JP2003179593A - Secret information management system and secret information management method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that it is difficult for conventional technology to keep the secrecy of secret information since the saving place of significant secret information such as a cryptographic key is recorded in a predetermined area and it is highly possible for a third person to easily know the localization of that saving place. <P>SOLUTION: An information processor A is provided for a user to perform various kinds of operation to the information processor A as shown in a figure 1 and equipped with an operation part 50 such as keyboard or mouse, for example, a communication part 40 for communicating with the other information processor or the like a data storage part 30 for storing various kinds of data provided in the information processor A, an electronic watermark processing part 20 for performing processing to mix the secret information with the data by using the technique of an electronic watermark, and a control part 10 for controlling the respective parts. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secret information management system or a secret information management method for mixing information to be concealed in arbitrary data as a digital watermark.

[0002]

2. Description of the Related Art In recent years, with the improvement of information communication technology, the usage of the information communication technology is diversified. In such a situation, the information handled may include information that needs to keep confidentiality (hereinafter referred to as “confidential information”), and an opportunity to handle such confidential information. Also has been increasing in recent years. Specific examples of this secret information include a credit card number and various personal identification numbers, but a key used for encrypting and restoring data on a computer (hereinafter, referred to as “encryption key”) is also secret. It is considered as one of information. The following techniques are available for handling this encryption key. For example, Japanese Unexamined Patent Publication No. 2000-339227 (hereinafter referred to as "publication 1") is for decrypting data encrypted using an encryption key (hereinafter simply referred to as "encrypted data"). A technique of embedding the encryption key of the above-mentioned encryption data into sample data to be added to the encrypted data by using a digital watermark technique and distributing the same is disclosed. Specifically, the technique described in the above publication 1 first generates encrypted data by encrypting data to be distributed using an encryption key, and extracts predetermined sample data from the data,
The encryption key is embedded in the extracted sample data using a digital watermark technique. After that, further, the sample data in which the encryption key is embedded and the encrypted data are combined (that is, an encryption key is added to the encrypted data), and the combined data is used by a user or the like. It is being delivered to the device. That is, the technique described in the above publication 1 prevents the copyright infringement such as illegal copying by encrypting the data and distributing it, and adds an encryption key for decrypting the encrypted data to the encrypted data. And deliver it. Therefore, as compared with the case where the encryption key and the encrypted data are individually delivered to the terminal device, the technique described in the above publication 1 can prevent the loss of the encryption key. In addition, Japanese Patent Laid-Open No. 2000-
Japanese Patent No. 244475 (hereinafter referred to as "publication 2") discloses an identifier for identifying encrypted data encrypted using an encryption key and an encryption key for decrypting the encrypted data. A technique for generating associated association information and storing the generated association information in a terminal device or the like is disclosed. In other words, the technique described in the above-mentioned publication 2 saves the encryption key for decrypting the encrypted data generated (encrypted) by the server only in the terminal device, so that the user other than the user who owns the terminal device can save the encryption key. The handling of data is prohibited.

[0003]

However, in the technique described in the above publication 1, it is not possible for the third party to directly use the encrypted data when the third party obtains the combined data. Although it seems possible, there is a possibility that the encrypted data can be easily decrypted by using the encryption key embedded in the sample data in the composite data. Further, in the technique described in the above publication 2, for example, the third
When a person obtains the terminal device, there is a possibility that the third party can easily decrypt the encrypted data simply by operating the terminal device. Such a problem arises in the above-mentioned conventional technique because, generally, the storage location of important confidential information of the encryption key is recorded in a fixed area in advance or is recorded without any protection. Since it is highly likely that the whereabouts will be known to a third party, it was difficult to keep the confidentiality of confidential information. Therefore, the present invention has been made in view of the above circumstances, and its object is to:
In order to enhance the confidentiality of the encryption key for decrypting the encrypted information, by embedding the encryption key in the data such as digital content by using the digital watermark technique,
A secret information management system or a secret information management method, in which only a user who recognizes the location of the encryption key can use the encryption key, and the confidentiality of the encryption key with respect to a third party is enhanced and stored and managed. To provide.

[0004]

In order to achieve the above object, the present invention is a secret information management system for managing secret information, wherein the secret information is mixed into arbitrary data as a digital watermark. And a extracting means for extracting the secret information from the data in which the secret information is mixed by the mixing means. With the configuration of the present invention as described above, since the secret information is mixed into arbitrary data, it becomes more difficult for a third party to obtain the secret information as compared with the conventional technique, and the secret information is obtained. The confidentiality of information is improved. The mixing unit and the extraction unit may perform the process of mixing or extracting the secret information according to a predetermined rule, and the predetermined rule is used for the process of mixing or extracting the secret information, for example. It may be based on a key. With this configuration, it becomes difficult for a third party who does not know the predetermined rule to extract the secret information even if the third party tries to extract the secret information. Furthermore, by using the predetermined rule as a key for a digital watermark for mixing or extracting the confidential information in data, the procedure relating to the predetermined rule can be simplified. Furthermore, by using the key as the secret information in another digital watermark process, the key may be further mixed with arbitrary data. With such a configuration, not only the confidential information to be originally concealed, but also the confidentiality of the key for the digital watermark for mixing or extracting the confidential information in arbitrary data is enhanced, and thus the secret information can be further protected. It is possible to improve confidentiality.

It is configured that the data in which the secret information is mixed has information about a history of a process of mixing or extracting the secret information or information about a process associated with the process of mixing or extracting the secret information. Is also good. With such a configuration, when an unauthorized access or extraction is attempted by a third party with respect to the data in which the confidential information is mixed, the history-related information and the processing associated with the extraction processing are performed. Based on the information, it is possible to prevent unauthorized access or extraction of confidential information.

When the present invention is regarded as a method invention, it is a secret information management method for managing secret information, which comprises a first step of mixing the secret information into arbitrary data as a digital watermark, and the above mixing. A second step of extracting the secret information from the data in which the secret information is mixed by means
It is considered that the method is configured as a secret information management method characterized by including the steps. With the configuration of the present invention as described above, since the secret information is mixed into arbitrary data, it becomes more difficult for a third party to obtain the secret information as compared with the conventional technique, and the secret information is obtained. The confidentiality of information is improved. Further, the process of mixing or extracting the secret information may be performed according to the rule of the key used for the process of mixing or extracting the secret information in the first step and the second step. In the first step, By using the key as the secret information in another digital watermark process, the key may be further mixed with arbitrary data. With this configuration,
Not only the confidential information that should be originally confidential, but also the confidentiality of the key for the digital watermark for mixing or extracting the confidential information into arbitrary data can be enhanced, and thus the confidentiality of the confidential information can be further improved. Becomes

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. It should be noted that the following embodiments and examples are merely examples embodying the present invention and are not of the nature to limit the technical scope of the present invention. Here, FIG. 1 is a schematic configuration diagram of an information processing apparatus A that employs the secret information system of the present invention, FIG. 2 is a conceptual explanatory diagram when secret information is mixed, and FIG. 3 is a conceptual explanatory diagram when secret information is extracted. Is an explanatory diagram of an example of extracting an encryption key with an extraction key, FIG. 5 is an explanatory diagram of an example of extracting an encryption key with a common extraction key, and FIG. 6 is an explanatory diagram of an example of mixing an extraction key as secret information into data 7 is an explanatory diagram of an example of extracting the extraction key mixed in the data, FIG. 8 is an explanatory diagram when the processing history and the processing information are mixed in the data together with the confidential information, and FIG. 9 is the confidential information management system of the present invention. FIG. 6 is an explanatory diagram of a case of operating the authentication system.

First, referring to FIG. 1, an information processing apparatus A that employs a secret information management system according to an embodiment of the present invention.
The general configuration of will be described. Of course, the confidential information management system of the present invention is not limited to the information processing apparatus A and is adopted, and any similar effect can be obtained by using the confidential information management system of the present invention. It may be adopted for any one.

As shown in FIG. 1, the information processing apparatus A is used by the user to perform various operations on the information processing apparatus A. For example, an operation unit 50 such as a keyboard or a mouse, other information processing apparatus, etc. A communication unit 40 for communicating with the data processing unit, a data storage unit 30 for storing various data included in the information processing apparatus A, and an electronic device for performing a process of mixing confidential information into the data by using a digital watermark technique. Watermark processing unit 20
And a control unit 10 for controlling each of the above units. The digital watermark processing unit 20 has a function of a mixing unit for mixing confidential information into arbitrary data as a digital watermark, and an extracting unit for extracting confidential information mixed by the mixing unit from data. It is an example of one having a function. A specific example of the data storage unit 30 is a generally known storage device such as a hard disk drive. Furthermore, the control unit 10 may collectively perform the processes performed by the digital watermark processing unit 20.

Information processing apparatus A having the above configuration
However, a process of mixing confidential information into arbitrary data will be described with reference to FIG. Here, various kinds of secret information can be considered such as a credit card number, a personal identification number, etc. Here, a case where an encryption key used for encryption or decryption of data is used as secret information will be considered.
Of course, the secret information can be freely set by the user who uses the information processing apparatus A by operating the operation unit 50. The control unit 50 of the information processing apparatus A selects data to be mixed with the “encryption key A” (see FIG. 2) to be concealed by the user operating the operation unit 50. Incidentally, here, it is assumed that “data 1” is selected. The above selection is performed by the control unit 10 in a data group stored in the data storage unit 30 (see FIG. 2).
It may be arbitrarily selected from among the above, but the above selection may be performed by the user designating predetermined data. Next, the control unit 10 transfers the encryption key A and the data 1 to the digital watermark processing unit 20. continue,
The digital watermark processing unit 20 mixes the encryption key A into the data 1 by using the extraction key 1 used when the information is mixed into the data by using the digital watermark technique. After that, the data 1 in which the encryption key A is mixed is preferably returned to the original data group of the data storage unit 30. The extraction key 1 is
Rules such as a method for mixing the encryption key A into the data 1 by using a digital watermark technique are defined.

Next, the process of extracting the secret information from the data in which the secret information is mixed will be described with reference to FIG. The digital watermark processing unit 20 extracts the encryption key A from the data 1 in which the encryption key A is mixed by using the extraction key 1. At this time, since the data 1 is acquired from the data group stored in the data storage unit 30 or the like, a specific example of acquiring the data 1 will be described. For example, when the operation unit 50 is operated by the user, a command for performing the process of extracting the encryption key A is input.
This command is, for example, a command for executing the extraction key 1 used when the encryption key A was mixed into the data 1 by using the digital watermark technique. In response to this command, the digital watermark processing unit 20 searches the data 1 using the extraction key 1 from the data group. That is, in this case, the extraction key 1 has the information that the encryption key A was previously mixed in the data 1. On the other hand, if the extraction key 1 does not include the information that the encryption key A has been previously mixed in the data 1, the brute force scanning method as shown in FIG. 4 may be used. That is, when the digital watermark processing unit 20 uses the extraction key 1 to perform extraction processing on all the data in the data group, only the data 1 can be acquired using the extraction key 1 described above. Therefore, the encryption key A can be extracted only when the extraction process is performed on the data 1. Therefore, in this case, nothing is extracted from the data 4 containing no secret information, the data 3 having a different encryption key B, and the like. In this way, since the encryption key A, which is an example of secret information, can be mixed or extracted from the data 1 arbitrarily selected from the data group, the encryption key A can be mixed by a third party. It is more difficult to specify the data 1 that is present than in the past, and the confidentiality of the encryption key A is improved. Further, in the above, only the extraction key 1 can acquire the encryption key A from the data 1, but as shown in FIG. 5, secret information (encryption key A and encryption key B in FIG. 5) is mixed. The encryption key A and the encryption key B may be extracted using a common extraction key that can be extracted for all existing data (data 1 and data 3 in FIG. 5). In the case of FIG. 5, the effect of confidentiality is weakened as compared with the case of FIG. 4, but the user who handles the information processing apparatus A is fixed, and the operation by a third party is extremely low. It can be said that it is simple and easy to use.

[0012]

(Embodiment 1) In the above embodiment, the case where the information to be concealed is mixed in the data has been described. However, in the following, the extraction key used when the secret information is mixed in the data. FIG. 6 shows a case where is mixed with arbitrary data by performing another digital watermark process.
Will be explained. FIG. 6A shows an encryption key A to be kept secret.
FIG. 11 is a diagram showing a situation in which is mixed into the data 10 by using the extraction key 10, which is the same processing as that of the embodiment already described. Next, as shown in FIG. 6B, the extraction key 10 used in the above mixing is used as a data 3 by using another extraction key 3.
Mix in. Further, the extraction key 3 used in the above mixing is mixed in the data 7 by using another extraction key 7 as shown in FIG. 6C. That is, as shown in FIG. 6D, information is mixed in the data in the order of encryption key A-data 10, extraction key 10-data 3, extraction key 3-data 7. That is, the encryption key A, the extraction key 10 in which the encryption key A is mixed, and the extraction key 3 in which the extraction key 10 is mixed are hierarchically mixed in the data. On the other hand, when extracting the encryption key A, first, the extraction key 3 is extracted from the data 7 using the extraction key 7 (FIG. 7A), and the extraction key 3 is extracted from the data 3 using the extracted extraction key 3. 10 (see FIG. 7)
(B)) Further, the encryption key A is extracted from the data 10 by using the extracted extraction key 10 (FIG. 7 (c)), and the processing is performed in the order. In this manner, not only the encryption key A that should be kept secret originally, but also the extraction key used when mixing the encryption key A into the data is mixed into the arbitrary data, whereby the encryption key A
It can be said that the confidentiality of is improved. That is, the third party uses the encryption key A
It is impossible to directly extract the encryption key A when trying to obtain the encryption key A. If the extraction process is not performed in order from the final extraction key (extraction key 7 in the above example) in the hierarchical structure, the encryption key A This is because A cannot be acquired.

(Embodiment 2) When secret information such as an encryption key is mixed into data, a history of processing of mixing or extracting the secret information (hereinafter referred to as "processing history"), the mixing or the extraction. Information (hereinafter, referred to as “processing information”) related to the processing that accompanies the processing (1) may be mixed in the data. Here, the processing history and the processing information will be described. Specifically, the processing history is a history such as the time when the secret information was mixed in the data, the number of times the secret information was tried to be extracted with different extraction keys, and the like. The above-mentioned processing information is, specifically, information regarding processing to be performed when the confidential information is extracted from the data when it fails, or processing content to be performed when the confidential information is successful.
The processing history and the processing information as described above are mixed into the data together with the encryption key to be concealed by using the extraction key as shown in FIG. By performing such processing, for example, when a third party illegally attempts to extract the encryption key, it becomes possible to record the time and the number of times of the unauthorized extraction attempt in the mixed processing history. Further, it becomes possible to perform the processing recorded in the processing information according to the number of times. Specifically, the processing recorded in the processing information is, for example, the information processing apparatus A when an illegal extraction attempt is made.
Is to forcibly stop the operation of, and perform processing such as issuing an alarm.

(Embodiment 3) Next, by using the secret information management system of the present invention in an authentication system as described below, it is possible to prevent "spoofing authentication" by a third party. Conventionally, a key that is a pair of a private key and a public key used for encryption and decryption of information in the user side device has been generated in advance, and as shown in FIG. By distributing the public key,
Generally, there is an authentication system that authenticates a user-side device. This authentication system generally uses the secret key to encrypt the ID, data, etc. necessary for the user-side device to access the server-side device when the user-side device accesses the server-side device. In this system, the server device receives the encrypted ID, data, etc. and decrypts them with the public key to perform authentication. Therefore, in the conventional authentication system, for example, when the user-side device is a device having good portability such as a mobile phone or a personal digital assistant, when the user encounters an accident such as loss or theft of the user-side device, There is a possibility that the secret key may be easily discovered by a third party and the server side device may be illegally accessed using the user side device. Therefore, by adopting the secret information management system of the present invention to the user-side device in the authentication system, the secret key to be concealed is converted into various data originally included in the user-side device as shown in FIG. 9B. It becomes possible to mix in, and it becomes possible to prevent the secret key from being easily discovered by a third party. If the third
Even if a person attempts to search the above-mentioned secret key from the device on the user side, the time such as "time to discover data containing secret key", "time to extract secret key from data", etc. Is required, and it is very difficult for a third party to obtain the private key. Also, during this time, if the user notices that the user-side device is lost or stolen, the user himself / herself can inquire the owner of the server-side device and take measures such as stopping the authentication with the public key. Becomes

[0015]

The present invention is a secret information management system for managing secret information, wherein the secret information is mixed into arbitrary data as a digital watermark, and the mixing means is used to realize It is configured as a secret information management system, comprising: an extracting unit for extracting the secret information from the data in which the secret information is mixed. With the configuration of the present invention as described above, since the secret information is mixed into arbitrary data, it becomes more difficult for a third party to obtain the secret information as compared with the conventional technique, and the secret information is obtained. The confidentiality of information is improved. The mixing unit and the extraction unit may perform the process of mixing or extracting the secret information according to a predetermined rule, and the predetermined rule is used for the process of mixing or extracting the secret information, for example. It may be based on a key. With this configuration, it becomes difficult for a third party who does not know the predetermined rule to extract the secret information even if the third party tries to extract the secret information. Furthermore, by using the predetermined rule as a key for a digital watermark for mixing or extracting the confidential information in data, the procedure relating to the predetermined rule can be simplified.
Furthermore, by using the key as the secret information in another digital watermark process, the key may be further mixed with arbitrary data. With this configuration,
Not only the confidential information that should be originally confidential, but also the confidentiality of the key for the digital watermark for mixing or extracting the confidential information into arbitrary data can be enhanced, and thus the confidentiality of the confidential information can be further improved. Becomes

The data in which the secret information is mixed is configured to include information about a history of a process of mixing or extracting the secret information, or information about a process associated with the process of mixing or extracting the secret information. Is also good. With such a configuration, when an unauthorized access or extraction is attempted by a third party with respect to the data in which the confidential information is mixed, the history-related information and the processing associated with the extraction processing are performed. Based on the information, it is possible to prevent unauthorized access or extraction of confidential information.

When the present invention is regarded as a method invention, it is a secret information management method for managing secret information, which comprises a first step of mixing the secret information into arbitrary data as a digital watermark, and the above mixing. A second step of extracting the secret information from the data in which the secret information is mixed by means
It is considered that the method is configured as a secret information management method characterized by including the steps. With the configuration of the present invention as described above, since the secret information is mixed into arbitrary data, it becomes more difficult for a third party to obtain the secret information as compared with the conventional technique, and the secret information is obtained. The confidentiality of information is improved. Further, the process of mixing or extracting the secret information may be performed according to the rule of the key used for the process of mixing or extracting the secret information in the first step and the second step. In the first step, By using the key as the secret information in another digital watermark process, the key may be further mixed with arbitrary data. With this configuration,
Not only the confidential information that should be originally confidential, but also the confidentiality of the key for the digital watermark for mixing or extracting the confidential information into arbitrary data can be enhanced, and thus the confidentiality of the confidential information can be further improved. Becomes

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an information processing apparatus A that employs a secret information system of the present invention.

FIG. 2 is a conceptual explanatory diagram when secret information is mixed.

FIG. 3 is a conceptual explanatory diagram when extracting confidential information.

FIG. 4 is an explanatory diagram of an example of extracting an encryption key with an extraction key.

FIG. 5 is an explanatory diagram of an example of extracting an encryption key with a common extraction key.

FIG. 6 is an explanatory diagram of an example in which an extraction key is mixed with data as confidential information.

FIG. 7 is an explanatory diagram of an example of extracting an extraction key mixed in data.

FIG. 8 is an explanatory diagram of a case where a processing history and processing information are mixed together with confidential information in data.

FIG. 9 is an explanatory diagram when the confidential information management system of the present invention is applied to an authentication system.

[Explanation of symbols]

A: Information processing equipment 10 ... Control unit 20 ... Digital watermark processing section 30 ......... Data storage section 40 ......... Communication section

Claims (8)

[Claims] 1. A confidential information management system for managing confidential information, comprising: mixing means for mixing the confidential information as a digital watermark into arbitrary data; and the confidential information mixed by the mixing means. A secret information management system, comprising: an extracting unit for extracting the secret information from the obtained data. 2. The secret information management system according to claim 1, wherein the mixing unit and the extraction unit perform a process of mixing or extracting the secret information according to a predetermined rule. 3. The secret information management system according to claim 2, wherein the predetermined rule is based on a key used for a process of mixing or extracting the secret information. 4. The secret information management system according to claim 3, wherein the key is further mixed with arbitrary data by using the key as the secret information in another digital watermark process. 5. The data in which the confidential information is mixed comprises information about a history of a process of mixing or extracting the confidential information, or information about a process associated with the process of mixing or extracting the confidential information. The secret information management system according to claim 3 or claim 4. 6. A secret information management method for managing secret information, comprising the first step of mixing the secret information as a digital watermark into arbitrary data, and the secret information being mixed by the mixing means. And a second step of extracting the confidential information from the data, the confidential information managing method. 7. The confidentiality according to claim 6, wherein the confidential information is mixed or extracted according to a rule of a key used for the mixing or extraction of the confidential information in the first step and the second step. Information management method. 8. The secret information management according to claim 7, wherein, in the first step, the key is further mixed with arbitrary data by using the key as the secret information in another digital watermark processing. Method.