JPH1032570A - Electronic signature system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic signature system by which a electronic signature method and the length of a signature key are easily revised in a network and a plurality of users make electronic signature with security. SOLUTION: One terminal equipment 3 or over operated by the user 4 and at least one electronic signature device 1 are provided on a network 2. The electronic signature device 1 is used in common by lots of users and has a function of inter-verification among the users 4, and a function substituting the electronic signature on behalf of the users 4 after the verification is successful. A secret key required for the verification and the signature is managed in the electronic signature device 1 with security. A document given to the terminal equipment 3 by the user 4 is ciphered and sent to the electronic signature device 1 and electronic signature is conducted in the electronic signature device 1 by using the secret key of the user 4. The document subject to electronic signature is ciphered again and the resulting document is returned to the terminal equipment 3, in which the document is decoded and the user 4 obtains the plain signature text document.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic signature system for a computer system using a network.

[0002]

2. Description of the Related Art Digital signatures are used to ensure the security of information in a network. The electronic signature is also called a digital signature, and a technique using a public key cryptosystem is used.

The electronic signature processing of the public key cryptosystem is performed by a signer encrypting hash information of a document to be signed using a secret key and adding the encrypted hash information to the document. The signature is verified using the signer's public key. If the information obtained by decrypting the signature part with the public key and the hash information of the document are the same, the signer verifies the document to be signed. Has performed the electronic signature processing, and that the document to be signed has not been tampered with.

A digital signature using the RSA encryption method, a digital signature using the E-SIGN encryption method, and an ELG
There is one using an amal encryption method. In either method, the length of the secret key used for the digital signature is variable and the encryption strength of the digital signature can be changed (for details, see Hideki Imai, "Cryptography").
Please refer to Japan Standards Association. ).

Conventionally, the electronic signature processing is performed by a program running on a user terminal (hereinafter referred to as a terminal), or transmitted to a user terminal through an RS232C interface, a PCMCIA slot, another expansion slot, or the like. IC card or PCMCI directly connected
This is performed by an electronic signature device such as an A card.

[0006]

When performing a digital signature process using a program running on a user's terminal, it is necessary to store the user's private key in the terminal. Therefore,
Particularly, in an environment where a plurality of persons use one terminal, there is a risk that each person's private key may be copied to another person.

On the other hand, when performing an electronic signature process using an electronic signature device directly connected to the terminal, the secret key is managed so that the electronic signature device cannot be accessed from outside, so that the private key can be copied to another person. You can prevent the danger of losing. However, in this method, since an electronic signature processing device must be individually provided for each terminal, the entire terminal becomes expensive. In addition, when an electronic signature device is individually provided for each terminal, when an attempt is made to change the electronic signature method or change the length of a key used for signature in the entire network, this cannot be easily performed. Furthermore, an electronic signature device for each terminal, for example, an IC card or PCMCIA
In the case of cards, etc., in terms of cost and mountable specifications,
It is difficult to support a plurality of electronic signature schemes or to have a function of making a secret key variable, and it is also difficult to provide a processing capability for performing electronic signature processing at a sufficiently high speed.

[0008] The digital signature is a technology based on the encryption technology, but the encryption is relatively easily decrypted as the processing speed of the computer increases. For this reason, the secret key used for digital signatures must be lengthened with the times, and in the near future, a digital signature device that cannot change the length of the private key will require a new digital key corresponding to a longer secret key. You will have to replace it with a signature device. On the other hand, if a long key is used from the beginning so that the same digital signature device can be used safely for a long time to a distant future, the processing time is insufficient and the time required for the digital signature processing becomes long, and the practicality is lacking. .

Further, with the progress of encryption technology, a defect may be suddenly discovered in a certain electronic signature scheme in the future. In such a case, it is necessary to change the electronic signature devices of all the terminals at the same time, and the maintenance cost becomes enormous.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electronic signature system in which it is easy to change an electronic signature method in a network or change the length of a key used for signature.

Another object of the present invention is to make it possible for a plurality of users to use one electronic signature device safely, and to reduce the cost per user and the cost of the entire system.

[0012]

According to the present invention, a user terminal and an electronic signature device are provided as separate devices on a network. The electronic signature device can be shared by a plurality of users, can collectively manage secret keys for the electronic signatures of the plurality of users, and responds to each user's request from the terminal, Acts for signature processing for each user.

Since the user's terminal and the digital signature device are different devices on the network, mutual authentication is performed between each user who operates the terminal and the digital signature device before executing the signature processing. It is desirable.

It is desirable that the information communicated between the electronic signature device and the terminal via the network during the authentication process and the signature process be encrypted.

In the system of the present invention, it is easy to use an expensive, high-performance, highly secure dedicated device as an electronic signature device. Therefore, the private key of each person is securely stored in the electronic signature device, and the signature processing is performed at high speed and in a short time in the electronic signature device, so that it is possible to cope with a plurality of signature methods and a variable-length private key. It is easy.
In addition, it is easy to change the signature method and the key length in the entire network.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram of an electronic signature system according to an embodiment of the present invention. In FIG. 1, a digital signature device 1 and a terminal 3 are connected to a network 2 respectively. In FIG. 1, one electronic signature device 1 and one terminal 3
Although only shown, a plurality of digital signature devices 1 and a plurality of terminals 3 can exist on the network 2. In particular, there are usually many terminals on a network. Each terminal 3 may be dedicated to one user or shared by a plurality of users. Each digital signature device 1 can be used by one or more (usually plural or many) users registered in advance. Hereinafter, a case where one user 4 uses one terminal 3 and uses one registered electronic signature device 1 will be described. It goes without saying that the present invention can be applied to a set of a user, a terminal, and an electronic signature device.

The digital signature device 1 has a user 4
The unique information (that is, identification (ID), authentication key, and signature key, which will be described later) of a plurality of predetermined persons is registered, and this unique information is used only inside the electronic signature device 1 and is It cannot be read out from the signature device 1.
The electronic signature device 1 is programmed with a plurality of types of electronic signature schemes (for example, an RSA encryption scheme, an E-SIGN encryption scheme, and an ELGamal encryption scheme), and externally specifies the scheme type. , An arbitrary type of digital signature scheme can be selected. In either method, the length of the key used for the signature is variable.

The user 4 can use the terminal 3 to request the digital signature device 1 via the network 2 for digital signature processing. The electronic signature device 1 performs an electronic signature process for the user 4 in response to the request from the user 4. The document information subjected to the signature processing by the electronic signature device 1 is returned to the terminal 3 via the network 2 again, and the user 4 obtains the electronic signature document.

Since the terminal 3 operated by the user 4 and the digital signature device 1 exist as separate devices on the network 2, the digital signature device 1 and the user 4 perform mutual authentication and perform mutual authentication. Only when the authentication is successful, the digital signature device 1 executes a digital signature process for the user 4.

FIG. 2 is a functional block diagram of the digital signature device 1.

As shown, the digital signature device 1 includes a communication unit 201, an authentication unit 202, an encryption unit 204, and a decryption unit 20.
5, a signature unit 206, an authentication key storage unit 203, and a signature key storage unit 207. The communication unit 201 executes a communication protocol of the network 2. The authentication unit 202 performs mutual authentication with the user 4. The authentication key of the user 4 is associated with the ID of the user 4 and stored in the authentication key storage unit 2.
03 is registered. The signature unit 206 performs an electronic signature process for the user 4. The signature key of the user 4 is associated with the ID of the user 4 and the signature key storage unit 207.
Registered in. A unique key is prepared for each signature scheme type, such as a key for the RSA encryption scheme, a key for the E-SIGN encryption scheme, and the like. And registered in the signature key storage unit 207. The encryption unit 204 and the decryption unit 205 are in charge of encryption and decryption processing using keys in authentication and signature processing.

The operation of the digital signature device 1 and the terminal 3 will be described below. The overall operation is divided into two phases, an authentication process and a signature process. FIG. 3 shows a processing sequence between the digital signature device 1 and the terminal 3 in the authentication process. FIG. 4 shows a sequence of a signature process performed subsequent to the authentication process.

First, the authentication process will be described with reference to FIGS.

Here, a challenge-response method using a common key encryption method using DES type encryption or FEAL type encryption is used as the authentication method. Challenge-response authentication using a common key encryption method means that a subject A (for example, a user) and a subject B (for example, a digital signature device) that perform authentication secretly have the same encryption key for authentication. The subject A generates a random number (challenge code) and sends it to the subject B. Upon receiving the random number, the subject B encrypts the random number with the secret key for authentication and sends it back to the subject A (the encrypted random number is sent to the response Code). The subject A encrypts the transmitted random number (challenge code) with a secret key for authentication and compares it with the encrypted random number (response code) sent from the subject B. If this is the same, subject A can authenticate that subject B has the same key as subject A. This is a mechanism in which the subject B can perform mutual authentication by performing the same authentication process on the subject A.

As shown in FIG. 3, the user 4 inputs a user ID and a user authentication key to the terminal 3 (30).
1). The terminal 3 independently generates a random number and sets it as a challenge code A (302). Then, the ID of the user 4 and the challenge code A are transmitted to the electronic signature device 1 (30).
3).

The electronic signature device 1 receives this in the communication unit 201 and passes it to the authentication unit 202. The authentication unit 202 passes the ID of the user 4 to the authentication key storage unit 203. Authentication key storage 2
03 extracts the authentication key of the user 4 based on the ID of the user 4 and passes it to the authentication unit 202. The authentication unit 202 transmits the challenge code A to the user 4 using the encryption unit 204.
And the response code A (304).

Further, the authentication unit 202 independently generates a random number and uses it as a challenge code B (305). The authentication unit 202 generates another random number, uses it as a communication key, passes it to the encryption unit 204 and the decryption unit 205, and then encrypts the communication key with the authentication key of the user 4 ( 306). The authentication unit 202 passes the response code A, the challenge code B, and the encrypted communication key to the communication unit 201. The communication unit 201 transmits the response code A, the challenge code B, and the encrypted communication key to the terminal 3 (307).

The terminal 3 compares the result of independently encrypting the challenge code A with the authentication key of the user and the received response code A, and if both are the same, the electronic signature device 1 is authenticated. , And if they are different, the communication is terminated as an authentication failure (308).

Terminal 3 that has authenticated electronic signature device 1 as valid
Next, the challenge code B is encrypted with the user's authentication key to obtain a response code B (309). Then, the response code B is transmitted to the electronic signature device 1 via the network 2 (310).

In the electronic signature device 1, the communication unit 201 receives the response code B and passes it to the authentication unit 202. The authentication unit 202 encrypts the challenge code B with the authentication key of the user and compares it with the response code B. If both are the same, the authentication process ends normally as mutual authentication succeeds,
If they are different, the communication is terminated as an authentication failure (31
1).

Next, the digital signature processing will be described with reference to FIGS.

When the authentication process is completed normally, the user 4 subsequently (or in advance) specifies a document to be subjected to an electronic signature (target document) and a type of electronic signature scheme to be used (scheme type). Input to the terminal 3 (401). The terminal 3 decrypts the encrypted communication key received in the authentication process with the authentication key of the user 4, and encrypts the ID of the user 4, the target document, and the scheme type using the communication key. (402), and sends the digital signature device 1 via the network 2.
(403).

In the electronic signature device 1, the communication unit 201 receives the information and passes it to the decryption unit 205. Decoding section 205
Decrypts this information using the communication key (40
4), pass it to the signature unit 206. The signature unit 206 passes the ID and scheme type of the user 4 to the signature key storage unit 207. The signature key storage unit 207 extracts the signature private key of the user 4 based on the received user ID and scheme type, and passes it to the signature unit 206.

The signature unit 206 performs an electronic signature process of the designated scheme type on the target document received from the terminal 3 using the signature private key (405). The signature unit 206 passes the digitally signed document to the encryption unit 204. Encryption unit 2
04 encrypts the received document using the communication key (406) and passes it to the communication unit 201. The communication unit 201 transmits the encrypted digital signature document to the terminal 3 via the network 2 (407).

The terminal 3 decrypts the received encrypted digital signature document with the communication key (408), so that the user 4 obtains a digitally signed plain text document. This completes the electronic signature processing.

The electronic signature device 1 executes the above-described electronic signature processing for a plurality of users registered therein. The unique information of each user is managed in the electronic signature device 1 so as not to leak to the outside, and the authentication process is always performed before the signature process, so that a plurality of users can perform the electronic signature safely. be able to.

Since one electronic signature device 1 can handle a large number of users, the cost per user and the cost of the entire system can be reduced. On the other hand, it is necessary to provide a high-performance electronic signature device that is highly secure in terms of key management and the like, can handle a plurality of signature schemes and variable-length keys, and can complete signature processing in a short time at high speed. Easy. Furthermore, when changing the network signature method or changing the key length, it is only necessary to perform the change for a small number of electronic signature devices, and it is not necessary to perform the change for each terminal, so such a change is easy. .

The electronic signature device 1 can be realized by a programmed computer. The program may be provided to the computer by a medium that fixedly holds information, such as a disk storage device or a semiconductor storage device, or may be provided to the computer by a medium that dynamically stores information, such as the network 2. You may.

It should be noted that the present invention is not limited to the above-described embodiment, but can be implemented in various other forms with various changes, improvements, and modifications.

[Brief description of the drawings]

FIG. 1 is a system diagram of an electronic signature system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing functions of the electronic signature device.

FIG. 3 is a sequence diagram of an authentication process performed between the electronic signature device and a terminal.

FIG. 4 is a sequence diagram of an electronic signature process performed between the electronic signature device and the terminal.

[Explanation of symbols]

 Reference Signs List 1 electronic signature device 2 network 3 terminal 4 user 201 communication unit 202 authentication unit 203 authentication key storage unit 204 encryption unit 205 decryption unit 206 signature unit 207 signature key storage unit

Claims (8)

[Claims] 1. At least one terminal device connected to a network and operated by a user, and at least one electronic signature device connected to the network, wherein the electronic signature device includes a plurality of electronic signature devices. A signature key storage unit capable of registering a signature key of each user, and a signature key of each user registered in the signature key storage unit in response to a request of each user from the terminal device. And a digital signature means for performing a digital signature process for each user by using the digital signature system. 2. The electronic signature system according to claim 1, wherein the electronic signature device further includes an authentication unit for performing mutual authentication with each user operating the terminal device. An electronic signature system, wherein the electronic signature means substitutes an electronic signature process for each user only when mutual authentication with each user is successful. 3. The electronic signature system according to claim 1, wherein said electronic signature means is programmed with a plurality of electronic signature schemes, and said plurality of electronic signature schemes can be selected. . 4. The electronic signature system according to claim 1, wherein the signature key storage unit and the electronic signature unit can correspond to a variable length of the signature key. 5. A communication means for communicating via a network with a terminal device operated by each user, a signature key storage means capable of registering signature keys of a plurality of users, Electronic signature means for performing electronic signature processing for each user by using a signature key of each user registered in the signature key storage means in response to a request of the user; An electronic signature device, comprising: 6. The electronic signature device according to claim 5, further comprising an authentication unit for performing mutual authentication with each user who operates the terminal device, wherein the electronic signature unit is configured to use each of the user devices. An electronic signature device for performing electronic signature processing for each user only when mutual authentication with a user is successful. 7. A method in which an electronic signature device connected to a network substitutes for an electronic signature process of each user, the method comprising: communicating with a terminal device operated by each user via the network; Responding to each user's request from the device and using a pre-registered signature key for each user to perform electronic signature processing on behalf of each user. An electronic signature method comprising: 8. A program medium for providing, to a computer connected to a network, a program for performing an electronic signature process for each user, comprising: a terminal device operated by each user; And performing electronic signature processing for each user by using a pre-registered signature key of each user in response to a request of each user from the terminal device. And an instruction group for causing a computer to execute the steps in a computer readable and understandable form.