JP2006285592A - Contract alteration preventing system, and contract alteration preventing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contract alteration preventing system, and a contract alteration preventing method disabling alteration of a contract prepared by preprinting. <P>SOLUTION: A contract preprinted on the basis of generated electronic contract information becomes impossible to alter by acquiring contract contents, carrying out generation of contract full text information including the contract contents, generating a two-dimensional barcode (restorable to the original contract full text information) including a digital signature from the contract full text information and a hash value of the contract full text information, and providing a means for generating the electronic contract information comprised thereof and sending it to a portable terminal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to general contract documents (hereinafter simply referred to as “contracts”) in which contracts are established by signing and stamping contracts printed using electronic data for generating contracts, such as mortgages, for example. The present invention relates to a contract falsification preventing system, a portable terminal and a contract falsification preventing method for preventing the contract (correct / sub) from being falsified after the fact.

Conventionally, as an example, a bank employee of a financial institution inputs application data corresponding to a loan application from a customer to a business terminal of a sales office, generates loan data from the application data, and the loan data is used as a loan condition. If it is satisfied, a contract is generated based on the data, and the contract is printed on the business terminal of the sales office (the printing of the contract using electronic data in this way is referred to as “ It is known that a loan transaction contract is established by receiving a signature and a seal from a customer. (See paragraphs 50 to 52 of Patent Document 1)
The contract targeted by the present invention is not limited to a contract such as a housing loan, that is, a money consumption loan contract.

Japanese Patent Laid-Open No. 2003-76848

  However, this conventional technique has the following problems. For example, there is a possibility of fraud in which a blank contract is signed and stamped and then pre-printed. Also, in order to create two copies of primary and secondary by pre-printing the contract, the same content is printed twice, so it is difficult to confirm that the primary and secondary are the same as for the handwritten copy type. Furthermore, tampering is easier than pre-printed contracts that have been created by handwriting.

  Therefore, the present invention can prevent fraud such as receiving a signature and a seal and then pre-printing, and can easily confirm that the contents of the pre-printed contract are the same as the original and sub-details. It is an object of the present invention to provide a contract falsification preventing system, a portable terminal, and a contract falsification preventing method that make it impossible in principle.

  In order to solve the above problem, the invention described in claim 1 is a contract falsification preventing system connected to a portable terminal via an information communication network, wherein the contract falsification preventing system includes a database for storing contract contents. A contract full text information generating means for acquiring the contract contents from the database and generating contract full text information including the contract contents, a digital signature means for generating a digital signature based on the contract full text information, and the contract Two-dimensional barcode generation means for generating a two-dimensional barcode based on full-text information and the digital signature; and electronic contract information generation means for generating electronic contract information including the full-text information and the two-dimensional barcode And transmission means for transmitting the electronic contract information to the portable terminal.

  According to a second aspect of the present invention, in the contract falsification preventing system according to the first aspect, the contract content includes contract conditions and contract wording template information.

  According to a third aspect of the present invention, in the contract falsification preventing system according to the first or second aspect, the contract full text information generating means includes the contract full text information including layout information that defines a print layout. It is characterized by generating.

  According to a fourth aspect of the present invention, in the contract falsification preventing system according to any one of the first to third aspects, the two-dimensional bar code included in the electronic contract information includes a part based on the digital signature. , The contract full-text information can be restored.

  According to a fifth aspect of the present invention, in the contract falsification preventing system according to any one of the first to third aspects, the two-dimensional bar code included in the electronic contract information is generated based on the digital signature. And a two-dimensional barcode that can be restored to the contract full text information.

  The invention described in claim 6 is the contract falsification preventing system according to any one of claims 1 to 5, further comprising a hash value calculation means for calculating a hash value based on the full text information of the contract, The hash value is included in the electronic contract information.

  According to a seventh aspect of the present invention, in the contract falsification preventing system according to any one of the first to sixth aspects, signature data obtained by converting the signature of the contractor's own signature into data is included in the contract full text information. It is characterized by.

  The invention according to claim 8 is the contract falsification preventing system according to claim 7, wherein the signature data is acquired by data input by a contractor's own signature using a tablet provided in the mobile terminal. And

  According to a ninth aspect of the present invention, in the contract falsification preventing system according to the eighth aspect, the sign data further includes writing pressure and stroke speed data.

  According to a tenth aspect of the present invention, in the contract falsification preventing system according to any one of the first to ninth aspects, the first and second contracts printed based on the electronic contract information are printed. Further, it is characterized by further comprising falsification detecting means for detecting falsification of the contract full text information from the contract full text information restored from the two-dimensional bar code and the digital signature.

  The invention according to claim 11 is a contract falsification preventing method using a computer system connected to a mobile terminal via an information communication network, wherein the contract contents are acquired from a database storing contract contents, and A procedure for generating contract full-text information including contract contents; a procedure for generating a digital signature based on the contract full-text information; a procedure for generating a two-dimensional barcode based on the contract full-text information and the digital signature; It is characterized by comprising a procedure for generating electronic contract information including the contract full text information and the two-dimensional barcode, and a procedure for transmitting the electronic contract information to the portable terminal.

  According to a twelfth aspect of the present invention, in the contract falsification preventing method according to the eleventh aspect, the contract content includes contract conditions and contract wording template information.

  According to a thirteenth aspect of the present invention, in the contract falsification preventing method according to the eleventh or the twelfth aspect, the contract full text information generating means includes the contract full text information including layout information defining a print layout. It is characterized by generating.

  According to a fourteenth aspect of the present invention, in the contract falsification preventing method according to any one of the eleventh to thirteenth aspects of the present invention, the received electronic contract information is transmitted to the mobile terminal side in two ways: primary and secondary. It is characterized by printing on the contract.

  According to a fifteenth aspect of the present invention, in the contract falsification preventing method according to any of the eleventh to fourteenth aspects, the two-dimensional barcode included in the electronic contract information includes a part based on the digital signature. , The contract full-text information can be restored.

  The invention according to claim 16 is the contract falsification preventing method according to any one of claims 11 to 14, wherein the two-dimensional bar code included in the electronic contract information is generated based on the digital signature. And a two-dimensional barcode that can be restored to the contract full text information.

  The invention according to claim 17 is the contract falsification preventing method according to any one of claims 11 to 16, further comprising a procedure of calculating a hash value based on the full text information of the contract. The hash value is included in the information.

  The invention according to claim 18 is the contract falsification preventing method according to any one of claims 11 to 17, wherein signature data obtained by converting the signature of the contractor's own signature into data is included in the contract full text information. It is characterized by.

  According to a nineteenth aspect of the present invention, in the contract falsification preventing method according to the eighteenth aspect, the signature data is acquired by data input by a contractor's own signature using a tablet provided in the portable terminal. And

  According to a twentieth aspect of the present invention, in the contract falsification preventing method according to the nineteenth aspect, the signature data further includes writing pressure and stroke speed data.

  According to a twenty-first aspect of the present invention, in the contract falsification preventing method according to any one of the eleventh to twentieth aspects, the second and second contracts printed based on the electronic contract information are printed. And further comprising a procedure for detecting falsification of the contract full text information from the contract full text information restored from the two-dimensional bar code and the digital signature.

  In the present invention, the contract conditions are directly heard from the customer, the contract full text information is generated based on the contract contents including the contract conditions, and the two-dimensional barcode and the hash value are generated from the contract full text information. , It is possible to prevent the fraud of signing and stamping a blank contract and then pre-printing it, and since the hash value is a short string of 20 characters, After the same contract is created, it can be easily determined that the two values are the same value, so that the contract contents of the primary and secondary contracts can be easily recognized.

  Furthermore, if the electronic contract document information with a digital signature is decrypted, for example, when trying to reduce the borrowing amount after the contract, it is impossible to re-assign the digital signature after the reduction, so fraud is performed. This is impossible in principle.

Hereinafter, the best mode of the present invention will be described. As an example of the best mode of the present invention, prevention of falsification of a mortgage contract will be described below.
FIG. 1 is an overall configuration diagram of a contract falsification preventing system 100 according to the present invention.

  A contract falsification preventing system 100 installed in a financial institution shown in FIG. 1 is an information communication network, for example, a mobile terminal 200 for an outsider who is an Internet mobile personal computer or a mobile phone via the Internet (hereinafter, “ The portable terminal 200 includes a mobile printer. Note that a customer's printer may be used as long as the printer can use a common recording medium.

  On the other hand, the contract document falsification prevention system 100 is connected to an in-line intra-personal computer, that is, an office center employee terminal via an in-line network, and is further connected to a TTP (Trusted Third Parties) via an in-line (and external) network. It is connected to the signature device 600 and enables digital signature by TTP as will be described later. Although the digital signature may be generated by the contract falsification preventing server 300, the digital signature by TTP is preferable in terms of reliability.

  The portable terminal 200 performs information display / input and operator instruction reception processing, and has an Internet connection function, an image photographing function, a two-dimensional bar code reading function, a recording medium output function, and a fingerprint recognition function. Each screen is processed by the browser. Further, the pre-print contract can be printed from the mobile printer 500 that is carried together via a recording medium (or connected by wire).

  The contract falsification preventing system 100 includes a contract falsification preventing server 300 and a database 400 as a storage unit in the contract falsification preventing server 300. The database 400 stores contract template information, contractor information, approval document information, and seal information. The contract document falsification preventing system 100 is connected to the approval system and the billing system via the local LAN.

  FIG. 2 is a diagram showing an example of a file structure included in the database 400 that is a storage unit in the contract falsification preventing server 300. The database is a relational database, and files included in the database include contract template information 401, contract document information 402, approval document information 403, and seal information 404. The contract template information 401 includes a used product number, a contract text template, layout information, and the like. The contract information 402 includes a store number, a supplier number, a contract number, a used product number, a contract condition, Status information, etc., the approval document information 403 includes the store number, supplier number, contract number, amount, borrowing date, and repayment method, and the seal information 404 includes the store number, supplier number, and seal image. Etc. are included. The contract template information 401 and the contract information 402 are linked by using the product number as a key, and the contract information 402 and the approval document information 403 are stored by using the store number, the supplier number, and the contract number as a key. The contract information 402 and the seal information 404 are linked using the store number and the business partner number as keys.

  Here, the used product number is a number assigned to each type of contract. For example, if it is a money consumption loan contract, there are mortgages, apartment loans, free loans, etc. Are given different numbers. In addition, the contract template information is character string information common to each type of contract, such as terms and conditions established for each type of contract, and layout information is information that determines the print layout. Based on the layout information, the contract terms and text of the contract text template information, ruled lines, and the like are printed.

The contractor information (not shown) is information about the contractor (so-called personal information when the contractor is an individual), and is provided from the contractor side when applying for a contract.
In the above description, the contract template information 401, the contract information 402, the approval document information 403, and the seal information 404 are described as files included in the database 400. Obviously, it may be managed by.

  FIG. 3 shows a general flow of information from the personal authentication and search screen transmission to the loan execution reservation processed by the contract falsification preventing system 100 of the present invention. In other words, the contract document between the portable terminal 200 and the contract document falsification prevention system 100 can be printed and output from the authentication of the bank employee of the financial institution, the signature and the seal can be received, and the seal stamp can be verified and matched. For example, it shows the flow of information until a loan execution reservation is made.

  A bank employee of a financial institution goes to a customer's home or workplace, etc., and inputs, for example, a bank ID, terminal ID, and bank fingerprint information as authentication information on the login screen of the mobile terminal 200, and the information is used as the contract falsification prevention system 100. Send to and perform personal authentication. When the contract document alteration prevention system 100 determines that the authentication information matches the authentication information stored in the database 400, it transmits a search screen to the mobile terminal 200 (step S1).

  In order to search for customer approval information stored in the database 400, the store number, business partner number, and contract number are input and transmitted as search information in the search screen of the mobile terminal 200 to prevent falsification of the contract. The system 100 searches for information corresponding to the search information, generates a registration screen based on the searched information, and transmits the registration screen to the mobile terminal 200 (step S2).

  The registration screen has columns for information necessary to create a contract, such as borrowing amount, use of funds, borrowing details such as the final repayment date, borrowing interest, repayment method, interest payment method, etc. This is to describe the matters that are not yet described among the matters necessary for the preparation of the contract.

  2 includes the store number, the business partner number, and the contract number, so that the customer's approval information can be specified by the search information transmitted from the mobile terminal 200. The registration screen is generated based on information such as the amount, borrowing date, repayment method, and the like included therein.

  If the information required for preparation of the contract is changed in the description field on the registration screen or if the information required for preparation of the contract is not described, for example, contract information such as the contract date is indicated in the description field. The contract document falsification prevention system 100 stores the transmitted contract information such as the contract date in the database 400 (step S3), and generates electronic contract information based on the contract information. (Step S4). This electronic contract information includes contract conditions described in the contract of the contract information 402 described above, contract text template information, a two-dimensional barcode and hash value, which will be described later, and layout information. . The portable terminal 200 receives the electronic contract information and prints the main / secondary of the contract with the mobile printer 500. In the printed primary / secondary contract, a two-dimensional barcode and a hash value are printed as shown in FIG.

  By the way, as a case where a matter necessary for preparation of the contract is changed, for example, a (borrowing) amount may be changed. In this case, when the (borrowed) amount is changed and input, the data of the changed and entered (borrowed) amount is transmitted to the contract alteration prevention system 100 together with the search information. It is checked whether it is within the request condition range of the request document information 403 referred to based on the search information. If it is within the condition range, change input is accepted, and if it is out of the condition range, an error message is transmitted to the portable terminal 200. In such a case, notification that the change is not accepted may be made.

  Next, when the main / sub contract is printed, the contractor signs and seals the main / sub contract. When the signature and the seal are captured by the camera built in the portable terminal 200 and transmitted as a seal image, the contract alteration prevention system 100 receives the seal image (step S5). The stamp image is compared with the photographed seal image and the seal image stored in the database 400 (step S6). If they match, the loan execution status information is stored in the database 400 until the loan execution date comes. (Loan execution reservation: S7). If they do not match, an error message is transmitted to the mobile terminal 200.

  FIG. 4 shows a detailed processing procedure of “generation and transmission of electronic contract information” in S4 in FIG. 3, and a function based on this processing procedure is referred to as electronic contract information generation means.

  The electronic contract document information generation means provided in the contract document falsification preventing server 300 is based on the store condition, the business partner number and the contract number (hereinafter referred to as “search information”) transmitted from the mobile terminal 200, and the contract conditions and A used product number is acquired (step S21), and based on the used product number, layout information and contract document template information are acquired from the contract template information 401 (step S22).

  The electronic contract document information generating means generates contract full text information based on contract conditions and contract text template information (step S23), and based on the generated contract full text information, a two-dimensional barcode and a hash value Is generated (step S24), and the above-described electronic contract information including the contract full text information, the two-dimensional barcode, the hash value, and the layout information is generated and transmitted to the portable terminal 200 (step S25).

  By the way, the full text information of the contract includes the contents of the contract, and the contents of the contract include at least the contract conditions such as the borrowing amount, the borrowing interest rate / repayment method / interest payment method, and interest withdrawal, and further information on the contractor. The character string information including the contract date and time, and the present embodiment further includes contract text template information. Layout information can also be included in the contract full text information. The full text information of the contract preferably includes signature data (handwriting image data) obtained by converting the signature of the contractor to his / her signature. Further, it is more preferable that the signature data includes writing pressure / stroke speed data. Since the signature of the contractor's own signature becomes unique data every time the signature is performed, the full text information of the contract becomes unique by including the signature data. This signature data is obtained by inputting a signature signed by the contractor using the tablet provided in the mobile terminal 200.

  Further, the two-dimensional barcode is composed of at least the character string information of the contract contents converted into a two-dimensional barcode so that it can be restored and the digital signature generated based on the character string information converted into a two-dimensional barcode ( Of course, the two-dimensional barcode of the digital signature can be restored to the original digital signature data). In this way, two types of two-dimensional barcodes may be generated. Of course, one two-dimensional barcode consisting of a part based on a digital signature and a part that can be restored to the original character string information is generated. You can also. The hash value is a short character string obtained by hashing the character string information of the contract content. For example, when SHA-1 is used, a short character string of 160 bits (20 characters) can be generated from the original text of 2 64 bits or less.

  What is important here is that the full contract information is different for each project (for example, if the contract number is different for each project, or if the contractor's signature data is included as described above). Therefore, the two-dimensional barcodes generated from the contract contents are all different, and the probability that the hash value is the same as the other is extremely low. On the other hand, since the hash value is a short character string, it is possible to easily determine that both hash values are the same value after creating the same two contracts, the primary and secondary contracts. .

  The hash function is information processing means for generating a short character string from a given original text, and the generated value is called a hash value. Since the irreversible one-way function is included, the original text cannot be reproduced from the hash value, and it is extremely difficult to create different original texts having the same hash value. In the present invention, a hash value, which is a short character string, is generated by applying a hash function using the character string information of the contract as a whole.

  By the way, since the creation method of the primary / secondary is not a copy type, it is necessary to confirm that the contents of the primary / secondary contract are the same when the contract is concluded. In the best mode, this confirmation is easily performed by checking that the hash values are the same in both primary and secondary. Since the hash value is a short character string, the above-described confirmation work is reduced (a method for performing more accurate verification will be described later).

  FIG. 5 shows a detailed processing procedure of “Receive seal image” in S5 and “Verification of seal” in S6 in FIG. 3, and this processing procedure is referred to as a seal verification unit.

  The seal collation means provided in the contract falsification prevention server 300 receives the seal image and search information (store number, customer number and contract number) taken by the camera of the portable terminal 200 (step S31), and stores the received information in the store. A seal image is acquired from the database 400 based on the number and the supplier number (step S32). It is determined whether the seal images of the two match (step S33). If NO, an error mail is transmitted to the portable terminal 200, and if YES, status information indicating the verification result is stored in the contract information 402. Then, a seal collation matching mail is generated and transmitted to the portable terminal 200 (step S34). Next, when execution instruction information is received from the portable terminal 200, status information indicating a loan execution reservation is stored in the contract information database 402 (step S35).

  Here, in order to make a loan execution reservation, the verification result by the seal verification means (matching of seal impression) is used as a condition as described above, but such a condition is determined as necessary.

FIG. 6 is a diagram illustrating a procedure from determination of contract contents between a customer and an outsider to return of a positive contract from the customer to the outsider.
In S <b> 2 of FIG. 3, the outside agent enters the database 400 by inputting the necessary item (1) instructed by the customer to the registration screen transmitted to the mobile terminal 200 and transmitting it to the contract falsification preventing system 100. Contract information is stored (2).
From the electronic contract information (previously described) generated based on the contract information (full text information of the contract), the primary and secondary contracts are preprinted by the mobile printer (3). The two-dimensional barcode and hash value (in the figure, “SHA-1” in the figure) of the printed primary / secondary contract are covered with a transparent film seal, and the bank seal is pressed on the film seal.

  Deliver the signed main / secondary contract to the customer (5), check whether the hash value (SHA-1) matches (6), and the customer signs the main / secondary contract (7) The secondary contract is stored (8), and the outside agent takes a picture of the seal of the returned positive contract (9) and transmits a seal image (10). When the self-signed image data signed on the tablet is printed on the contract, it is only necessary to seal the contract.

  Instead of covering the two-dimensional bar code and hash value of the above-mentioned primary / secondary contract with a transparent film seal and pressing the bank seal on the film seal, the film seal is coated with a transparent film seal. In addition, although the object of the present invention can be achieved without the bank signing, the above method is effective as a method for further enhancing the safety.

FIGS. 7A and 7B are schematic diagrams of a contract on which the above-described two-dimensional barcode, hash value, contract content, and the like are preprinted.
FIG. 8 shows a schematic diagram when a transparent film seal is attached to the contract shown in FIG. As shown in the figure, the transparent film seal is pasted so that both the two-dimensional barcode and the hash value are within the transparent film seal, and the index is pressed. Although the object of the present invention can be achieved in the form of the contract shown in FIG. 7, it is possible to further enhance safety by sticking a transparent film seal to the contract and pressing a tally.

  As described above, the present invention directly listens to the contract conditions from the customer, generates contract full text information including at least the contract conditions, and generates a two-dimensional barcode and hash value from the contract full text information. Therefore, it is possible to prevent an illegal act of signing and stamping a blank contract and then pre-printing it, and since the hash value is a short character string of 20 characters, After creating two identical contracts, it can be easily determined that the two values are the same, so it is easy to recognize that the contract contents of the primary and secondary contracts are the same. It becomes.

  Furthermore, the principle is that fraud can be detected by decrypting the electronic contract document information (two-dimensional barcode) given with a digital signature, for example, even if tampering is attempted to reduce the borrowing amount. Is impossible.

Here, the details of the digital signature adding process will be described more specifically.
In the following, the procedure and processing performed after the contract conditions are determined in the procedure between the contractor and the outside agent will be described with reference to FIG.

  The customer (contractor) signs his / her own signature using the portable terminal 200 (tablet PC) on the proof of agreeing to the contract contents. The portable terminal 200 generates signature data obtained by converting the input signature into data (step S41). The mobile terminal 200 is provided with data (contract signature data) obtained by adding search information (store number, business partner number, contract number) and contract agreement date / time to which the contractor has agreed to the sign data. A digital signature is performed using the signature key (private key), and the digitally signed contract signature data is transmitted to the contract falsification preventing system 100 (step S42).

  The contract tampering prevention system 100 verifies the received data using the public key of the mobile terminal 200. That is, it is verified whether or not the contract signature data has been falsified from the contract signature data and the digital signature. If this data is valid, the date and time received by the bank is added to the contract signature data and stored in the database 400 (step S42). On the other hand, if the contract signature data is invalid, an error message is transmitted to the mobile terminal 200 (not shown). The public key certificate for the public key to be used is preferably signed by a third party CA server.

  Next, based on the search information included in the contract signature data, the contract alteration / anti-honey prevention system 100 acquires information to be included in the above-mentioned contract full text information from the database 400 based on the search information included in the contract signature data, and includes the contract full text including the signature data. Information is generated (step S44).

  Here, the contract full-text information is formatted for adding a digital signature and converting it into a two-dimensional barcode (described later). When a digital signature is requested to the outside (TTP), the digital signature added by the portable terminal 200 is further signed by the contract alteration / anti-honey prevention system 100 (multiple signature), so that the security is further improved. However, in this case, since the signature length to be transmitted to the external TTP server becomes long and it takes time to verify, in fact, in step S43, after confirming that the digital signature by the portable terminal 200 is valid, By using the method of truncating the digital signature part and re-adding the digital signature to the part to be signed by the contract falsification preventing system 100, an increase in the signature length is prevented. That is, when the received data from the portable terminal 200 is m || SIG_A (m) as the digital signature SIG_A (m) by the portable terminal 200 for the signature target portion m (where || represents a simple combination of data) ), The digital signature portion SIG_A (m) by the mobile terminal 200 is discarded, and the signed data m || SIG_BK (m) is generated by using the digital signature SIG_BK (m) by the contract tampering prevention system 100 as a new signature. . Here, it is assumed that the TTP signature device 600 is in a row. In this case, verification of the digital signature on the TTP signature apparatus 600 side is unnecessary.

Next, the full text information of the contract to be signed (also data to be two-dimensional barcode) is transmitted to the TTP signature device 600 (step S45).
The TTP signature device 600 applies a digital signature to the full contract information as will be described later, and generates a signature portion (digital signature) of data to be converted into a two-dimensional barcode (step 46).
Next, the TTP signature device 600 returns the generated signature part (digital signature) to the contract falsification preventing system 100 (step S47).

The contract alteration prevention system 100 converts the full text information of the contract into a two-dimensional barcode so that it can be restored, converts the signature part received from the TTP signature device 600 into a two-dimensional barcode, and calculates a hash value of the full text of the contract To do. Then, a contract file (electronic contract information) including the contract full text information, the two-dimensional barcode, and the hash value is generated (step S48).
Then, the generated contract document file is transmitted to the portable terminal 200 (step S49).

  The portable terminal 200 that has received the contract file prints it (step S50) and receives a seal (and signature) from the customer (step S51). Note that the signature after the contract is printed in step S51 can be made unnecessary by printing the image of the signature received when the contract is agreed (step S41).

  Next, details of the digital signature generation processing by the TTP signature apparatus 600 will be described.

First, an example of signature target data signed by the TTP signature apparatus 600 is shown in FIG.
The data to be signed (contract full text information) shown in the figure is composed of a set of contractor information contractor_info, contract content content_contract, contract date / time date_contract and bank reception date / time date_bank, and contractor's signature data Signed_data. .
For the signature target data configured as described above, the TTP signature apparatus 600 generates a digital signature as shown in FIG. This digital signature generation process will be described below with reference to FIG.

  First, the contract data receiving unit 601 of the TTP signature device 600 receives signature target data from the contract falsification preventing system 100 (step S101). If the TTP signature device 600 is external, the received data is also verified.

  Of the data to be signed, the data of the contractor information, the data obtained by simply combining the contract contents, the contract date / time, and the bank reception date / time are given to the hash value calculation unit 602 of the TTP signature device 600. The hash value calculation unit 602 has a hash value H (contractor_info) of the contractor information, that is, a hash value H (content_contract || date_contract | That is, m2 is calculated (steps S102 and S103). Each calculated hash value is supplied to the TTP signature calculation unit 603 of the TTP signature device 600. The reason why the hash value is obtained by dividing the contractor information from the contract contents, the contract date and time, and the bank reception date and time is that the contractor information is usually changed little and can be reused.

On the other hand, the signature data of the signature target data is given from the contract data receiving unit 601 to the cryptographic operation unit 604 of the TTP signature device 600, and the cryptographic operation unit 604 stores the TTP secret key stored in the TTP storage device 605. (Common key) Encrypted signature data using K _TTP and encrypted data

Is supplied to the TTP signature calculation unit 603. On the other hand, the contract data receiving unit 601 supplies the TTP signature date / time date_TTP to the TTP signature calculation unit 603.

  The above data H (contractor_info), that is, m1, H (content_contract || date_contract || date_bank), that is, m2,

That is, the TTP signature calculation unit 603 that has received m3 and date_TTP, that is, m4 is a digital signature by using the _TTP signature key SK _TTP stored in the TTP storage device 605.

Is generated. Then, this digital signature is returned to the contract falsification preventing system 100 (step S105).

  As described above, the digital signature generated as described above is converted into a two-dimensional barcode together with the full text information of the contract, and is included in the electronic contract information.

  Next, details of the method for verifying the printed primary / secondary contract will be described with reference to FIG.

  First, the two-dimensional barcodes of the primary contract and the secondary contract are each read out by imaging using the camera of the mobile terminal 200 (step S201).

  Next, the portable terminal 200 determines whether the read two-dimensional barcodes match each other and whether the two-dimensional barcodes are valid based on the digital signature (step S202). In order to make it possible to judge whether the contract contents written in the primary and secondary contracts are the same as the contract contents converted into a two-dimensional bar code, and to verify tampering with a digital signature, a two-dimensional bar Restore the contract contents from the code. As described above, a part of the two-dimensional barcode can be restored to the original plaintext. If it is determined in step S202 that the contract is valid and matches, then the outside agent checks whether or not the restored contract content matches the printed contract content (step S203).

  Here, if the contract contents restored from the two-dimensional barcode and the printed contract contents match, it is determined that the primary and secondary contracts are correct contract contents (step S204).

  On the other hand, if it is determined in step S202 that the two-dimensional barcodes read by the portable terminal 200 do not match, the portable terminal 200 restores the contract contents from the two-dimensional barcode. Next, the outside agent confirms whether or not the restored contract content matches the printed contract content (step S203).

Here, out of the contract contents of the primary and secondary contracts, the one that matches the contract contents restored from the two-dimensional barcode is the correct contract contents (in this case, of course, the two-dimensional barcode digital first) It is necessary to verify that the signature has not been tampered with).
As described above, the validity of the preprinted contract can be verified.

1 is an overall configuration diagram of a loan contract office work contract falsification preventing system 100 according to the present invention. 6 is a diagram illustrating an example of a file structure included in a database 400 that is a storage unit in the contract falsification preventing server 300. FIG. It is a flowchart which shows the general flow of the information from the transmission of a personal authentication and a search screen to loan execution reservation which the contract document tampering prevention system 100 of this invention processes. FIG. 6 shows a detailed processing procedure for generating and transmitting electronic contract information in S4 of FIG. FIG. 4 shows a detailed processing procedure for receiving a seal image and checking a seal in S5 and S6 of FIG. It is a figure which shows the procedure from the determination of the content of a contract between a customer and an outsider to return of a positive contract from a customer to an outsider. It is the schematic of the contract by which the two-dimensional barcode, the hash value, and the contract content were preprinted. It is a figure which shows the other example which coat | covered the transparent film seal | sticker on the contract of FIG. It is a sequence diagram which shows the process after contract content confirmation, and the process of contract preparation. It is a figure which shows the example of the signature object data which the TTP signature apparatus 600 signs. 6 is a diagram for explaining processing by a TTP signature apparatus 600. FIG. 5 is an operation flowchart of digital signature generation by the TTP signature apparatus 600. It is a flowchart explaining the verification method of the printed primary / secondary contract.

Explanation of symbols

100 Contract document falsification prevention system 200 Mobile terminal 300 Contract document falsification prevention server 400 Database 401 Contract document template information 402 Contract document information 403 Approval document information 404 Seal information 500 Mobile printer

Claims (21)

In a contract falsification prevention system connected to a mobile terminal via an information communication network,
The contract falsification preventing system includes a database for storing contract contents,
Contract full text information generating means for acquiring the contract contents from the database and generating contract full text information including the contract contents;
A digital signature means for generating a digital signature based on the full text information of the contract;
Two-dimensional barcode generation means for generating a two-dimensional barcode based on the contract full text information and the digital signature;
Electronic contract information generating means for generating electronic contract information including the contract full text information and the two-dimensional barcode;
A contract falsification preventing system comprising: transmission means for transmitting the electronic contract information to the portable terminal.   2. The contract falsification preventing system according to claim 1, wherein the contract content includes contract conditions and contract text template information.   The contract document falsification preventing system according to claim 1 or 2, wherein the contract document full text information generating unit generates the contract document full text information including layout information defining a print layout.   4. The two-dimensional barcode included in the electronic contract information includes a part based on the digital signature and a part that can be restored to the full text of the contract. The falsification prevention system for contracts described in 1.   The two-dimensional barcode included in the electronic contract information includes a two-dimensional barcode generated based on the digital signature and a two-dimensional barcode that can be restored to the contract full text information. The contract falsification preventing system according to any one of claims 1 to 3.   The contract according to any one of claims 1 to 5, further comprising hash value calculation means for calculating a hash value based on the contract full text information, wherein the hash value is included in the electronic contract information. Document falsification prevention system.   The contract document falsification preventing system according to any one of claims 1 to 6, characterized in that signature data obtained by converting a signature of a contractor's own signature into data is included in the contract full text information.   8. The contract falsification preventing system according to claim 7, wherein the signature data is acquired by data input by a contractor's own signature using a tablet provided in the mobile terminal.   9. The contract falsification preventing system according to claim 8, wherein the sign data further includes data on writing pressure and stroke speed.   Falsification detection for detecting falsification of contract full text information from the contract full text information restored from the two-dimensional barcode printed on the primary and secondary contracts printed based on the electronic contract information and the digital signature 10. The contract falsification preventing system according to claim 1, further comprising means. A method for preventing contract falsification using a computer system connected to a mobile terminal via an information communication network,
A procedure for acquiring the contract content from a database storing the contract content and generating full text information of the contract including the contract content;
Generating a digital signature based on the full contract information;
Generating a two-dimensional barcode based on the contract full text information and the digital signature;
Generating electronic contract information including the contract full text information and the two-dimensional barcode;
And a procedure for transmitting the electronic contract information to the portable terminal.   12. The contract falsification preventing method according to claim 11, wherein the contract content includes contract conditions and contract text template information.   13. The contract document falsification preventing method according to claim 11 or 12, wherein the contract document full text information generating unit generates the contract document full text information including layout information defining a print layout.   The contract falsification preventing method according to any one of claims 11 to 13, wherein the received electronic contract information is printed on a main / secondary contract on the portable terminal side. .   15. The two-dimensional barcode included in the electronic contract information includes a part based on the digital signature and a part that can be restored to the full text of the contract. The method for preventing falsification of the contract described in 1.   The two-dimensional barcode included in the electronic contract information includes a two-dimensional barcode generated based on the digital signature and a two-dimensional barcode that can be restored to the contract full text information. The contract falsification preventing method according to any one of claims 11 to 14.   The contract document falsification prevention according to any one of claims 11 to 16, further comprising a procedure of calculating a hash value based on the full text information of the contract, wherein the hash value is included in the electronic contract information. Method.   The contract falsification preventing method according to any one of claims 11 to 17, wherein signature data obtained by converting a signature of the contractor's own signature into data is included in the contract full text information.   19. The contract falsification preventing method according to claim 18, wherein the sign data is acquired by data input by a contractor's own signature using a tablet provided in the mobile terminal.   The contract signature falsification preventing method according to claim 19, wherein the signature data further includes data of writing pressure and stroke speed. A procedure for detecting falsification of the contract full text information from the contract full text information restored from the two-dimensional barcode printed on the primary and secondary contract printed based on the electronic contract information and the digital signature; 21. The contract falsification preventing method according to any one of claims 11 to 20, further comprising:

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