JP2000151577A - Ciphering and deciphering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable ciphering/deciphering superior in an intensity of a code by a circuit relatively in small scale by allowing a key enciphering circuit for key input conversion and a ciphering circuit which enciphers data or a deciphering circuit which deciphers the data to use information for circuit overwriting in accordance with a code decided at random to overwrite the circuit. SOLUTION: An enciphering/deciphering 100 enciphers input data 171 at an enciphering circuit 111 and makes these output data 177, or deciphers the one enciphered at the enciphering circuit 111 at a deciphering circuit 121, further inputs decoded data to the enciphering circuit 112, enciphers them and makes them output data 176. Key input conversion key enciphering circuits 115, 115A, 116 and 116A for key input conversion convert a key input 181 and generate enciphering and decoding key data. In addition, this device is equipped with a random number generator 14 and a ROM 150 storing circuit overwriting data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encryption / decryption device, and more particularly to an encryption / decryption device capable of appropriately changing an encryption / decryption algorithm at random.

[0002]

2. Description of the Related Art In recent years, since computers have become deeply involved in daily work and daily life, it is more important than ever to protect information security. Many information, including businesses, governments, and individuals, have a need for confidentiality. For this reason, an encryption / decryption method which encrypts information and obtains it by decrypting the information has been adopted.
For example, DES (Data Encryption St)
Andard) is known as a standard of a typical secret key encryption algorithm adopted mainly in the United States. In the DES encryption algorithm, plaintext data that has been digitized is divided into fixed-length blocks of, for example, 64 bits, and various operations using a secret key are performed in block units to encrypt the plaintext data. I do. The DES decryption algorithm is basically the same as the encryption algorithm. Also, RSA (Rivest-Shamir) that performs encryption using a public key is used.
-Adleman) is also known. The RSA encryption algorithm is a very strong public key encryption algorithm that can not only encrypt data but also authenticate messages and users. This algorithm uses two encryption keys, a public key and a secret key. Public keys are published in the form of documents and data on a network and are accessible to anyone, but private keys must be kept strictly by users.

A circuit for performing such encryption / decryption processing basically includes an encryption circuit, a decryption circuit, and a key input unit. It is often affected by the circuit scale, and it has been difficult to realize a small-sized circuit with excellent encryption strength.

[0004]

Under such circumstances, there has been a demand for an encryption / decryption device which is a small-scale circuit and has excellent encryption strength. The present invention
It is an object of the present invention to provide an encryption / decryption device which is a circuit corresponding to this and has a relatively small scale and excellent encryption strength.

[0005]

According to the present invention, there is provided an encryption / decryption device comprising: an encryption circuit for encrypting data; a decryption circuit for decrypting data;
Encryption including a key encryption circuit for key input conversion for converting key input to generate key data for encryption and decryption, a random number generator, and a ROM storing circuit rewrite data; A decryption device, wherein a key encryption circuit for key input conversion and / or the encryption circuit and the decryption circuit store information of a ROM storing circuit rewrite data in accordance with a code randomly determined by an output from a random number generator. , The circuit can be rewritten. A part or all of the above circuit is implemented by an FPGA (Field Programmable).
A rewritable device such as a Gate Array (which is referred to as a PLD (Programmable Lo)
gic device), and electronic commerce (E) that requires encryption processing.
C: an abbreviation for Electronic Commercial). Here, the code randomly determined by the output from the random number generator is a code corresponding to the address of the ROM storing the circuit rewrite data, and the number output from the random number generator is a code. It is obtained by coding in the conversion unit, and is determined at random. Also, rewriting a circuit by using information of a ROM storing circuit rewriting data in accordance with a code determined at random means rewriting a circuit by using circuit rewriting data of the ROM address corresponding to the code. It is done.

[0006]

According to the encryption / decryption device of the present invention, it is possible to provide an encryption / decryption device having a relatively small circuit and excellent encryption strength by employing the above-described configuration. I have. Specifically, an encryption circuit for encrypting data, a decryption circuit for decrypting data, the encryption circuit,
A key encryption circuit for key input conversion for converting key input to generate key data for encryption and decryption, which is different from the decryption circuit, a random number generator, and a ROM storing circuit rewrite data An encryption / decryption device comprising: a key encryption circuit for key input conversion and / or the encryption circuit and the decryption circuit are configured to rewrite a circuit according to a code determined at random by an output from a random number generator. R storing data
This is achieved because the circuit can be rewritten using the OM information. Specifically, an encryption circuit for encrypting and decrypting data, a decryption circuit, and / or an encryption circuit for key input conversion different from the encryption circuit and the decryption circuit are codes determined at random by an output from a random number generator. ROM for storing circuit rewrite data
The information can be used to rewrite the circuit, so that the encryption algorithm and the decryption algorithm can be changed without being uniquely determined. That is, it is possible to change the encryption and decryption algorithms randomly (in any order) by a code randomly determined by the output from the random number generator. More specifically, part or all of the circuit is implemented by an FPGA (Fie
ld Programmable Gate Arra
rewritable device such as PLD (P
(which may be referred to as a programmable logic device), which makes it possible to easily change those circuits repeatedly. In particular, E which requires encryption processing
It is effective when used in C (electronic commerce), that is, when used as a terminal device or system used in EC (electronic commerce) or the like.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An encryption / decryption device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit configuration diagram of a first example of the embodiment, FIG. 2 is a circuit configuration diagram of a second example of the embodiment, and FIG. 3 is a first operation flowchart. In FIG. 1, for the sake of simplicity, the flow of data (signal) is indicated by arrows, the key input wiring is indicated by a thick dotted line, and the input wiring from the key encryption circuit to the encryption circuit and the decryption circuit is indicated by a dotted line. , And the output wiring from the ROM is shown by thin lines. The connection portions of the wires are indicated by black circles. Also,
1 and 2, the code conversion unit for coding the number from the random number generator is omitted. 1 and 2
Among them, 100 is an encryption / decryption device, 111 and 112 are encryption circuits, 115, 115A, 116 and 116A are key encryption circuits, 121, 121A, 122 and 122A are decryption circuits, 140 is a random number generator, and 150 is ROM, 171 is input data, 175 and 178 are confirmation output data, 17
6, 177 are output data, 181 is key input, 185, 1
85A, 186, 186A, 187, 188 are key data, 191 and 192 are input data confirmation data, 200
Is an encryption / decryption device, 211 and 212 are encryption circuits, 2
15 and 216 are key encryption circuits, 221A and 222A are decryption circuits, 240 is a random number generator, 250 is a ROM, 271
Is input data, 275 and 276 are output data, 277 is output data for confirmation, 281 is key input, 285 to 288 is key data, and 291 and 292 are input data confirmation data.

First, a first embodiment of an encryption / decryption device according to the present invention will be described with reference to FIG. The encryption / decryption device 100 of this example shown in FIG. 1 includes a plurality of encryption circuits 111 and 112, and decryption circuits 121, 121A and 12
2, 122A; a key encryption circuit 115, 115A, 116, 116A for key input conversion for converting a key input 181 to generate key data for encryption and decryption; a random number generator 140; ROM storing data for rewriting
150, the input data 171 can be simply encrypted by the encryption circuit 111 and used as output data 177, or the data encrypted by the encryption circuit 111 (output The data 177) is decrypted by the decryption circuit 121, and the decrypted data is input to the encryption circuit 112 and encrypted, and this is output data 1
76. Encryption circuit 111 and decryption circuit 12
1 or the encryption circuit 112 and the decryption circuit 122
The encrypted data between the two can be used freely. In this example, the entire circuit is implemented by an FPGA (Field Program).
key encryption circuit for key input conversion.
15, 115A, 116, 116A and encryption circuit 11
1, 112, decoding circuits 121, 121A, 122, 12
The circuit 2A can appropriately rewrite the circuit according to the code determined at random by the output from the random number generator 140, using the information in the ROM 150 storing the data for circuit rewriting. In other words, the encryption / decryption device 100 of this example
The encryption / decryption algorithm can be changed as appropriate, and an encryption / decryption device with excellent encryption strength can be obtained by appropriately changing the algorithm. The key encryption circuits 115, 115A, 116, and 116A can be rewritten and used independently of the encryption circuit and the decryption circuit to which the output is input.
1 and the decryption circuits 121 and 121A correspond to each other, and the encryption circuit 112 and the decryption circuits 122 and 122A correspond to each other.

In FIG. 1, when encrypting and decrypting the encryption circuit 111 and the decryption circuit 121, the key encryption circuit 11 is used.
5, the key data 185 and 185A from the encryption circuit 111,
Each is input to the decoding circuit 121 and used.
Note that the key data 185 and 185A are outputs when the key input 181 is input to the key encryption circuit 115. Similarly, when encrypting and decrypting the encryption circuit 112 and the decryption circuit 122, the key data 186, 18 from the key encryption circuit 116 is used.
6A to the encryption circuit 112 and the decryption circuit 122, respectively.
Entered and used. The key data 186, 186A
Is an output when the key input 181 is inserted into the key encryption circuit 116.

[0010] The input data confirmation data 192 is obtained by inputting the output from the encryption circuit 112 to the decryption circuit 122A and decrypting it. The decoding circuit 122A is
The key data 187 from the key encryption circuit 116A having the same configuration as that of the key encryption circuit 116 is used for decryption. The key data 187 is an output when the key input 181 is input to the key encryption circuit 116A.

The input data confirmation data 191 is obtained by inputting the output from the encryption circuit 111 to the decryption circuit 121A and decrypting the output. The decoding circuit 121A is
The key data 188 from the key encryption circuit 115A having the same configuration as that of the key encryption circuit 115 and having the same configuration as that of the key encryption circuit 115 is used for decryption. The key data 188 is an output when the key input 181 is input to the key encryption circuit 115A.

The output data for confirmation 178 is the input data 17
1 is output as it is, and the output data for confirmation 175
Is for outputting encrypted data (corresponding to the output data 176), which is further decrypted by the decryption circuit 122. These are usually for confirmation of the system (device) administrator. is there. In an environment where security is an issue, the confirmation output data 178 does not necessarily need to be configured as output data.

Hereinafter, an example of the circuit rewriting operation of the encryption / decryption device of this embodiment will be briefly described with reference to FIG. S310 to S380 indicate each step.
First, the encryption circuits 111 and 112 and the decryption circuit 1
21, 121A, 122, 122A, a key circuit 115,
The circuits 115A, 116, and 116A are written. (S320) Next, use of the circuit is started (S330), information to be encrypted is input as input data 171, and key input 1 is performed.
81, the corresponding output data 176, 177 and the output data for confirmation 175 are obtained, and the use of the circuit is terminated. (S340) Thereafter, the circuit is rewritten as necessary. (S36
0) Rewriting of the circuit is performed in accordance with a code determined at random by the output of the random number generator 140, using predetermined write data in the ROM 150, and using the key encryption circuit 115, 1
15A, 116, 116A, encryption circuits 111, 112,
This is performed by writing to the decoding circuits 121, 121A, 122, and 122A. Next, after each circuit section is rewritten,
Predetermined information is input as input data 171 and key input 1
81, the output data 175 for confirmation and the data 191 and 192 for input data confirmation are obtained, and the operation is confirmed by comparing the respective data. (S370) In this way, input of the next information to be encrypted is awaited.
(S380) If it is not necessary to rewrite the circuit, the process waits for input of the next information to be encrypted. (S380) In this way, the administrator of the system (device) can randomly (in any order) change the encryption and decryption algorithms as needed.

Next, a second embodiment of the encryption / decryption device according to the present invention will be described with reference to FIG. In the second example, similarly to the first example, the encrypted data is used as output data as it is. Also in the case of this example, as in the first example, the entire circuit is formed by being written into the FPGA, and the key encryption circuits 215, 215A,
16 and 216A, and the encryption circuits 211 and 212 and the decryption circuits 221A and 222A rewrite the circuit using the information of the ROM 250 storing the circuit rewrite data according to a code determined at random from the output from the random number generator 240. As in the first example, the encryption and decryption algorithms can be appropriately changed. Then, by appropriately changing the algorithm, an encryption / decryption device having excellent encryption strength can be obtained. The encryption / decryption device 200 of the present example shown in FIG.
1, 212, decoding circuits 221, 221A, 222, 22
2A and a key encryption circuit 2 for key input conversion for converting key input 281 to generate key data for encryption and decryption
15, 215A, 216, 216A and a random number generator 24
0, and a ROM 250 storing data for circuit rewriting, the encryption / decryption device simply converts the input data 271 into the output data 276 by directly encrypting the input data 271 with the encryption circuit 211, or Encryption circuit 211
(Corresponding to the output data 276) is further encrypted by the encryption circuit 212 to produce output data 275.

When encrypting the encryption circuit 211, the key data 285 from the key encryption circuit 215 is encrypted.
Is used as input to The key data 285 is an output when the key input 281 is input to the key encryption circuit 215. Similarly, when encrypting the encryption circuit 212, the key data 286 from the key encryption circuit 216 is
Is used as input to The key data 286 is an output when the key input 281 is input to the key encryption circuit 216.

The input data confirmation data 292 is obtained by inputting the output from the encryption circuit 212 to the decryption circuit 222A and decrypting it. The decryption circuit 222A uses the key data 287 from the key encryption circuit 216A having the same configuration as the key encryption circuit 216 at the time of decryption. The key data 287
Is an output when the key input 281 is put into the key encryption circuit 216A.

The input data confirmation data 291 is obtained by inputting the output from the encryption circuit 211 to the decryption circuit 221A and decrypting the same. The decryption circuit 221A uses the key data 288 from the key encryption circuit 215A having the same configuration as the key encryption circuit 215 at the time of decryption. The key data 288
Is an output when the key input 281 is inserted into the key encryption circuit 215A.

The output data for confirmation 277 is the input data 2
71 is output as it is, and is normally used for confirmation by a system (device) administrator. If it is considered that there is a security problem, the confirmation output data 277 is not required. good.

The operation of the circuit rewriting of this embodiment is basically the same as that of the first embodiment, and the description is omitted here.

[0020]

According to the present invention, as described above, it is possible to provide an encryption / decryption device having a predetermined encryption strength without increasing the circuit scale. See FP
By rewriting each circuit using a rewritable device such as a GA, the algorithm of the encryption circuit can be easily changed, and thereby the encryption strength can be ensured. As a result, there is no need to construct a complicated encryption / decryption algorithm, the circuit scale is not increased, and the encryption strength can be secured at a practical level such as EC (electronic commerce).

[Brief description of the drawings]

FIG. 1 shows an embodiment of an encryption / decryption device according to the present invention.
Example configuration diagram

FIG. 2 shows an encryption / decryption device according to a second embodiment of the present invention.
Example configuration diagram

FIG. 3 shows an embodiment of an encryption / decryption device according to the present invention;
Flow chart for explaining the rewriting operation of each circuit section of the example

[Explanation of symbols]

Reference Signs List 100 encryption / decryption device 111, 112 encryption circuit 115, 116 key encryption circuit 121, 122 decryption circuit 140 random number generator 150 ROM 171 input data 175, 178 confirmation output data 176, 177 output data 181 key input 185, 185A, 186, 186A, 187, 188
Key data 191, 192 Input data confirmation data 200 Encryption / decryption device 211, 212 Encryption circuit 215, 216 Key encryption circuit 221A, 222A Decryption circuit 240 Random number generator 250 ROM 271 Input data 275, 276 Output data 277 Confirmation Output data 281 key input 285-288 key data 291, 292 input data confirmation data

Claims (3)

[Claims] 1. An encryption circuit for encrypting data, a decryption circuit for decrypting data, and key data for encryption and decryption by converting a key input, which is different from the encryption circuit and the decryption circuit. An encryption / decryption device including a key encryption circuit for key input conversion for generating a key, a random number generator, and a ROM storing circuit rewrite data, wherein the key encryption circuit for key input conversion is provided. And / or the encryption circuit and the decryption circuit are capable of rewriting the circuit by using information of a ROM storing circuit rewriting data in accordance with a code determined at random by an output from a random number generator. Encryption and decryption device. 2. A circuit according to claim 1, wherein a part or the whole of the circuit is a FPGA (Field Programmable).
An encryption / decryption device characterized by being formed by a rewritable device such as Gate Array). 3. An electronic commerce requiring encryption processing, which is used for electronic commerce.
An encryption / decryption device as described.