JPH0691530B2 - Key generator - Google Patents

Description

The present invention relates to a key generation device for generating a key used for communication encryption or file encryption.

[Conventional technology]

One of the conventionally known key generation devices is a key generation device using a public key distribution system. This method is IEE Transactions
On Information Theory (IEEE Transac
tions on Information Theory) Vol. 22, No. 6, pp. 644-654.

This key generation device needs public information corresponding to each correspondent (or a file writer or a reader, which will be hereinafter referred to as a correspondent). For example, when the correspondent A communicates with the correspondent B in encrypted communication, A is public information of _B Y _B and secret information of A only (Mod p) creates the encryption key wk. Where p
Is a publicly available large prime number (about 256 bits), and a (mod b) represents a remainder obtained by dividing a by b. B is the same To create wk.

Has been defined. α is a constant.

Even if you know Y _A , α, and p, It is difficult to obtain X _A that satisfies the above, that is, the so-called discrete logarithm difficulty is described in the above-mentioned document.

[Problems to be solved by the invention]

The conventional key generation device described above requires public information corresponding to each correspondent, and the list of public information increases as the number of members increases. Also, management is required to prevent falsification. These drawbacks also exist in file encryption.

The object of the present invention is to eliminate the above drawbacks by simple means,
An object of the present invention is to provide a key generation device capable of generating a highly confidential encryption key.

[Means for solving problems]

The configuration of the key generation device of the first invention is a transmission side of communication in a key generation device that generates a key for encryption between one station and another station of a communication network including a plurality of stations. The station has a random number generated within itself, a secret code of the station that has a certain relationship with the identification information of the station, identification information of the partner station that is the receiving side of the communication, and a code common to the plurality of stations. And are converted by a predetermined conversion method to generate the encryption key.

According to the configuration of the key generation device of the second invention, a key generation device for generating an encryption key between one station and another station of a communication network including a plurality of stations receives the encrypted information. The receiving station to be decrypted has a certain relationship with the random number received from the partner station which is the transmitting station which transmits the encrypted information, and the identification information of the own station which is the receiving station of the encrypted information. The secret code, the identification information of the partner station, and the code common to the plurality of stations are converted by a predetermined conversion method to generate the decryption key.

According to the configuration of the key generating apparatus of the third invention, in the key generating apparatus which generates a key when encrypting the record information used by a plurality of users, the encryption user who encrypts the record information is automatically generated. Common number to the plurality of users, the random number, the secret code of the encrypted user having a fixed relationship with the identification code of the encrypted user, the identification information of the decryption user that decrypts the encrypted record information, And the code is converted by a predetermined conversion method to generate the encryption key.

According to a fourth aspect of the present invention, there is provided a key generation device for generating a key for decrypting encrypted record information used by a plurality of users, wherein the decryption user decrypts the encrypted record information. Is a random number read from a recording device in which an encrypted encrypted user has recorded, a decryption user secret code having a certain relationship with the decryption user identification information, and the encoding user identification information And a code common to the plurality of users is converted by a predetermined conversion method to generate the decryption key.

〔Example〕

FIG. 1 is a diagram showing the principle of one embodiment of the first to fourth inventions.

Although the station in the first and second inventions is a communication subject such as a terminal and a user, the word user which is the subject of the third and fourth inventions is used in common.

FIG. 1 shows the common principle of the first to fourth inventions. It is assumed that the side activating the key distribution or the side writing the file is user 1 and the other is user 2. User 1 generates a random number R and either sends it to User 2 or writes it in part of the file.

Next, the encryption key (hereinafter referred to as the work key) Calculate with.

Here, n is a product p ₁ p ₂ ... p _k of a plurality of prime numbers, about 200
It is a large integer of about one digit.

The ID _i is identification information of the user i, and is public information that can identify the user i, such as a name, an address, and a telephone number, is coded and regarded as an integer.

Furthermore, S _i is a secret integer held only by user i. These S _i , n are calculated by a reliable administrator and distributed to the user i in advance. The method of this calculation will be shown later. User 2 does the same with work key wk Calculate by Here, the relationship between ID _i and S _i is Has become. α is an integer. At this time, the work keys wk calculated by user 1 and user 2 are both Is equal to

Here, even if the ID _i , α, n is known, since n is large, S
_i cannot be obtained. Therefore, even if a third party other than User 1 and User 2 knows R, Can't make These are due to the difficulty of discrete logarithm.

On the other hand, the administrator factors p _1, p ₂ of n, ... if you each small p _k, for any ID X _j satisfying the above can be calculated.

Here, α is an arbitrary integer that is a generator in mod p _j .

For the specific method of calculating x _j , for example, the 20th Annual Symposium on Foundations of Computer Science (Annual Symposium on
Foundations of Computor Science) Proceedings 56--60
Page (1979).

FIG. 2 is a diagram showing the configuration of the first and second embodiments of the present invention.

The IC card reader 202 is installed in the terminal 203 of the network. The IC card 201 is a card in which the administrator writes the secret code S _i and the public integer n and distributes it to each user.

The work to be performed by the terminal 203 is shown in the flowchart of FIG. It is assumed that the user 1 performs encrypted communication with the user 2.

User 1 inputs an encrypted communication request to terminal 203 and
Insert the C card 201 into the reader 202. Then, the terminal checks the validity of the user 1. This can be done by checking the validity of the IC card. For example, the personal identification number is entered in the memory area of the IC card that cannot be read and written at the IC card manufacturing stage and matches the personal identification number entered by the user 1 on the terminal. Whether or not the user 1 is valid is determined. If they match, the terminal generates a random number R, reads the S _i and n from the IC card 201.

The work key wk is generated based on formula (1), and the work key
The message to be sent by wk is encrypted and the ciphertext is sent to the user 2 together with R. When the user 2 receives R and the ciphertext, the terminal similarly checks the validity of the user 2,
When the check is positive, S _i and n are read from the IC card to generate the work key wk. And that wk
The ciphertext sent using is returned to the original plaintext.

FIG. 4 is a diagram showing the configurations of the third and fourth embodiments. The terminal 203 in FIG. 2 is a personal computer with a floppy disk (personal computer). The operation is only that the communication text in FIG. 2 is a text recorded on a floppy disk. However, it differs from FIG. 2 in that the encrypting user and the encrypting user may be the same.

In this embodiment, the floppy disk and the personal computer are merely examples, and other recording media and computers may be used.

〔The invention's effect〕

As described above in detail, the use of the present invention brings about an effect of eliminating the need for a table listing public information corresponding to each user.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of the first to fourth embodiments, FIG. 2 is a block diagram of the first and second embodiments, and FIG. 3 is a flow chart of work to be performed by a terminal or a personal computer. FIG. 4 is a block diagram of the third and fourth embodiments. 101,102 ... Processing performed by users 1 and 2 for key generation,
201,401 …… IC card, 202,402 …… reader, 203 …… terminal, 403 …… PC.

Claims (4)

[Claims] 1. A key generation device for generating a key for encryption between one station and another station in a communication network composed of a plurality of stations, wherein a transmission station which is a transmission side of communication generates a random number R. This is transmitted to the receiving station via the communication network, and the transmitting station is provided between the codes n and α common to the plurality of stations and the identification code ID _{1 of} its own station. The secret code S _{1 of} your own station and the identification information of the other station
ID ₂ , the common code, and the random number A key generating device, wherein the key generating device generates a key wk for encryption by converting with the above. 2. A key generation device for generating a key for encryption between one station and another station in a communication network comprising a plurality of stations, wherein a receiving station which receives and decrypts encrypted information is A random number R received via the communication network from a partner station that is a transmitting station that transmits the converted information;
Between the codes n and α common to the plurality of stations and the identification code ID ₂ of the own station The secret code S _{2 of} your own station and the identification information of the other station
ID ₁ and the code common to all the stations, A key generating device, wherein the key generating device generates a key wk for encryption by converting with the above. 3. A key generation device for generating a key for encrypting record information used by a plurality of users, wherein a random number R generated by an encryption user for encrypting the record information and recorded in the recording device by himself / herself. Between the encrypted user identification code ID ₁ and the codes n and α common to the plurality of users. The secret code S ₁ of the encrypted user having the relationship of and the identification information ID of the decrypted user who decrypts the encrypted record information
₂ and the common code, A key generating device, wherein the key generating device generates a key wk for encryption by converting with the above. 4. A key generation device for generating a key for decrypting encrypted record information used by a plurality of users, wherein a decryption user who decrypts the encrypted record information performs encryption. Random number R read from the recording device recorded by the encrypted user, and identification information ID of the decrypted user
_{Between 2} and the codes n and α common to the users. The secret code S ₂ of the decryption user having the following relationship, the identification information ID ₁ of the encryption user, and the common code are converted into A key generating device, wherein the key generating device generates the decryption key wk.