JP2003069561A - User authentication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct secure authentication with less communication. SOLUTION: An in-house server 12 sends in offline an electronic certificate including a public key and a user ID to an out-of-house device 20. When the out-of-house device 20 accesses the in-house server 12, it takes the public key from the electronic certificate and signs electronically on an electronic certificate C including the user ID by the public key to supply it to the in-house server 12. The in-house server 12 identifies and decrypts the public key from the user ID. According to this arrangement, the out-of-house device 20 can be authenticated. In addition, the out-of-house device 20 transmits data in which the user ID is encrypted by its own specific key during the previous communication. The in-house server 12 encrypts the received data and returns it to the out-of- house device 20. According to this arrangement, the in-house server 12 can be also authenticated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a user authentication system when a client and a server communicate with each other via an external communication network.

[0002]

2. Description of the Related Art Conventionally, as a user authentication system,
Various things are used. The following are typical ones.

(I) Password method: A user is authenticated by inputting a password registered in advance.

(Ii) Challenge-response method one-time password: The authentication side presents a random number sequence, and the authentication requester performs "operation / conversion" unique to the user on this random number sequence and sends back the resulting value.

(Iii) User authentication method using common key cryptosystem: Communicating parties store a common key,
Authentication is performed using this common key. This method is disclosed in, for example, Japanese Patent Laid-Open No. 5-344117.

(Iv) User authentication method using public key cryptosystem: Each terminal distributes a public key for encrypting information addressed to itself. Then, the predetermined data encrypted with the public key of the communication partner is transmitted, and this is decrypted with the corresponding private key. This public key cryptosystem is based on PKI (Public).
Key Infrastructure: Public key infrastructure)
Is becoming more and more popular.

[0007]

As described above, a larger number of conventional authentication systems are known. Among them, the common key cryptography is an efficient authentication method if the condition that the common key can be shared in advance is satisfied.

[0008] However, in this common key method, first, the self ID is transmitted when communication is started, and thereafter, the other party is authenticated by using the common key. Therefore, it is necessary to perform communication for ID transmission and mutual authentication, and even if data for a plurality of purposes are transmitted at the time of communication, the mutual authentication requires at least three times of communication. In particular, the conventional method is premised on that communication terminals are apart from each other, and if not, there is a possibility that more efficient authentication can be performed.

[0009] For example, in a system such as remote control of home appliances from outside the home, the remote control terminal (client) is in the home when the user is at home. Therefore, the client and the server controlling the home device can be directly connected to each other without using an external communication network.

An object of the present invention is to provide an appropriate user authentication system in an environment where direct communication is possible.

[0011]

SUMMARY OF THE INVENTION The present invention is a user authentication system when a client and a server communicate via an external communication network, in which a common key generated in the server and user identification information are stored in the external communication network. Pass it directly to the client without going through, and when the client accesses the server through the external communication network,
The user identification information and an electronic certificate containing an electronic signature encrypted with the common key are sent to the server, and the server refers to the table stored by the user identification information and receives the common key. Is specified, the digital certificate is decrypted based on the specified common key, and the client is authenticated.

As described above, according to the present invention, the user identification information and the common key are directly passed to the client without using the external communication network. Therefore, the client can easily recognize the user by supplying the user identification information and the electronic certificate including the electronic signature to the server by using the common key. In particular, if the client is a mobile terminal and the server is a home server, the mobile terminal is carried when the user goes out, but the mobile terminal is also at home when the user is at home.
Therefore, direct data transfer is basically possible, and such a system is very suitable.

The user identification information is the user ID initially set stored in the server, encrypted with the server unique key, and the server obtains the user identification information based on the server unique key. It is preferable that the user ID is decrypted to obtain the user ID, and the common key is specified using the user ID.

By thus encrypting with the server unique key, it is possible to prevent erroneous recognition from occurring when erroneous access is made to a different server.

Further, the client transmits information obtained by encrypting the user identifying information with a user unique key to the server, the server encrypts the received information with a common key and returns it, and the client uses the common key as a reply. It is preferable to authenticate the server by decrypting based on the above. This allows mutual authentication.

Further, it is preferable that the server updates the user ID with a new one when receiving the user specifying information from the client. This makes it possible to deal with spoofing due to wiretapping of communications.

Further, it is preferable that the server encrypts the updated user ID with a common key and supplies the encrypted user ID to the client. This makes it possible to deal with the case where the user ID is stolen by communication.

[0018]

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 diagram showing the overall configuration of the system. An in-home server 12 including, for example, a computer having a communication function is installed in the home 10. In addition, the home network 1 includes a home network 1
An in-home device 16 is connected via 4. The in-home device 16 is an electronically controllable device such as an air conditioner, a television, a video device, an audio device, a personal computer and a digital camera, and a plurality of devices can be connected. And
The home server 12 controls the connection of these home devices 16 to the external network 30. In addition, each home device 1
Basically, 6 can be manually operated individually.

An external device 20 is connected to the home server 12 of the home 10 via an external network 30. The external network is a network using a public line such as the Internet. The out-of-home device 20 is a terminal device carried by the user, and is preferably a mobile phone, a PDA (Personal Digital Assistant), or the like.

Further, the home server 12 of the home 10 is provided with an interface 18, and the external equipment 20 is directly connected to the interface 18 so that data can be exchanged without passing through the external network 30. Has become.

With this configuration, when the user carries the out-of-home device 20 and goes out, he / she connects to the home server 12 of the home 10 through the external network 30 from outside to perform various operations of the home device. Can be controlled. Also, when the user is at home, the out-of-home device 20 is connected to the interface 18 of the home server 12, and direct communication is performed between the out-of-home device 20 and the home server 12.

FIG. 2 shows a functional block diagram of the home server 12. The user ID generation unit 12c generates a user ID for the user by performing a predetermined operation. Further, the common key generation unit 12d generates a common key E _KK for the generated user ID. Then, the user ID and the common key E _KK
Are stored in the user ID common key storage unit 12f in association with each other. Further, the user ID updating unit 12a updates the user ID each time the user is authenticated.

The electronic certificate issuing unit 12g issues an electronic certificate from the common key E _KK and the user ID (user identification information). Further, at this time, the user ID is encrypted by the server unique key E _SK supplied from the server unique key generating unit 12e. That is, the user ID (user identification information) included in the electronic certificate is the user ID encrypted with the server unique key E _SK .

Data comparison unit 12h for client authentication
Decrypts the electronic signature of the electronic certificate sent from the out-of-home device with the common key EKK associated with the user ID stored in the user ID common key storage unit 12f, and issues the electronic certificate. Authenticate the client by comparing with the digest of the digital certificate generated in 12g.

Further, the server authentication data encryption unit 12b.
Encrypts the server authentication data sent from the client with the common key.

FIG. 3 shows a functional block diagram of the external device 20. The client authentication digital certificate issuing unit 20a generates data for server authentication. This server authentication data is obtained by encrypting the user ID issued by the home server 12 with the server unique key E _SK , and further encrypted with the client unique key E _RK generated by the client unique key generating unit 20d.

The server authentication data comparison unit 20c compares the server authentication data sent from the home server 12 with the common key to obtain the correct server authentication data.

Next, the operation of such a system will be described with reference to the flow charts and sequence diagrams shown in FIGS.

First, as shown in FIG. 4, the home server 1
In 2, the user ID is set (S101). This is done by the user operating the home server 12. As a result, in the user ID generation unit 12c, the user ID
Is set. Next, the common key generation unit 12d generates a common key E _KK corresponding to the set user ID (S10).
2). This common key is usually a random number, and various conventionally known methods are used for this generation. And
The generated user ID and common key E _KK are stored in the user ID common key storage unit 12f (S103).

Next, the electronic certificate issuing unit 12g sends the user I
D is the server unique key E _SK from the server unique key generating unit 12e
Then, the user ID is encrypted to obtain E _SK (user ID), and the common key E _KK is attached to this to issue an electronic certificate (S104).

Then, the obtained electronic certificate is used as the outside device 2
It is copied to 0 (S105). Where this copy is
The external network 30 is not used. That is, when the user is at home 10, the external device 20 is connected to the home 10
It is in. Therefore, the user directly connects to the interface 18 which is one of the connecting means of the home server 12 at home 10 and copies the electronic certificate. For example, it may be communication via the home network 14.

For example, when the user goes out, it is preferable that the copy in S105 is automatically executed by connecting the external device 20 and the interface 18. Further, it is preferable that the copied electronic certificate has an expiration date, and it is also preferable that the expiration date can be set by the user. It should be noted that the method of copying the electronic certificate may be any method as long as it is not communication through the external network.

In this way, the user carries out the out-of-home device 20 storing the electronic certificate and goes out. The user uses the out-of-home device 20 and the in-home device 16 of the home 10
Mutual authentication is performed as follows when operating.

First, as shown in FIG. 5, the common key E _KK is taken out from the copied digital certificate in the outside device (client) 20 (S201). Then, to create a digital certificate C was performed digital signature by the common key E _KK for portions client authentication for electronic certificate issuing unit 20a is removed symmetric key E _KK (S202). The electronic certificate C is a user ID E encrypted with the server unique key E _SK included in the electronic certificate.
Include _SK (User ID).

Furthermore, in the outside device 20, the server authentication
The certificate data creation unit 20b creates server authentication data.
(S203). That is, the server authentication data creation unit
Is the server unique key E included in the digital certificate_SKEncrypted with
User ID E_SKClient (user ID)
Client unique key E generated by the unique key generation unit 20d _RK
Server authentication data E encrypted with_RK(E_SK(User I
D)) is created.

Then, the created electronic certificate C and the server authentication data E _RK (E _SK (user ID)) are transmitted to the home server 12 (S204). It should be noted that although FIG. 6 describes the transmission of two data separately, the two transmissions indicated by (ii) in the figure are performed simultaneously.

In the home server 12, the received
Digital certificate C to E_SKRetrieve (user ID) (S2
05). And this E_SK(User ID) is unique to the server
Key E _SKDecryption is performed to obtain the user ID (S206).

Next, the user I is obtained from the obtained user ID.
Referring to the D common key storage unit 12f, the common key E of the user
_KK is specified (S207). Then, in the client authentication data comparison unit 12h, the specified common key E _KK
Then, the electronic signature is decrypted to authenticate the electronic certificate C. That is, the client is authenticated by confirming that the electronic signature of the electronic certificate C is signed by the common key E _KK (S208).

On the other hand, the user ID updating unit 12a updates the user ID to a new user ID ', and the updated user ID' is encrypted with the server unique key E _SK and further with the common key E _KK. (S209). By this, E
_KK (E _SK (user ID ')) is obtained. By updating the user ID in this way, spoofing due to eavesdropping can be dealt with. Furthermore, since it is encrypted with the common key E _KK , the user ID 'will not be stolen even if the information obtained in S209 is sent to the client. The user ID in the home 10 may be updated to the user ID ', but it may be left as it is without being updated. However, the data in the user ID common key storage unit 12f needs to be updated.

Further, the server authentication data encryption unit 12b.
Is the E received from the client _RK(E_SK(User I
For D)), the common key E_KKEncrypt with (S21
0).

Then, the home server 12 uses the E _KK (E _SK
(User ID ')) and server authentication data E _KK (E _RK (E _SK (user ID))) encrypted with the common key E _KK are transferred to the client (S211). In FIG.
The two pieces of information described in (iii) are transferred at the same time.

The server authentication data comparison unit 20c of the client decrypts the server authentication data E _KK (E _RK (E _SK (user ID))) encrypted from the information from the server with the common key E _KK. Confirm (S212). In addition, the received E _KK (E _SK (user ID ') is decrypted with the common key E _KK ,
E information to be used in client authentication for electronic certificate issuing unit 20a from E _SK (user ID) _SK (user I
D '), and the electronic certificate C issued individually is updated (S213).

As described above, the present embodiment provides the user authentication method based on the common key encryption method. The features are summarized below.

(I) An electronic certificate similar to the public key certificate used in the public key cryptosystem is used. Here, at least, the user ID encrypted with the server unique key and the common key used between the user and the user are included. The reason why the user ID is encrypted with the server unique key is to confirm whether the certificate was sent to a different server.

(Ii) Further, the home server 12 issues this electronic certificate and provides it offline to the device taken out of the house. That is, the digital certificate is provided by direct connection. In this way, by providing the issued electronic certificate to the out-of-home device offline, user authentication between the out-of-home device and the in-home server can be realized in two communications.

(Iv) The home server 12 is the out-of-home device 20
In the client authentication for authenticating, the remote device 20 removes the common key from the electronic certificate obtained off-line, sends the signature with the common key to the home server 12, and the home server 12 receives the received electronic certificate. From the user ID
Then, it is used as a key to find a common key for users, and the signature is decrypted to confirm the client's legitimacy.
Therefore, the common key can be used to efficiently authenticate the client.

(V) The home server 12 updates the user ID for the next user authentication in order to prevent eavesdropping on the communication and spoofing. Further, the updated user ID is encrypted with the unique key of the server, encrypted with the common key, and passed to the client. Since it is encrypted with the common key, it is possible to effectively prevent the user ID used by the home server from leaking.

(Vi) In the server authentication seen from the client, the user ID encrypted with the server unique key is regarded as a keyword for authenticating the user ID encrypted with the client unique key, and this is sent to the home server 12. The home server 12 encrypts this with a common key and returns it to the client. The client decrypts this and compares it with what it sends to authenticate the server. By using the client unique key, forgery of communication by only the home server 12 can be prevented.

In the above description, the encrypted key is used for decryption, but a decryption key that forms a pair with the encryption key may be used for decryption.

Further, in this embodiment, the common key is changed every time the electronic certificate is issued offline, but it is not always necessary to change it.

[0052]

As described above, according to the present invention,
Pass the user identification information and common key directly to the client without using the external communication network. Therefore, the client can easily recognize the user by supplying the user identification information and the electronic certificate including the electronic signature to the server by using the common key. In particular, if the client is a mobile terminal and the server is a home server, the mobile terminal is carried when the user goes out, but the mobile terminal is also at home when the user is at home. Therefore, direct data transfer is basically possible, and such a system is very suitable.

Further, by using the user identification information in which the user ID is encrypted with the server unique key, it is possible to prevent erroneous recognition from occurring when erroneous access is made to a different server.

Further, when the server receives the user identification information from the client, the server updates the user ID to a new one, so that the server can cope with spoofing due to wiretapping of communication.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a system.

FIG. 2 is a functional block diagram of a home server.

FIG. 3 is a functional block diagram of an external device (client).

FIG. 4 is a flowchart showing a procedure for issuing a digital certificate.

FIG. 5 is a flowchart showing a mutual authentication procedure.

FIG. 6 is a diagram showing a procedure of mutual authentication.

[Explanation of symbols]

10 home, 12 home server, 14 home network, 16 home equipment, 18 interface, 20
Out-of-home equipment, 30 external network.

Claims (5)

[Claims] 1. A user authentication system for communication between a client and a server via a communication network, wherein a common key and user identification information generated in the server are directly passed to the client without passing through an external communication network. When the server accesses the server through the external communication network, it sends the user identification information and the digital certificate containing the electronic signature encrypted with the common key to the server, and the server receives the user identification information from the received user identification information. A user authentication system that refers to a stored table to identify a common key, decrypts a digital certificate based on the identified common key, and authenticates the client. 2. The system according to claim 1, wherein the user identification information is an initially set user ID stored in the server encrypted with a server unique key, and the server is unique to the server. A user authentication system that decrypts user identification information based on a key to obtain a user ID, and uses this user ID to identify a common key. 3. The system according to claim 1, wherein the client further transmits information obtained by encrypting the user identification information with a user unique key to the server, and the server receives the received information as a common key. A user authentication system that authenticates the server by decrypting based on a common key, and then replying after encrypting with. 4. The user authentication system according to claim 1, wherein the server updates the user ID with a new one when the user identification information is received from the client. 5. The user authentication system according to claim 4, wherein the server encrypts the updated user ID with a common key and supplies the encrypted user ID to the client.