JP2003263647A - Signing method in electronic document - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signing method for attaching an autographic signature close to a real signature to an electronic document. <P>SOLUTION: The handwritten signature image data of a user generated by handwritten input are attached to an electronic document with the electronic signature and electronic certificate of the user, and transmitted. The handwritten signature image is displayed on the electronic document as the visible expression of the electronic signature, and turned into an autographic signature close to a real signature so that the receiver of the electronic document can be prevented from feeling any incompatibility. Also, the electronic document is attached with the electronic signature and the electronic certificate in the conventional way so that any danger specific to electronic transaction such as denial, impersonation, and tampering can be prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method of signing an electronic document in which a user's electronic signature is attached to an electronic document communicated via a network.

[0002]

2. Description of the Related Art It has been pointed out that electronic documents communicated via a network have a high risk of denial, spoofing, tampering, etc., unlike conventional paper documents. In these, avoiding these risks is an important issue. Therefore, electronic signatures have been conventionally used as an effective means for avoiding these risks.

An electronic signature is generally created by using a public key encryption system represented by RSA, and is a creator / sender of an electronic document (referred to as a user in this specification).
Converts a digital document into fixed bit length compressed data (message digest) using a hash function, and then encrypts it using a user's private key. This encrypted data is an electronic signature, and this electronic signature is attached to the original electronic document and transmitted via the network. It also sends its public key at the same time. The public key and the electronic certificate described later may be included in the signature data at the same time.

The receiver decrypts the electronic signature with the sender's public key and extracts the message digest. Also, the received electronic document is compressed with a hash function to create a message digest. If the two match, it is confirmed that the received electronic document is encrypted with the private key corresponding to the public key, and it is confirmed that the electronic document was created by the user who owns the private key. be able to.

When the electronic document is tampered with, the above-mentioned electronic signature is effective for tampering because the message digest obtained by compressing the electronic document with a hash function does not match the message digest obtained by decrypting the electronic signature. It is a means. However, even if another person impersonates the user himself, creates a digital signature using the secret key of the other person, and sends the electronic document with the corresponding public key attached, the recipient will not be able to impersonate the person using the above procedure. Can't find Therefore, it is necessary to prove that the public key belongs to the user.

For this reason, an electronic certificate issued by a certification authority (certificate authority) called CA is attached to an electronic document together with an electronic signature. This electronic certificate is obtained in advance by requesting the CA to issue it, and the data such as the issuer's identification name, the requester's public key, the validity period of the certificate, the CA's identification name, and the CA Contains the electronic signature of. The recipient of the electronic document with such an electronic certificate first verifies the validity of the CA's electronic signature using the CA's public key, and then certifies with the electronic certificate to which the electronic signature is attached. It is possible to confirm the correspondence relationship between the generated public key and the user himself. By the above procedure, it is possible to protect the electronic document to which the user's electronic signature and electronic certificate are attached from the risk of denial, spoofing, falsification, and the like.

By the way, the above-mentioned electronic signature and electronic certificate are merely electronic data, and in principle, it is not necessary to visually attach them to an electronic document. However, especially in Japan, there is a well-established culture in which a paper document is stamped with a personal seal to prove that the document was created by the person himself. Therefore, by electronically attaching the user's seal imprint image data to an electronic document with an electronic signature attached, an electronic seal stamp system has been developed that produces the same visual effect as when a self-seal is imprinted on a paper document. Already sold by the applicant company.

However, this electronic seal stamp system is a system for pasting the user's seal image data registered in the server in advance on the seal field of the electronic document, and the seal image data must be registered in advance. Further, with respect to an electronic document that is communicated in a foreign country where a handwritten signature is common, there is a problem that it is not always preferable to display a seal imprint image on the electronic document.

[0009]

SUMMARY OF THE INVENTION The present invention solves such a conventional problem and eliminates the need to register the user's imprint image data in advance, and realizes a realistic signature as a visual representation of an electronic signature. This is done in order to provide a method for signing an electronic document in which a near handwritten signature can be attached to the electronic document.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a user's electronic signature image data generated by handwriting input to a user's electronic document on an electronic document created on a terminal screen. It is characterized in that it is attached together with a signature and a digital certificate, and this handwritten signature image is displayed on a digital document as a visual representation of the digital signature. Note that handwriting input can be performed directly on the screen of a display device that displays an electronic document.

According to the method of signing an electronic document of the present invention,
The handwritten signature image created when creating the electronic document can be displayed on the electronic document as a visual representation of the electronic signature, so there is no need to register the user's imprint image data in advance, and a realistic paper The handwritten signature image can have the same effect as the handwritten signature in the document creation scene. Moreover, the electronic document itself is protected from the risk of denial, spoofing, falsification, etc. by attaching the user's electronic signature and electronic certificate as in the conventional case.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention are shown below. In FIG. 1, reference numeral 1 denotes a terminal device for creating an electronic document, which includes a display device 2 such as a liquid crystal monitor, an input device 3 such as a keyboard, a handwriting input pad 4, and the like. The display device 2 is the handwriting input pad 4
If it has a function as, the handwriting input pad 4 can be omitted. A program capable of executing the steps described below is installed in the terminal device 1. It should be noted that the terminal device 1 or the server to which the terminal device 1 is connected stores the data of the electronic certificate of the user acquired in advance from the certification authority.

As shown in the flow sheet of FIG. 2, after the electronic document is created, the user causes an event to start the electronic signature, and opens the handwriting input window as shown in FIG. 3 on the screen of the display device 2. It is preferable to provide a pen setting button in the handwriting input window so that the thickness and color of the electronically signed signature can be selected. The user uses an appropriate handwriting input device such as a mouse or a pen to make a signature by handwriting input in the handwriting input window via the handwriting input pad 4 as shown in FIG. When the screen of the display device 2 has a function as the handwriting input pad 4, the electronic document displayed on the screen of the display device 2 can be directly input so as to be signed.

It is often the case that handwriting input with a mouse or the like cannot be performed well without getting used to it. Therefore, it is preferable to provide a retry button on the handwriting input window so that rewriting can be repeated as many times as desired.
The handwritten signature of the user thus generated is input to the terminal device 1 as image data. Further, when the handwritten signature can be written successfully, it can be saved in a storage device or the like so that it can be reused at the next electronic signature. At that time, the security for reusing the saved handwritten signature is generally a mechanism that works in conjunction with a password or login information to the network, and here it is possible to choose according to the security policy of the user side. .

If the user has a single digital certificate, there is no choice, but if the user has multiple digital certificates, select the next electronic certificate. To do. The electronic certificate includes an electronic certificate issued by a CA such as Verisign, and an electronic certificate for a specific range of persons such as a CA established by a specific corporate group. Further, even the electronic certificates issued by the same CA vary in level depending on the difference in the procedure of identity verification at the time of issuance. Therefore, it is preferable that an appropriate electronic certificate can be selected according to the type of electronic document created by the user and the recipient.

Next, the electronic signature condition is set. As shown in FIG. 5, conditions such as a signer, a reason for signing, and a place of signature are set. If the previous setting is displayed as the initial value, the setting is easy.

When the signature execution button is clicked after the above settings are completed, the electronic signature and the selected electronic certificate are automatically attached to the electronic document as electronic data, and the handwritten signature image data is also attached as electronic data. To be done. At the same time, as shown in FIG. 6, this handwritten signature image is displayed in the signature field on the electronic document as a visual representation of the electronic signature. As shown in FIG. 6, properties of the digital signature (signer, reason for signing, place of signature, etc.) and details of the digital certificate (version of digital certificate, owner, email address, serial number, expiration date, signature) (Algorithms, etc.) can be called up on the screen so that the user and the recipient of this electronic document can easily confirm their contents.

FIG. 7 shows the overall structure of an electronic document signed by using the signature method of the present invention. A document body 10 and an electronic signature 11 created from the document body 10 by using the private key of the user. , Handwritten signature image data 12 handwritten by the user, and an electronic certificate 13 selected by the user. The electronic certificate 13 also includes the public key 14 of the user to be certified and the electronic signature 15 of the CA. Such electronic documents are sent to the recipient via a network such as the Internet.

The recipient first decrypts the CA's electronic signature 15 using the CA's public key to confirm the validity of the electronic certificate 13 itself, and then confirms the public key 14 of the certified sender (user).
Make sure that the sender is who they say they are. Next, using the sender's public key 14, the electronic signature 11 is decrypted to extract the message digest, and the message digest is created from the document body 10 by the hash function to determine whether the message digests match. Check if If they match, it can be confirmed that the transmitted document body 10 was created by the user himself and was not tampered with on the way. All of the above confirmation operations can be automatically performed inside the computer, and the warning can be displayed on the document only when an abnormality is detected.

Moreover, since the handwritten signature image of the sender (user) is visually displayed on the received electronic document, the receiver can feel the same feeling as a handwritten signature on a real paper document without any resistance. Can receive documents. However, in the signature method of the present invention, the handwritten signature image does not directly guarantee the legitimacy of the electronic document itself, and the function of protecting the electronic document itself from the risk of denial, spoofing, falsification, etc. is the same as the conventional one. It is owned by the user's digital signature and digital certificate. However, it is also possible to make a special agreement between the sender and the receiver and change the handwritten signature image each time it is sent.

The signature method of the present invention can be used in the form of a client-server system in which a number of terminals are connected to a server, or in a mobile environment independent of the server. When used in a mobile environment, it is preferable to use it in combination with a storage means such as an IC card that stores electronic certificate data.

[0022]

As described above, by using the signature method of the present invention, the user can paste a handwritten signature close to a real signature as a handwritten signature image on the created electronic document, and the recipient can Even foreigners will not feel any strangeness. Further, since the electronic signature and the electronic certificate are attached to the electronic document as in the conventional case, it is possible to avoid the risks peculiar to the electronic transaction such as denial, spoofing and falsification. Moreover, unlike the electronic seal stamp, the user does not need to register the seal image data in advance, and it is possible to change the handwritten signature on the spot or use it properly according to the content of the created electronic document and the recipient. .

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus used in the method of the present invention.

FIG. 2 is a flow sheet of the present invention.

FIG. 3 is a diagram showing a screen of a handwriting input window.

FIG. 4 is a diagram showing a screen in a state where handwriting is input.

FIG. 5 is a diagram showing a setting screen for electronic signature conditions.

FIG. 6 is a diagram showing a display screen of an electronic document.

FIG. 7 is a block diagram of an entire electronic document signed by the method of the present invention.

[Explanation of symbols]

1 terminal device 2 Display device 3 input devices 4 Handwriting input pad 10 document body 11 Electronic signature 12 Handwritten signature image data 13 Electronic certificate 14 User's public key Electronic signature of 15 CA

Claims (2)

[Claims] 1. A user's handwritten signature image data generated by handwriting input is attached to a digital document created on a terminal screen together with a user's digital signature and a digital certificate, and the handwritten signature image is visualized as a digital signature. A method of signing an electronic document, which is characterized by displaying it on the electronic document as a dynamic expression. 2. The method of signing an electronic document according to claim 1, wherein handwriting can be directly input on a display device screen for displaying the electronic document.