JP2012085212A - Device, method and program for electronic signature key management - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly reliable verification by the prevention of data forgery and tampering on the electronic signature applying side.SOLUTION: A random number generator 13 generates a random number. A secret key and public key generator 14 generates a pair of a secret key and a public key by calculation using the random number. An electronic signature unit 16 applies an electronic signature to a digital data, using the generated secret key. A secret key discard unit 18 discards the secret key immediately after using it once in the electronic signature. A unique ID and public key pair generation and preservation unit 15 manages the public key by making the unique ID and the public key corresponding to each other by one-to-one. By this, even the electronic signature applying side becomes unable to know the secret key used in the electronic signature.

Description

  The present invention relates to an electronic signature key management apparatus, an electronic signature key management method, and an electronic signature key that can be used for authentication of various digital data such as digital image data, digital audio data, digital document data, and digital measurement data. Regarding management programs.

  In recent years, digital signatures have been widely used to prevent forgery and falsification of digital image data taken with a digital camera, digital audio data recorded with a digital recorder, and digital document data created using a computer. ing. Generally, a digital signature based on a public key cryptosystem is used for the electronic signature mechanism. The digital signature based on such a public key cryptosystem is described on pages 210 to 220 of Non-Patent Document 1, for example.

  For public key cryptography used for digital signatures, RSA (Rivest, Shamir, Adleman) systems are often used. In RSA, the encryption key and the decryption key are different. In the digital signature, an encryption key is used as a secret key, a decryption key is used as a public key, and data is encrypted with the secret key to create an electronic signature. Then, verification is performed by obtaining data obtained from the electronic signature using the public key.

Book “Introduction to Cryptographic Technology”, Hiroshi Yuki, Softbank Creative Corporation, ISBN 4-7793-2297-7

  One of the features of electronic signatures is that a person who does not know the secret key cannot forge or tamper. In other words, a person who knows the secret key can forge or tamper. The fact that a person who knows the secret key can forge or tamper with digital data becomes a problem in the following cases.

  For example, consider the case where a company is recording the content of a call with a customer. Assume that an electronic signature is added to the recorded data in order to prove that the recorded data has not been forged or altered. If an electronic signature is given to the recorded data, it is expected that the pros and cons of the objection can be judged by referring to the recorded data when the customer disputes the agreement made by telephone in the future.

  However, since the recording device is generally placed on the company side, the private key for electronic signature built in the recording device is managed by the company side, and it is considered that the company side knows the private key. . Companies that know the secret key can forge and tamper with the recorded data. As described above, if a company that knows the secret key can forge and tamper with the recorded data, the reliability of verification by the electronic signature is doubtful, and the objection from the customer may be unfairly processed.

  In view of the above-described problems, the present invention provides an electronic signature key management apparatus, an electronic signature key management method, which can prevent forgery and falsification of data by a user who gives an electronic signature and can perform highly reliable verification. An object is to provide an electronic signature key management program.

  In order to solve the above-described problems, an electronic signature key management apparatus according to the present invention includes a digital data acquisition unit that acquires digital data, a unique ID generation unit that generates a unique ID, a secret key / public A random number generator for generating a random number for randomly generating a key, a secret key / public key pair generator for generating a pair of a secret key and a public key using the random number generated by the random number generator, and a secret A unique ID / public key pair generation unit that generates a pair of a unique ID and a public key from a public key generated by the key / public key pair generation unit and a unique ID generated by the unique ID generation unit, and a secret key / public An electronic signature unit for giving an electronic signature to the digital data acquired by the digital data acquisition unit using the secret key generated by the key pair generation unit, and a unique ID generation unit for the digital data acquired by the digital data acquisition unit And a unique ID · electronic signature applying section a unique ID and electronic signature unit that generated is put string an electronic signature was applied, characterized in that the electronic signature unit is made from a discarded secret key discarding unit a secret key used.

  The digital signature key management method according to the present invention includes a digital data acquisition step for acquiring digital data, a unique ID generation step for generating a unique ID, and a random number for randomly generating a secret key / public key. Generates a random number generation step that generates a secret key, a public key pair generation step that generates a private key / public key pair that uses the random number generated by the random number generation step, and a private key / public key pair generation step The unique ID / public key pair generation step for generating a pair of the unique ID and the public key from the public key generated by the unique ID generation step and the secret key generated by the secret key / public key pair generation step A unique ID generation process is added to the digital signature process for giving an electronic signature to the digital data acquired by the digital data acquisition process and the digital data acquired by the digital data acquisition process. And a unique ID · electronic signature application process to put string an electronic signature unique ID and the electronic signature process has been granted the form, characterized in that it comprises a secret key with an electronic signature process has been used from the discard secret key destruction process.

  A digital signature key management program according to the present invention includes a digital data acquisition step for acquiring digital data, a unique ID generation step for generating a unique ID, and a random number for randomly generating a secret key / public key. Generates a random number generation step that generates a secret key, a public key pair generation step that generates a private key / public key pair that uses the random number generated by the random number generation step, and a private key / public key pair generation step The unique ID / public key pair generation step for generating a unique ID / public key pair from the public key generated by the unique ID generation step and the secret key generated by the secret key / public key pair generation step An electronic signature step for giving an electronic signature to the digital data acquired by the digital data acquisition step, and a digital data acquisition step. A unique ID / electronic signature assigning step for linking the unique ID generated by the unique ID generating step and the electronic signature assigned by the electronic signature step to the digital data acquired by the user, and a secret for destroying the private key used by the electronic signature step A key destruction step.

  According to the present invention, after the private key is used once for giving an electronic signature, the private key is immediately discarded without being exposed to the outside of the system. I can't know the key. As a result, forgery / falsification cannot be performed by the side to which the electronic signature is attached, and the reliability of the electronic signature can be improved.

It is a functional block diagram based on operation | movement of the key management system for electronic signatures concerning the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the key management system for electronic signatures concerning the 1st Embodiment of this invention. It is explanatory drawing of an example of the preservation | save form in the case of preserve | storing a unique ID and a public key as a pair. It is a functional block diagram based on operation | movement of the key management system for electronic signatures concerning the 2nd Embodiment of this invention. It is a block diagram of an example of the random number generator which used the temperature value for the internal state change of the random number generation unit. It is a functional block diagram based on operation | movement of the key management system for electronic signatures concerning the 3rd Embodiment of this invention. It is a functional block diagram based on operation | movement of the key management system for electronic signatures concerning the 4th Embodiment of this invention. It is a flowchart which shows a series of operation | movement at the time of verifying an electronic signature. It is a functional block diagram which shows the structure of the key management system for electronic signatures at the time of authenticating digital image data. It is a functional block diagram which shows an example of the camera apparatus with a key management apparatus for electronic signatures. It is a functional block diagram which shows an example of the scanner apparatus with a key management apparatus for electronic signatures. It is a functional block diagram which shows the structure of the key management system for electronic signatures at the time of authenticating digital audio data. It is a functional block diagram which shows an example of the recording device with an electronic signature key management apparatus. It is a block diagram which shows the structure of the key management system for electronic signatures at the time of authenticating digital document data. It is a functional block diagram showing an example of a document creation device with an electronic signature key management device. It is a functional block diagram which shows the structure of the key management system for electronic signatures at the time of authenticating digital measurement data. It is a functional block diagram which shows an example of a measuring device with a key management apparatus for electronic signatures.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a functional block diagram based on the operation of the electronic signature key management system according to the first embodiment of the present invention, and FIG. 2 is a flowchart showing the operation.

  As shown in FIG. 1, the electronic signature key management system according to the first embodiment of the present invention includes a digital data acquisition unit 11, a unique ID generation unit 12, a random number generation unit 13, a secret key / public key. The pair generation unit 14 includes a unique ID / public key pair generation / save unit 15, an electronic signature unit 16, a unique ID / electronic signature assignment unit 17, and a secret key discard unit 18.

  The digital data acquisition unit 11 acquires digital data that is a target of an electronic signature. The unique ID generation unit 12 generates a unique ID having uniqueness that uniquely indicates digital content. The random number generator 13 generates a random number for randomly generating a secret key / public key. The private key / public key pair generation unit 14 uses the random number generated by the random number generation unit 13 for calculation to generate a private key / public key pair. The unique ID / public key pair generation / save unit 15 generates and stores a pair of the public key generated by the secret key / public key pair generation unit 14 and the unique ID generated by the unique ID generation unit 12. The electronic signature unit 16 gives an electronic signature to the digital data acquired by the digital data acquisition unit 11 using the secret key generated by the secret key / public key pair generation unit 14. The unique ID / electronic signature adding unit 17 associates the digital data acquired by the digital data acquiring unit 11 with the unique ID generated by the unique ID generating unit 12 and the electronic signature added by the electronic signature unit 16. The private key discarding unit 18 discards the private key used by the electronic signature unit 16 in order to reduce the chance of eavesdropping on the private key and prevent the electronic signature from being forged using the private key.

  As described above, in the electronic signature key management system according to the first embodiment of the present invention, the secret key / public key pair generation unit 14 uses the random number generated by the random number generation unit 13 for calculation and publicly discloses the secret key. A key pair is generated, and the electronic signature unit 16 assigns an electronic signature to the digital data acquired by the digital data acquisition unit 11 using the secret key generated by the secret key / public key pair generation unit 14. Then, the secret key discarding unit 18 immediately discards the secret key for giving the electronic signature without exposing it to the outside after being used once. As a result, the secret key used for the electronic signature cannot be known even on the side where the electronic signature is given, and forgery and tampering by the user on the side where the electronic signature is given can be prevented. Since the private key is required only when the electronic signature is given, and only the public key is required when verifying the electronic signature, discarding the private key does not affect the verification of the electronic signature. Also, the unique ID generation unit 12 generates a unique ID, and the generated unique ID is associated with digital data to which an electronic signature is to be assigned. This unique ID identifies digital data as content. Then, the unique ID / public key pair generation / save unit 15 manages the public key by associating the unique ID with the public key on a one-to-one basis.

  Next, the basic configuration of the operation of the electronic signature key management system according to the present invention will be described with reference to the flowchart of FIG.

  In FIG. 2, first, the digital data acquisition unit 11 acquires digital data to which a digital signature is to be assigned (step S101).

  Next, the unique ID generation unit 12 generates a unique ID (step S102). The generated unique ID is linked to the digital data to which the electronic signature is attached and is used to identify the digital data. Even when there are a plurality of electronic signature key management systems according to the present invention, the unique IDs do not overlap among them, and all the unique IDs generated by the same system are past and future. It is necessary to generate so as not to overlap.

  A unique ID having such properties can be realized by including a system-specific identification number and time information, for example. As an identification number unique to the system, for example, in the case of a PC (Personal Computer), an IPv6 (Internet Protocol Version 6) address or a MAC (Media Access Control address) address of a network interface can be used. It is possible to include a random number in the unique ID, and including a random number in the unique ID helps to prevent the IDs from overlapping. For example, when processing is performed continuously in a short time in the same system, it is useful to use a random number because it cannot be distinguished only by the identification number unique to the system and the time information. For the same purpose as the random number, the hash value of the digital data can be included in the unique ID. It is also possible to include both a random number and a hash value in the unique ID.

  Next, the random number generation unit 13 generates a random number for randomly generating a secret key / public key (step S103). In the electronic signature key management system according to the present invention, a random key is used to generate a secret key so that no one can predict the generated secret key so that no one knows the secret key. ing. Random numbers are created using existing methods with randomness and unpredictability. A random number having randomness and unpredictability is described, for example, on page 299 of Non-Patent Document 1 ("Introduction to Cryptographic Techniques" by Hiroshi Yuki). Further, page 308 of Non-Patent Document 1 describes a method of generating a random number using, for example, a one-way hash function (for example, SHA-1).

  Next, the secret key / public key pair generation unit 14 generates a secret key / public key using the random number generated by the random number generation unit 13 (step S104). An existing method can be used as the secret key / public key generation method. For example, a method for generating an RSA private key / public key is described on pages 127 to 130 of Non-Patent Document 1, for example. For example, as a method of generating a specific prime number in the part of preparing two large prime numbers in this method, for example, “Survey Report“ Survey / Development Survey Report of Prime Number Generation Algorithm ”Information Processing Promotion Corporation Security Center , February 2003 ”, page 17 to page 22, in which a random number generated by a random number generator is used when a number is randomly selected. It is better to generate a private key / public key after acquiring digital data in order to shorten the period in which the private key exists, but since it takes several seconds for a general PC to generate a private key / public key, digital data acquisition A method of generating in advance can also be selected. In this case, the digital data acquisition is waited after the secret key and the public key are generated.

  Next, the unique ID / public key pair generation / save unit 15 generates a pair of the unique ID generated by the unique ID generation unit 12 and the public key generated by the secret key / public key pair generation unit 14. Save (step S105). FIG. 3 shows an example of a storage form when a unique ID and a public key are stored as a pair. In FIG. 3, the serial number, which is a serial number starting from “1”, a unique ID / public key pair, and the time when they are stored are stored. The storage time in FIG. 3 suppresses an attack in which a malicious person inserts fake data other than the end of the stored data, and the serial number also has the same function. For this reason, in this example, the storage time and the serial number are provided, but the storage time and the serial number may be omitted.

  The unique ID / public key pair generation / save unit 15 can generate only a unique ID / public key pair and store it only by the electronic signature key management system according to the present invention, and cannot store it from other external systems. Need to be configured. For this purpose, the storage element that is the storage destination of the unique ID / public key pair in the unique ID / public key pair generation / storage unit 15 is configured so that it cannot be physically removed from the electronic signature key management system. It ’s fine. In addition, the casing of the electronic signature key management system is sealed so that the storage device of the storage destination of the unique ID / public key pair storage unit 15 of the unique ID / public key pair generation storage unit 15 cannot be physically accessed. You may make it do.

  Next, the electronic signature unit 16 generates an electronic signature for the digital data acquired by the digital data acquisition unit 11 using the private key generated by the private key / public key pair generation unit 14 (step S106). As a method for generating an electronic signature, a generally known method, for example, a method described on pages 228 to 230 of Non-Patent Document 1 can be used for generating a signature by RSA.

  Next, the unique ID / electronic signature adding unit 17 adds the unique ID generated by the unique ID generating unit 12 and the electronic signature generated by the electronic signature unit 16 to the digital data acquired by the digital data acquiring unit 11 ( Step S107). As a method for assigning an electronic signature in the unique ID / electronic signature assigning unit 17, a method generally known as an electronic signature assigning method can be used. For example, if the digital data is text data, there is a method of adding a unique ID and an electronic signature as text to the end of the text data. For example, if the digital data is JPEG (Joint Photographic Experts Group) image data, there is a method of storing a unique ID and an electronic signature in the header portion of the data. For example, if the digital data is an electronic mail, there is a method in which a file in which a unique ID and an electronic signature are recorded is used as an attached file of the electronic mail. For example, as a method that can be used regardless of the format of digital data, there is a method in which a digital data file and a file in which a unique ID and an electronic signature are recorded are merged into one file by archive software. Similarly, as a method that can be used regardless of the format of digital data, there is a method in which a digital data file and a file in which a unique ID and an electronic signature are recorded are stored in one directory created for each unique ID.

  Next, the secret key discarding unit 18 discards the secret key generated by the secret key / public key pair generating unit 14 (step S108). It is desirable to destroy the secret key promptly so that the secret key does not remain in storage elements (main memory, cache memory, fixed disk device, etc.) in the system.

  As described above, in the electronic signature key management system according to the present invention, the private key is immediately discarded without being exposed to the outside after being used once for providing the electronic signature. Even a person who is a person cannot know the secret key. As a result, it is possible to prove that the user on the side of the digital signature is not (or cannot) forged or altered. Since the private key is required only when the electronic signature is given, and only the public key is required when verifying the electronic signature, discarding the private key does not affect the verification of the electronic signature.

  In general, a public key used for verification of an electronic signature is a public key that has a one-to-one correspondence with the person or computer that has given the electronic signature. In contrast, in the electronic signature key management system according to the present invention, the public key is generated using a random number, and there is a public key for each digital content to which the electronic signature is attached. Therefore, a unique ID that uniquely indicates the digital content is introduced, and the unique ID / public key pair generation / save unit 15 makes the unique ID and the public key correspond one-to-one so that the public key can be managed using the unique ID. I have to.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. FIG. 4 is a functional block diagram based on the operation of the electronic signature key management system according to the second embodiment of the present invention.

  As shown in FIG. 4, the digital signature key management system according to the second embodiment of the present invention includes a digital data acquisition unit 21, a unique ID generation unit 22, a random number generation unit 23, a secret key / public key. The pair generating unit 24, the unique ID / public key pair generating / storing unit 25, the electronic signature unit 26, the unique ID / electronic signature giving unit 27, the secret key discarding unit 28, and the temperature measuring unit 29 are included. Digital data acquisition unit 21, unique ID generation unit 22, random number generation unit 23, private key / public key pair generation unit 24, unique ID / public key pair generation storage unit 25, electronic signature unit 26, unique ID / electronic signature assignment unit 27, the secret key destruction 28 is the digital data acquisition unit 11, the unique ID generation unit 12, the random number generation unit 13, the secret key / public key pair generation unit 14, the unique ID / public key pair generation storage unit in the first embodiment. 15, the same as the electronic signature unit 16, the unique ID / electronic signature adding unit 17, and the secret key discarding unit 18. In the electronic signature key management system according to the second embodiment of the present invention, a temperature measurement unit 29 is further provided, and the temperature measurement unit 29 measures the ambient temperature. The temperature value measured by the temperature measurement unit 29 is used to change the internal state of the random number generation unit 23 and increase randomness irregularities when the random number generation unit 23 generates a random number.

  Thus, in the electronic signature key management system according to the second embodiment of the present invention, the temperature measurement unit 29 is added, and the temperature measurement unit 29 converts the measured temperature value into the internal state of the random number generation unit. Used for change. As a result, the random number can be made non-reproducible, and can be made more robust against attacks. The non-reproducibility of random numbers is described on page 299 of Non-Patent Document 1.

  FIG. 5 shows an example of a random number generator that uses temperature values for changing the internal state of the random number generator. The basic configuration of this random number generator is described as a pseudo random number generator on page 308 of Non-Patent Document 1. The configuration of the random number generator shown in FIG. 5 is obtained by changing the part of the pseudo random number generator that increases the internal state by “1” to the absolute temperature value increasing unit 94.

  In FIG. 5, an initial value setting unit 91 generates an initial value using a pseudo random number seed, and initializes a counter 92 indicating an internal state. The one-way hash function unit 93 acquires the hash value (for example, SHA-1) of the counter 92. The absolute temperature value increasing unit 94 adds the temperature value measured by the temperature measuring unit 29 to the counter 92. In this way, the initial value is generated using the seed of the pseudo random number, the counter 92 of the internal state generation unit is initialized, the hash value of the counter 92 is acquired, the random number is generated, and the temperature measurement unit 29 measures The process of adding the temperature value to the counter 92 is repeated, and the random value 95 is output from the output of the one-way hash function unit 93.

  In the configuration of FIG. 5, the value of the counter 92 indicating the internal state is an integer. For this reason, when the absolute temperature value is added to the value of the counter 92 indicating the internal state by the absolute temperature value increasing unit 94, the decimal point position is moved to the rightmost end of the temperature value so that the temperature value becomes an integer. Processing is performed.

  In the configuration of FIG. 5, the change in the temperature value added by the absolute temperature value increasing unit 94 is a natural phenomenon, and is also subject to fluctuation due to the inherent wrinkling / aging change of the temperature measuring device. For this reason, the absolute temperature value becomes a value that cannot be predicted and reproduced, and contributes to the non-reproducibility of random numbers.

  In the configuration of FIG. 5, the absolute temperature is used as the temperature value to be added to the counter 92 indicating the internal state. The reason is that the absolute temperature does not take a value of “0”. For example, the temperature may be 0 degrees at a Celsius temperature, and if this continues for a long time, the same value is continuously generated as a random number, which is not desirable. For the same reason, the use of Fahrenheit temperature is also undesirable.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. FIG. 6 shows a third embodiment of the present invention.

  As shown in FIG. 6, the digital signature key management system according to the third embodiment of the present invention includes a digital data acquisition unit 31, a unique ID generation unit 32, a random number generation unit 33, a secret key / public key. The pair generation unit 34, the unique ID / public key pair generation / save unit 35, the electronic signature unit 36, the unique ID / electronic signature assignment unit 37, the secret key discard unit 38, and the time measurement unit 39 are included. Digital data acquisition unit 31, unique ID generation unit 32, random number generation unit 33, private key / public key pair generation unit 34, unique ID / public key pair generation storage unit 35, electronic signature unit 36, unique ID / electronic signature assignment unit 37, the secret key discard 38 is the digital data acquisition unit 21, the unique ID generation unit 22, the random number generation unit 23, the secret key / public key pair generation unit 24, the unique ID / public key pair generation storage unit in the second embodiment. 25, the same as the electronic signature unit 26, the unique ID / electronic signature adding unit 27, and the secret key destruction 28. The time measuring unit 39 measures the current time. The time measured by the time measurement unit 39 is used to change the internal state of the random number generation unit 33 when the random number generation unit 33 generates a random number, as in the temperature measurement unit 29 in the second embodiment. It is done.

  As described above, in the electronic signature key management system according to the third embodiment of the present invention, the time measurement unit 39 is added, and the time measurement unit 39 changes the internal state of the random number generation unit, Used to increase irregularity. As a result, the random number can be made non-reproducible and can be made more robust against attacks.

  As the random number generator in the third embodiment of the present invention, the one described as a pseudo random number generator on page 308 of Non-Patent Document 1 is used as in the second embodiment. That is, the random number generator according to the third embodiment of the present invention uses an absolute temperature value increasing unit 94 that changes the internal state at the absolute temperature in the random number generator configured as shown in FIG. This can be realized by changing to a time value increasing unit that changes the internal state. In order to realize the non-reproducibility of random numbers, it is desirable that the time value includes year / month / day / hour / second and that the second measures as many digits after the decimal point as possible. The form including year / month / day / hour / second may be configured such that these values (2010, 08, 12, 15, 30, etc.) are arranged, or a predetermined time, for example, midnight on January 1, 2000 A configuration expressed by the number of seconds from 0 minute 0 second may be used.

<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described. FIG. 7 shows a configuration of an electronic signature system according to the fourth embodiment of the present invention.

  As shown in FIG. 7, an electronic signature system according to the fourth embodiment of the present invention includes a digital data acquisition unit 41, a unique ID generation unit 42, a random number generation unit 43, and a private key / public key pair generation unit. 44, a unique ID / public key pair generation / transmission unit 45, an electronic signature unit 46, a unique ID / electronic signature giving unit 47, and a secret key destruction 48. The digital data acquisition unit 41, the unique ID generation unit 42, the random number generation unit 43, the secret key / public key pair generation unit 44, the electronic signature unit 46, the unique ID / electronic signature assignment unit 47, and the secret key discard unit 48 are The digital data acquisition unit 11, the unique ID generation unit 12, the random number generation unit 13, the secret key / public key pair generation unit 14, the electronic signature unit 16, the unique ID / electronic signature assignment unit 17, the secret key destruction unit 18 in the embodiment It is the same. The unique ID / public key pair generation / transmission unit 45 generates a pair of the public key generated by the secret key / public key pair generation unit 44 and the unique ID generated by the unique ID generation unit 42, and the public key and the unique ID. Send a pair with.

  In the first to third embodiments described above, a public key / unique ID pair is generated and stored in the unique ID / public key pair generation storage units 15, 25, and 35. In contrast, in the fourth embodiment, the unique ID / public key pair generation / transmission unit 45 transmits the pair of the unique ID and the public key to the outside using the communication path 49. Yes. The transmitted unique ID / public key pair is stored in the external recording device 50.

  In such a configuration, it is necessary to use a communication path 49 that is robust against eavesdropping / tampering attacks. As a method for configuring the communication path 49 that is robust against eavesdropping / tampering attacks, for example, there is a method using a dedicated line. Further, as a method of configuring the communication channel 49 that is robust against eavesdropping / tampering attacks, for example, SSL (Secure Sockets Layer) communication (described on pages 346 to 366 of Non-Patent Document 1) is used on the Internet network. There is a way to configure. In addition, as a method of configuring the communication path 49 that is robust against eavesdropping / tampering attacks, for example, there is a method of configuring the communication path 49 on the mobile phone network using SSL communication. Any of these multiple methods may be used.

  The external recording device 50 is for storing a unique ID / public key pair. The external recording device 50 functions to return a public key paired with a unique ID when an inquiry is made by designating a unique ID. This public key is used to verify the digital signature of the digital data associated with the unique ID.

  FIG. 8 is a flowchart showing a series of operations when the user inquires the external recording device 50 about the public key and verifies the electronic signature.

  In FIG. 8, the user first acquires digital data, an accompanying unique ID, and an electronic signature (step S201). The unique ID and electronic signature are obtained from the unique ID / electronic signature assigning unit 47 in FIG.

  Next, the user inquires of the external recording device 50 about the public key using the acquired unique ID as a clue (step S202). Then, the user determines whether or not a public key has been obtained (step S203). Here, if the reply is that there is no public key from the external recording device 50, the user determines that the acquired digital data is not authentic and ends the process (step S204).

  When the public key corresponding to the acquired unique ID is obtained, the user verifies the digital data and the electronic signature using the public key obtained from the external recording device 50 (step S205). Then, the user determines whether or not the verification has been correctly performed (step S206).

  Here, if the verification can be performed correctly, the user determines that the digital data is authentic and ends the process (step S207). If the verification cannot be performed correctly, the user determines that the acquired digital data is not authentic and ends the process (step S204).

  The external recording device 50 is preferably configured so that anyone can make a public key inquiry. Further, it is desirable that the unique ID / public key pair can be written to the external recording device 50 only from a digital signature key management system permitted in advance. This is to prevent forgery of the unique ID / public key pair. The electronic signature key management system according to the present invention is configured to have a unique identification number as described in the process of generating a unique ID. For this reason, by using the identification number, it can be determined whether the system is permitted in advance, and writing of the unique ID / public key pair to the external recording device 50 can be permitted. Further, the storage form of the unique ID and the public key in the external recording device 50 can be the same as that shown in FIG.

<Example of using digital signature key management system for digital image data authentication>
Next, a specific usage example of the electronic signature key management system according to the present invention will be described. First, an example in which the digital signature key management system according to the present invention is used for authentication of digital image data will be described.

  FIG. 9 shows the configuration of a digital signature key management system for authenticating digital image data. As shown in FIG. 9, the digital signature key management system for authenticating digital image data includes a digital image data acquisition unit 51, a unique ID generation unit 52, a random number generation unit 53, a private key / public key pair. The generating unit 54, the unique ID / public key pair generation / storing unit 55, the electronic signature unit 56, the unique ID / electronic signature adding unit 57, and the secret key discarding unit 58 are included. The digital image data acquisition unit 51 is a module that digitizes received light data in the camera device or the scanner device. The configuration shown in FIG. 9 is basically the same as that of the first embodiment shown in FIG.

  As described above, when digital image data authentication is performed, the digital image data acquisition unit 51 acquires the received light data in the camera device or the scanner device. A private key / public key pair generation unit 54 generates a private key / public key pair using the random number generated by the random number generation unit 53 for calculation, and an electronic signature unit 56 generates the private key / public key pair generation unit. Using the secret key generated by 54, an electronic signature is added to the digital data acquired by the digital image data acquisition unit 51. Then, the secret key discarding unit 58 discards the secret key immediately after using it once to give an electronic signature without exposing it to the outside.

<Camera device with electronic signature key management device>
FIG. 10 shows an example of the camera device 100 with a digital signature key management device. The configuration shown in FIG. 10 is a more specific embodiment of the fourth embodiment shown in FIG. 7, and is a camera device 100 with a digital signature key management device.

  In FIG. 10, light input through a lens 101 is converted into an electrical signal by a photoelectric conversion unit 102 such as a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, followed by analog-digital conversion. The unit 103 converts the digital data. The photoelectric conversion unit 102 and the analog / digital conversion unit 103 constitute a digital image data acquisition unit 151.

  The unique ID generation unit 152 generates a unique ID having uniqueness that uniquely indicates digital content. The random number generation unit 153 generates a random number for randomly generating a secret key / public key. The private key / public key pair generation unit 154 generates a private key / public key pair that uses the random number generated by the random number generation unit 153 for calculation. The unique ID / public key pair generation / transmission unit 155 generates a pair of the public key generated by the secret key / public key pair generation unit 154 and the unique ID generated by the unique ID generation unit 152 and transmits the pair to the external recording device 160. To do. The transmission path to the external recording device 160 is configured using an SSL communication protocol using a wireless Internet network such as the Bluetooth (registered trademark) standard or the IEEE 802.11a / b / g / n standard. The external recording device 160 stores the sent public key and unique ID pair.

  The electronic signature unit 156 gives an electronic signature to the digital image data acquired by the digital image data acquisition unit 151 using the private key generated by the private key / public key pair generation unit 154. The unique ID / electronic signature providing unit 157 associates the digital data acquired by the digital image data acquisition unit 151 with the unique ID generated by the unique ID generation unit 152 and the electronic signature provided by the electronic signature unit 156. The digital image data to which the unique ID and the electronic signature are assigned by the unique ID / electronic signature assigning unit 157 is stored in a storage element 161 such as a memory or a memory card built in the camera device 100 with the electronic signature key management device. Is done. The secret key discarding unit 158 discards the secret key used by the electronic signature unit 156 in order to reduce the chance of eavesdropping on the secret key and prevent forgery of the electronic signature using the secret key.

  The digital signature of the image data acquired by the digital image data acquisition unit 151 can be given by the camera device 100 with a digital signature key management device configured as described above. Since the secret key used at this time is discarded by the secret key discarding unit 158, it is possible to prevent forgery or falsification of data by the user of the camera device 100 with the electronic signature key management device.

<Scanner with electronic signature key management device>
FIG. 11 shows an example of a scanner device 200 with a digital signature key management device. The configuration shown in FIG. 11 is a more specific embodiment of the fourth embodiment shown in FIG. 7 and is a scanner device 200 with a digital signature key management device.

  In FIG. 11, light input through a lens 201 is converted into an electric signal by a photoelectric conversion unit 202 such as a CCD image sensor or a CMOS image sensor, and then converted into digital data by an analog-digital conversion unit 203. The photoelectric conversion unit 202 and the analog / digital conversion unit 203 constitute a digital image data acquisition unit 251.

  The unique ID generation unit 252 generates a unique ID having uniqueness that uniquely indicates the digital content. The random number generation unit 253 generates a random number for randomly generating a secret key / public key. The private key / public key pair generation unit 254 generates a private key / public key pair that uses the random number generated by the random number generation unit 253 for calculation. The unique ID / public key pair generation / transmission unit 255 generates a pair of the public key generated by the secret key / public key pair generation unit 254 and the unique ID generated by the unique ID generation unit 252 and transmits the generated pair to the external recording device 260. To do. The transmission path uses a wired Internet network such as Ethernet (registered trademark) and is configured using the SSL communication protocol. The external recording device 260 stores the sent public key and unique ID pair.

  The electronic signature unit 256 assigns an electronic signature to the digital image data acquired by the digital image data acquisition unit 251 using the private key generated by the private key / public key pair generation unit 254. The unique ID / electronic signature assigning unit 257 associates the digital data acquired by the digital image data acquisition unit 251 with the unique ID generated by the unique ID generation unit 252 and the electronic signature provided by the electronic signature unit 256. The digital image data to which the unique ID and the electronic signature are added by the unique ID / electronic signature adding unit 257 is transmitted to the external computer 261 using Ethernet (registered trademark) or USB (Universal Serial Bus). The secret key discarding unit 258 discards the secret key used by the electronic signature unit 256 in order to reduce the chance of eavesdropping on the secret key and prevent forgery of the electronic signature using the secret key.

  The electronic signature of the image data acquired by the digital image data acquisition unit 251 can be given by the scanner device 200 with a digital signature key management device configured as described above. Since the secret key used at this time is discarded by the secret key discarding unit 258, it is possible to prevent forgery or falsification of data by the user of the scanner device 200 with the electronic signature key management device.

<Example of using digital signature key management system for digital audio data authentication>
Next, an example in which the present invention is used for authentication of digital audio data will be described. FIG. 12 shows the configuration of a digital signature key management system for authenticating digital audio data.

  As shown in FIG. 12, the digital signature key management system for authenticating digital audio data includes a digital audio data acquisition unit 61, a unique ID generation unit 62, a random number generation unit 63, a private key / public key pair. The generating unit 64 includes a unique ID / public key pair generation / storing unit 65, an electronic signature unit 66, a unique ID / electronic signature adding unit 67, and a secret key discarding unit 68. The digital audio data acquisition unit 61 is a module that digitizes input audio data in the recording device.

  As described above, when the digital audio data is authenticated, the audio data is acquired by the digital audio data acquisition unit 61. A private key / public key pair generation unit 64 generates a private key / public key pair by using the random number generated by the random number generation unit 63 for calculation, and an electronic signature unit 66 generates the private key / public key pair generation unit. The digital signature is added to the digital data acquired by the digital audio data acquisition unit 61 using the secret key generated by the H.64. Then, the secret key discarding unit 68 discards the secret key immediately after using it once to give an electronic signature without exposing it to the outside.

<Recording device with key management device for electronic signature>
FIG. 13 shows an example of a recording apparatus 300 with a digital signature key management apparatus. The configuration shown in FIG. 13 is a more specific example of the fourth embodiment shown in FIG. 7, and is a recording device 300 with a digital signature key management device.

  In FIG. 13, the sound input by the microphone 301 is converted into digital data by the analog / digital conversion unit 302. The microphone 301 and the analog / digital conversion unit 302 constitute a digital audio data acquisition unit 361.

  The unique ID generation unit 362 generates a unique ID having uniqueness that uniquely indicates the digital content. The random number generation unit 363 generates a random number for randomly generating a secret key / public key. The private key / public key pair generation unit 364 generates a private key / public key pair that uses the random number generated by the random number generation unit 363 for calculation. The unique ID / public key pair generation / transmission unit 365 generates a pair of the public key generated by the secret key / public key pair generation unit 364 and the unique ID generated by the unique ID generation unit 362, and sends it to the external recording device 370. Send. The transmission path uses a wired Internet network such as Ethernet (registered trademark) and is configured using the SSL communication protocol. The external recording device 370 stores the sent public key and unique ID pair.

  The electronic signature unit 366 gives an electronic signature to the digital image data acquired by the digital audio data acquisition unit 361 by using the secret key generated by the secret key / public key pair generation unit 364. The unique ID / electronic signature assigning unit 367 associates the digital data acquired by the digital audio data acquisition unit 361 with the unique ID generated by the unique ID generation unit 362 and the electronic signature provided by the electronic signature unit 366. The digital image data to which the unique ID and the electronic signature are assigned by the unique ID / electronic signature assigning unit 367 is stored in the storage element 371. The secret key discarding unit 368 discards the secret key used by the electronic signature unit 366 in order to reduce the chance of eavesdropping on the secret key and prevent forgery of the electronic signature using the secret key.

  The recording device 300 with the electronic signature key management device configured as described above can give the electronic signature of the audio data acquired by the digital audio data acquisition unit 361. Since the secret key used at this time is discarded by the secret key discarding unit 368, it is possible to prevent forgery or falsification of data by the user of the recording device 300 with the electronic signature key management device.

<Example of using digital signature key management system for digital document data authentication>
Next, an example in which the present invention is used for authentication of digital document data will be described. FIG. 14 shows the configuration of a digital signature key management system for authenticating digital document data.

  As shown in FIG. 14, a digital signature key management system for authenticating digital document data includes a digital document data acquisition unit 71, a unique ID generation unit 72, a random number generation unit 73, a private key / public key pair. The generating unit 74 includes a unique ID / public key pair generation / storing unit 75, an electronic signature unit 76, a unique ID / electronic signature giving unit 77, and a secret key discarding unit 78. The digital document data acquisition unit 71 is a document input module in the document creation device.

  As described above, when the digital document data is authenticated, the digital document data acquisition unit 71 acquires the digital document data. A private key / public key pair generation unit 74 generates a private key / public key pair by using the random number generated by the random number generation unit 73 for calculation, and an electronic signature unit 76 generates the private key / public key pair generation unit. Using the private key generated by 74, an electronic signature is added to the digital data acquired by the digital document data acquisition unit 71. Then, the secret key discarding unit 78 discards the secret key immediately after using it once to give an electronic signature without exposing it to the outside.

<Document creation device with electronic signature key management device>
FIG. 15 shows an example of a document creation device 400 with a digital signature key management device. The configuration shown in FIG. 15 is a more specific example of the fourth embodiment shown in FIG. 7, and is a document creation device 400 with a digital signature key management device.

  In FIG. 15, the character code input from the keyboard 401 is formatted as digital document data by the data shaping unit 402. The data shaping unit 402 is configured by word processor software or editor software installed in a computer. The keyboard 401 and the data shaping unit 402 constitute a digital document data acquisition unit 471.

  The unique ID generation unit 472 generates a unique ID having uniqueness that uniquely indicates the digital content. The random number generation unit 473 generates a random number for randomly generating a secret key / public key. The private key / public key pair generation unit 474 generates a private key / public key pair that uses the random number generated by the random number generation unit 473 for calculation. The unique ID / public key pair generation / transmission unit 475 generates a pair of the public key generated by the secret key / public key pair generation unit 474 and the unique ID generated by the unique ID generation unit 472, and sends it to the external recording device 480. Send. The transmission path uses a wired Internet network such as Ethernet (registered trademark) and is configured using the SSL communication protocol. The external recording device 480 stores the sent public key and unique ID pair.

  The electronic signature unit 476 adds an electronic signature to the digital image data acquired by the digital document data acquisition unit 471 using the private key generated by the private key / public key pair generation unit 474. The unique ID / electronic signature adding unit 477 associates the digital document data acquired by the digital document data acquisition unit 471 with the unique ID generated by the unique ID generation unit 472 and the electronic signature provided by the electronic signature unit 476. The digital document data provided with the unique ID and the electronic signature by the unique ID / electronic signature adding unit 477 is stored in a storage element 481 such as a memory or a fixed disk device built in the apparatus. The secret key discarding unit 478 discards the secret key used by the electronic signature unit 476 in order to reduce the chance of eavesdropping on the secret key and prevent forgery of the electronic signature using the secret key.

  The electronic signature of the document data acquired by the digital document data acquisition unit 471 can be assigned by the document creation device 400 with the electronic signature key management device configured as described above. Since the secret key used at this time is discarded by the secret key discarding unit 478, it is possible to prevent forgery or falsification of data by the user of the document creation apparatus 400 with the electronic signature key management apparatus.

<Example of using digital signature key management system for authentication of digital measurement data>
Next, an example in which the present invention is used for authentication of digital measurement data will be described. FIG. 16 shows the configuration of a digital signature key management system for authenticating digital measurement data.

  As shown in FIG. 16, the digital signature key management system for authenticating digital measurement data includes a digital measurement data acquisition unit 81, a unique ID generation unit 82, a random number generation unit 83, a private key / public key pair. A generation unit 84, a unique ID / public key pair generation / storage unit 85, an electronic signature unit 86, a unique ID / electronic signature assignment unit 87, and a secret key discard unit 88 are included. The digital measurement data acquisition unit 81 is a digital measurement data input module.

  As described above, when the digital measurement data is authenticated, the digital measurement data acquisition unit 81 acquires the digital measurement data. The private key / public key pair generation unit 84 generates a private key / public key pair using the random number generated by the random number generation unit 83 for calculation. The electronic signature unit 86 generates the private key / public key pair generation unit. Using the secret key generated by 84, an electronic signature is added to the digital data acquired by the digital measurement data acquisition unit 81. Then, the secret key discarding unit 88 discards the secret key immediately after it is used once for giving an electronic signature without exposing it to the outside.

<Measurement device with electronic signature key management device>
FIG. 17 shows an example of a measuring apparatus 500 with a digital signature key management apparatus. The configuration shown in FIG. 17 is a more specific example of the fourth embodiment shown in FIG. 7, and is a measuring device 500 with a digital signature key management device.

  In FIG. 17, a signal input by the measurement sensor 501 is converted into measurement data of a digital signal by an analog / digital conversion unit 502. The measurement sensor 501 is a sensor that measures a physical quantity and converts it into an electronic signal, such as a temperature sensor, a humidity sensor, a pressure sensor, an electrocardiogram (figure) sensor, or an X-ray imaging apparatus. The measurement sensor 501 and the analog / digital conversion unit 502 constitute a digital measurement data acquisition unit 581.

  The unique ID generation unit 582 generates a unique ID having uniqueness that uniquely indicates the digital content. The random number generator 583 generates a random number for randomly generating a secret key / public key. The private key / public key pair generation unit 584 generates a private key / public key pair using the random number generated by the random number generation unit 583 for calculation. The unique ID / public key pair generation / transmission unit 585 generates a pair of the public key generated by the secret key / public key pair generation unit 584 and the unique ID generated by the unique ID generation unit 582, and sends it to the external recording device 590. Send. The transmission path uses a wired Internet network such as Ethernet (registered trademark) and is configured using the SSL communication protocol. The external recording device 590 stores the sent public key and unique ID pair.

  The electronic signature unit 586 gives an electronic signature to the measurement data acquired by the digital measurement data acquisition unit 581 using the secret key generated by the private key / public key pair generation unit 584. The unique ID / electronic signature adding unit 587 associates the measurement data acquired by the digital measurement data acquisition unit 581 with the unique ID generated by the unique ID generation unit 582 and the electronic signature provided by the electronic signature unit 586. The measurement data provided with the unique ID and the electronic signature by the unique ID / electronic signature adding unit 587 is stored in a storage element 591 such as a memory or a fixed disk device built in the apparatus. The secret key discard unit 588 discards the secret key used by the electronic signature unit 586 in order to reduce the chance of eavesdropping on the secret key and prevent the electronic signature from being forged using the secret key.

  The electronic signature of the measurement data acquired by the digital measurement data acquisition unit 581 can be given by the measurement apparatus 500 with the electronic signature key management apparatus configured as described above. Since the secret key used at this time is discarded by the secret key discarding unit 588, forgery and tampering of data by the user of the measuring apparatus 500 with the electronic signature key management apparatus can be prevented.

<Modifications and application examples>
The present invention is not limited to the above-described embodiments, and various modifications and applications can be made without departing from the gist of the present invention. For example, in the above description, a random number for randomly generating a secret key / public key is generated, and in order to increase irregularity of the random number, the second embodiment uses a temperature measurement value, In the third embodiment, the use of time measurement values has been described. In addition, measurement values of packet intervals (unit picoseconds) of Ethernet (registered trademark), solar radiation (infrared rays, visible rays, ultraviolet rays, X-rays, etc.) ) Measurement value of intensity, measurement value of key input interval (unit picosecond), or measurement value of radio wave intensity may be used.

11, 21, 31, 41: Digital data acquisition units 12, 22, 32, 42: Unique ID generation units 13, 23, 33, 43: Random number generation units 14, 24, 34, 44: Private key / public key pair generation Units 15, 25, 35: Unique ID / public key pair generation / save units 16, 26, 36, 46, 56: Electronic signature units 17, 27, 37, 47, 57: Unique ID / electronic signature assigning units 18, 28, 38, 48, 58: Secret key discarding unit 45: Unique ID / public key pair generation / transmission unit 49: Communication path 50: External recording device

Claims (6)

A digital data acquisition unit for acquiring digital data;
A unique ID generation unit for generating a unique ID;
A random number generator for generating a random number for randomly generating a secret key / public key;
A secret key / public key pair generation unit that generates a pair of a secret key and a public key using the random number generated by the random number generation unit;
A unique ID / public key pair generation unit for generating a pair of a unique ID and a public key from the public key generated by the secret key / public key pair generation unit and the unique ID generated by the unique ID generation unit;
An electronic signature unit for giving an electronic signature to the digital data acquired by the digital data acquisition unit using the secret key generated by the private key / public key pair generation unit;
A unique ID / electronic signature giving unit for linking the unique ID generated by the unique ID generation unit and the electronic signature given by the electronic signature unit to the digital data acquired by the digital data acquisition unit;
An electronic signature key management device comprising: a secret key discarding unit that discards a secret key used by the electronic signature unit.   2. The electron according to claim 1, further comprising: a temperature measurement unit that measures temperature, wherein randomness generated by the random number generation unit is increased by a temperature value measured by the temperature measurement unit. Signature key management device.   2. The electronic device according to claim 1, further comprising a time measuring unit that measures time, wherein irregularity of the random number generated by the random number generating unit is increased by a time value measured by the time measuring unit. Signature key management device.   The unique ID / public key pair generation unit generates a pair of a public key from the secret key / public key pair generation unit and a unique ID from the unique ID generation unit, and sets the public key and the unique ID. 4. The electronic signature key management apparatus according to claim 1, wherein the pair is transmitted using a communication path. A digital data acquisition process for acquiring digital data;
A unique ID generation process for generating a unique ID;
A random number generation step for generating a random number for randomly generating a secret key / public key;
A private key / public key pair generating step for generating a private key and public key pair using the random number generated by the random number generating step;
A unique ID / public key pair generation step for generating a pair of a unique ID and a public key from the public key generated by the secret key / public key pair generation step and the unique ID generated by the unique ID generation step;
An electronic signature step of giving an electronic signature to the digital data acquired by the digital data acquisition step using the secret key generated by the secret key / public key pair generation step;
A unique ID / electronic signature attaching step for linking the unique ID generated by the unique ID generating step and the electronic signature attached by the electronic signature step to the digital data obtained by the digital data obtaining step;
An electronic signature key management method comprising: a secret key destruction step of destroying a secret key used in the electronic signature step. A digital data acquisition step for acquiring digital data;
A unique ID generation step for generating a unique ID;
A random number generation step for generating a random number for randomly generating a secret key / public key;
A secret key / public key pair generation step for generating a pair of a secret key and a public key using the random number generated in the random number generation step;
A unique ID / public key pair generation step for generating a pair of a unique ID and a public key from the public key generated by the secret key / public key pair generation step and the unique ID generated by the unique ID generation step;
An electronic signature step of giving an electronic signature to the digital data acquired by the digital data acquisition step using the secret key generated by the secret key / public key pair generation step;
A unique ID / electronic signature assigning step for linking the unique ID generated by the unique ID generating step and the electronic signature given by the electronic signature step to the digital data obtained by the digital data obtaining step;
An electronic signature key management program executable by a computer, comprising: a secret key destruction step for destroying a secret key used in the electronic signature step.

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