JP2000224407A - Image formation device, image formation method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of print relating to an electronic signature by calculating a value intrinsic to file data by using a unidirectional function from the data of a file with a signature electronically signed by a secret key, adding the value intrinsic to the file data to print data and generating intrinsic print data. SOLUTION: At the time of printing received electronic mail, whether normal print 901 is selected or electronic signature print 902 is selected is judged at the time of the operation of printing execution 900. Then, in the case that the electronic signature print 902 is selected, the message digest value of received electronic mail data is calculated and added to the print data by a prescribed form. Then, the print data are generated by adding the calculated message digest value by low density characters so as to be difficult to be visually recognized in the entire print image area and printing is finally executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus, an image forming method, and a storage medium.

[0002]

2. Description of the Related Art Conventionally, an electronic signature technique has been used as a means for confirming whether a transmitted electronic mail is really written by the person himself or herself. FIG. 13 and FIG. 14 are diagrams conceptually explaining the digital signature. In this technique, the points are “message digest value” and “public key encryption” in FIG. The message digest is a method of obtaining a unique value for each message.

That is, a message digest value is calculated for a message (text or binary) to be signed. The message digest value is created from the message data to be signed using a one-way function (hash function), and is unique to the message data. Then, the message digest value created as described above is encrypted with the secret key.

[0004] The sender sends the message digest value encrypted with the secret key as a signature to the receiver together with the message to be signed. The receiver decrypts the received signature data with the signer's public key to obtain a message digest value. The message digest value is compared with a message digest value calculated from the received message to be signed. The digital signature is realized by verifying the signature in the above-described procedure.

[0005]

The received message digitally signed is composed of a message and signature data as shown in FIG. When the received message with the digital signature is printed and stored, if the message is binary data such as image data, it is difficult to calculate the message digest value of the message portion from the printed one.

[0006] Therefore, even if a received message that has been electronically signed is stored in a print form, the signature cannot be verified, and when storing important document data, the electronic data and the printed data are usually used. There was a problem that the method of double storage cannot be taken.

[0007] By printing a message digest value on a print as shown in FIG. 12, the signature can be verified. However, the encryption / electronic signature program PGP (Pret
The message digest value generated by the digest function of “Ty Good Privacy” has a size of 16 bytes, and the falsification of the printed message digest value is relatively easy. Therefore, the value of the digitally signed document data is low. Would.

Therefore, if it becomes possible to add a message digest value in a form that is difficult to falsify when printing a received message digitally signed as described above,
The reliability of the print related to the electronic signature can be improved.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to improve the reliability of a print related to an electronic signature by enabling a message digest value to be added to a print in a form that is difficult to falsify.

[0010]

An image forming apparatus according to the present invention calculates a value unique to file data using a one-way function from data of a signed file electronically signed with a secret key. It is characterized in that unique print data is generated by adding a unique value to file data to print data. Another feature of the image forming apparatus of the present invention is that the image forming apparatus prints a signed file electronically signed with a secret key,
A unique value calculating unit that calculates a value unique to the file data from the data of the signed file by using a one-way function; and adding a unique value to the file data calculated by the unique value calculating unit to the print data. A unique value adding means for generating unique print data. Another feature of the image forming apparatus of the present invention is that the unique value adding unit generates the unique print data using a watermark image. According to another feature of the image forming apparatus of the present invention, the unique value adding unit generates the unique print data using a digital watermark. Another feature of the image forming apparatus according to the present invention is an image forming apparatus that prints a signed file digitally signed with a secret key, and calculates a one-way function from the data of the signed file. A unique value calculating means for calculating a unique value for the file data using the file data; a unique value adding means for generating a unique print data by adding a unique value to the print data to the file data calculated by the unique value calculating means; And printing means for printing as numerical data. Another feature of the image forming apparatus according to the present invention is an image forming apparatus that prints a signed file digitally signed with a secret key, and calculates a one-way function from the data of the signed file. A unique value calculating means for calculating a unique value for the file data by using the same, and an additional designating means for designating that a unique value for the file data calculated by the unique value calculating means is added to the print data to generate unique print data. Are provided. Another feature of the image forming apparatus of the present invention is that an instructing unit instructs to image the data of the file with the electronic signature, and the image is formed in accordance with the instruction to the instructing unit. In this case, there is provided an image forming means for forming an image by adding the message digest value in a state where visual recognition is difficult. Another feature of the image forming apparatus of the present invention is that the image forming means performs the addition using low-density characters. Another feature of the image forming apparatus according to the present invention is that the image forming unit performs the addition using a digital watermark. Another feature of the image forming apparatus according to the present invention is that the image forming unit performs the image forming with the addition in response to a selection instruction as to whether or not to perform the addition from an operation unit of an external device. Or not is switched.

According to the image forming method of the present invention, a value unique to file data is calculated using a one-way function from data of a signed file digitally signed with a secret key, and a value unique to the file data is calculated. Is added to the print data to generate unique print data. Another feature of the image forming method of the present invention is an image forming method for printing a signed file electronically signed with a secret key, wherein a one-way function is obtained from the data of the signed file. Performing a unique value calculating step of calculating a unique value of the file data by using the file data; and a unique value adding step of adding a unique value to the file data calculated by the unique value calculating step to the print data to generate unique print data. It is characterized by. Another feature of the image forming method of the present invention is that the unique value adding step generates the unique print data using a watermark image. Another feature of the image forming method of the present invention is that the unique value adding step generates the unique print data using a digital watermark. Another feature of the image forming method of the present invention is an image forming method for printing a signed file electronically signed with a secret key, wherein a one-way function is obtained from the data of the signed file. A unique value calculating step of calculating a unique value of the file data by using the file data; a unique value adding step of adding a unique value to the file data calculated by the unique value calculating step to the print data to generate unique print data; Is printed as numerical data. Another feature of the image forming method of the present invention is an image forming method for printing a signed file electronically signed with a secret key, wherein a one-way function is obtained from the data of the signed file. A unique value calculating step of calculating a unique value of the file data using the file data, and an additional specifying step of specifying that the unique value of the file data calculated by the unique value calculating step is added to the print data to generate unique print data. And is performed. Another feature of the image forming method of the present invention is that an instruction step for giving an instruction to image data of a file with a digital signature, and the data is image-formed in accordance with an instruction to the instruction step. In this case, an image forming step of forming an image by adding the message digest value in a state where visual recognition is difficult is performed. Another feature of the image forming method of the present invention is that in the image forming step, the addition is performed using low-density characters. Another feature of the image forming method of the present invention is that in the image forming step, the addition is performed by a digital watermark. According to another feature of the image forming method of the present invention, the image forming step includes the step of forming the added image according to an instruction to select whether to perform the addition from an operation unit of an external device. Or not is switched.

A storage medium according to the present invention is characterized in that a program for causing a computer to function as means constituting the image forming apparatus is stored so as to be readable from the computer. Another feature of the storage medium of the present invention is that a program for causing a computer to execute the procedure of the image forming method is stored so as to be readable from the computer.

[0013]

Since the present invention has the above technical means, when an electronic mail to which an electronic signature is added is formed into an image, a file using a one-way function is obtained from the data of the signed file electronically signed with a secret key. By calculating a unique value for the data and adding a unique value to the print data to the print data to generate unique print data,
The message digest value can be added in a form that is difficult to falsify, and the reliability of the print related to the electronic signature can be improved. According to another feature of the present invention, the message digest value is added over the entire area of the image data in the form of watermark information, so that the message digest value is added to the image data in a form that is more difficult to falsify. Becomes possible.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image forming apparatus, an image forming method, and a storage medium according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of the image processing apparatus according to the present embodiment. In FIG. 1, a reader unit 1 reads an image of a document, and outputs image data corresponding to the document image to a printer unit 2 and an image input / output control unit 3.

The printer unit 2 records an image corresponding to image data from the reader unit 1 and the image input / output control unit 3 on a recording sheet. The image input / output control unit 3 is connected to the reader unit 1 and includes a facsimile unit 4, a file unit 5, a network interface unit 7, a LIPS formatter unit 8, a postscript formatter unit 9, a core unit 10, and the like.

The facsimile unit 4 decompresses the compressed image data received via the telephone line, and transfers the decompressed image data to the core unit 10. Further, it compresses the image data transferred from the core unit 10 and transmits the compressed compressed image data via a telephone line.

A magneto-optical disk drive unit 6 is connected to the file unit 5. The magneto-optical disk drive unit 6 compresses the image data transferred from the core unit 10 and sends the compressed image data to the magneto-optical disk drive unit 6 together with a keyword for searching the image data. The data is stored in the set magneto-optical disk.

The file section 5 searches for compressed image data stored in the magneto-optical disk based on the keyword transferred via the core section 10, reads out the searched compressed image data, and decompresses it. The decompressed image data is transferred to the core unit 10.

The computer / network interface unit 7 is for performing an interface between the personal computer or workstation (PC / WS) 11 and the core unit 10.

Reference numeral 12 denotes a network server, which is the center of network control. Formatter parts 8 and 9 are P
PDL (Page Description Language) transferred from C / WS11
The data is developed into image data that can be recorded by the printer unit 2.

Although the core unit 10 will be described later, the core unit 10 includes a reader unit 1, a facsimile unit 4, a file unit 5,
It controls the flow of data between the network interface unit 7 and the formatter units 8 and 9.

FIG. 2 is a sectional view of the reader unit 1 and the printer unit 2. The document feeder 101 of the reader unit 1 feeds a document one by one sequentially from the last page onto the platen glass 102, and after the reading operation of the document is completed, the platen glass 10
2 is for discharging the original.

When the document is conveyed onto the platen glass 102, the lamp 103 is turned on and the movement of the scanner unit 104 is started, and the document is exposed and scanned.
The reflected light from the original at this time is reflected by mirrors 105, 106,
The light is guided to a CCD image sensor (hereinafter, referred to as a CCD) 109 by a lens 107 and a lens 108.

As described above, the scanned image of the original is CC
The image data read by the D109 and output from the CCD 109 is subjected to predetermined processing and then transferred to the printer unit 2 and the core unit 10 of the image input / output control unit 3.

The laser driver 221 of the printer unit 2
It drives the laser light emitting unit 201, and the reader unit 1
Causes the laser light emitting unit 201 to emit laser light corresponding to the image data output from.

The laser beam emitted from the laser emitting section 201 is irradiated on the photosensitive drum 202, whereby a latent image corresponding to the laser beam is formed on the photosensitive drum 202. A developer is attached to the latent image portion of the photosensitive drum 202 by a developing device 203.

Then, at a timing synchronized with the start of laser beam irradiation, a recording sheet is fed from one of the cassettes 204 and 205 and transported to the transfer section 206 to record the developer adhered to the photosensitive drum 202. Transfer to paper.

The recording paper onto which the developer has been transferred in this manner is conveyed to the fixing unit 207, and the developer is fixed on the recording paper by the heat and pressure of the fixing unit 207.

The recording paper that has passed through the fixing unit 207 is discharged by discharge rollers 208. The sorter 220 sorts the recording paper by storing the discharged recording paper in each pin. If the sorting is not set, the sorter 220 stores the recording paper at the uppermost pin.

When double-sided recording is set,
After the recording paper is conveyed to the discharge roller 208, the rotation direction of the discharge roller 208 is reversed, and the flapper 209 is rotated.
To the re-feeding conveyance path.

When multiplex recording is set,
The recording paper is guided to the re-feeding conveyance path by the flapper 209 so as not to be conveyed to the discharge roller 208. The recording paper guided to the re-feed conveyance path is fed to the transfer unit 206 by the re-feed conveyance roller 210 at the timing described above.

FIG. 3 is a block diagram showing a schematic configuration of the reader unit 1. As shown in FIG. As shown in FIG. 3, the image data output from the CCD 109 is subjected to analog / digital conversion by the A / D / SH unit 110 and is subjected to shading correction.

The image data processed by the A / D / SH unit 110 is sent to the printer unit 2 via the image processing unit 111.
Is transferred to the core unit 10 of the image input / output control unit 3 via the interface unit 113. C
The PU 114 controls the image processing unit 111 and the interface 113 according to the settings set by the operation unit 115.

For example, when a copy mode for performing a trimming process and performing a copy is set by the operation unit 115,
The image processing unit 111 performs a trimming process and transfers the image data to the printer unit 2. When the facsimile transmission mode is set by the operation unit 115, the interface unit 113 transfers the image data and a control command corresponding to the set mode to the core unit 10.

The control program of the CPU 114 is stored in the memory 116, and the CPU 114 performs control while referring to the memory 116. Also, the memory 11
Reference numeral 6 is also used as a work area of the CPU 114.

FIG. 4 is a block diagram showing a schematic configuration of the core unit 10. As shown in FIG. The image data from the reader unit 1 is transferred to the data processing unit 121 via the interface 122, and the control command from the reader unit 1 is
23.

The data processing section 121 performs image processing such as image rotation processing and scaling processing.
The image data transferred to the data processing unit 121 is processed by the data processing unit 121 in accordance with the control command transferred from the reader unit 1 and the facsimile unit 4 via the interface 120 in accordance with the control command. The file 5 is transferred to the network interface 7.

Code data representing an image input via the computer (network) interface unit 7 is transferred to the data processing unit 121 via the interface 120, and whether the PDL (page description language) is LIPS or not. , Or postscript (ie, determine the type of page description language)
Then, the data is transferred to the appropriate formatter unit 8 or 9 and is developed into image data. Then, after the image data is transferred to the data processing unit 121, the image data is transferred to the facsimile unit 4 and the printer unit 2.

The image data from the facsimile unit 4 is transferred to the data processing unit 121 and then to the printer unit 2, the file unit 5, and the computer (network) interface unit 7. The image data from the file unit 5 is transferred to the data processing unit 121, and then transferred to the printer unit 2, the facsimile unit 4, and the network interface unit 7.

The CPU 123 performs such control according to a control program stored in the memory 124 and a control command transferred from the reader unit 1. The memory 124 is also used as a work area of the CPU 123.

The computer (network) interface unit 7 has an M1B (Management Inf)
A database called an “operation base” is constructed, and communicates with a computer on a network via an SNMP protocol to enable printer management. The number of prints and other various settings that can be set for each department ID can be set and managed from the operation unit 125 of the apparatus or a computer on a network.

As described above, the image forming apparatus according to the present embodiment reads the original image with the core 10 as the center.
It is possible to perform processing combining functions of printing an image, transmitting and receiving an image, storing an image, and inputting and outputting data from a computer.

FIG. 5 is a view for explaining the operation section screen of the operation section 125 shown in FIG. 4 according to this embodiment.
The operation unit 125 is configured by a touch panel. The operator selects either the normal print 901 or the electronic signature print 902 on this screen, and selects print execution 900 to print the e-mail.

FIG. 6 is a flowchart for explaining the operation procedure of the CPU 123 in FIG. 4 when printing the received electronic mail. In the first step 801, it is determined whether the normal print 901 or the digital signature print 902 has been selected at the time of the print execution 900 operation. If the result of this determination is that the electronic signature print 902 has been selected, steps 802-803
Is performed.

In this case, in step 802, a message digest value of the received e-mail data is calculated. In the present embodiment, as shown in FIG.
The message digest value is calculated by using a hash function called "." MD5 is one of the encryption programs currently used in practice, PG
It is used as a message digest function in P (Pretty Good Privacy). Then, the calculated message digest value is stored in FIG.
2 is added to the print data in the format shown in FIG.

Next, in step 803, the message digest value calculated in step 802 is
As shown in (1), print data is generated by adding light density characters (for example, yellow characters) to the entire print image so that visual recognition is difficult. Finally, printing is executed in step 804. If the result of determination in step 801 is that normal printing has been selected, the flow jumps from step 801 to step 804 to execute normal printing.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An embodiment will be described. FIG. 8 is a diagram for explaining a main configuration of an image forming apparatus according to the second embodiment of the present invention.
In the above-described first embodiment, as shown in FIG. 9, a message digest value is added to the entire area of a print image using characters 1200 of low density.

On the other hand, in the second embodiment,
As shown in FIG. 8, a message digest value is added to a print image as digital watermark information. The electronic watermarking technique is a known technique, and is described in detail in, for example, Japanese Patent Application Laid-Open No. 9-191394.

As described above, by using a digital watermark, a message digest value can be added to a printed image in a perceptually difficult form, and falsification can be made more difficult.

(Third Embodiment) FIG. 10 is a diagram for explaining a third embodiment of the present invention. In the above-described first and second embodiments, the received message 141 is printed in the format displayed on the display.

On the other hand, in the third embodiment, in addition to the above printing, the received data is printed in a hexadecimal format. By doing so, it is possible to accurately verify the validity of the message digest value from the print data, and it is possible to make the storage of the received digitally signed message in print more reliable. .

(Other Embodiments of the Present Invention) The present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), and is applied to a single device (for example, a copying machine). , A facsimile machine).

Further, in order to realize the functions of the above-described embodiments, a device connected to the above-mentioned various devices or a computer in a system is operated so as to operate various devices so as to realize the functions of the above-described embodiments. The present invention also includes programs implemented by supplying the program code of the software described above and operating the various devices according to programs stored in a computer (CPU or MPU) of the system or apparatus.

In this case, the program code of the software implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer are provided.
For example, a storage medium storing such a program code constitutes the present invention. As a storage medium for storing such a program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM,
A magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (operating system) or other operating system running on the computer. Needless to say, the program code is also included in the embodiment of the present invention when the functions of the above-described embodiment are realized in cooperation with application software or the like.

Further, after the supplied program code is stored in a memory provided in a function expansion board of the computer or a function expansion unit connected to the computer, the function expansion board or the function expansion unit is specified based on the instruction of the program code. It is needless to say that the present invention also includes a case where the CPU or the like provided in the first embodiment performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0057]

As described above, according to the present invention,
When printing a received message that has been digitally signed, from the data of the signed file digitally signed with the private key,
A unique value is calculated for the file data by using the one-way function, and a unique value is added to the print data to generate the unique print data. A message digest value can be added to the above, and the reliability of the print related to the electronic signature can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a reader unit and a printer unit.

FIG. 3 is a block diagram of a reader unit.

FIG. 4 is a block diagram illustrating a configuration of a core unit.

FIG. 5 is a diagram illustrating an operation unit screen for designating a digital signature print.

FIG. 6 is an explanatory diagram of a digital signature and a message digest value.

FIG. 7 is an explanatory diagram showing the relationship between document data and a message digest value.

FIG. 8 is an explanatory diagram of a digital watermark according to the second embodiment.

FIG. 9 is an explanatory diagram of a message digest value added as a watermark image to a digital signature print.

FIG. 10 is an explanatory diagram of a digital signature print according to the third embodiment.

FIG. 11 is a diagram showing a normal print side of a received message digitally signed.

FIG. 12 is a diagram illustrating a print example in which a message digest value is added to an electronically signed received message.

FIG. 13 is an explanatory diagram of an electronic signature.

FIG. 14 is an explanatory diagram of an electronic signature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reader part 2 Printer part 3 Image input / output control part 4 Facsimile part 5 File part 7 Network interface part 8 Formatter part 9 Image memory part

Claims (22)

[Claims] 1. A one-way function is used to calculate a value unique to file data from data of a signed file digitally signed with a secret key, and to add a value unique to the file data to print data. An image forming apparatus for generating unique print data. 2. An image forming apparatus for printing a file with a signature digitally signed with a secret key, wherein a unique value is calculated from the data of the signed file using a one-way function. An image forming apparatus comprising: a calculating unit; and a unique value adding unit configured to add a unique value to the file data calculated by the unique value calculating unit to the print data to generate unique print data. 3. The image forming apparatus according to claim 2, wherein the unique value adding unit generates the unique print data using a watermark image. 4. The image forming apparatus according to claim 2, wherein the unique value adding unit generates the unique print data using a digital watermark. 5. An image forming apparatus for printing a file with a signature digitally signed with a secret key, wherein a unique value is calculated from the data of the signed file using a one-way function. Calculating means; unique value adding means for adding unique values to the print data calculated by the unique value calculating means to the print data to generate unique print data; and printing means for printing the file data as numerical data. An image forming apparatus comprising: 6. An image forming apparatus for printing a signed file digitally signed with a secret key, wherein the unique value is calculated from the data of the signed file using a one-way function. An image forming apparatus comprising: a calculation unit; and an addition designating unit that designates generation of unique print data by adding a unique value to the print data to the file data calculated by the unique value calculation unit. . 7. An instructing means for instructing image formation of data of a file with a digital signature, and in accordance with an instruction to said instructing means, when forming the data, it is difficult to visually recognize the message digest value. An image forming apparatus comprising: an image forming unit that adds an image in a state to form an image. 8. The image forming apparatus according to claim 7, wherein the image forming unit performs the addition using low density characters. 9. The image forming apparatus according to claim 7, wherein the image forming unit performs the addition using a digital watermark. 10. An image forming apparatus according to claim 1, wherein the image forming unit switches whether or not to perform the image formation with the addition in accordance with a selection instruction as to whether or not to perform the addition from an operation unit of an external device. The image forming apparatus according to claim 7. 11. A one-way function is used to calculate a value unique to file data from data of a signed file digitally signed with a secret key, and to add a value unique to the file data to print data. An image forming method for generating unique print data. 12. An image forming method for printing a signed file digitally signed with a secret key, comprising: a unique value for calculating a value unique to file data from the data of the signed file using a one-way function. An image forming method, comprising: performing a calculating step; and adding a unique value to the print data to generate unique print data by adding a unique value to the file data calculated in the unique value calculating step. 13. The image forming method according to claim 12, wherein the unique value adding step generates the unique print data using a watermark image. 14. The image forming method according to claim 12, wherein the unique value adding step generates the unique print data using a digital watermark. 15. An image forming method for printing a signed file digitally signed with a secret key, wherein the unique value is calculated from the data of the signed file by using a one-way function. Performing a calculating step, a unique value adding step of adding a unique value to the print data calculated by the unique value calculating step to the print data to generate unique print data, and a printing step of printing the file data as numerical data. An image forming method comprising: 16. An image forming method for printing a file with a signature digitally signed with a secret key, wherein a unique value for calculating a value unique to the file data from the data of the signed file using a one-way function. An image forming method comprising: performing a calculation step; and an addition specifying step of specifying generation of unique print data by adding a unique value to the print data to the file data calculated in the unique value calculation step. 17. An instruction step for instructing image formation of data of a file with a digital signature, and in response to the instruction to the instruction step, when the data is imaged, it is difficult to visually recognize the message digest value. An image forming step of forming an image by adding the image in a state. 18. The image forming method according to claim 17, wherein in the image forming step, the addition is performed using low density characters. 19. The image forming method according to claim 17, wherein said adding is performed by a digital watermark in said image forming step. 20. The image forming step according to claim 15, further comprising: selecting from the operation unit of an external device whether or not to perform the addition.
18. The image forming method according to claim 17, wherein whether to perform the image formation with the addition is switched. 21. A storage, wherein a program for causing a computer to function as means for configuring each function of the image forming apparatus according to claim 1 is stored so as to be readable from the computer. Medium. 22. A storage medium storing a program for causing a computer to execute the procedure of the image forming method according to claim 11 so as to be readable from the computer.