JP3515408B2 - Time authentication device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention certainly does not change a digital document including a text document, image information, voice information and the like, and the digital document has not been changed since the time stamp was applied. The present invention relates to a time authentication device that proves that a target digital document exists when the time stamp is pressed, and more specifically, the time authentication device on a network to which an unspecified number of users such as the Internet are connected. This prevents the unauthorized use of the time authentication device by anyone other than the user who is authorized to use the time authentication device while the time authentication device is installed. The present invention relates to a time authentication device.

[0002]

2. Description of the Related Art As a time authenticating device of this type, for example, in Japanese Patent Application Laid-Open No. 7-254897 "Personal date and time authenticating device", a time authenticating device is incorporated in a smart card or the like, and when a digital signature is made, the time is verified. Authentication is done together. In Japanese Patent Laid-Open No. 3-185551 “Digital Time Authentication Device”, the time authentication device is configured as one hardware platform, and the creator of the document performs time authentication using this device. In all of these conventional devices, the document creator performs time authentication, which makes it easy to forge and is not reliable because it is not a certification by a third party.

Further, in Japanese Unexamined Patent Publication No. 6-14018, "Electronic Notarization Method and Device", CRC (Cy
Clic Redundancy Check), parity, and checksum are combined to create a compressed document for time authentication. A compressed document created by this method is a forgery of a digital document having the same compressed document as compared with a compressed document created by using a hash function such as MD5 or SHA-1, which is widely used as a cryptographic technique at present. Easy to peel off. Furthermore, JP-A-6
In "501574" Method of reliably stamping time stamps on numerical documents ", an external institution that performs time authentication independently creates a time authentication certificate. In this method, the external institution forges the time authentication certificate. It is easy to do.

In order to make up for the above-mentioned conventional drawbacks,
Create a time authentication certificate by digitally signing the compressed document obtained by applying the hash function to the digital document that combines the received time authentication request and the time authentication certificate issued immediately before by the external institution. Some have suggested methods. This method makes it virtually impossible for an external authority to forge a time authentication certificate, but in order to prove that the time authentication certificate is authentic, the certificate issued before it cannot be used. A digital signature is required. That is, unless all the time authentication certificates issued by the time authentication external organization are stored, it is not possible to prove that the time authentication certificate is authentic, so a huge storage capacity is required.

[0005]

As described above, among the conventional time authentication devices, the conventional devices proposed in JP-A-7-254897 and JP-A-3-185551 are all document creators. Is a method of performing time authentication, it is easy to forge, and there is a problem that reliability is poor because it is not a proof by a third party.

Further, as disclosed in Japanese Patent Laid-Open No. 6-14018, C
A compressed document in the conventional method that creates a compressed document by combining RC, parity, and checksum and performs time authentication is
There is a problem that it is easy to forge a digital document having the same compressed document.

Further, in the method in which an external institution that performs time authentication independently creates a time authentication certificate as in JP-A-6-501574, there is a problem that it is easy for the external institution to forge the time authentication certificate. is there.

In order to make up for the above-mentioned conventional drawbacks, a digital signature obtained by combining a time authentication request and a time authentication certificate issued immediately before by an external institution with a hash function is digitally signed to obtain a time authentication certificate. In the conventional method of creating a certificate, it is not possible to prove that the time authentication certificate is authentic unless all the time authentication certificates issued by the time authentication external organization are stored. There is a problem that it requires capacity and is uneconomical.

Further, a standardization of a protocol for sending a digital document compressed by a hash function in IETF to an external institution and creating a time authentication certificate for the sent digital document is in progress. Since an external organization creates a time authentication certificate in one place, there is a possibility of forgery of the time authentication certificate and a malicious third party who is not allowed to obtain the time authentication certificate illegally authenticates the time. There is a problem that the risk of obtaining a certificate cannot be eliminated.

The present invention has been made in view of the above,
It is an object of the present invention to provide a safe and reliable time authentication device by accurately preventing forgery of a time stamp by digitally signing a plurality of divided partial secret keys.

[0011]

In order to achieve the above object, the present invention according to claim 1 is a document receiving means for receiving a digital document M created by an author, and a first means for obtaining a time .
Of time acquisition means, combining means for combining the time information t acquired by the time acquisition means with the digital document M to create one time stamped digital document Mt, and receiving the time stamped digital document Mt. A plurality of digital signature means for independently creating digital signatures, and a plurality of digital signatures independently created by the plurality of digital signature means are received and combined to create an integrated digital signature c. Means and the time stamped digital document Mt
And a time authentication certificate sending means for sending the set of the integrated digital signature c to the author as a time authentication certificate, and each of the digital signature means first acquires time information t ′ independently. Have separate or the same second time acquisition means, and when the time stamped digital document Mt is received, the time information t is immediately acquired from the time stamped digital document Mt, and the time information t is uniquely combined with the time information t. The gist is that the acquired time information t ′ is compared and the digital signature is created only when the difference between them is within a predetermined allowable time difference.

According to the first aspect of the present invention, the digital document M created by the author is combined with the time information t from the first time obtaining means to form one time stamped digital document M.
t, the time-stamped digital document Mt is sent to a plurality of digital signature means, each digital signature is independently created, and the plurality of digital signatures independently created by the plurality of digital signature means are combined. To create an integrated digital signature and send the set of this integrated digital signature and time stamped digital document to the author as a time certification certificate. Therefore, the time stamp is forged by each unique digital signature by multiple digital signature means. It is difficult to perform, secure and reliable time authentication service is possible, and the risk of theft of the private key can be reduced. Further, the storage capacity can be greatly reduced without storing the time authentication certificate issued in the past. Moreover, when each digital signature means receives the time-stamped digital document Mt, it immediately obtains the time information t from the time-stamped digital document Mt, and this time information t is independently or identical to the first obtained independently. The second of
The time information t ′ acquired by the time acquisition means is compared,
The digital signature is created only when the difference between the two is within a predetermined allowable time difference.

The present invention according to claim 2 provides the invention according to claim 1.
In the invention described above, the combining means sends the time-stamped digital document Mt to the plurality of digital signature means, and a plurality of digital signature sending means, and a plurality of digital signatures sent from the plurality of digital signature means. Digital signature receiving means for receiving the time-stamped digital document Mt, wherein each of the plurality of digital signature means receives the time-stamped digital document Mt sent from the time-stamped digital document sending means. It has a digital signature creating means for independently creating a digital signature for each of the received time-stamped digital documents Mt, and a signature sending means for sending the created digital signature to the digital signature receiving means. And

According to another aspect of the present invention, a plurality of digital signature means are provided externally as external digital signature means, and the time stamped digital document Mt from the combining means is externally transmitted from the time stamped digital document sending means. The digital signature receiving means sends the digital signatures created by the digital signature receiving means to the digital signature receiving means. The signature makes it even more difficult to forge the time stamp, and enables a safe and reliable time authentication service.

Furthermore, the present invention according to claim 3 receives a digital document M created by the author, and receives the digital document M.
And the validity period information P of the certification required by the certification requester, a digital signature Q is created, and a public key certificate C for the key used to create the digital signature Q is added to the validity period. Signature request means with validity period for sending the signature request (MP, Q, C) and the signature request with validity period (MP, Q, C) sent from the signature request means with validity period It is verified that the time-limited signature request (MP, Q, C) is a request from a legitimate contractor, and the time information t is combined with the digital document M to digitally sign the time authentication certificate (Mt, c). A time certification device having a time certification means to be created, wherein the signature requesting means with valid period is a digital document M created by an author.
A digital document receiving means, a key creating means for creating a set of a public key and a private key in the public key cryptosystem, and sending the created public key to the time authenticating means, and a digital document receiving means for receiving A digital document M is combined with a valid period P of the authentication required by the certification requestor to create the information MP, and a digital document Q for creating a digital signature Q using a secret key for the information MP. Request with a validity period that sends a set of a signature means, the information MP, the digital signature Q, and the public key certificate C received from the time certification means to the time certification means as a signature request (MP, Q, C) with a validity period. Sending means, the time authenticating means receives the public key sent from the signature requesting means with validity period, and responds to the request from the signature requesting means with validity period. A public key certificate that creates a digital signature for the public key with the private key of the time authentication means, and sends a public key certificate C, which is a combination of the public key and the created digital signature, to the signature requesting means with validity period. A document return means, a validity period signature request reception means for receiving the validity period signature request (MP, Q, C) sent from the validity period signature request means, and the received validity period signature request (MP, Q, C). Q, and verifies the digital signature Q and a public key certificate C contained in C), and with the effective period signature verifying means for verifying that the signature requester is contractor legitimate, the acquiring time information t When the verification result by the one time acquisition unit and the signature verification unit with valid period is valid, the time information t acquired by the time acquisition unit is included in the signature request with valid period (MP, Q, C). Effectiveness A valid period in the time information verifying unit whether to verify comprised between P, the time information t the verification by the valid period in the time information verification means
Is included in the validity period P, the time information t acquired by the time acquisition means is added to the signature request with validity period (MP,
Q, C), a time information combining unit for combining the digital document M included in the digital document M to create the time stamped digital document Mt, and a plurality of units for receiving the time stamped digital document Mt and independently creating a digital signature. Of the digital signature means, an integrated digital signature creating means for receiving and combining a plurality of digital signatures independently created by the plurality of digital signature means to create an integrated digital signature c, the time stamped digital document Mt, and The gist is to have a time authentication certificate sending means for sending the set of integrated digital signatures c to the author as a time authentication certificate (Mt, c).

According to the third aspect of the present invention, the digital document M created by the author is received, the validity period information P of the certification required by the certification requester is combined with the digital document M, and the digital signature Q is received. , And a signature request (MP, Q, C) with a valid period, which is made up of a set obtained by adding the public key certificate C to the key used to create the digital signature Q.
And sends the signature request (MP,
Q, C) is received, it is verified that this request is a request from a legitimate contractor, and the verification result is valid,
It is verified whether or not the time information t is included in the valid period P, and only when the time information t is included in the valid period P, the time information t is combined with the digital document M to combine the time stamped digital document Mt.
, The time-stamped digital document Mt is sent to a plurality of digital signature means, each digital signature is independently created, and the plurality of digital signatures independently created by the plurality of digital signature means are combined. , The integrated digital signature is created, and the set of the integrated digital signature and the digital document with the time stamp is sent to the author as a time authentication certificate. Therefore, the forgery of the time stamp can be performed by each unique digital signature by a plurality of digital signature means. It is possible to provide a difficult, safe and reliable time authentication service and reduce the risk of theft of a private key. Further, the storage capacity can be greatly reduced without storing the time authentication certificate issued in the past. Further, by verifying the digital signature Q and the public key certificate C, it is possible to confirm that the signature request is an authorized contractor.

According to a fourth aspect of the present invention, in the third aspect of the invention, the time information combining means sends the time stamped digital document Mt to the plurality of digital signature means. Means, and digital signature receiving means for receiving a plurality of digital signatures sent from the plurality of digital signature means, each of the plurality of digital signature means is sent from the time stamped digital document sending means. The time-stamped digital document receiving means for receiving the time-stamped digital document Mt, the digital signature creating means for independently creating a digital signature for the received time-stamped digital document Mt, and the created digital signature The gist is to have a signature sending means for sending to the digital signature receiving means.

According to another aspect of the present invention, a plurality of digital signature means are provided outside as external digital signature means, and the time stamped digital document Mt from the combining means is transferred from the time stamped digital document sending means to the outside. The digital signature receiving means sends the digital signatures created by the digital signature receiving means to the digital signature receiving means. The signature makes it even more difficult to forge the time stamp, and enables a safe and reliable time authentication service.

The present invention according to claim 5 provides the invention according to claim 1.
In the invention described above, an inquiry for confirming whether or not the plurality of digital signature means is normally operating is periodically made to each digital signature means, and the confirmation result is generated by the combining means and the integrated digital signature generation. The combining means further includes an operation confirmation means for supplying the time stamp to the digital signature means M for only the digital signature means operating normally based on the confirmation result from the operation confirmation means.
The summary is that t is sent and the integrated digital signature creating means is configured to receive the digital signature only from the digital signature means operating normally based on the confirmation result from the operation confirming means.

In the present invention according to claim 5, the operation confirming means confirms the operation of each digital signature means, and supplies the confirmation result to the combining means and the integrated digital signature creating means, and the combining means confirms the result. The time stamped digital document Mt is sent only to the digital signature means operating normally based on the above, and the integrated digital signature creating means receives the digital signature only from the digital signature means operating normally based on the confirmation result. Therefore, it is possible to confirm that the digital signature means has not been stolen by the malicious third party using, for example, a memory dump.

Further, the present invention according to claim 6 is the same as claim 2
In the invention described above, an inquiry for confirming whether or not the plurality of digital signature means is normally operating is periodically made to each digital signature means, and the confirmation result is sent to the time stamped digital document sending means. And a digital signature receiving means for supplying operation to the digital signature receiving means, wherein the time-stamped digital document sending means sends time to only the digital signature means operating normally based on the confirmation result from the operation checking means. It is configured that the digital signature receiving unit Mt is sent and the digital signature receiving unit is configured to receive the digital signature only from the digital signature unit operating normally based on the confirmation result from the operation confirming unit. And

According to the sixth aspect of the present invention, the operation confirming means confirms the operation of each digital signature means, and supplies the confirmation result to the time stamped digital document sending means and the digital signature receiving means. The stamped digital document sending means sends the time stamped digital document Mt only to the digital signature means operating normally based on the confirmation result,
Since the digital signature receiving means receives the digital signature only from the digital signature means that is operating normally based on the confirmation result, the digital signature means may be stolen by a malicious third party using, for example, a memory dump. You can be sure that not.

According to the present invention of claim 7, in the invention of claim 1, a set of a public key Kp and a secret key Ks in a public key cryptosystem is created, and the created secret key Ks is divided, Expressed as the sum of the numerical values of the plurality of digital signature means, distribute each numerical value to each of the plurality of digital signature means, and create a key to delete the private key before division after the distribution is completed. Distributing means is further provided, and each of the plurality of digital signature means holds a private key distributed from the key creating / distributing means, and is distributed from the combining means by a public key cryptosystem using the private key. A digital signature is created for the time-stamped digital document Mt, and a plurality of digital signatures from the respective digital signature means are combined by the integrated digital signature creating means to create an integrated digital signature c. The certificate sending means is configured to send the time-stamped digital document Mt, the integrated digital signature c, and the public key Kp as a set to the author as a time authentication certificate (Mt, c, Kp). Use as a summary.

In the present invention according to claim 7, the key creating / distributing means creates a set of the public key Kp and the secret key Ks in the public key cryptosystem, divides the secret key Ks, and divides the secret key Ks into a plurality of sets. Expressed as a sum of the numerical values of the number of digital signature means, distribute each numerical value to each of the plurality of digital signature means, delete the private key before the division after the distribution is completed, Each of them creates a digital signature for the time stamped digital document Mt by the public key cryptosystem using the private key distributed from the key creation / distribution means, and combines a plurality of digital signatures from each digital signature means. The integrated digital signature c is created, and the time stamped digital document Mt, the integrated digital signature c, and the public key Kp are paired and sent to the author as a time authentication certificate (Mt, c, Kp).

The present invention according to claim 8 provides the invention according to claim 7.
In the invention described above, an inquiry for confirming whether or not the plurality of digital signature means is normally operating is periodically made to each digital signature means, and the confirmation result is generated by the combining means and the integrated digital signature creation. Means and an operation confirmation means for supplying to the key generation / distribution means, and when the key generation / distribution means receives an operation confirmation result from the operation confirmation means that there is a digital signature means not operating normally, A new public key and a private key are created, the newly created private key is divided into the sum of the numbers of the plurality of digital signature means, and the private key obtained by this division is provided to each digital signature means. And the combining means sends the time stamped digital document Mt only to the digital signature means operating normally based on the confirmation result from the operation confirming means. Each digital signature means to which the time stamped digital document Mt has been sent creates a digital signature for the time stamped digital document Mt distributed from the combining means using the private key distributed from the key creation / distribution means, The integrated digital signature creating means receives the digital signature only from the digital signature means operating normally based on the confirmation result from the operation confirming means, and combines the received digital signatures by the integrated digital signature creating means. The integrated digital signature c is created, and the time authentication certificate sending means combines the time stamped digital document Mt, the integrated digital signature c, and the public key Kp as a set to the author as a time authentication certificate (Mt, c, Kp). The gist is that it is configured to send.

According to the present invention of claim 8, when the key creating / distributing means receives an operation confirmation result from the operation confirming means that there is a digital signature means that is not operating normally, a new public key and secret are obtained. Create a key, divide this private key into the sum of the number of digital signature means, distribute this divided private key to each digital signature means, and the combining means only for the digital signature means operating normally. The time-stamped digital document Mt is sent, the digital signature means creates a digital signature for the time-stamped digital document Mt using the newly distributed secret key, and the integrated digital signature creation means operates normally. The digital signature is received only from the signature means, the digital signatures are combined to create the integrated digital signature c, and the time stamped digital document Mt, integrated digital signature c, and In order to send a fine public key Kp time authentication certificate to a set (Mt, c, Kp) as the author,
By confirming the operation of each digital signature unit, the digital signature unit uses a memory dump or the like by a malicious third party,
It is possible to confirm that the private key has not been stolen, and if there is a digital signature method that is not working properly, each digital signature means can independently create a digital signature with the newly created split private key. By doing so, the risk of theft of the private key is reduced, and the time stamp cannot be forged unless all the time acquisition means and each digital signature means are colluded, and a time authentication service that provides a safe and reliable time authentication service is performed. It is possible to operate an external organization, and there is no need to store any time authentication certificates issued in the past, and the storage capacity can be greatly reduced compared to the conventional case.

Furthermore, the present invention according to claim 9 provides the invention according to claim 7.
In the invention described above, the combining means sends the time-stamped digital document Mt to the plurality of digital signature means, and a plurality of digital signature sending means, and a plurality of digital signatures sent from the plurality of digital signature means. And a digital signature receiving means for receiving.

In the present invention according to claim 9, a plurality of digital signature means are provided outside as external digital signature means, and the time stamped digital document Mt from the combining means is externally transmitted from the time stamped digital document sending means. The digital signature receiving means sends the digital signatures created by the digital signature receiving means to the digital signature receiving means. The signature makes it even more difficult to forge the time stamp, and enables a safe and reliable time authentication service.

[0029]

[0030]

According to a tenth aspect of the present invention, in the invention according to the fourth aspect, a set of a public key Kp2 and a secret key Ks2 in the public key cryptosystem is created, and the created secret key Ks2 is divided. Is expressed as the sum of the numerical values of the plurality of digital signature means, each of these numerical values is distributed to each of the plurality of digital signature means, and after the distribution is completed, the private key before division is deleted. An operation confirmation unit further comprising a distribution unit, and the time authentication unit periodically makes an inquiry to each digital signature unit to confirm whether or not the plurality of digital signature units are normally operating. Each of the digital signature means further includes a second time acquisition means which is separate from or identical to the first time information acquisition means for independently acquiring the time information t ′, and when the time stamped digital document Mt is received, The time stamp The time information t is immediately obtained from the digital document Mt, this time information t is compared with the independently acquired time information t ′, and a digital signature is created only when the difference between them is within a predetermined allowable time difference. When the key creation / distribution means receives an operation confirmation result from the operation confirmation means that there is a digital signature means that is not operating normally, a new public key and a secret key are created, and this new key is generated. The private key created in Step 1 is divided into the sum of the numbers of the plurality of digital signature means, and the private keys obtained by the division are distributed to each digital signature means one by one, and the combining means causes the operation confirming means. When the digital signature means Mt sends the time-stamped digital document Mt only to the digital signature means operating normally based on the confirmation result from FIG. The time information t is immediately obtained from the time stamped digital document Mt, the time information t is compared with the independently acquired time information t ′, and only when the difference between them is within a predetermined allowable time difference, key generation is performed.・
Using the private key distributed by the distributing means, a digital signature is created for the time stamped digital document Mt distributed by the combining means, and the integrated digital signature creating means operates normally based on the confirmation result from the operation confirming means. The digital signature is received only from the operating digital signature means, the received digital signatures are combined by the integrated digital signature creating means to create the integrated digital signature c, and the time authentication certificate sending means sends the time stamped digital document Mt. , The integrated digital signature c and the public key Kp2 are paired and sent as a time authentication certificate (Mt, c, Kp2) to the author.

According to the tenth aspect of the present invention, when the key creation / distribution means receives from the operation confirmation means an operation confirmation result that there is a digital signature means that is not operating normally, a new public key and secret Create a key, divide this private key into the sum of the number of multiple digital signature means, distribute this private key to each digital signature means, and combine the time stamps only to the digital signature means that are operating normally. When the digital signature means sends the time-stamped digital document Mt and the digital signature means receives the time-stamped digital document Mt, it immediately acquires the time information t from the time-stamped digital document Mt, and the time information t and the first acquired independently. Is a separate or identical second time acquisition means
Compared with the time information t ′ obtained by the above, only when the difference is within a predetermined allowable time difference, a digital signature is created for the time stamped digital document Mt using the secret key distributed from the key creation / distribution means. Then, the integrated digital signature creating means receives the digital signature only from the digital signature means that is operating normally, combines the received digital signatures to create the integrated digital signature c, and creates the integrated digital signature Mt with the time stamp, the integrated digital signature The signature c and the public key Kp2 are paired and sent to the author as a time authentication certificate (Mt, c, Kp2).

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the time authentication device according to the first embodiment of the present invention. In the time authentication device shown in the figure, 5 is a digital document receiving means for receiving the digital document (M) 3 created by the author, 7 is a time acquiring means for acquiring the time, and 9 is time information t acquired by the time acquiring means 7. Is combined with the digital document M to create one time stamped digital document Mt, and 11 is a time stamped digital document M from the combining unit 9.
In the present embodiment, a plurality of s digital signature means 11 each receiving t and independently creating a digital signature, and 13 a plurality of digital signatures c1, c2, respectively independently created by the plurality of digital signature means 11. ..., cs receives and combines them to create an integrated digital signature c, and an integrated digital signature creating means for creating a integrated digital signature c, and a set of the time stamped digital document Mt and the integrated digital signature c is a time authentication certificate (Mt, c).
17 is a time authentication certificate sending means for sending to the author.

In the time authentication device having the above-described structure, the digital document (M) composed of the text document created by the author, the voice information, the image information, or a combination thereof.
3 is received by the digital document receiving means 5 and supplied to the combining means 9. The combining unit 9 acquires the time information t by using the time acquisition unit 7, combines the acquired time information t with the digital document M, and creates the time stamped digital document Mt. The time acquired by the time acquisition means 7 is acquired from an accurate timepiece that has been calibrated by comparing with an accurate timepiece owned by a third party. That is, the time information t acquired by the time authentication device is reliable, and there is no forgery regarding the time information t by the time authentication device.

The time stamped digital document Mt combined by the combining means 9 makes a plurality of copies by the combining means 9 and is sent to all of the plurality of digital signature means 11. The plurality of digital signature means 11 create digital signatures c1, c2, ..., Cs using the private keys held for the received time stamped digital documents Mt.

An example of creating this digital signature will be described. In this example, RSA is used as an example of public key encryption. For a description of RSA public key cryptography, see Shigeo Tsujii and Masao Kasahara, “Cryptography and Information Security” (Shokoido).

Let p and q be sufficiently large prime numbers, and let n = pq. Then, an integer e relatively prime to φ (n) = (p−1) (q−1) is appropriately determined. That is, when gcd (e, (p-1) (q-1)) = 1 n and e are public keys, and d is an integer ed = 1 mod φ (n), p, q, d are secret. Use as a key.

MD5 or SH is added to the time stamped digital document Mt.
Let m be a digest obtained by applying a hash function such as A-1. Furthermore, c = ^md mod n is set. At this time, the set (Mt, c) is the integrated digital signature finally created by the integrated digital signature creating means 13. Figure 1
Let s be the sum of the digital signature means 11 in. At this time, d is represented by the sum of numbers. d = d ₁ + d ₂ + ... + d _s
far. When c ₁ = m ^d1 mod n, ..., C _s = m ^ds mod n, (Mt, c ₁ ), ..., (Mt, c _s ) are digital signatures created by s digital signature means 11. .
In this embodiment, the RSA public key cryptography is used, but the elliptic public key cryptography and DSA (Digital Signature Algorithm) can also be used to similarly create the digital signature and the integrated digital signature.

A plurality of digital signatures c1, c created by the plurality of digital signature means 11 created as described above
2, ..., Cs are supplied from each digital signature means 11 to the integrated digital signature creation means 13 and are combined by the integrated digital signature creation means 13 to create an integrated digital signature c. The integrated digital signature c combined and created by the integrated digital signature creating means 13 is paired with the time stamped digital document Mt, and is sent from the time authentication certificate sending means 15 to the author as the time authentication certificate (Mt, c) 17. Will be sent.

As described above, in the present embodiment, since a plurality of digital signature means 11 individually make digital signatures, forgery of the time stamp is difficult and safe unless the plurality of digital signature means 11 cooperate. A reliable time authentication service is possible and the risk of theft of a private key can be reduced. Further, the storage capacity can be greatly reduced without storing the time authentication certificate issued in the past.

FIG. 2 is a block diagram showing the configuration of the time authentication device according to the second embodiment of the present invention.

In the time authentication device shown in the figure, each of the plurality of digital signature means 11 in the time authentication device of the first embodiment shown in FIG. 1 is provided externally as external digital signature means 19, and this external digital signature is provided. Mt sending means 21 for sending the time stamped digital document Mt and digital signature receiving means 23 for receiving digital signatures from a plurality of external digital signature means 19 are provided to each of the means 19, and each of the external digital signature means 19 is provided. , Mt receiving means 25 for receiving the time stamped digital document Mt from the Mt sending means 21, the digital signature means 11 for independently creating a digital signature for the received time stamped digital document Mt, and the created digital signature means 11. Signature sending means 2 for sending the digital signature to the digital signature receiving means 23
7 is different, and other configurations and operations are the same.

In the time authentication device having such a configuration, the digital document (M) 3 created by the author is received by the digital document receiving means 5 and supplied to the combining means 9. The combining means 9 uses the time acquisition means 7 to obtain the time information t.
Is obtained and the obtained time information t is combined with the digital document M to create a time stamped digital document Mt.

The time stamped digital document Mt combined by the combining means 9 is supplied to the Mt sending means 21, multiple copies are made by the Mt sending means 21, and sent to all of the plurality of external digital signature means 19. It

Each of the plurality of external digital signature means 19 has a time stamped digital document Mt from the Mt sending means 21.
Is received by the Mt receiving means 25, and the received time-stamped digital document Mt is supplied to the digital signature means 11. The digital signature means 11 uses the time stamped digital document M.
A digital signature is created using the private key held for t and is supplied to the signature sending means 27. Signature sending means 27
Sends the digital signature created by the digital signature means 11 to the digital signature receiving means 23.

The digital signature receiving means 23 receives the plurality of digital signatures c1, c2, ..., Cs sent from the signature sending means 27 of the plurality of external digital signature means 19 and supplies them to the integrated digital signature creating means 13. The integrated digital signature creating means 13 uses the plurality of digital signatures c.
, Cs are combined to create an integrated digital signature c. The integrated digital signature c combined and created by the integrated digital signature creating means 13 is paired with the time stamped digital document Mt, and is sent from the time authentication certificate sending means 15 to the author as the time authentication certificate (Mt, c) 17. Will be sent.

In the present embodiment, since a plurality of external digital signature means 19 individually make digital signatures, forgery of the time stamp is difficult unless the plurality of external digital signature means 19 cooperate, and it is safe and reliable. Time authentication service is possible.

FIG. 3 is a block diagram showing the configuration of the time authentication device according to the third embodiment of the present invention.

The time authentication device shown in the same figure is different from the time authentication device shown in FIG. 1 in that the time authentication device shown in FIG. 1 is provided with a function for requesting a signature with a valid period. The signature verification means 31 with a validity period for verifying the signature with a validity period for the corresponding function and the time information t are valid periods P
, The time authentication unit 35 with the valid time information verifying means 33 for verifying whether it is included in the valid period and the digital document (M) 3 are received from the author, and the valid period P is combined with the digital document (M) 3. Then, a digital signature Q is created for the combined digital document M and validity period P, and the MP and Q and the public key certificate C supplied from the time authentication unit 35 are combined into a digital signature Q to add a validity period. Signature request (MP, Q,
C) includes a signature requesting unit 37 with a valid period which is sent to the time authenticating unit 35. Note that the time authenticating unit 35 only shows the digital document receiving unit 5 and the time authentication certificate sending unit 15 in addition to the signature verification unit with valid period 31 and the time information within valid period verifying unit 33. In addition to these, in addition to these, in the same way as the configuration of FIG. 1, the time acquisition means 7, the combining means 9, the plurality of digital signature means 11,
It also has an integrated digital signature creating means 13.

The signature requesting unit 37 with a valid period previously creates and holds the public key Kp and the secret key Ks in the public key cryptosystem, and sends the created public key Kp to the time authentication unit 35. It has become. Also, the time authentication unit 3
5 creates a digital signature for the public key Kp sent from the signature requesting unit 37 with a valid period using the secret key Ks ^t of the time authenticating unit 35, and a public key including the public key Kp and the created digital signature. The certificate C is sent back to the signature requesting unit 37 with a valid period.

Then, the signature request unit 37 with a valid period is
A digital document receiving means 39 for receiving the digital document (M) 3 from the author, and a combination for connecting the received digital document M with a valid period P in which the time authentication unit 35 set by the signature requester can perform time authentication. A means 41, a digital signature means 43 for creating a digital signature Q using the secret key Ks for the MP composed of the combined digital document M and the validity period P, a combined MP of the digital document M and the validity period P, The digital signature Q and the public key certificate C received from the time authenticating unit 35 are paired and sent to the time authenticating unit 35 as a signature request with an effective period.

Next, the operation of the time authentication device configured as described above will be described. The digital document (M) 3 created by the author is received by the digital document receiving means 39 of the signature requesting unit 37 with a valid period and sent to the combining means 41. The signature requester sets an effective period P during which the time authenticating unit 35 can perform time authentication, and the combining unit 41 combines the digital document M received via the digital document receiving unit 39 with the effective period P. , And sends it to the digital signature means 43.
The digital signature means 43 creates a digital signature Q for the MP using the secret key Ks. The signature request sending means with validity period 45 sends a pair of the MP in which the digital document M and the validity period P are combined, the digital signature Q, and the public key certificate C to the time authentication unit 35 as a signature request with validity term. .

When the time authentication section 35 receives the signature request with validity period (MP, Q, C) digital document receiving means 5, the public key certification included in the signature request with validity period (MP, Q, C). As described in Book C, the time authentication unit 3 is prepared in advance.
5 with a validity period signature verification means by using the public key Kp ^t of the time authentication unit 35 whether or not the public key certificate C issued by the 3
Verify with 1. That is, by verifying that the public key certificate C is decrypted using the public key of the time authentication unit 35 and the digital signature Q is decrypted using the public key Kp obtained as a result, it matches MP. It is confirmed that the signature request with validity period (MP, Q, C) is a request from an authorized contractor of the time authentication unit 35.

When the digital signature Q is created by using the secret key Ks with respect to the result of applying the hash function to MP, as is usually done with the public key digital signature, the digital signature Q Is the result obtained by decoding
Apply the hash function to and verify that it matches the result.

Further, the time authenticating section 35 confirms that the time information t is included in the effective period P by using the in-effective period time information verifying means 33, so that the signature request with effective period (MP, Q, Verify that C) was created within the valid period P from now on.

Further, since the time authenticating section 35 has the same configuration as shown in FIG. 1 as described above, the signature request with validity period (MP, Q, The digital document M included in C) is supplied to the combining means 9, and the combining means 9 combines the time information t acquired from the time acquisition means 7 with the digital document M to create the time stamped digital document Mt. This time stamped digital document Mt is made into a plurality of copies by the combining means 9 and sent to all of the plurality of digital signature means 11. The plurality of digital signature means 11 create digital signatures c1, c2, ..., Cs using the private keys held for the received time stamped digital documents Mt.

A plurality of digital signatures c1, c2, ..., Cs created by the plurality of digital signature means 11 are supplied from each digital signature means 11 to the integrated digital signature creation means 13 and combined by the integrated digital signature creation means 13. Then, the integrated digital signature c is created. The integrated digital signature c is paired with the time stamped digital document Mt, and the time authentication certificate sending unit 15 sends the time authentication certificate (Mt, c) 1
7 will be sent to the author. In this way, since a plurality of digital signature means individually make digital signatures, it is difficult to forge the time stamp, and a safe and reliable time authentication service is possible.

In the above embodiment, the time authenticating section 35 has a structure in which a signature verifying means with valid period 31 and a time information within valid term verifying means 33 are added to the time authenticating device shown in FIG. However, instead of the time authentication device shown in FIG. 1, a plurality of digital signature means 11 are provided outside as shown in FIG.
Receiving means 25, digital signature means 11, signature sending means 2
The time authentication device of FIG. 2 having a plurality of external digital signature means 19 composed of 7 may be used.

FIG. 4 is a block diagram showing the configuration of the time authentication device according to the fourth embodiment of the present invention.

In the time authentication device shown in the figure, each of the plurality of digital signature means 11 in the time authentication device of the third embodiment shown in FIG. 3 is provided externally as external digital signature means 19, and this external digital signature is provided. The time authenticating section 3 includes an Mt sending means 21 for sending the time stamped digital document Mt to each of the means 19 and a digital signature receiving means 23 for receiving the digital signatures from the plurality of external digital signature means 19.
5 is the same as that of the third embodiment shown in FIG. 3, and the description thereof is omitted.

FIG. 5 is a block diagram showing the configuration of the time authentication device according to the fifth embodiment of the present invention. The time authentication device shown in the figure is different only in that the time authentication device of the first embodiment shown in FIG. 1 is provided with an operation confirmation means 49 for confirming the operation of a plurality of digital signature means 11, and other The configuration and operation of are the same as those of the time authentication device of FIG.

The operation confirmation means 49 periodically inquires of each digital signature means 11 to confirm the operation of the plurality of digital signature means 11, and the digital signature means 11 which responds within a fixed time is normal. Is determined to be operating, and the determination result is supplied to the combining unit 9 and the integrated digital signature creating unit 13. Further, the combining means 9 sends the time stamped digital document Mt only to the digital signature means 11 operating normally according to the determination result from the operation confirming means 49, and the integrated digital signature creating means 13 operates normally. The digital signature means 11 receives the digital signature only.

By confirming the operation of each digital signature means 11 in this manner, it is confirmed that the digital signature means 11 is not stolen by a malicious third party using a memory dump or the like. be able to. If there is a digital signature means 11 that is determined not to operate normally, the determination result is notified to the combining means 9 and the integrated digital signature creating means 13. The digital signature means 11 determined to be normal holds a new secret key. The combining unit 9 and the integrated digital signature creating unit 13 create the integrated digital signature c using the digital signature from only the digital signature unit 11 that is determined to be operating normally.

FIG. 6 is a block diagram showing the configuration of the time authentication device according to the sixth embodiment of the present invention. The time authentication device shown in the figure is the time authentication device of the second embodiment shown in FIG. 2 provided with the operation confirmation means 49 shown in FIG. 5, and specifically, the time authentication device shown in FIG. The time authentication device of the second embodiment is different only in that an operation confirmation means 49 for confirming the operation of a plurality of external digital signature means 19 provided outside is provided, and other configurations and operations are the time authentication shown in FIG. Same as the device.

The operation confirming means 49 periodically makes an inquiry to each of the external digital signature means 19 to confirm the operation of the plurality of external digital signature means 19 and receives a response within a fixed time. 19 is determined to be operating normally, and the determination result is Mt sending means 2
1 and the digital signature receiving means 23.

Further, the Mt sending means 21 sends the time stamped digital document Mt only to the external digital signature means 19 operating normally according to the judgment result from the operation checking means 49, and the digital signature receiving means 23. Only the digital signature means 11 operating normally can receive the digital signature.

By confirming the operation of each external digital signature means 19 in this way, the external digital signature means 19 is memorized by a malicious third party as in the case of the fifth embodiment shown in FIG. It is possible to confirm that the private key has not been stolen by using a dump or the like.

FIG. 7 is a block diagram showing the configuration of the time authentication device according to the seventh embodiment of the present invention. The time authentication device shown in the figure is different from the time authentication device of the first embodiment shown in FIG. 1 in that a key generation / distribution means 51 is provided, and other configurations and operations are the same. is there.

The key creating / distributing means 51 creates a set of a public key Kp and a secret key Ks in the public key cryptosystem, divides the created secret key Ks, and the digital signature means 11
Is expressed as a sum of s (s> 1) numerical values, and each numerical value is distributed to s digital signature means 11 one by one, and after distribution is completed, the private key Ks before division is deleted. Have a function.

Each of the plurality of digital signature means 11 holds the private key distributed by the key generation / distribution means 51, and the private key is added to the time stamped digital document Mt distributed by the combining means 9. , To create digital signatures c1, c2, ..., Cs using the public key cryptosystem.

The plurality of digital signatures c1, 1c2, ..., Cs thus created are supplied from each digital signature means 11 to the integrated digital signature creation means 13, combined by the integrated digital signature creation means 13, and integrated digitally. Signature c
Is created. The integrated digital signature c is supplied to the time authentication certificate sending means 15, which combines the time stamped digital document Mt, the integrated digital signature c, and the public key Kp into the time authentication. Certificate (M
(t, c, Kp) to the author.

FIG. 8 is a block diagram showing the configuration of the time authentication device according to the eighth embodiment of the present invention. The time authentication device shown in the figure is provided with an operation confirmation means 49 for confirming the operation of the plurality of digital signature means 11 in the time authentication device of the seventh embodiment shown in FIG. 7 as in the embodiment of FIG. Only the points are different, and other configurations and operations are the same as those of the time authentication device of FIG.

The operation confirming means 49 is provided with a plurality of digital signature means 11 on a regular basis, as described in the embodiment of FIG.
Is sent to each of the digital signature means 11, and it is determined that the digital signature means 11 that responds within a fixed time is operating normally, and the determination result is combined with the combining means 9 and the integration means 9. Digital signature creation means 1
In addition to supplying the data to the digital signature means 3, the operation confirming means 49 confirms the operation of each digital signature means 11,
When it is determined that there is even one digital signature unit 11 that is not operating normally, the determination result is combined with the combining unit 9,
In addition to the integrated digital signature creation means 13, the key creation / distribution means 51 is also supplied.

When the key creating / distributing means 51 receives from the operation confirming means 49 a determination result that there is at least one digital signature means 11 that is not operating normally, the new public key Kp and secret key are added. The key Ks is created, and the created secret key Ks is divided into the sum of the numbers of the digital signature means 11 which are confirmed to operate normally. Then, the private key obtained by this division is distributed one by one to each of the digital signature means 11 determined to be normal. After distribution, delete the private key before dividing. Each digital signature means 11 determined to be normal holds the newly distributed secret key.

When the combining means 9 receives the notification of the determination result from the operation confirming means 49, the key creating / distributing means 51.
After distributing to the digital signature means 11 as described above,
The time stamped digital document Mt is sent only to the digital signature means 11 that is determined to be normal.

Further, the combining means 9 sends the time stamped digital document Mt only to the digital signature means 11 operating normally according to the judgment result from the operation confirming means 49, and the integrated digital signature creating means 13 operates normally. The digital signature is received only from the digital signature means 11 operating in the above. The digital signature means 11 creates a digital signature for the time stamped digital document Mt using the newly distributed secret key. Similarly, the integrated digital signature creating means 13 also determines that the digital signature means 11 is normal.
The digital signature is received only from, and the integrated digital signature c is created using only the received digital signature. The integrated digital signature c is supplied to the time authentication certificate sending means 15, which combines the time stamped digital document Mt, the integrated digital signature c, and the public key Kp into the time authentication. Certificate (Mt, c, K
p) to the author.

By thus confirming the operation of each digital signature means 11, it is confirmed that the digital signature means 11 is not stolen by the malicious third party using a memory dump or the like. be able to. Also,
The operation confirmation unit 49 confirms the operation of each digital signature unit 11, and the digital signature unit 1 that is not operating normally
If there is 1, a new public key Kp and new secret key Ks
And divides the created secret key Ks into the sum of the numbers of the digital signature means 11 operating normally, and the secret key obtained by this division is used for each of the digital signature means 11 determined to be normal. Of the time-stamped digital documents Mt.
To receive a digital signature for
In addition, a plurality of digital signature means 11 divides and possesses the private key, and each digital signature means 11 independently performs digital signature, thereby reducing the risk of theft of the private key and obtaining the time. The time stamp cannot be forged unless all the institutions that execute the means for digitally signing up collude, and it is possible to operate a time certification external institution that provides a safe and reliable time certification service. Further, it is not necessary to store any time authentication certificate issued in the past, and the storage capacity can be significantly reduced as compared with the conventional one.

FIG. 9 is a block diagram showing the structure of the time authentication device according to the ninth embodiment of the present invention. The time authentication device shown in the figure is provided with each of a plurality of digital signature means 11 as an external digital signature means 19 in the time authentication device of the seventh embodiment shown in FIG. Digital documents with time stamps Mt
7 is the same as the embodiment shown in FIG. 7, except that the Mt sending means 21 for sending the digital signature and the digital signature receiving means 23 for receiving the digital signatures from the plurality of external digital signature means 19 are provided. Because there is
The description is omitted.

FIG. 10 is a block diagram showing the configuration of the time authentication device according to the tenth embodiment of the present invention. The time authentication device shown in the figure is the same as the time authentication device of the fourth embodiment shown in FIG.
9, the key creation / distribution means 51 is provided, each external digital signature means 19 is further added to the Mt receiving means 25 and the signature sending means 27, and the time validity determining means 55 is provided.
4 is the same as that of FIG.

The time correctness judging means 55 provided in each external digital signature means 19 is provided with each external digital signature means 1.
9 compares the time information t added to the time stamped digital document Mt received from the Mt sending means 21 with the time information t ′ independently acquired by each external digital signature means 19, and the difference between the two is sufficiently small. Only in this case, each external digital signature means 19 creates a digital signature for the time stamped digital document Mt using the private key already created by the key creation / distribution means 51, and the created digital signature is sent to the signature sending means 27. Is configured to be sent to the digital signature receiving means 23 of the time authentication unit 35.

More specifically, in this embodiment, the signature request sending unit 45 of the signature request unit with valid period 37 sends the signature request with valid period (MP, Q, Kp, C) is sent to the time authentication unit 35. Instead of Q with Kp obtained by decoding the C with the public key Kp ^t of the time authentication unit 35 verifies that it is the digital signature of the MP, (M
P, Q, Kp, the result of decoding the Q using Kp contained in C) is in the MP, and that Kp and decrypts the public key Kp ^t time authentication unit 35 is obtained a C Verify. When the digital signature Q is created using the secret key Ks with respect to the result of applying the hash function to MP, the result obtained by decrypting the digital signature Q is M
Apply the hash function to P and verify that it matches the result.

The operation confirming means 49 provided in the time authenticating section 35 periodically confirms whether or not the plurality of external digital signature means 19 are operating normally, and confirms the operation normally. External digital signature means 1 not working
When there is even one 9, the key creation / distribution means 51 is requested to create a new public key Kp2 and secret key Ks2. In response to this request, the key creation / distribution means 51 creates a new public key Kp2 and secret key Ks2, divides this secret key Ks into the sum of the numbers of external digital signature means 19 operating normally, The private key obtained by this division is distributed to each of the normally operating external digital signature means 19.

On the other hand, when the digital document receiving means 5 of the time authenticating section 35 receives the signature request with valid term (MP, Q, Kp, C) from the signature requesting section with valid term 37, at this time, the digital document receiving means 5 from the time obtaining means 7. The time information t is acquired. Then, the same verification as that of the embodiment shown in FIGS. 3 and 4 is performed, and as a result of the verification, the digital document M is extracted from the signature request (MP, Q, Kp, C) with the valid period, and the extraction is performed. The previously acquired time information t is combined with the digital document M by the combining unit 9. Then, the combined time-stamped digital document Mt is sent from the Mt sending means 21 to the external digital signature means 19 operating normally.
The external digital signature means 19 compares the time information t added to the received time stamped digital document Mt with the time information t ′ previously acquired by the external digital signature means 19, and if the difference between the two is sufficiently small. Only, the private key already created by the key creation / distribution means 51 is used to create a digital signature for the time stamped digital document Mt, and the created digital signature is sent from the signature sending means 27 to the time authentication unit 35.
To the digital signature receiving means 23.

The digital signature receiving means 23 receives the digital signature from each external digital signature means 19 and supplies it to the integrated digital signature creating means 13. The integrated digital signature creating means 13 combines the digital signatures to create an integrated digital signature c. Time authentication certificate sending means 15
Is a time stamped digital document Mt, an integrated digital signature c,
And the public key Kp2 as a set, the time authentication certificate (Mt,
c, Kp) and send it to the author.

[0085]

As described above, according to the first aspect of the invention, the digital document M created by the author is combined with the time information t to create the time stamped digital document Mt. The stamped digital document Mt is sent to a plurality of digital signature means, each digital signature is independently created, and the plurality of digital signatures independently created by the plurality of digital signature means are combined to create an integrated digital signature. However, since the set of this integrated digital signature and digital document with time stamp is sent to the author as a time certification certificate, it is difficult to forge the time stamp by each unique digital signature by a plurality of digital signature means, and it is safe and secure. A reliable time authentication service is possible and the risk of theft of a private key can be reduced. Further, the storage capacity can be greatly reduced without storing the time authentication certificate issued in the past. Moreover, when each digital signature means receives the time stamped digital document Mt, the time stamped digital document Mt.
The time information t is immediately obtained from t, the time information t is compared with the independently acquired time information t ′, and the digital signature is created only when the difference between them is within a predetermined allowable time difference. A safe and reliable time authentication service is possible.

[0086]

According to the invention of claim 3, the digital document M created by the author is received, and the valid period information P of the authentication required by the authentication requester for the digital document M is received.
, A digital signature Q is created, and a signature request (MP, Q,
C) is sent, and the sent signature request (M
P, Q, C), verify that this request is from a legitimate contractor, and if the verification result is valid, verify whether the time information t is included in the valid period P. Only when the time information t is included in the valid period P, the time information t is combined with the digital document M to create the time stamped digital document Mt, and the time stamped digital document Mt is sent to a plurality of digital signature means. The digital signatures are independently created, and the multiple digital signatures independently created by the multiple digital signature means are combined to create an integrated digital signature. Since the set is sent to the author as a time authentication certificate, it is difficult to forge the time stamp by each unique digital signature by a plurality of digital signature means. for that reason,
In addition to the effect of the invention described in claim 1, by further verifying the digital signature Q and the public key certificate C, it is possible to confirm that the signature request is an authorized contractor.

[0088]

[0089]

[0090]

[0091]

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a time authentication device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a time authentication device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a time authentication device according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a time authentication device according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a time authentication device according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a time authentication device according to a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a time authentication device according to a seventh embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a time authentication device according to an eighth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a time authentication device according to a ninth embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of a time authentication device according to a tenth embodiment of the present invention.

[Explanation of symbols]

5 Digital document receiving means 7 Time acquisition means 9 coupling means 11 Digital signature means 13 Integrated digital signature creation means 15 Time authentication certificate sending means 19 External digital signature means 21 Mt sending means 23 Digital signature receiving means 31 Signature verification means with validity period 33 Time information verification means within validity period 35 Time Authentication Section 37 Signature request section with validity period 45 Means of sending signature request with validity period 49 Operation confirmation means 51 Key creation and distribution means 55 Time validity determination means

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 9/32 G09C 1/00 640 G06F 13/00 354

Claims (10)

(57) [Claims] 1. A document receiving means for receiving a digital document M created by an author, a first time obtaining means for obtaining time information t, and time information t obtained by the time obtaining means is combined with the digital document M. Then, combining means for creating one time-stamped digital document Mt, a plurality of digital signature means for receiving the time-stamped digital document Mt and independently creating digital signatures, and the plurality of digital signature means Independent digital signature creation means for receiving and combining a plurality of digital signatures created independently by the above, and a set of the time stamped digital document Mt and integrated digital signature c as a time authentication certificate. and a time authentication certificate sending means for sending to the author, further, each of said digital signature means, distinct from the first to get its own time information t ' Others have the same second time acquisition means receives the digital document Mt with Timestamp said, acquires immediate time information t from the digital document Mt with said time stamp, the originally acquired with the time information t The time authentication device is characterized in that it is configured to compare the time information t'and the time information t'and to create a digital signature only when the difference between them is within a predetermined allowable time difference. 2. The combining unit sends the time-stamped digital document Mt to the plurality of digital signature units, and the time-stamped digital document sending unit, and the plurality of digital signatures sent from the plurality of digital signature units. A digital signature receiving means for receiving the time-stamped digital document Mt, wherein each of the plurality of digital signature means receives the time-stamped digital document Mt sent from the time-stamped digital document sending means. Digital signature creating means for independently creating a digital signature for each of the received time stamped digital documents Mt,
The time authentication device according to claim 1, further comprising a signature sending unit that sends the created digital signature to the digital signature receiving unit. 3. A digital document M created by the author is received, and the validity period information P of the certification required by the certification requester is combined with the digital document M, and a digital signature Q is obtained.
And a signature request means with a validity period, which sends a signature request (MP, Q, C) with a validity period, which comprises a set obtained by adding the public key certificate C to the key used to create the digital signature Q, and The signature request with validity period (MP, Q, C) sent from the signature requesting means with validity period is received, and the signature request with validity period (MP, Q, C) is a request from an authorized contractor. A time certification device having a time certification means for verifying that the time information t is combined with the digital document M to create a digitally signed time certification certificate (Mt, c), the signature requesting means with a valid period. Creates a digital document receiving means for receiving the digital document M created by the author and a set of a public key and a private key in the public key cryptosystem,
A key creating means for sending the created public key to the time authenticating means, and a digital document M received by the digital document receiving means.
And a validity period combining means for combining the validity period P of the authentication required by the authentication requester to create the information MP, and a digital signature means for creating a digital signature Q using a secret key for the information MP. And a request sending unit with a valid period for sending the set of the information MP, the digital signature Q, and the public key certificate C received from the time authenticating unit to the time authenticating unit as a signature request (MP, Q, C) with a valid period. The time authenticating means receives the public key sent from the signature requesting means with validity period, and issues a digital signature for the public key to the time authenticating in response to a request from the signature requesting means with validity period. A public key certificate returning means for sending the public key certificate C, which is created by using the private key of the means, and which is a set of the public key and the created digital signature, to the signature requesting means with validity period; Includes a signature request receiving means (MP, Q, C) with a validity period for receiving a signature request (MP, Q, C) with a validity period sent from the signature requesting means with a validity period A digital signature Q and a public key certificate C to be verified to confirm that the signature requester is a legitimate contractor; and a first time acquisition means for acquiring time information t. If the verification result by the signature verification unit with valid period is valid, the time information t acquired by the time acquisition unit is included in the valid period P included in the signature request with valid period (MP, Q, C). The time information t acquired by the time acquisition means is provided only when the time information t is included in the validity period P as a result of verification by the validity time information verification means for verifying whether or not the validity time P is verified. Previous With a validity period signing request (M
P, Q, C) to combine with the digital document M included in the digital document M to create a time stamped digital document Mt, and to receive the time stamped digital document Mt to independently create a digital signature. A plurality of digital signature means, an integrated digital signature creating means for receiving and combining a plurality of digital signatures independently created by the plurality of digital signature means to create an integrated digital signature c; A time authentication device comprising a time authentication certificate sending means for sending a set of Mt and integrated digital signature c to an author as a time authentication certificate (Mt, c). 4. The time information combining means includes time stamp digital document sending means for sending the time stamp digital document Mt to the plurality of digital signature means, and a plurality of plurality of digital signature sending means sent from the plurality of digital signature means. A digital signature receiving means for receiving a digital signature, wherein each of the plurality of digital signature means receives the time-stamped digital document Mt sent from the time-stamped digital document sending means. And a digital signature creating means for independently creating a digital signature for the received time stamped digital document Mt,
4. The time authentication device according to claim 3, further comprising a signature sending unit that sends the created digital signature to the digital signature receiving unit. 5. An inquiry for confirming whether or not the plurality of digital signature means are normally operating is periodically made to each digital signature means, and the confirmation result is generated by the combining means and the integrated digital signature creation. Further comprising operation confirming means for supplying the time stamping digital document Mt to only the digital signature means operating normally based on the confirmation result from the operation confirming means, 2. The time according to claim 1, wherein the integrated digital signature creating means is configured to receive the digital signature only from the digital signature means operating normally based on the confirmation result from the operation confirming means. Authentication device. 6. An inquiry for confirming whether or not the plurality of digital signature means are operating normally is periodically made to each digital signature means, and the confirmation result is sent to the time stamped digital document sending means. And an operation confirming means for supplying the digital signature receiving means to the digital signature receiving means, wherein the time stamped digital document sending means sends the time to only the digital signature means operating normally based on the confirmation result from the operation confirming means. The stamped digital document Mt is sent, and the digital signature receiving means is configured to receive the digital signature only from the digital signature means operating normally based on the confirmation result from the operation confirming means. The time authentication device according to claim 2. 7. A set of a public key Kp and a secret key Ks in a public key cryptosystem is created, and the created secret key Ks is divided and expressed as a sum of the numerical values of the plurality of digital signature means. , Each of the plurality of digital signature means is distributed to each of the plurality of digital signature means, and after the distribution is completed, key generation / distribution means for deleting the private key before division is further provided, and each of the plurality of digital signature means. Holds a private key distributed from each of the key creation / distribution means, creates a digital signature for the time stamped digital document Mt distributed from the combining means by a public key cryptosystem using the private key, The plurality of digital signatures from the respective digital signature means are combined by the integrated digital signature creating means to create an integrated digital signature c, and the time authentication certificate sending means integrates the time stamped digital document Mt. Time authentication certificate and digital signature c, and a public key Kp to the set (Mt, c, K
The time authentication device according to claim 1, wherein the time authentication device is configured to be sent to the author as p). 8. An inquiry for confirming whether or not the plurality of digital signature means are operating normally is periodically made to each digital signature means, and the confirmation result is produced by the combining means and the integrated digital signature creation. Means and an operation confirmation means for supplying the key generation / distribution means, wherein the key generation / distribution means receives from the operation confirmation means an operation confirmation result indicating that there is a digital signature means not operating normally. , A new public key and a private key are created, the newly created private key is divided into the sum of the numbers of the plurality of digital signature means, and the private key obtained by this division is set to 1 for each digital signature means. The combining means sends the time stamped digital document Mt only to the digital signature means operating normally based on the confirmation result from the operation confirming means. With Engraving digital document Mt
Each digital signature means which has sent the digital signature creating means creates a digital signature for the time stamped digital document Mt distributed by the combining means by using the private key distributed by the key creating / distributing means, and the integrated digital signature creating means. Receives the digital signature only from the digital signature means that is operating normally based on the confirmation result from the operation confirming means, and combines the received digital signatures by the integrated digital signature creating means to create the integrated digital signature c. Then, the time authentication certificate sending means is configured to send the time stamp digital document Mt, the integrated digital signature c, and the public key Kp as a set to the author as a time authentication certificate (Mt, c, Kp). The time authentication device according to claim 7, wherein 9. The joining means sends time-stamped digital document Mt to the plurality of digital signature means, and a plurality of digital signatures sent from the plurality of digital signature means. 8. The time authentication device according to claim 7, further comprising a digital signature receiving means for receiving the. 10. A public key Kp in a public key cryptosystem.
2 and a secret key Ks2 are created, the created secret key Ks2 is divided and expressed as the sum of the numerical values of the plurality of digital signature means, and each of these numerical values is converted into a plurality of digital signature means. And further has a key generating / distributing means for deleting the private key before division after the distribution is completed, and the time authenticating means confirms whether or not the plurality of digital signature means are operating normally. The digital signature means further includes an operation confirmation means for periodically making an inquiry to the digital signature means, each of the digital signature means being separate from or the same as the first to obtain the time information t ′ independently . Second time acquisition means is further provided, and when the time stamped digital document Mt is received, the time information t is immediately sent from the time stamped digital document Mt.
Is obtained, the time information t is compared with the independently obtained time information t ′, and a digital signature is created only when the difference between them is within a predetermined allowable time difference. When the distribution means receives an operation confirmation result from the operation confirmation means that there is a digital signature means that is not operating normally, it creates a new public key and secret key, and the newly created secret key The digital signature means is divided into the sum of the number of digital signature means, and the private key obtained by the division is distributed to each digital signature means one by one, and the combining means normally operates based on the confirmation result from the operation confirming means. The time stamped digital document Mt is sent only to the operating digital signature means, and when the digital signature means receives the time stamped digital document Mt, it immediately starts from the time stamped digital document Mt. Time information t is acquired, and this time information t
And the time information t'obtained independently are compared, and only when the difference between the two is within a predetermined allowable time difference, the time distributed by the combining means using the secret key distributed by the key creation / distribution means. The integrated digital signature creating means creates a digital signature for the stamped digital document Mt, and the integrated digital signature creating means receives the digital signature only from the digital signature means operating normally based on the confirmation result from the operation confirming means, and the received digital signature. Are combined by an integrated digital signature creating means to create an integrated digital signature c, and the time authentication certificate sending means combines the time stamped digital document Mt, the integrated digital signature c, and the public key Kp2 into a time authentication certificate ( M
5. The time authentication device according to claim 4, wherein the time authentication device is configured to be sent to the author as t, c, Kp2).