JPH03131139A - Key management system for cryptographic key - Google Patents

Abstract

PURPOSE:To realize the cryptographic processing in the unit of users by providing a user key for each user in addition to a master key and a data key and applying the cryptographic processing based on the user key. CONSTITUTION:A master key secret key 10 is stored safely in a cryptographic device 2. A master key open key 11 is stored in a host computer 1. As user keys for users A, B, C,...Z, a user A secret key 20 and a user A open key 30, a user B secret key 21 and a user B open key 31, a user C secret key 22 and a user C open key 32,... a user Z secret key 23 and a user Z open key 33 are generated, the user secret keys 20, 21, 22, 23 are ciphered by the master key open key 11 and stored in the host computer 1 and the user open keys 30, 31, 32, 33 are as they are stored in the host computer 1 and a terminal equipment 3. Moreover, the user secret key 24 of the user of a terminal equipment 3 is stored in an IC card 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a key management system for encryption keys used for data encryption and data authentication.

[Conventional technology]

Encryption keys are used for data encryption and data authentication.

Conventionally, this encryption key consists of a master key, a terminal part or file key, and a data key, and commonly used encryption is generally used for each key. A terminal key or file key is encrypted and kept secret using a mask key, a data key is encrypted and kept secret using a terminal key or a file key, and data is kept secret using a data key. As a result, the security of the key is protected by the master key. Furthermore, encryption processing is performed on a terminal processing basis and on a file basis. Data authentication is performed using commonly used cryptography.

Regarding the key management system for this type of conventional conventional cryptography, for example, D.W., Davies, W.

"Network Security" by L. Price
Discussed on pages 133-159 (published by Nikkei McGraw-Hill).

[Problem to be solved by the invention]

The above conventional technology has the following problems.

(1) The method of key management for file encryption and data communication encryption consists of two keys: a file key and a terminal key, and management is complicated.

(2) File keys and terminal keys must be held by multiple computers, and there is a possibility that the keys may be stolen during key distribution.

(3) Public digital authentication cannot be performed using conventional cryptography.

(4) Data communication encryption is based on the terminal key. For this reason, even when multiple users use the same terminal, the terminal keys will be the same, reducing security against encryption.

An object of the present invention is to provide a key management system for encryption keys that solves the above problems.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a user key for each user in addition to a master key and a data key, and performs cryptographic processing on a per-user basis by performing cryptographic processing based on the user key. It is characterized by

Furthermore, the present invention is characterized in that a public key encryption is used for the master key, a public key encryption is used for the user key, and a conventional encryption is used for the data key.

[For production]

By providing a user key for each user, the generated data key is kept secret with the user key when starting data communication encryption or file encryption. Thereby, both data communication encryption and file encryption can be processed based on the user key.

Since the master key is public key cryptography, when registering a user key on multiple computers, it can be encrypted and registered using the public key of each computer's master key.

As a result, even if the key is stolen during delivery, it will not be deciphered because it is encrypted. Each computer can decrypt it using its own masked private key.

Since the user key is public key cryptography, public digital authentication for each user is possible.

Since encryption processing is performed based on user keys, even if multiple users are using one host computer or terminal device, encryption processing can be performed using a different key for each user.
Safety can be increased.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a system configuration diagram of an embodiment of the present invention. The host computer 1 is connected to an encryption device 2, a terminal device 3, and a magnetic tape device 4, and an IC card 5 is inserted into the terminal device 4. Here, R8A encryption (public key encryption) is used as the master key, R3A encryption is used as the user key, and DES is used as the data key.
Suppose that a cipher (common cipher) is used.

The master key private key 10 is securely stored within the cryptographic device 2. The master key public key 11 is within the host computer 1.

The user keys are for users A, B, and C.

...User A private key 20 and user A public key 30 for each Z
, user C private key 21 and user B public key 31, user C
A private key 22, a user C public key 32, . . . a user C private key 23, and a user 2 public key 33 are created, and the user private key 2
0, 21, 22, 23 are encrypted with the master key public key 11 and stored in the host computer 1, and the user public keys 30, 3 are encrypted with the master key public key 11 and stored in the host computer 1.
1, 32, and 33 are stored in the host computer 1 and the terminal device 3 as they are. Also, stored in the IC card 5 is a user secret key 22 of the user of the terminal device 3 (user C is assumed in this embodiment). data key α
30. The data key β31 is randomly created by the host computer 1 when the need arises, and is encrypted with the user public key of the user of the data key.

First, the processing procedure of data communication encryption will be explained using FIG. When a data communication request is made from the terminal device 3 to the host computer 1, the host computer 1 first sends a random number 10.
2, a data key α40 is created. Next, the user C is determined from the user ID 101 sent from the terminal device 3, and the R8A of the data key α4o is determined using the public key 32 of the user C.
Encryption 103 is performed to create ciphertext 104. The host computer 1 sends this ciphertext 104 to the terminal device 3.

The terminal device 3 performs R8A decryption 105 on the ciphertext 104 using the user C private key 24 stored in the IC card 5, and obtains the data key α40. As a result, the host computer 1 and the terminal device 3 share the data key α40. Transmission data 1 from host computer 1 to terminal device 3
06, the host computer 1 transmits the main transmission data 106.
is DES-encrypted 107 using the data key α40 to create a ciphertext 108, which is transmitted to the terminal device 3. The terminal device 3 performs DES decryption 109 on the ciphertext 108 using the data key α40 to obtain received data 106. The same applies when transmission data 110 is sent from the terminal device 3 to the host computer 1.

Next, the file encryption processing procedure will be explained using FIG. When encrypting data to be stored in a file, first, from the user ID 210 of the owner of the file, the public key 30 of the user (assumed to be user A in the example)
seek. Next, a data key β41 is created using a random number 201, R8A encryption 202 is performed using the public key 30 of user A, and the encrypted data key 203 is written to the magnetic tape device 4. Next, the plaintext data 204 to be stored in the file is DES-encrypted 205 using the data key β41.
Similarly, when decrypting a file by writing the encrypted data 206 to the magnetic tape device 4, the data 206 is encrypted using the mask key public key 11 from the user ID 210 of the owner of the file. User A's private key 2
Find 0. Next, the mask key private key 1 in the encryption device 2
0 is used to perform R8A decryption 211 and obtain a user secret key 212. Next, read the encrypted data #203 from the magnetic tape device 4 and store it as a user secret.
212 to R8A decryption 207 and data key β41
get. Next, the encrypted data 206 is read from the magnetic tape device 4, and DES decryption 208 is performed using the data key β41 to obtain plaintext data 204.

Next, the procedure for data authentication will be explained using FIG. 4. It is assumed that a certificate is created using the terminal device 3, authenticated and sent to the host computer 1, and verified by the host computer 1.

First, the certificate 301 is compressed 302 in the CBC mode of DES encryption using the terminal device 11ffi3, and the compression code 3
Next, the compressed code 303 is RSA encrypted using the private key 306 of the user (assumed to be user B in this embodiment) in the IC card 5, and an authentication code 305 is created. Terminal device 4 receives this certificate 301 and authentication code 305
is sent to host computer 1. Host computer 1 has certificate 31
1 is again compressed 312 to create a compressed code 313.

At the same time, the user B's public key 31 is obtained from the user ID 307 of the authenticated user, and the authentication code 314 sent from the terminal device 3 is sent to R8 using the user public key 31.
Perform A decoding 315 and create compressed code 31
6 and the previously obtained compressed code 313, and if they match, it is considered to have been correctly authenticated.

In this way, according to this embodiment, both the data communication encryption procedure and the file encryption procedure can conceal the data key based on the user key. Therefore, the procedures for data communication encryption and file encryption are similar.

Also, the user key private key on the host computer 1 is.

Encrypt and register using mask key public key. Therefore, the key cannot be stolen during key registration.

Further, the user secret key on the terminal device 3 side is stored in the IC card 5. Therefore, even if the terminal device 3 is used by a plurality of users, the security of the user private key is guaranteed because each user has an IC card.

Furthermore, since the user key is R8A encryption, digital authentication is possible for each user.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the following effects can be obtained.

(1) By using a user key, data communication encryption and file encryption can be performed using the same key management.

(2) Since the master key is public key cryptography, when registering a user key, it can be encrypted and registered using the master key public key. Therefore, there is no fear that the user key will be stolen, and it is also possible to easily register the user key in multiple host computers.

(3) Since the user key is public key cryptography, digital authentication is possible for each user.

(4) Since cryptographic processing is performed based on user keys, security among users can be maintained even if one host computer or terminal device is used by multiple users.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the system configuration and encryption key arrangement of an embodiment of the present invention, Fig. 2 is a diagram showing the processing procedure of data communication encryption, Fig. 3 is a diagram showing the processing procedure of file encryption, and Fig. 4 is a diagram showing the processing procedure of file encryption. The figure is a diagram showing a processing procedure diagram of data authentication. 1...Host computer, 2...Encryption device, 3...
Terminal device, 4... Magnetic tape device, 5... IC card, 10... Master key private key, 11... Master key public key, 20.21, 22, 23, 24... User secret key, 3
0.31, 32, 33. ...User public key, 40.4
1...Data key. Figure 3 (=!■=1210

Claims (1)

[Claims] (1) In a key management method for encryption keys used for data encryption and authentication, the encryption keys are a master key for each system, a user key for each user, and data for each data encryption processing unit. A key management method for encryption keys characterized by having three layers of keys. (2) The key management system for cryptographic keys according to claim (1), characterized in that a public key cryptosystem is used as the master key, a public key cryptosystem is used as the user key, and a conventional cryptosystem is used as the data key. (3) Two types of master keys: public key cryptography and conventional cryptography;
2. The encryption key management system according to claim 1, wherein a public key encryption is used as the user key and a conventional encryption is used as the data key. (4) Encrypt and conceal data with a data key,
Claim (2) characterized in that the data key is encrypted and kept secret using a user key, and the user key is encrypted and kept secret using a master key.
The key management method for the encryption keys described. (5) Claim (3) characterized in that the data is encrypted and kept secret using a data key, the data key is encrypted and kept secret using a common encryption key of a user key or a master key, and the user key is encrypted and kept secret using a master key. ) Key management method for encryption keys. (6) A claim characterized in that the same user key is safely registered in a plurality of systems by encrypting the user key with a public master key assigned to each system and registering it in secret. (4) or (5) key management method for encryption keys;