JP2005184796A - Digital certificate system and its certificate data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital certificate system and its certificate data in which digital data themselves become certificates and the certificates are not forged. <P>SOLUTION: The present invention relates to certificate data 10 and a digital certificate system using the same, the certificate data including external layer information 20 which results from digitizing information of an original for certification and is provided to be read by a reading apparatus, and internal layer information 30 which results from digitizing information of an original for certification and creating the digitized information of the original for certification to have the identity with the information of the original for certification as the external layer information 20, and is provided to be read by the reading apparatus. As a result, it is possible to obtain certificate data which are the certificates and are not forged. Furthermore, since the information of the original for certification is digital data, it can be instantaneously delivered via the Internet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a digital certificate system and its certificate data, and more particularly to a system for creating and verifying a certificate composed of digital data (certificate data) and a technology for the certificate data.

Today, most documents are handled digitally, but there is one exception. It is a so-called “certificate”. There is no such thing as digital data for any certificate, and the original information on the certificate must be handwritten or printed on the surface of a paper or plastic card. For example, a car driver's license and passport are always printed materials and are not allowed to be substituted with digital data.
Currently, each certificate consists of certification information data and a mount (paper or plastic). There is no essential meaning to the mount, and it is simply written and provided for carrying.
The reason why digital data (document data) is not accepted as a certificate is obvious. In other words, the document data currently used can be easily falsified, and no evidence of falsification remains. Moreover, no one knows whether the document data for proof in front of the eyes is genuine or counterfeit.
In general, printed materials are believed to be much safer than digital data. The reason for this is that the latest anti-counterfeiting printing technology is improving day by day. Furthermore, handwritten certificates, such as signatures, are also considered difficult to counterfeit. This is because it is difficult for ordinary people to imitate the handwriting characteristics and habits of others. For this reason, it is common that the issuer's signature is attached to the certificate in a form that cannot be separated from the text.
On the other hand, with the progress of computerization of society, a technique for embedding important information in image data is disclosed. Among the embedding techniques, the BPCS steganography technique filed by the present inventor is disclosed in detail in the following patent documents.

US Pat. No. 6,473,516

Today, with the progress of computerization of society, the desire for the public to become able to exchange certificates on the Internet is increasing. However, the reality is that there is no method other than sending and receiving the proof as a time-consuming and expensive mail.
In such a situation, the invention of a digital certificate system that is not counterfeited is what everyone expects. If such an invention is invented, the digital data itself can be instantly sent as a certificate anywhere in the world through the Internet.
At present, an authentication mechanism called a digital signature system has been realized. This uses a public key-private key system, and a public authority is required to obtain a public key. Using the system is quite expensive.

An object of the present invention is to provide a digital certificate system in which digital data itself that can be handled on the Internet or the like becomes a certificate, and the certificate is not forged, and the certificate data.
It is another object of the present invention to provide a digital certificate system and its certificate data that can reliably confirm that the certificate data has been forged.
It is another object of the present invention to provide a digital certificate system that can determine a genuine certificate without requiring a certificate authority as a third party organization and its certificate data.

According to the first aspect of the present invention, the information of the original document for proof is digitized, the outer layer information provided so as to be readable by a reading device, and the information of the original document for proof are digitized and digitized. Certificate data including inner layer information prepared so that the information of the original for certification as the outer layer information is identical to the information of the original for certification as provided by the reading device. .
The original information for certification includes letters, numbers, tables, illustrations, photo data, and the like. In some cases, it includes acoustic data such as music and voice. All of these data are visible, readable, audible, and all understandable to humans. These digitalized data are certificate data and are handled as computer files.
The certificate data created by the usual method is data that can be seen and heard with all information, and has a single-layer information structure. That is, information other than what can be seen or heard is not included in the data of the certificate data. Therefore, it is easy for an ordinary person to use a certificate creation system (by computer) to create invalid certificate data that cannot be distinguished from a genuine certificate. It is also easy to partially modify the original certificate data using various editors, and no one can determine whether such a certificate is a genuine certificate or a falsified certificate.
As described above, certificate data having a single layer information structure is easily forged. Therefore, certificate data that cannot be forged must not have a single-layer information structure. That is, certificate data that cannot be forged should have a multilayer information structure including outer layer information and inner layer information.

In the certificate data according to claim 1, the certificate data includes outer layer information and inner layer information. That is, the outer layer information is provided so as to be readable by a reading device. The inner layer information is created so that the original information for certification is digitized, and the digitized original information for certification has the same identity as the original information for certification as the outer layer information, It is provided so that it can be read (extracted) by the reading device. The external layer information can be recognized from the outside by a reading device or the like.
The outer layer information and the inner layer information have a certain relationship. That is, the original information for proof of outer layer information and the original information for proof of inner layer information are the same, and if the outer layer information is altered, the inner layer information becomes unreadable, or This is different from the original information for proof of outer layer information.
As a result, it is possible to obtain certificate data in which the certificate is not forged. Further, since the original information for certification is digital data, it can be sent instantaneously through the Internet.

  In the invention according to claim 2, if the information of the original for certification as the outer layer information is falsified, the information of the original for certification as the inner layer information becomes unreadable by the reading device, Alternatively, the certificate data according to claim 1, which is different from original information for proof of outer layer information.

In the certificate data according to claim 2, the outer layer information and the inner layer information have a certain relationship. That is, the outer layer information and the inner layer information data are strongly coupled and are not separated from each other. Also, inner layer information cannot be extracted unless special means are used. Furthermore, if the outer layer information data is altered, the inner layer information is broken. That is, the inner layer information cannot be altered from the outside.
In general, one piece of image data is composed of bit planes divided into a plurality of color strengths (gradations). It consists of multiple bit planes, such as upper bits that capture large color changes, middle bits that capture medium changes, and lower bits that capture small changes. The number of bit planes to be divided is not limited, and image data becomes finer as the number increases. Each bit plane can be distinguished into a part that contributes to appearance from the outside (a part whose shape is known as outer layer information) and a part that is simply noise (a part whose shape is unknown as inner layer information).

  The invention according to claim 3 is the certificate according to claim 1 or 2, wherein the inner layer information is created by a replacement operation (embedding operation) of the original inner layer information using steganography or digital watermark. It is data.

In the certificate data according to the third aspect, the certificate image is generated from the original information of the certificate input by the certificate image generation unit in the certificate system. At this time, the certificate image is generated so as to have a sufficient amount of data for embedding the original data of the certificate by using the steganography method or other methods.
The visible information in the certificate image is outer layer information having the same content as the original information of the certificate. Subsequently, the certificate creation subsystem embeds all or part of the original information of the certificate in the certificate image. This operation is executed by the data creation means. The embedded certificate data becomes the inner layer information.

  The invention according to claim 4 is the certificate data according to any one of claims 1 to 3, wherein the information of the original document for certification includes a photograph, a logo mark, text, or sound. .

In the certificate data according to the fourth aspect, the information of the original certificate includes a photograph, a logo mark, text, or sound. These pieces of information can only change the outer layer information, and the inner layer information cannot be altered as intended. Therefore, in order to know the presence or absence of tampering, it is only necessary to extract the information of the inner layer information and compare it with the information of the outer layer information.
If the inner layer information matches the outer layer information, the certificate data is authentic, and if it is slightly different, it can be determined that the certificate is a falsified certificate. As a result of falsification, the internal layer information is destroyed and nothing can be extracted from the inside. In such a case, it can be immediately determined that the certificate is a falsification certificate.

  According to a fifth aspect of the present invention, the information of the original document for proof includes the time and / or place of the digitized information of the original document for proof. The certificate data according to any one of the items.

  In the certificate data according to the fifth aspect, information (TS: time stamp data) when the certificate data is digitized is captured. This time stamp data is original information when the certificate data is digitized, and it is virtually impossible to modify the certificate data.

The invention according to claim 6 is the certificate data according to claim 5, wherein the digitized time is acquired by an NTP server.
The NTP server is referred to as a time server, and is a server in which a network (Network Time Product) for synchronizing with a fixed world time (UTC) is incorporated.

7. The certificate data according to claim 6, wherein time information (TS: time stamp data) obtained by digitizing the certificate is obtained by a computer called an NTP server (network time protocol server) on the Internet. To do. This time information is information data supplied to a computer on the Internet very accurately, and it is virtually impossible to modify it.
Therefore, if the certificate creation time information is held in the inner layer information and the outer layer information of the certificate data, the information becomes unique to the certificate. Further, there is virtually no identical certificate data having the same certificate creation time information.

  The invention described in claim 7 is the certificate data according to any one of claims 4 to 6, wherein the digitized place and the place where the photograph is taken are acquired by GPS.

  In the certificate data according to claim 7, the radio wave from the artificial satellite is received, the latitude and longitude are measured, and the current position data of the shooting location is acquired. This position data can be acquired as the original certificate information. That is, when a photograph is taken with a camera, unique information regarding the photographing location is taken in by GPS, and certificate data that can specify a certificate creation location, that is, a photographing location, can be created. Since the shooting location is unique information, it is difficult to forge.

  The invention according to claim 8 is the certificate data according to any one of claims 4 to 7, wherein the photograph and the time and place are acquired by a digital camera.

  In the certificate data according to the eighth aspect, the image data (photograph data) taken by the digital camera can be used as the original information for certification. In addition, the time information at the time of shooting can also be used as information on the original document for certification. The time information at the time of shooting can be obtained from, for example, a camera built-in clock system synchronized with a standard time broadcast radio wave. These pieces of information are unique information and are difficult to forge.

  According to the ninth aspect of the invention, the original information for proof is digitized, the external layer information provided so as to be readable by a reading device, and the original information for the proof is digitized and digitized. It handles certificate data including inner layer information prepared so that the original information for certification as the outer layer information is the same as the original information for certification as the outer layer information and readable by the reading device A digital certificate system comprising a managing means for managing the certificate data and a reading means for reading the original information for the certification.

  According to a tenth aspect of the present invention, when the certificate data is altered, the original information for certification as the inner layer information cannot be read by the reading device. The digital certificate system according to claim 9, wherein the digital certificate system is enabled or different from outer layer information.

  The digital certificate system according to claim 9 and claim 10 comprises management means for managing certificate data and reading means for reading the original information for certification. Certificate data is managed by a management means such as a server. The certificate data can be printed and output on a monitor of a personal computer or a printed material, for example. If the original data for certification as the external layer information is tampered with, the original data for certification as the internal layer information cannot be read by the reading device.

  The invention described in claim 11 is the digital certificate system according to claim 9 or 10, further comprising a creating means for creating the certificate data.

In the digital certificate system according to the eleventh aspect, the certificate image is generated from the original information of the certificate input by the certificate image generation unit in the certificate system. At this time, the certificate image is generated so as to have a sufficient data amount for embedding the original data of the certificate using the steganography method or other methods.
The visible information in the certificate image is outer layer information having the same content as the original information of the certificate. Subsequently, the certificate creation subsystem embeds all or part of the original information of the certificate in the certificate image. This operation is executed by the data embedding unit. The embedded certificate data becomes the inner layer information.

  The invention described in claim 12 is the digital certificate system according to any one of claims 9 to 11, wherein the creation of the inner layer information is performed using steganography or digital watermark.

  In the digital certificate system according to claim 12, a digital steganography technique is known as one of means for realizing a multilayer information structure. In particular, the BPCS steganography technique having a large data embedding capacity is such an example. Usually, the steganography technique is for concealing secret information without being noticed by a third party. In the present invention, as the information is multilayered, the secret information is not hidden, but the same information content as the outer layer information is provided as the inner layer information. The multi-layer structure is not limited to the steganography technique, and can be realized by using a digital processing technique having another name. For example, realization by a method called digital watermarking is also conceivable.

  According to a thirteenth aspect of the present invention, in the digital certificate system according to any one of the ninth to twelfth aspects, the creation of the inner layer information uses key data.

  In the digital certificate system according to the thirteenth aspect, key data for secret management is provided and the digital certificate system is used. Thereby, only a certain member group can use the digital certificate system by using the key data unique to the group.

  According to the fourteenth aspect of the present invention, a creation key composed of a plurality of digits or numerical values is converted into a verification key composed of a plurality of digits or numeric values by one-way scramble function processing, and the verification key is used to The digital certificate system according to any one of claims 9 to 13, which creates inner layer information.

  In the digital certificate system according to the fourteenth aspect, first, the certificate issuer inputs a creation key consisting of a multi-digit numerical value to the writing device. Next, the creation key is converted into a verification key consisting of a multi-digit numerical value by one-way scramble function processing. Then, a numerical value of a plurality of digits of this verification key is output by the output device. This verification key is made public by the certificate issuer as a certificate verification key.

  According to a fifteenth aspect of the present invention, in the digital certification according to any one of the ninth to fourteenth aspects, the one-way scramble function processing converts the verification key into a verification key that cannot be converted into the original creation key. System.

  In the digital certificate system according to the fifteenth aspect, the scramble function is converted into a verification key that cannot be converted into the original creation key. The creation key is kept secret, and the creation key cannot be found from the verification key. As a result, it is impossible to create a forged certificate.

  The invention according to claim 16 can extract the inner layer information from the certificate data by using the key data and using the key data. The digital certificate system described in 1.

  In the digital certificate system according to the sixteenth aspect, the verification key is made public by the certificate issuer as a certificate verification key. With this verification key, the creation key before generation of the verification key cannot be detected. The person who knows the creation key is the issuer of the certificate, and only the issuer can know the creation key.

  According to a seventeenth aspect of the present invention, the management unit is configured by a server, the reading unit is configured by a terminal, and the server and the terminal are connected by a communication network. The digital certificate system described in 1.

  The invention according to claim 18 is the digital certificate system according to any one of claims 9 to 17, wherein the creating means is a digital camera.

  The invention according to claim 19 is the digital certificate system according to any one of claims 9 to 18, wherein the digital camera obtains shooting location information using GPS.

In the digital certificate system according to any one of claims 17 to 19, the management means is constituted by a server. The reading means is constituted by a terminal, and these servers and the terminal are connected by a communication network. The certificate data is managed by a server, can be read by a computer monitor, etc., and can be communicated via the Internet.
By constructing such a system, the certificate data can be taken into the computer, and the certificate data can be displayed on the computer monitor to identify the identity. This eliminates the need to bring a printed certificate. Further, an IC card in which certificate data is built in a memory chip can be used instead of a passport. Furthermore, the image data (photo data) taken by the digital camera can be added as certificate data. Furthermore, it is also possible to capture the data of the creation location using GPS.

According to the present invention, the certificate data includes outer layer information and inner layer information. That is, the outer layer information is provided so as to be readable by a reading device. The inner layer information is created so that the original information for proof is digitized, and the digitized original information for the proof is created to have the same identity as the original information for proof as the outer layer information. It is provided so that it can be read (extracted) by a reading device. The external layer information can be recognized from the outside by a reading device or the like.
The outer layer information and the inner layer information have a certain relationship. That is, the original information for proof of outer layer information and the original information for proof of inner layer information are identical, and if the outer layer information is altered, the inner layer information cannot be read, or This is different from the original information for proof of outer layer information.
As a result, it is possible to obtain certificate data and a digital certificate system in which the certificate is not forged. Further, since the original information for certification is digital data, it can be sent instantaneously through the Internet.

Embodiments of the present invention will be described below with reference to FIGS.
First, the configuration of certificate data will be described.
As shown in FIG. 1, the original information of the certificate includes a photograph 11, a text 12, a logo mark 13, and the like. The original information of this certificate indicates a single layer information structure. The information on the original certificate is visible, legible and understandable.
As shown in FIG. 2, the original information of the certificate is generated into a certificate image (digital image) using some image generation means (computer program). At this stage, the single-layer information structure of only the outer layer information 20 remains. The image of the outer layer information 20 has the same visual information as the original certificate information. The data amount of the image of the external layer information 20 is generally larger than the data amount of the original certificate information.
As shown in FIG. 3, certificate data 10 having a multilayer information structure of the present invention is shown. That is, the certificate data has outer layer information 20 and inner layer information 30. The external layer information 20 has visually the same information as the original information of the certificate. The inner layer information 30 has the same information as the outer layer information 20. The inner layer information 30 is created by using the steganographic technique or similar information processing technique on the original certificate information.

Here, a method of creating internal information using steganography technology will be specifically described.
Generally, a color image has 8 bits each as intensity data (red, green, and blue intensity data) of each of the three primary colors, and is expressed as data of a total of 24 bits.
If such a color image is taken out only for one bit of specific bit data ("same bit data" in the sense of "number" from the most significant bit), one binary value is taken out. It becomes an image. Such a binary image screen is called a “bit plane”. Therefore, one 24-bit color image is composed of 24 bit planes.
A monochrome image is usually composed of 8 bits of 8 gradations from white to black (8 bit planes). For example, FIG. 4 shows an example of one monochrome image, and FIG. 5 shows the first bit plane (A), the fifth bit plane (B), and the eighth bit plane (C), respectively. Here, an example of eight bit planes has been taken, but the number of bit planes to be divided is not limited, and image data becomes finer as the number increases.
Among such image data, the most significant bit plane (A) has the most influence on human vision. The next most significant influence is the second bit plane, the third bit plane next, the fourth bit plane,. . . It becomes. The lower bit plane (C) such as the seventh and eighth bits hardly affects human vision.
In the bit plane, there are a “region where the shape is recognized” and a “noise-like region” where the shape is not recognized.
For example, in the bit plane of (B) shown in FIG. 5, “a lump of white areas” can be seen at the shoulders and fists of the person (that is, the shape is recognized). On the other hand, there are no very distinctive shapes in the vicinity of the armpit, chest or face. That is, it can be said that it is a noise-like region.
In this case, if the region where the shape is recognized is artificially deformed (for example, the shoulder opening is widened or narrowed), the deformation affects human vision. That is, it can be easily understood that the deformation has occurred. On the other hand, even if a noise-like region is replaced with “another noise-like region”, such replacement does not affect human vision at all. That is, the data in the noise-like area is an information data portion that cannot be seen by human eyes. However, if a noise-like area is replaced with “another, area-visible data”, it affects the human eye.
Therefore, in the present invention, for example, internal information having the same original information as the external information is embedded in a noise area that is the bit plane of (B) and cannot be seen from the outside, using steganography technology. Specifically, information data to be concealed (embedded) is randomized by a randomizing program (transformed into a series of small noise-like binary image data). This is replaced with the original noise-like area (distributed in one screen). Even if such replacement, ie, embedding information data and concealing it, does not affect human vision.
The BPCS steganography technique for embedding information data such as the internal information in the noise region is described in detail in the above-mentioned patent document.
As a result, certificate data having external information and internal information having a multilayer structure as described above can be created.

Next, a system block diagram showing the hardware configuration of the digital certificate system will be described.
As shown in FIG. 6, a computer 100 is mainly used as hardware of the digital certificate system. The computer 100 has a writing device and a reading device. The writing device writes the original certificate information (external layer information) in the certificate data 10. In addition, the inner layer information 30 is embedded in the outer layer information 20. Specific hardware includes a keyboard 101 and a scanner 102.
The reading device 102 reads the original information for proof of the outer layer information 20 from the outside. Specific hardware includes a monitor 103 and a printer 104. Certificate data written or read by a computer may be managed by the host computer 105. The host computer 105 is connected to the NTP server 106 through the Internet line.
Further, the invention is not limited to the computer, and an IC card reader / writer 107 or the like may be used. The writing device and the reading device may be separated.
Furthermore, the input of the original certificate information is not limited to the computer 100, and the digital camera 108 may be combined. The time and the place of creation may be captured by GPS 109 (Global Positioning System).

Next, the digital certificate system has forms from type-1 type to type-3 type. The digital certificate system is composed of two subsystems. That is, a certificate creation subsystem and a certificate verification subsystem.
The digital certificate system from type-1 type to type-3 type will be described in detail below.
<Type-1 system>
First, a type-1 type certificate creation subsystem will be described.
FIG. 7 shows a type-1 type certificate creation subsystem. Each consists of computer hardware and software. The operation of the type-1 certificate creation subsystem is as follows.
First, original information 111 of a certificate desired to be a non-forgeable certificate is input to the type-1 certificate creating subsystem 110 through the certificate input unit 112. Specific hardware of the certificate input unit 112 includes, for example, the keyboard 101 and the scanner 102. Next, a certificate image is generated from the original information of the certificate input by the certificate image generation unit 113 in the certificate creation subsystem. At this time, the certificate image is generated so as to have a sufficient data amount for embedding the original data of the certificate using the steganography method or other methods. The visible information in the certificate image is the outer layer information 20 having the same contents as the original information of the certificate.
Subsequently, the certificate creation subsystem embeds the entire original certificate or a part of the original certificate using, for example, BPCS steganography technology. This operation is executed by the data embedding unit 114. The embedded certificate data becomes the inner layer information 30. Through the above procedure, certificate data (Doc) having a multilayer information structure is generated and output to the outside as a computer file through the certificate output unit 115. Other specific hardware of the certificate output unit 115 includes, for example, the monitor 103 and the printer 104. These devices are used for output on a monitor or printed matter. Or it is good also as an IC card which stored the outer layer information 20 and the inner layer information 30 in the memory chip.
The original information 111 of the certificate in this subsystem is various. Usually, it is often data edited by a computer certificate editing program, an image editing program, or an acoustic data editing program. In some cases, the image data itself is captured by a digital camera or a scanner.
This type-1 type certificate creation subsystem 110 can be realized as an independent system or as an embedded system in a digital image processing device such as a digital camera.

Next, a type-1 type certificate verification subsystem will be described.
As shown in FIG. 8, the operation of the type-1 certificate verification subsystem is as follows.
First, certificate image data (Doc) having a multi-layer information structure is input to the certificate verification subsystem 120 from the input unit 121. Next, embedded data (Doc _int ) is extracted by the data extraction unit 122, and comparison processing with the outer layer information 20 (Doc _ext ) is executed in the output unit 123. At this time, if there is a correspondence between the two data (Doc _int ⊆ Doc _ext ), it is determined that the certificate is a genuine certificate, otherwise it is a forged certificate. The comparison process at this time is executed manually, and the determination can be left to human judgment.

In the present invention, “tampering the certificate data” means that the external information part of the image data obtained by imaging the original certificate is transformed for some purpose. This means that a portion whose shape is visible from the outside (the shape portion, for example, the face or the hat portion in the bit plane of (A)) is deformed. To deform a shape portion is to change its shape. However, since the certificate data has a shape portion where image data and the like can be seen from the outside and a noise-like portion that cannot be seen from the outside, the noise-like portion is always deformed whenever the shape portion is deformed.
The noise-like portion of the noise area in which the original information of the certificate is embedded is processed as “internal information” by the information extraction program. Therefore, “transformed certificate information” is always extracted from the altered certificate image data. That is, the original certificate can be extracted only from certificate image data that has not been tampered with. The third party cannot know the information existing in this area. Therefore, when the original certificate data is destroyed, the destroyed certificate data is extracted from the extraction program.
The deformed internal information data does not conform to the extraction program created on the premise of “untransformed internal data”, and is often unprocessable (cannot be extracted).
As a result, when the extraction process is performed using a regular extraction program,
(1) When corrupted certificate data is extracted (2) When not extracted at all, it can be determined that the digital certificate document has been tampered with. This is not limited to BPCS steganography, and is the same for other steganographic methods.
FIG. 9 illustrates certification data extracted from certificate image data without falsification, and FIG. 10 illustrates certification data extracted from certificate image data that has been falsified, and shows certification data that has been partially destroyed. ing.

<Type-1 system used only within the group>
The above type-1 type system is an open digital certificate system because anyone who has the same certificate creation subsystem and its verification system can use it.
However, in some cases, a system that is only available to certain restricted members may be required. One countermeasure in such a case is to use a system with different specifications from the others.
As another countermeasure, it is conceivable to introduce a key unique to the member group into the type-1 system. FIG. 11 shows such a certificate creation subsystem, and FIG. 12 shows a corresponding certificate verification subsystem. As shown in FIGS. 11 and 12, the inner layer information is created and extracted from the key input unit 131. Specific hardware of the key input unit 131 is, for example, the keyboard 101. Other system configurations are the same as those in FIGS. A single private key is used for the certificate generation subsystem and the certificate verification subsystem. Each member manages the key secretly.

<Type-2 type system>
Type-2 counterfeiting is a digital certificate system issued by an organization, group, individual, etc. having authority that does not require other authentication. Passport forgery is just such an example. The type-2 system is also composed of a certificate creation subsystem and a certificate verification subsystem. Each system is realized by computer hardware or software.
The type-2 type system is realized by introducing a pair of keys, that is, a certificate creation key Kp and a certificate verification key Kv into the type-1 type system. A method for generating the verification key Kv will be described.
First, the certificate issuer determines an arbitrary creation key Kp and keeps it secret. That is, as shown in step 501 of FIG. 14, a 10-digit numerical value (Kp = 1390255378) is input as Kp. This creation key Kp is input to the certificate creation subsystem 210 through the key input unit 211.
Next, a new verification key Kv is generated from the generated key Kp by the one-way scramble function processing unit 212. That is, as shown in the process 502 of FIG. 14, the third smallest numerical digit is compared among the numerical values of the ten digits, and the third digit from the left is compared with the third digit from the right. Replace with a numerical value (1390955378).
Then, as shown in step 503 in FIG. 14, the difference between adjacent numerical values is 1, the left numerical value is the third largest numerical value among all the 10-digit numerical values in the first numerical pair from the left. Add However, if the result is 10 or more, 10 is subtracted from that number. If there is no such numerical pair, 5 is added to the whole.
As a result, nothing is done if it becomes an 11-digit numerical value (1390955348). Finally, as shown in step 504 of FIG. 14, the first digit, the fourth digit, the third digit, the ninth digit, the fifth digit, and the seventh digit from the left are exchanged (Kv = 0341559398). In this way, the verification key Kv is generated.
For KP = 1390255378, one-way scramble determines Kv = 0341559398. However, even if Kv determined from a certain Kp becomes Kv = 39138895296, it is impossible to determine such KP by following the above procedure in reverse.
In this way, calculation processing in only one direction is possible, but the processing in which the first numerical value cannot be determined by following the reverse is unidirectional scrambling function processing.
Even if the acoustic data is included in the certificate data, it is possible to make it forgery by the same principle process.

Next, a type-2 type certificate creation subsystem will be described.
As shown in FIG. 13, the operation of the type-2 certificate creation subsystem is as follows. First, the certificate issuer determines an arbitrary creation key Kp and keeps it secret. The creation key Kp is input to the document creation subsystem 210 through the key input unit 211. Further, a new verification key Kv is generated from the generated key Kp by the one-way scramble function processing unit 212 by the above method.
The creation key Kp is used when creating the multilayer information certificate data so as not to be visible outside the computer. Further, the scramble function is introduced so as not to be visible outside the system, and is implemented so as not to be separated from the certificate creation subsystem. Therefore, the system user operates so that the creation key Kp is used when the certificate is created.
The verification key Kv generated from the created key Kp is output from the key output unit 213 as a key for certificate verification. This verification key Kv is made public by the certificate issuer as a certificate verification key.
Next, information on the original of the certificate that is desired to be a forgery-proof certificate is input from the certificate input unit 214. The certificate image generation unit 215 generates a certificate image from the original certificate information. At this time, the certificate image is generated so as to have a sufficient amount of data for embedding the original data of the certificate using a steganography technique or other techniques. The visible information in the certificate image is the outer layer information 20 having the same contents as the original information of the certificate.
Subsequently, the certificate creation subsystem embeds the entire original certificate or a part thereof in the certificate image. This operation is actually executed by the data embedding unit 216 using the verification key Kv. However, since this operation is executed inside the system and is not visible outside the system, it is equivalent to the system user that the embedding operation is executed with the creation key (Kp). The embedded certificate data becomes the inner layer information 30. This inner layer information 30 can be extracted only by using the verification key Kv in the corresponding type-2 type certificate verification subsystem.
Through the above procedure, certificate data (Doc) having a multilayer information structure is generated and output to the outside through the certificate output unit 217.
An important point in the type-2 type certificate creation system is that the certificate verification key Kv is made public by the certificate issuer. For example, in the case of a digital passport, the passport issuance government directly communicates the verification key Kv to other countries or makes it public on the Internet or the like so that it can be used by ordinary people.
This type-2 type certificate creation system 210 may be an independent system or may be realized as an embedded system in a digital image processing device such as a digital camera.

As shown in FIG. 15, the operation of the type-2 certificate verification subsystem is as follows.
First, the person who wants to verify the certificate directly receives the certificate verification key Kv from the certificate issuer or obtains it by another method.
A certificate image (Doc) having a multi-layer information structure is input from the certificate image input unit 221 in the type-2 certificate verification subsystem 220. Further, the verification key Kv is also input from the key input unit 222. Next, the data extraction unit 223 extracts the inner layer information 30 (Doc _int ) embedded using the verification key Kv. Next, Doc _int is compared with the outer layer information 20 (Doc _ext ) in the output unit 224.
If both match (Doc _int ⊆ Doc _ext ), the certificate image is a genuine certificate. Otherwise, it is a falsification certificate. This comparison / determination process can also be performed manually. A person who knows the creation key Kp that is the generation source of the verification key Kv is determined to be the creator of the type 2 certificate data.
The type-2 type system has a type-2 type certificate forgery prevention effect for the following reason. That is, a person who forges a type-2 type counterfeit (forger) is determined that the forged certificate is a genuine certificate by the type-2 type certificate verification subsystem using the public verification key Kv. is required. For this purpose, the forger needs to create a forged certificate (multi-layer information structure certificate) using the creation key Kp that is the source of the verification key Kv in the regular type-2 certificate creation subsystem. . However, the creation key Kp is kept secret, and the creation key Kp cannot be detected from the verification key Kv. Therefore, it is impossible to create a forged certificate with the type-2 certificate verification subsystem.
The difference between this type-2 system and the existing digital certification system is obvious. First, the certificate of the existing system has a single-layer information structure and has no forgery prevention capability. On the other hand, the certificate in the present invention has a multilayer information structure, and the certificate itself has a forgery prevention effect. Furthermore, while the existing system is premised on the existence of a public key certificate authority as a third party organization, the type-2 type system does not require a third party organization.
Since the type-2 type system has all the functions required for the type-1 type system, it also functions as a type-1 type system.

<Type-3 system>
For digital documents that are not certificates, it is necessary to verify the originality of the certificate. In other words, it may be necessary to have a function for determining who created the document first. For example, in the case of a digital painting (digital work) having artistic value, the creator is specified.
Assume that a digital work is first created as a type-2 document (Doc (X)) by a certain producer (X). In this case, the original work (Ox) is the inner layer information 30 of Doc (X), and anyone can extract this Doc (X) with the verification key (Kx) published by X. It is possible for another person (Y) to acquire Ox in this way, intercept it as an original work (Oy) of Y, and create a new type-2 type document (Doc (Y)). Oy at that time can be extracted by Ky published by B using a type-2 certificate verification subsystem.
Under these circumstances, a third party cannot determine who is the original creator of this digital work (who is the original creator), and X cannot protect his rights. .
This problem can be solved by the following type-3 type system in which other information (unique information) is added to the type-2 type system. An example of such unique information is a time stamp (TS data) on the Internet when the certificate data 10 of the multilayer information is created by the certificate creation subsystem. That is, it is time information for creating the certificate data 10.
This time stamp is information data that is supplied to a computer on the Internet very accurately by a computer called an NTP server (network time protocol server) on the Internet. It is impossible.
Therefore, if this TS data is added to the type-2 system and the TS data is held in the inner layer information 30 and the outer layer information 20 of the multilayer information certificate, the information becomes unique to the certificate. Accordingly, there is virtually no identical certificate data 10 (digital work) having the same TS data. Since the verification key Kv for extracting the inner layer information 30 (the original information of the certificate, that is, the original work) of the multilayer information certificate is made public, the third party can obtain the earliest TS data. It can be determined that the person who knows the certificate creation key (the creation key Kp that is the basis of the verification key Kv) is the first creator of the certificate (digital work).
In addition to the time-specific information as described above, if the original document is photograph data taken with a camera, unique information regarding the shooting location can be incorporated into the system, and the document creation location, that is, the shooting location can be specified. Documents can be created. The specific information regarding such a place can be acquired by GPS (Global Positioning System).
Such a system is a type-3 system.
One type-3 system must not be compatible with another type-3 system, so each certificate creation system must have its own logo mark (added inside and outside the multilayer information certificate) ) Etc. to distinguish them from other systems. In the certificate verification system, the logo mark is inspected as a process invisible from the outside, and each system is identified.

Next, a type-3 type certificate creation subsystem will be described.
As shown in FIG. 16, the operation of the type-3 type certificate creation subsystem is as follows. This system always connects to the Internet during operation.
First, the original information of the certificate that is desired to be a forgery certificate is prepared. Then, the certificate creator defines an arbitrary creation key Kp and keeps it secret. The creation key Kp is input to the certificate creation subsystem 310 through the key input unit 311.
Further, a new verification key Kv is generated from the generated key Kp by the one-way scramble function processing unit 312. This verification key Kv is used when creating multi-layer information certificate data so as not to be visible to the outside. This scramble function is made unknown to the outside of the system, and cannot be separated from the certificate creation subsystem. Therefore, the system user operates so that the creation key Kp is actually used when the certificate is created. The verification key Kv generated from the created key Kp is output from the key output unit 317 as the certificate verification key. This verification key Kv is made public by the certificate issuer as a certificate verification key.
This type-3 certificate creation subsystem is connected to the Internet, and acquires a time stamp (TS) at the time of certificate creation from an NTP server on the Internet.
The original certificate information is input from the certificate input unit 313 and is sent to the certificate and time stamp image generation unit 314 together with the time stamp data to generate image data (certificate and time stamp image). This image is generated by a steganography technique or other techniques so as to have a sufficient data size for embedding the original certificate information and the time stamp data. Then, the generated image has visual outer layer information 20 that is the same as the original certificate information and time stamp.
Subsequently, the data embedding unit 315 embeds all or part of the original information of the certificate and the time stamp data in the certificate and the time stamp image using the verification key Kv to obtain the inner layer information 30. As a result, a certificate image (Doc) having a multilayer information structure is obtained. The inner layer information 30 can be extracted using the verification key Kv in the corresponding type-3 type certificate verification subsystem, and cannot be extracted by any other method.
Finally, the multilayer certificate image (Doc) is output from the certificate output unit 316.
The time stamp data in the type-3 type certificate creation subsystem can also be acquired based on the standard time broadcast radio wave.
In the type-3 type document creation subsystem, unique information regarding the creation location can be acquired by GPS, and can be used as the inner layer information 30 and the outer layer information 20.
The type-3 type certificate creation subsystem can take various configurations other than those described above. For example, the verification key Kv may be handled as the inner layer information 30 and the outer layer information 20 (see application examples (1) and (2)).
The type-3 type certificate creation subsystem may be an independent system. Alternatively, it can be realized as an embedded system in a digital image processing device such as a digital camera.

Next, a type-3 type certificate verification subsystem will be described.
As shown in FIG. 17, the operation of the type-3 type certificate verification subsystem is as follows.
First, a certificate image (Doc) having a multilayer information structure to be verified is input from the certificate image input unit 321 to the type-3 type certificate verification subsystem 320. Further, the certificate verification key Kv is input from the key input unit 322.
Next, the certificate image is sent to the data extraction unit 323, and inner layer information 30 (Doc _int ) composed of the certificate and time stamp data is extracted using the verification key Kv.
Next, the inner layer information 30 (Doc _int ) is compared with the outer layer information 20 (Doc _ext ) in the output unit 324.
If they match (Doc _int ⊆ Doc _ext ), the input certificate image (Doc) is determined to be a genuine certificate, and otherwise, it is determined to be a forged certificate. The comparison determination process at this time can also be performed manually.
Since the type-3 type system has all the functions necessary for the type-1 type and type-2 type systems, it also functions as a type-1 type and type-2 type system.

<Application example>
(1) Digital ID FIG. 18 shows a digital ID 410 displayed on a computer monitor. Reference numeral 411 denotes a logo mark unique to this type-3 type system. Further, 412 is a proof content sentence of the identification card. A photo of the owner of the identification card is 413, and 414 indicates a verification key Kv of the identification card. The time when this certificate was created is represented as a time stamp 415.

(2) Digital Passport Stored in IC Memory FIG. 19 shows an example of a digital passport stored in the IC memory. This is a plastic card with an IC memory 515 mounted, and the passport contents are printed on the card surface 510. This printing is auxiliary to make the information content of the passport easy to understand for the human eye. All the digital passport data is stored in the IC memory, and the contents can be read by a normal computer, so that the digital passport can be sent to other places through the Internet.
The immigration officer at the international airport first compares the person on the surface of this passport card with the person, and then verifies this passport with a computer installed with passport verification software (type-3 certificate verification subsystem). This card is inserted into a card reading device to verify whether this digital passport is authentic. That is, whether the passport data 512, the face photograph 511, the verification key 513, and the time stamp 514 at the time of issuance all match the outer layer information 20 and the inner layer information 30 of the digital passport in the IC memory. Check out. If all match, it is a genuine passport, and if some match, it is a forged passport.
Since this passport verification key 513 is generated by a one-way scramble function from a passport creation key secretly managed by the issuing government, it is impossible to forge a passport that can use this verification key.
An important feature of this passport is that passport verification can be performed on-site (for immigration) without connecting to other computer systems. That is, it can work offline.

(3) System embedded in a digital camera A type-1, 2, or 3 type system can be realized as a system embedded in a digital camera.
In a digital camera incorporating this system, image data (photo data) having a multiple information structure is created inside, and a logo mark unique to the camera and a time stamp at the time of shooting are added to the inner layer information 30 and the outer layer. . The time stamp is obtained from, for example, a camera built-in clock system synchronized with a standard time broadcast radio wave. Furthermore, current position data is acquired from the GPS system as shooting location information. The verification key is publicly disclosed by the camera manufacturer.
It is impossible to tamper with a photograph taken with such a camera, and it functions as an absolute evidence photograph in a court.

It is a perspective view which shows the information of the original of the certificate data based on one Example of this invention. It is a perspective view which shows the outer layer information of the certificate data which concerns on one Example of this invention. It is a perspective view which shows the structure of the certificate data which are the multilayer information based on one Example of this invention. It is a front view which shows the image data based on one Example of this invention. It is the front view which decomposed | disassembled the said image data based on one Example of this invention for every bit plane. It is a system block diagram which shows the structure of the hardware of the digital certificate system which concerns on one Example of this invention. It is a flowchart which shows the structure of the type-1 type certificate production subsystem which concerns on one Example of this invention. It is a flowchart which shows the structure of the type-1 type | mold certificate verification subsystem which concerns on one Example of this invention. It is a front view which shows the certificate data which is not falsified which concerns on one Example of this invention. It is a front view which shows the falsified certificate data based on one Example of this invention. It is a flowchart which shows the structure of the type-1 type certificate production subsystem utilized only within the group which concerns on one Example of this invention. It is a flowchart which shows the structure of the type-1 type | mold certificate verification subsystem utilized only within the group which concerns on one Example of this invention. It is a flowchart which shows the structure of the type-2 type certificate production subsystem which concerns on one Example of this invention. It is a flowchart which shows the structure of the type-2 type key creation system which concerns on one Example of this invention. It is a flowchart which shows the structure of the type-2 type | mold certificate verification subsystem which concerns on one Example of this invention. It is a flowchart which shows the structure of the type-3 type certificate production subsystem which concerns on one Example of this invention. It is a flowchart which shows the structure of the type-3 type | mold certificate verification subsystem based on one Example of this invention. It is a front view which shows the certificate data data displayed on the computer monitor which concerns on one Example of this invention. It is a front view which shows the certificate data data displayed on the IC card based on one Example of this invention.

Explanation of symbols

10 Certificate data,
20 outer layer information,
30 Inner layer information,
11 photos,
12 text,
13 Logo mark,
106 NTP server,
108 digital camera,
TS time (time stamp),
109 GPS,
Kp creation key,
Kv verification key.

Claims (19)

The outer layer information provided so that the information of the original document for proof is digitized and can be read by a reading device,
The original information for the certification is digitized, and the digitized original information for the certification is created so as to be the same as the original information for the certification as the outer layer information and is read by the reading device. Certificate data including internal layer information provided as possible.   If the original information for certification as the outer layer information is tampered with, the original information for certification as the inner layer information becomes unreadable by the reading device or is used for certification of the outer layer information. The certificate data according to claim 1, which is different from the original information.   The certificate data according to claim 1, wherein the inner layer information is created using steganography or digital watermark.   The certificate data according to any one of claims 1 to 3, wherein the information of the original for certification includes a photograph, a logo mark, text, or sound.   The certificate according to any one of claims 1 to 4, wherein the information on the original for certification includes the time and / or place of the digitized information on the original for certification. data.   The certificate data according to claim 5, wherein the digitized time is acquired by an NTP server.   The certificate data according to any one of claims 4 to 6, wherein the digitized place and the place where the photograph is taken are acquired by GPS.   The certificate data according to any one of claims 4 to 7, wherein the photograph and the time and place are acquired by a digital camera. The information of the original document for proof is digitized, the outer layer information provided so as to be readable by a reading device, and the information of the original document for proof are digitized. A digital certificate system that handles certificate data including inner layer information that is created so as to be identical to original information for certification as outer layer information and is readable by the reading device,
A management means for managing the certificate data;
A digital certificate system comprising reading means for reading the original information for certification.   If the original data for certification as external layer information is falsified, the original information for certification as internal layer information may not be readable by the reading device or the external data The digital certificate system according to claim 9, which is different from information.   The digital certificate system according to claim 9 or 10, further comprising creation means for creating the certificate data.   The digital certificate system according to any one of claims 9 to 11, wherein the creation of the inner layer information is performed using steganography or digital watermarking.   The digital certificate system according to any one of claims 9 to 12, wherein the creation of the inner layer information uses key data.   The creation key composed of a plurality of digits or numerical values is converted into a verification key composed of a plurality of digits or characters by one-way scramble function processing, and the inner layer information is created using the verification key. The digital certificate system according to claim 13.   The digital certificate system according to any one of claims 9 to 14, wherein the one-way scramble function processing is converted into a verification key that cannot be converted into an original creation key.   The digital certificate system according to claim 9, wherein the inner layer information can be extracted from the certificate data using the key data.   The digital certificate system according to any one of claims 9 to 16, wherein the management unit is configured by a server, the reading unit is configured by a terminal, and the server and the terminal are connected by a communication network.   The digital certificate system according to any one of claims 9 to 17, wherein the creating means comprises a digital camera.   The digital certificate system according to any one of claims 9 to 18, wherein the digital camera obtains shooting location information using GPS.

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