCD 70 in addition to an area for temporarily storing image data. The LCD controller 33 periodically displays the display data. The display data stored in the area is read, and the display data is output to the LCD 70 in synchronization with the synchronization signal output by the LCD 70 on the control panel 7. The LCD 70 sequentially displays display data.
[0045]
Next, the internal configuration of the PM-COM 35 of the page memory 300 will be described. FIG. 4 is a configuration diagram showing the internal configuration of the PM-COM 35.
[0046]
The PM-COM 35 includes a transfer channel that interfaces data transfer between the page memory 300 and other processing blocks, a data processing block (compression processing 3530 and decompression processing 3531), a rotation processing 3532, and a page memory for each transfer channel. It has an address generation unit for generating 30 addresses and a PDRAM control unit 36.
[0047]
The transfer channels are: scanner IF 3501, printer IF 3509, HDD transfer (ch 0) 3504, HDD (ch 1) 3506, compression (input) 3502, compression (output) 3503, decompression (input) 3507, decompression ( Output) 3508, memory clear 3510, CPUIF 3511, and LCDIF 3512.
[0048]
The address generation unit includes AGC (ch0) 3520, AGC (ch1) 3521, AGC (ch2) 3522, AGC (ch3) 3523, AGC (ch4) 3524, AGC (ch5) 3525, and FIFO. (Ch1-A) 3526, FIFO (ch1-B) 3527, FIFO (ch0-A) 3528, and FIFO (ch0-B) 3529.
[0049]
Note that the function of each component of the PM-COM 35 in FIG. 4 will be described in detail in the description of the operation described later.
[0050]
Returning to FIG. 1, the scanner subsystem 2 optically converts the document into line-by-line optical signals in synchronism with at least a document transport unit (not shown) that transports the document at a predetermined timing. The CCD 201 and an electrical signal output from the CCD 201 are converted into predetermined pixels (for example, 8 bits / pixel), and image processing suitable for a designated image mode such as a character mode, a character photograph mode, and a photograph mode is executed, and then 1 bit / A gradation processing is performed on pixel data, and a scanner image processing unit 202 that outputs image data to the page memory control unit 3 via the scanner image IF 92 at a predetermined timing, a scanner CPU 203 that controls the scanner subunit 2, and the like. Is.
[0051]
The printer subsystem 4 reads at least image data temporarily stored in the page memory 300 at a predetermined timing via the printer image IF 91, and performs image processing in a designated mode, and a printer image processing unit 41. A laser drive circuit 42 that converts image data from the printer image processing unit 41 into an optical signal, and an image is formed by electrostatic recording on the basis of the optical signal from the laser drive circuit 42 and transferred to a predetermined sheet. An image forming unit (not shown) for outputting, a printer CPU 43 for controlling the printer subsystem 4, and the like are included.
[0052]
The control panel 7 includes an LCD 70 for displaying the state of the machine or displaying information on various parameters, a touch panel 71 disposed on the LCD 70, a numeric keypad 72, a plurality of LED units 73, and these control panels. 7 has a panel CPU 74 for controlling the respective components.
[0053]
In the present embodiment, the touch panel 71 and the key 72 are provided as input means, but the present invention can be widely applied as long as an input operation is performed by the user.
[0054]
(A-2) Operation of the first embodiment
Hereinafter, the operation of the image forming apparatus according to the first embodiment will be described with reference to the drawings.
[0055]
First, the copy sequence will be described with reference to FIG.
[0056]
The scanner IF 3501 takes in image data (for example, image data in units of 8 pixels) from the scanner subsystem 2 in synchronization with a synchronization signal output from the scanner subsystem 2, and transfers data to the page memory 300 (for example, for example). When the data of 32 pixels) is fetched, a transfer request is output to the PDRAM control unit 36.
[0057]
The scanner IF 3501 sends image data and an address generated by the address generation channel AGC (ch0) 3520 corresponding to the scanner transfer channel to the PDRAM control unit 36 in synchronization with the data transfer permission signal output from the PDRAM control unit 36. Output.
[0058]
The PDRAM control unit 36 arbitrates transfer requests for each transfer channel, and determines a transfer-permitted channel according to a priority such as round robin.
[0059]
In the case of the write processing from the transfer channel to the page memory 300, the PDRAM control unit 36 first outputs a transfer permission signal to the transfer channel permitted to transfer, and the image data from the transfer channel output in synchronization with this signal. And receive an address.
[0060]
Next, the PDRAM control unit 36 converts the received address into an address corresponding to the SDRAM constituting the page memory 300, generates a control signal corresponding to the SDRAM, and receives the received signal in an area corresponding to the address. Write image data.
[0061]
The address generators (AGC (ch0) 3520, AGC (ch1) 3521, AGC (ch2) 3522, AGC (ch3) 3523, AGC (ch4) 3524, AGC (ch5) 3525) are two-dimensional corresponding to the document or paper. This address is generated by two counters, a main scanning address counter and a sub scanning address counter.
[0062]
The main scanning address counter is incremented every time access to the corresponding transfer channel is permitted to the PDRAM control unit 36 and access is completed. When the main scanning address counter reaches a predetermined set value for the document or paper, the sub-scanning address counter is counted up and the main scanning address counter is cleared.
[0063]
By repeating such processing, when both the sub-scanning address counter and the main-scanning address counter reach a predetermined set value of the document or paper, the transfer of one page is completed. The main scanning address counter is cleared, and at the same time, the system CPU 10 is notified via the page memory end interrupt 1201 that one page has been accessed.
[0064]
As a result, the image data read by the scan subsystem 2 is stored on the page memory 300.
[0065]
Next, compression processing of image data stored on the page memory 300 will be described.
[0066]
When a request is output from the compression (input) channel 3502 to the PDRAM control unit 36 in response to an input request from the compression processing unit 3530, the image data on the page memory 300 is read and the image data is compressed. Part 3530.
[0067]
At this time, the setting of the address generation unit AGC (ch1) 3521 to be used is the same as the setting of the address generation unit AGC (ch0) 3520 used when receiving the image data from the scanner subsystem 2, and therefore the scanner sub The image data transferred from the system 2 and stored in the page memory 300 is compressed by the compression processing unit 3530.
[0068]
If the image data compressed by the compression processing unit 3530 (hereinafter, also referred to as compressed data) can be output to the page memory 300 (that is, there is a unit (for example, 32 bits) of compressed data to be written to the page memory 300), A data output request is output from the compression processing unit 3530 to the compression (output) channel 3503, and the compressed output channel 3503 writes the compressed data to the page memory 300 in the same manner as the scanner channel 3501.
[0069]
The address generation units (FIFO (ch1-A) 3528, FIFO (ch1-B) 3529, FIFO (ch0-A) 3526, FIFO (ch0-B) 3527) are each a one-dimensional address generation channel, A register (not shown) for setting the final address and a loop counter (not shown) that counts up the address every access from the initial address, loads the initial address when the final address is reached, and counts up again from the initial address Not).
[0070]
Further, FIFO (ch1-A) 3528 and FIFO (ch1-B) 3529, and FIFO (ch0-A) 3526 and FIFO (chO-B) 3527 are paired with each other, and two channels (ch0, ch1) are provided. Perform FIFO counter operation.
[0071]
Here, the FIFO counter operation refers to an operation for adjusting the read operation of the page memory 300 so as not to overtake the write operation of the page memory 300. For example, the FIFO counter operation in ch0 will be described as an example. , FIFO (ch0-A) 3526 performs a write operation to page memory 300, and FIFO (ch0-B) 3527 performs a read operation, read-out of page memory 300 by FIFO (ch0-B) 3527 is FIFO ( ch0-A) When the counter value of FIFO (ch0-B) 3527 becomes equal to the counter value of FIFO (ch0-A) 3526 so as not to overtake writing by 3526, the FIFO (ch0-B) 3527 An operation for waiting for read access is performed.
[0072]
In this case, the FIFO (ch0-A) 3526 that performs the write operation monitors the difference between the counter values. When the difference between the counter values is equal to “final address−initial address”, the read operation is performed. In order to avoid this, the FIFO (ch0-B) 3526 overwrites the data before the FIFO (ch0-B) 3527 reads the data, and the data disappears. -A) The operation of waiting for the request of 3526 is performed.
[0073]
Thereby, the FIFO (ch0-B) 3527 on the reading side can read only the compressed data compressed by the compression processing unit 3530 from the page memory 300.
[0074]
The HDD transfer channels 3504 and 3506 interface data transfer between the HDD 830 and the page memory 300, and the HDD (ch0) 3504 outputs a transfer request to the PDRAM control unit 36 if compressed data can be input. The compressed data is taken from the page memory 300.
[0075]
When the compressed data is taken into the HDD (ch0) 3504, the IDE controller 800 acquires the control right of the system bus 9, and the compressed data in the HDD (ch0) 3504 is transferred to the encryption circuit 810 via the system bus 9. Is output.
[0076]
In the encryption circuit 810, the compressed data from the HDD (ch0) 3504 is encrypted based on the encryption key stored in advance in the encryption key memory 820 when the power is turned on.
[0077]
Here, the encryption method uses DES (Data Encryption Standard) generally used in data communication. The encryption method is not limited to this, and can be widely applied as long as it is a reversible encryption method capable of restoring encrypted data.
[0078]
The encrypted encryption code (encrypted image data) is written to the HDD 830 by the encryption circuit 810.
[0079]
By repeating such processing, the compression processing operation is completed when the compression processing for one page is completed.
[0080]
Next, the decompression printing operation of the encryption code written in the HDD 830 will be described. This encryption code decompression printing operation operates in the reverse order of the compression processing operation described above.
[0081]
First, the corresponding compressed and encrypted image data (encryption code) from the HDD 830 is read out by the encryption circuit 810 and based on the encryption key stored in the encryption key memory 820 by the encryption circuit 810. The encrypted code is decrypted and restored to the original compressed data, and the restored compressed data is given to the IDE controller 800.
[0082]
The IDE controller 800 outputs a transfer request to the system CPU 10 to acquire the system bus 9. During the transfer permission period, the compressed data from the encryption circuit 810 is transferred to the HDD (ch1 in the PM-CON 35 via the system bus 9. ) Transferred to 3506
Here, the system bus controller 106 in the system CPU 1O arbitrates transfer requests from each device on the system bus 9, and permits the IDE controller 800 to transfer when the order of the IDE controller 800 is reached.
[0083]
If data can be input, HDD (ch1) 3506 takes in compressed data from HDD 830 in response to a transfer request from IDE controller 800. If the data input by the above processing exists in the HDD (ch1) 3506, a transfer request is output to the PDRAM control unit 36, and the compressed data is written to the page memory 300.
[0084]
The decompression (input) channel 3507 outputs a request to the PDRAM control unit 36 if data can be taken into the channel, and the compressed data from the HDD 830 taken into the page memory 300 by the HDD (ch1) 3506 is output. The compressed data is read from the page memory 300 and transferred to the decompression processing unit 3531.
[0085]
The decompression processing unit 3531 decompresses the compressed data with a predetermined algorithm.
[0086]
If the decompressed data after decompression processing can be output, the decompression processing unit 3531 outputs a request to the decompression (output) 3508 and gives the decompressed data to the decompression (output) 3508.
[0087]
A decompression (output) 3508 outputs a request to the PDRAM control unit 36 and writes the received decompressed data to the page memory 300.
[0088]
By repeating such processing, the expansion processing operation is completed when the expansion processing for one page is completed.
[0089]
If there is no rotation printing instruction, the printer IF 3509 reads the image data stored in the print area on the page memory 300 using the AGC (ch2) 3522. If there is a rotation printing request, the printer IF 3509 performs rotation processing. After the rotation processing in the unit 3532, the image data is output to the printer subsystem 4 in synchronization with the synchronization signal output from the printer subsystem 4.
[0090]
Next, a boot sequence of the image forming apparatus according to the present embodiment will be described with reference to FIGS.
[0091]
FIG. 6 shows the memory map of the system CPU 10 and the memory contents inside the boot ROM 11. FIG. 7 shows a processing sequence of the boot program.
[0092]
When the power is turned on, the system CPU 10 starts access from address I where the boot program on the memory map of FIG. 6 is stored.
[0093]
First, the system CPU 10 initializes each block in the system CPU 10 shown in FIG. 2 (S21).
[0094]
The OS unit, application unit, and display data are sequentially read from the ROM 11 and copied to a predetermined area on the main memory 12 (S22 to S24).
[0095]
The system CPU 10 starts the main task from the application program copied on the main memory 12 and completes the boot process (S25).
[0096]
Next, a software configuration relating to the operation of the image forming apparatus of the present embodiment will be described with reference to FIG. FIG. 5 shows a software configuration related to the operation of the image forming apparatus. Note that the library layer and the driver layer shown in FIG. 5 belong to the OS section of the ROM 11 shown in FIG.
[0097]
The main task activated by the boot process described above activates an application task.
[0098]
The application task activated by the main task includes a copy application for controlling copy processing, a print application for LAN printer for controlling a printing operation in response to a print request from a terminal (for example, a personal computer) connected to the network, and control. There are various user interfaces (UI) for controlling the interface with the user via the panel 7, and a self-diagnosis application that operates when the machine is activated in the adjustment mode.
[0099]
As the user interface (UI), there is a machine UI that notifies the user of the state of the machine via the LCD, such as displaying a jam location on the LCD when a jam occurs.
[0100]
The copy UI and printer UI provide controls for the user to set parameters for copying operation and LAN-printer operation, respectively, and control for notifying the user of each operation state of copying operation and LAN-printer operation. Do.
[0101]
The Windows (registered trademark) system performs multi-window control of display information from each UI and performs display management on the LCD.
[0102]
A self-diagnosis application that operates when started in the self-diagnosis mode sets an adjustment value unique to a machine. A typical example is a shading correction value of a scanner.
[0103]
In the present embodiment, the process of storing the encryption key and the random number in one area of the NVRAM 14 is executed as one function of the self-diagnosis mode.
[0104]
Next, encryption of the encryption key in the self-diagnosis mode, storage of the encrypted encryption key and random number in the NVRAM 14, reading of the encryption key in the normal operation mode from the NVRAM 14, and the encryption key to the encryption key memory 820 The storing process will be described with reference to FIG. FIG. 8 is a schematic flow of a machine control program.
[0105]
When the machine is turned on, the boot process described above is performed (S1).
[0106]
During the boot process, the system controller 1 and the control panel 7 shown in FIG. 1 are initialized (S2).
[0107]
After the boot process, when the control program starts operating on the main memory 12, it is confirmed whether or not there is a key input in the main task (S3).
[0108]
At this time, when no key is pressed when the power is turned on, the operation shifts to the normal operation mode, and when the key is pressed, the operation shifts to the self-diagnosis mode (S4). ).
[0109]
For example, a specific key to be pressed to shift to the self-diagnosis mode is determined in advance. For example, when the specific key is “1” and “9” pressed simultaneously, when the power is turned on, the user When the numeric keys “1” and “9” of the key 72 are pressed at the same time, the mode shifts to the self-diagnosis mode (S5).
[0110]
In the self-diagnosis mode, the screen display of the self-diagnosis mode is displayed on the LCD 70, and a display is made to input the number of the self-diagnosis function, thereby entering a standby state.
[0111]
When a function number other than the encryption key encryption process is input, a self-diagnosis function determined based on the input function number is executed (S10).
[0112]
For example, if the encryption key encryption process number is “123” and “123” is input by the user, the process proceeds to the encryption key encryption process (S6).
[0113]
First, an encryption key is displayed on the LCD 70 so as to be input from the key 72. When the user inputs the encryption key, the encryption key code is temporarily stored in the main memory 12, a random number is generated by a software-generated random number generation function, and the random number is also temporarily stored in the main memory 12 ( S7).
[0114]
Next, the encryption key code is encrypted using a random number as an encryption key (S8).
[0115]
The encryption method at this time uses the above-described DES and is executed by the system CPU 10 in software.
[0116]
Next, the encrypted encryption key and random number are stored in a predetermined specific area of the NVRAM 14 which is a nonvolatile memory (S9).
[0117]
Finally, the fact that the storage of the encryption key code is completed is displayed on the LCD 70 to notify the user, and at the same time, the same is displayed on the LCD 70 to notify the user to turn off the power (S11).
[0118]
Based on this instruction, this process is completed when the user turns off the power (S12).
[0119]
If the user does not press any key of KEY72 when the power is turned on, the system shifts to the normal mode after the boot process (returns to S4).
[0120]
First, in the normal mode, the system CPU 10 issues a command to initialize the scanner subunit 2 and the printer subunit 4 (S13).
[0121]
Next, the system CPU 10 reads the encrypted encryption key and the random number stored in the NVRAM 14 (S14), and decrypts the encryption key using the random number as a key (S15).
[0122]
Next, the system CPU 10 sets the decrypted encryption key in the volatile encryption key memory 820 via the system bus 9 (S16).
[0123]
Next, the system CPU 10 waits for the initialization completion (end) from the scanner subunit 2 and the printer subunit 4, and confirms that the completion (end) notification has been received and that the other blocks are in the ready state. The LCD 70 displays that it is in the “ready” state, and waits in a request waiting state (S17 and S18).
[0124]
When the user presses the copy start key of the key 72, the system CPU 10 executes the above-described copy sequence and assumes a standby state when processing is completed, assuming that there is a copy request (19).
[0125]
If the power is turned off while waiting for a request (S20), a power-off process is executed to turn off the machine (S11).
[0126]
The key input from the control panel 7 is that the panel CPU 74 periodically checks the touch panel 71 and the key 72, and when the key is pressed when the check is made, the panel CPU 74 displays a code corresponding to the pressed key. Is transmitted to the system CPU 10 via the serial IF 1100.
[0127]
The serial I / O (SIO) 105 in the system CPU 10 receives the transmitted code data, and notifies the CPU core 100 through the interrupt controller 104 that the received code is present.
[0128]
The CPU core 100 recognizes the pressed key by reading the received data from the SI0105.
[0129]
(A-3) Effects of the first embodiment
As described above, according to the present embodiment, by providing the encryption / decryption circuit 810, the image data encrypted based on the encryption key is stored in the HDD 830, so that the encrypted data is stored even if the HDD 830 is stolen. Since it is necessary to decrypt the data, simple data leakage can be prevented.
[0130]
In addition, an NVRAM 14 which is a nonvolatile memory on a circuit board different from the HDD and its peripheral control circuit board is provided, and only the HDD and its peripheral control circuit are stored by storing the encryption key used for encryption in this NVRAM 14. Even if it is stolen, the encryption key itself can be prevented from being stolen, so that it is difficult to decrypt the encrypted data.
[0131]
Further, the encryption key code stored in the NVRAM 14 which is a non-volatile memory is encrypted based on a random number code which is stored in another area of the same NVRAM 14 and which is obtained in advance by generating a random number at the time of machine shipment. Therefore, the NVRAM 14 is stolen at the same time as the HDD, and it is difficult to decrypt the encryption key from the stored data in the NVRAM 14.
[0132]
(B) Second embodiment
In the second embodiment, a predetermined compression process is performed on an encryption key used for encrypting image data, and the compressed encryption key (compressed encryption key) is stored in NVRAM. Different from the embodiment.
[0133]
Therefore, in the following, the system control circuit 5 will be described in detail, and detailed function descriptions of other components will be omitted. Further, in the second embodiment, description will be made by using the configuration requirements and symbols in FIG. 1 as they are.
[0134]
(B-1) Configuration and operation of the second embodiment
FIG. 9 is a flowchart showing the operation of the second embodiment.
[0135]
In FIG. 9, the operations from the power-on (S1) to the determination (S4) whether the current mode is the normal mode or the self-diagnosis mode based on the key input confirmation are the same as in the first embodiment (S1). ~ S4). In this embodiment, the encryption key compression process is executed as one function of the self-diagnosis mode.
[0136]
When the mode is shifted to the self-diagnosis mode and the function number for the encryption key compression process is input by the user, the mode is shifted to the compression mode (S91).
[0137]
First, an encryption key is input by the user via the key 72, and the input encryption key temporarily stores the encryption key (S92).
[0138]
Next, the encryption key is given to the compression processing unit 3530 of the page memory control unit 35, and the encryption key is compressed by the compression processing unit 3530 (S93).
[0139]
Here, the compression processing method of the encryption key is performed as follows, for example.
[0140]
When the encryption key is given to the compression processing unit 3530, the number of bits of the encryption key is adjusted so as to be the number of unit bits of the area where the compression process is possible. For example, if the number of bits of the encryption key is smaller than the unit bit number of the area where compression processing is possible, the encryption key is positioned at the head of the compression processing area and “all 0 (or all 1)” is left in the remaining area Is inserted into the unit of the compression processing area.
[0141]
When the compression processing area is adjusted, the compression processing unit 3530 performs compression processing. The encryption key compression processing method of this embodiment will be described assuming that the method used for image data compression processing is used as it is. However, any method can be used as long as the compression processing and the decompression processing are reversible. There may be.
[0142]
The encryption key (compressed encryption key) compressed by the compression processing unit 3530 in this way is given to the NVRAM 14 and stored in a predetermined area of the NVRAM 14 (S94).
[0143]
Subsequent operations are the same as those in the first embodiment, and a description thereof will be omitted.
[0144]
Next, when it is determined that the operation mode is the normal operation mode based on the confirmation of the key input when the power is turned on, the compression encryption key stored in the NVRAM 14 is expanded as described below.
[0145]
A command is given to shift to the normal mode and advance initialization of the scanner subsystem 2 and the printer subsystem 4 (S13).
[0146]
Next, in response to a command from the system CPU 10, the compressed encryption key stored in the NVRAM 14 is given to the page memory control unit 301, and the decompression processing unit 3531 decompresses the compressed encryption key (S95).
[0147]
This decompression processing method is performed in the same manner as the image data decompression processing in the first embodiment. If the decompression (input) channel 3507 can capture data in the channel, a request is sent to the PDRAM control unit 36. Thus, the compressed encryption key data is supplied from the page memory 300 to the decompression processing unit 3561.
[0148]
Since the subsequent operation is the same as that of the first embodiment, the description thereof is omitted.
[0149]
(B-2) Effects of the second embodiment
As mentioned above, according to 2nd Embodiment, there exists an effect similar to 1st Embodiment.
[0150]
Further, according to the second embodiment, the NVRAM 14 stores the compression of the encryption key, so even if the NVRAM 14 is stolen and the stored compressed encryption key is read, Since it is necessary to perform decompression processing of the compressed encryption key, it becomes difficult to decrypt the encryption key, and data leakage can be prevented.
[0151]
(C) Other embodiments
(C-1) In the first embodiment described above, the NVRAM 14 stores the generated random number and the encrypted encryption key for the encryption key. However, even if this NVRAM 14 is stolen, the encryption key is used. However, it is sufficient that the NVRAM 14 can store a form that cannot be easily understood.
[0152]
For example, the NVRAM stores an encryption key encrypted using a different encryption key with respect to the encryption key related to the encryption of the image data, and the encryption key used for encryption of this encryption key is stored separately. You may make it memorize | store in a means (nonvolatile).
[0153]
【The invention's effect】
As described above, the image forming apparatus of the present invention is an image forming apparatus that forms an image based on input image data. (1) When the input image data is stored in the image storage means, the image data is always encrypted using the encryption key, and the encrypted image data stored in the image storage means is read out. Encrypting / restoring means to restore the encrypted image data And (2) encryption key compression / decompression processing means for compressing or decompressing the encryption key by a predetermined compression / decompression processing method, and (3) storing the compressed encryption key in the non-volatile storage means for storing the encryption key At the same time, when the encryption key is used, the compressed encryption key is read, and as the encryption key compression / decompression processing means, image compression / decompression processing means for performing compression / decompression processing of image data is applied. , Leakage of stored image data can be prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an internal configuration of an image forming apparatus according to a first embodiment.
FIG. 2 is a block diagram showing an internal configuration of a system CPU 10 according to the first embodiment.
FIG. 3 is a block diagram showing an internal configuration of a page memory control unit 301 according to the first embodiment.
FIG. 4 is a block diagram showing an internal configuration of a PM-COM 35 according to the first embodiment.
FIG. 5 is an explanatory diagram illustrating a software configuration of the image forming apparatus according to the first embodiment.
6 is an explanatory diagram showing a memory map of a system CPU 10 and contents of an internal memory of a ROM 11 according to the first embodiment. FIG.
FIG. 7 is a processing sequence of a boot program according to the first embodiment.
FIG. 8 is a flowchart of a control program of the image forming apparatus according to the first embodiment.
FIG. 9 is a flowchart of a control program of the image forming apparatus according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... System control part, 80 ... HDD block, 810 ... Encryption / restoration circuit.

Claims (4)

In an image forming apparatus that forms an image based on input image data,
When the input image data is stored in the image storage means, the image data is always encrypted using an encryption key, and the encrypted image data stored in the image storage means is stored in the image storage means. When reading, an encryption / restoration means for restoring the encrypted image data ,
Encryption key compression / decompression processing means for compressing or decompressing the encryption key by a predetermined compression / decompression processing method;
With
The compressed encryption key is stored in the nonvolatile storage means for storing the encryption key, and the compressed encryption key is read when the encryption key is used.
An image forming apparatus characterized by applying image compression / decompression processing means for performing compression / decompression processing of image data as the encryption key compression / decompression processing means . The upper Symbol encryption and restoring means, the image data in reading out the image data from and or the image storage means when accumulated in the image storage means, one time with a built-in the encryption key from the non-volatile memory means The image forming apparatus according to claim 1, wherein the image forming apparatus is loaded into a storage unit.   The image forming apparatus according to claim 2, wherein the encryption / restoration unit and the nonvolatile storage unit are provided in separate units.   The image forming apparatus according to claim 1, further comprising: an encryption key forming unit that generates a random number and forms an encryption key including at least a part of the generated random number.

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