JP2019124713A - Encryption device, decryption device, channel coding system, encryption method and its program - Google Patents

Abstract

To provide an encryption device which enables a safe and fast encryption of big data without affecting its processing capacity.SOLUTION: An encryption device 1 comprises: a key schedule part 12 which generates at least one sub-key from a first common key input from outside by using a key schedule; a common key decoding part 14 which obtains the sub-key and decodes a second common key; a common key comparison part 16 which compares the first common key with the second common key; a data scramble part 17 which encrypts a plaintext block input from outside into a ciphertext block by using the sub-key; and an output determination part 18 which determines whether or not the ciphertext block should be output according to the result of comparison performed by the common key comparison part 16.EFFECT: The comparison of the first common key and the second common key decoded by the sub-key is done in parallel with the process of data encryption, and therefore processing errors of abnormal common keys and sub-keys can be done without affecting data encryption performance.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an encryption device, a decryption device, a line encryption system, an encryption method, and a program. In particular, the present invention relates to an encryption device, a decryption device, a line encryption system, an encryption method, and a program using a block cipher.

  With the development of the information society, the risk of information leakage and falsification is increasing. Information security technology is important to ensure the safety and reliability of information. Encryption technology is one of the elements that make up information security technology. Encryption technology is used in various products regardless of hardware and software.

  The encryption technology is roughly classified into two systems of a public key cryptosystem and a common key cryptosystem. In the public key cryptosystem, two types of keys are used: a public key which can be obtained by anyone and a secret key which only the receiving side holds. The public key cryptosystem is characterized in that the key can be easily delivered. On the other hand, in the common key cryptosystem, the same key called a common key is used. The common key cryptosystem is characterized in that the processing is fast because the mechanism is simple.

  Common key cryptography can be divided into two types, stream ciphers and block ciphers, according to the type of cryptographic algorithm. Stream encryption is an encryption algorithm that performs processing in small units such as 1 byte. On the other hand, block encryption is an encryption algorithm that performs processing by dividing a unit of encryption processing into blocks of a fixed length called a block. Block ciphers have a structure that performs an iterative process called a round. In block encryption, a key scheduling unit generates subkeys to be used in each round, and a data scrambler converts plaintext into ciphertext using each subkey. Block ciphers are suitable for encrypting large amounts of data.

  Patent Document 1 discloses an encryption processing apparatus that executes common key block encryption processing. The apparatus of Patent Document 1 includes an encryption processing unit that performs data conversion processing that repeats a round function for multiple rounds, and a key scheduling unit that generates a round key to be applied to the execution of the round function. The key schedule unit inputs an intermediate key generation unit that generates an intermediate key by inputting a secret key to an encryption function including a round function used by the encryption processing unit, and inputs an intermediate key generated by the intermediate key generation unit. And an intermediate key expansion unit for generating a key.

  As one of the block encryption methods, there is a method of limiting the number of times of generation of subkeys in order to encrypt a large amount of data at high speed. For example, the processing of the key scheduling unit is performed only in the first block, and the subkey generated by the key scheduling unit is stored in a storage unit such as a register or a memory. In the second and subsequent encryption blocks, plaintext encryption is performed using the subkey stored in the storage unit. When this method is used, not only the common key but also the subkeys are managed in order to perform encryption processing safely.

JP 2008-058831 A

  In common block encryption of common key encryption method, the common key is stored in the storage unit, and a key schedule is executed each time encryption is performed, so it is time to encrypt a large amount of data The problem is that it takes

  Further, the apparatus of Patent Document 1 can increase the difficulty of key analysis by using a plurality of types of keys such as a secret key, an intermediate key, and a round key when encrypting plaintext. However, the device of Patent Document 1 has a problem that the key management becomes complicated.

  Also, according to the method of limiting the number of times of sub key generation, a large amount of data can be encrypted at high speed. However, in the case of this method, in addition to the common key, since the subkey generated by the key schedule is also stored in the storage unit, there is a problem that the risk of leakage or tampering of the key is increased.

  An object of the present invention is to provide an encryption apparatus capable of safely and rapidly encrypting a large amount of data without affecting the processing performance, in order to solve the problems described above.

  The encryption apparatus according to one aspect of the present invention uses a key schedule from the first common key holding unit holding the first common key, and at least one subkey from the first common key held in the first common key holding unit. A subkey generation unit to be generated, a subkey holding unit holding a subkey generated by the subkey generation unit, and a common key for acquiring a subkey held in the subkey holding unit and decrypting a second common key A decryption unit, a second common key holding unit holding a second common key decrypted by the common key decryption unit, a first common key held by the first common key holding unit, and a second common key holding unit A common key comparison unit for comparing the held second common key, an encryption unit for generating a ciphertext block by encrypting a plaintext block using the subkey held in the subkey holding unit, and a common key comparison Generated by the encryption unit and the comparison result between the first common key and the second common key by the Is entered and the ciphertext block, and an output determining unit that determines whether to output the ciphertext block based on a comparison result by the common key comparing unit.

  The decryption apparatus according to one aspect of the present invention generates at least one subkey from the first common key holding unit holding the first common key and the first common key held by the first common key holding unit using a key schedule. Subkey generation unit, a subkey holding unit for holding the subkey generated by the subkey generation unit, and common key decryption for obtaining the subkey held in the subkey holding unit and decrypting the second common key , The second common key holding unit holding the second common key decrypted by the common key decryption unit, the first common key held in the first common key holding unit, and the second common key holding unit A common key comparison unit that compares the received second common key, a decryption unit that decrypts a plaintext block from the ciphertext block using the subkey held in the subkey holding unit, and a first common by the common key comparison unit The comparison result between the key and the second common key, and the plaintext block decrypted by the decryption unit Click and is input, and an output determining unit that determines whether to output the plaintext block based on the comparison result by the common key comparing unit.

  The line encryption system according to one aspect of the present invention generates at least one subkey from the first common key with a key schedule and encrypts a plaintext block using the generated subkey to generate a ciphertext block, An encryption device that decrypts the second common key using the generated subkey, and determines whether to output a ciphertext block based on the comparison result between the first common key and the second common key; At least one subkey is generated from the first common key according to the key schedule, the plaintext block is decrypted from the ciphertext block using the generated subkey, and the second common key is decrypted using the generated subkey And a decryption apparatus that determines whether to output a plaintext block based on the comparison result of the first common key and the second common key, the encryption apparatus comprising: a ciphertext block obtained by encrypting the plaintext block Decoding Transmitted to the decoding device decodes the plaintext block from the ciphertext block received from the encryption device.

  In the encryption method according to one aspect of the present invention, the first common key is held in the first common key holding unit, and at least one subkey from the first common key held in the first common key holding unit is a key schedule. And the generated subkey is held in the subkey holding unit, and the second common key is decrypted using the subkey held in the subkey holding unit, and the decrypted second common key is used as the second common key. The first common key held in the key holding unit and held in the first common key holding unit is compared with the second common key held in the second common key holding unit, and held in the sub key holding unit A plaintext block is encrypted using the subkey to generate a ciphertext block, and it is determined whether to output a ciphertext block based on the comparison result between the first common key and the second common key.

  The program according to one aspect of the present invention includes a process of holding the first common key in the first common key holding unit, and at least one subkey from the first common key held in the first common key holding unit using a key schedule. A process of generating, a process of holding the generated subkey in the subkey holding unit, a process of decoding the second common key using the subkey held in the subkey holding unit, and a second common decrypted A process of holding the key in the second common key holding unit, a process of comparing the first common key held in the first common key holding unit, and the second common key held in the second common key holding unit Outputting a ciphertext block based on a result of processing of generating a ciphertext block by encrypting a plaintext block using the subkey held in the subkey holding unit and a comparison result of the first common key and the second common key A program that causes a computer to execute a process of determining whether to

  According to the present invention, it is possible to provide an encryption apparatus capable of encrypting a large amount of data safely and at high speed without affecting processing performance.

It is a block diagram showing an example of composition of an encryption device concerning a 1st embodiment of the present invention. It is a flowchart for demonstrating the operation example of the encryption apparatus concerning the 1st Embodiment of this invention. It is a block diagram showing an example of composition of an encryption device concerning a 2nd embodiment of the present invention. It is a flowchart for demonstrating the operation example of the encryption apparatus concerning the 2nd Embodiment of this invention. It is a block diagram showing an example of composition of an encryption device concerning a 3rd embodiment of the present invention. It is a flowchart for demonstrating the operation example of the encryption apparatus concerning the 3rd Embodiment of this invention. It is a block diagram showing an example of composition of an encryption device concerning a 4th embodiment of the present invention. It is a flowchart for demonstrating the operation example of the encryption apparatus concerning the 4th Embodiment of this invention. It is a block diagram which shows an example of a structure of the encryption apparatus which concerns on the 5th Embodiment of this invention. It is a flowchart for demonstrating the operation example of the encryption apparatus concerning the 5th Embodiment of this invention. It is a block diagram which shows an example of a structure of the decoding apparatus based on the 6th Embodiment of this invention. It is a block diagram which shows an example of a structure of the circuit | line encryption system which concerns on the 7th Embodiment of this invention. It is a block diagram showing an example of hardware constitutions of an encryption device concerning an embodiment of the present invention, and a decryption device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are technically preferable limitations for carrying out the present invention, but the scope of the invention is not limited to the following. Further, in all the drawings used in the description of the embodiments below, the same reference numerals are given to the same parts unless there is a particular reason. In the following embodiments, the same configuration and operation may not be repeatedly described. In addition, the direction of the arrow in the drawing shows an example, and does not limit the direction of the signal.

First Embodiment
First, an encryption apparatus according to a first embodiment of the present invention will be described with reference to the drawings. At least one plaintext block constituting encryption target data (also referred to as target data) and a common key for encrypting the plaintext block are input to the encryption apparatus of the present embodiment. The encryption apparatus of the present embodiment generates a subkey from the common key, and generates a ciphertext block by encrypting the plaintext block using the generated subkey. The encryption apparatus of the present embodiment may be configured to encrypt a plaintext block into an encrypted block using a common key stored in advance.

(Constitution)
FIG. 1 is a block diagram showing an example of the configuration of the encryption device 1 of the present embodiment. As shown in FIG. 1, the encryption device 1 includes a first common key holding unit 11, a key scheduling unit 12, a sub key holding unit 13, a common key decryption unit 14, a second common key holding unit 15, and a common key comparison unit 16. , A data scramble unit 17 and an output determination unit 18.

  The first common key holding unit 11 (also referred to as a first common key holding unit) holds the input common key (hereinafter also referred to as a first common key). For example, the first common key holding unit 11 is realized by a register or a memory.

  The key schedule unit 12 (also referred to as a sub key generation unit) acquires the first common key held in the first common key holding unit 11. The key scheduling unit 12 generates a sub key from the acquired first common key. For example, the key scheduling unit 12 generates N subkeys used in all rounds from the first common key (N is a natural number). The key scheduling unit 12 stores the generated subkey in the subkey holding unit 13.

  For example, the key scheduling unit 12 performs key scheduling using a common key block encryption algorithm such as AES (Advanced Encryption Standard). The key scheduling unit 12 may perform key scheduling using a block encryption algorithm such as DES (Data Encryption Standard) or triple DES. The key scheduling unit 12 may also perform key scheduling using a block encryption algorithm such as MISTY 1 (Mitsubishi Improved Security Technology) or Camelia. However, the key schedule by the key schedule part 12 is not limited to the method mentioned here.

  The sub key holding unit 13 (also referred to as a sub key holding unit) stores the sub key generated by the key scheduling unit 12. For example, the sub key holding unit 13 is realized by a register or a memory.

  The common key decryption unit 14 (also referred to as a common key decryption unit) decrypts the common key (hereinafter also referred to as a second common key) from the subkey stored in the subkey storage unit 13. For example, the common key decryption unit 14 decrypts the second common key from the N subkeys stored in the subkey storage unit 13 (N is a natural number). The common key decryption unit 14 causes the second common key holding unit 15 to hold the decrypted second common key.

  The second common key holding unit 15 (also referred to as a second common key holding unit) holds the second common key decrypted by the common key decryption unit 14. For example, the second common key holding unit 15 is realized by a register or a memory.

  The common key comparison unit 16 (also referred to as a common key comparison unit) compares the first common key held in the first common key holding unit 11 with the second common key held in the second common key holding unit 15 Do. The common key comparison unit 16 outputs the comparison result of the first common key and the second common key to the output determination unit 18.

  At least one plaintext block constituting data to be encrypted (also referred to as target data) is input to the data scramble unit 17 (also referred to as encryption unit), and a sub key is input from the sub key storage unit 13. The data scramble unit 17 generates a ciphertext block by encrypting the input plaintext block using the subkey. The data scramble unit 17 outputs the generated ciphertext block to the output determination unit 18.

  The ciphertext block is input from the data scramble unit 17 to the output determination unit 18 (also referred to as output determination means), and the comparison result between the first common key and the second common key is input from the common key comparison unit 16. The output determination unit 18 determines whether to output a ciphertext block based on the comparison result by the common key comparison unit 16. When the first common key and the second common key are the same, the output determination unit 18 determines to output the ciphertext block. On the other hand, when the first common key and the second common key are different, the output determination unit 18 detects an abnormality (also referred to as an error) such as a failure or falsification in the sub key and discards the ciphertext block without outputting it. .

  The above is the description of the configuration of the encryption device 1. Next, the operation of the encryption device 1 will be described with reference to the drawings.

(Operation)
FIG. 2 is a flowchart for explaining an example of the operation of the encryption device 1. That is, FIG. 2 is a flowchart showing the procedure of the encryption process performed by the encryption device 1. In the following description following the flowchart of FIG. 2, the encryption device 1 will be described as the subject of the operation.

  In FIG. 2, first, when the common key is input, the encryption device 1 stores the common key (also referred to as a first common key) in the first common key holding unit 11 (step S101).

  Next, the encryption device 1 generates a subkey from the first common key stored in the first common key holding unit 11 by performing key scheduling according to the common key block encryption algorithm (step S102).

  Next, the encryption device 1 stores the generated sub key in the sub key storage unit 13 (step S103).

  The encryption device 1 encrypts the input plaintext block according to the common key block encryption algorithm using the subkey stored in the subkey storage unit 13 (step S104).

  In addition, the encryption device 1 executes the common key decryption process using the subkey stored in the subkey storage unit 13 in parallel with the encryption process of step S104 and executes the common key (also referred to as a second common key). ) Is decoded (step S105).

  Next, the encryption device 1 stores the decrypted second common key in the second common key holding unit 15 (step S106).

  Next, the encryption device 1 compares the first common key stored in the first common key holding unit 11 with the second common key stored in the second common key holding unit 15 (step S107).

  Then, when the first common key and the second common key match (Yes in step S108), the encryption device 1 outputs a ciphertext block (step S109).

  On the other hand, when the first common key and the second common key do not match (No in step S108), the encryption device 1 detects an abnormality in the sub key, performs error processing, and discards the ciphertext block. (Step S110).

  The above is the description of an example of the operation of the encryption device 1 along the flowchart of FIG.

  As described above, the encryption apparatus according to the present embodiment causes the input common key (first common key) and the common key decrypted from the subkey (second common key) to be input in parallel with the data encryption process. And the presence or absence of abnormality of the common key or the sub key. Also, the encryption apparatus of the present embodiment determines whether to output a ciphertext block based on the determination result regarding the presence or absence of an abnormality of the common key or the sub key. When there is an abnormality in the common key or the sub key, the encryption device according to the present embodiment does not output an incorrect ciphertext block by performing an error process.

  That is, according to the encryption apparatus of the present embodiment, a large amount of data can be encrypted safely and at high speed without affecting the processing performance.

Second Embodiment
Next, an encryption apparatus according to a second embodiment of the present invention will be described with reference to the drawings. The encryption device of this embodiment differs from the first embodiment in that it determines whether or not to generate a subkey based on the presence / absence of a subkey corresponding to the input common key. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description may be omitted.

  FIG. 3 is a block diagram showing an example of the configuration of the encryption device 2 of the present embodiment. As shown in FIG. 3, the encryption device 2 has a configuration in which a sub-key generation determination unit 21 is added to the encryption device 1 of the first embodiment.

  The common key is input to the sub key generation determination unit 21 (also referred to as a sub key generation determination unit). The sub key generation determination unit 21 determines whether the input common key is equal to the first common key stored in the first common key storage unit 11. In other words, the sub key generation determining unit 21 determines whether the input common key is different from the current common key.

  If the input common key has not changed, the sub-key generation determining unit 21 does not cause the key scheduling unit 12 to execute the key schedule. On the other hand, when the input common key is changed, the sub key generation determination unit 21 causes the first common key holding unit 11 to hold the new common key as the first common key, and causes the key schedule unit 12 to set the key schedule. Run it.

  The key schedule unit 12 executes the key schedule according to the determination result of the sub key generation determination unit 21. That is, the key scheduling unit 12 does not execute the key schedule when the sub-key generation determining unit 21 determines that the common key has not changed. On the other hand, when the sub-key generation determination unit 21 determines that the common key is changed, the key schedule unit 12 executes the key schedule for the new common key held in the first common key holding unit 11.

  The other configuration is the same as that of the encryption device 1 of the first embodiment, and thus the detailed description is omitted.

  The above is the description of an example of the configuration of the encryption device 2. Next, an example of the operation of the encryption device 2 will be described with reference to the drawings.

(Operation)
FIG. 4 is a flowchart for explaining an example of the operation of the encryption device 2. That is, FIG. 4 is a flowchart showing the procedure of the encryption process performed by the encryption device 2. In the following description based on the flowchart of FIG. 4, the encryption device 2 will be described as the subject of the operation.

  In FIG. 4, first, when the common key is input, the encryption device 2 determines whether or not the subkey of the common key has been generated (step S201).

  If the sub key has been generated (Yes in step S201), the process proceeds to step S205 and step S206. On the other hand, when the subkey has not been generated (No in step S201), the encryption device 2 stores the input common key as the first common key in the first common key holding unit 11 (step S202).

  Next, the encryption device 2 generates a sub-key from the first common key stored in the first common key holding unit 11 by performing key scheduling according to the common key block encryption algorithm (step S203).

  Next, the encryption device 2 stores the generated sub key in the sub key storage unit 13 (step S204).

  The encryption device 2 encrypts the input plaintext block according to the common key block encryption algorithm using the subkey stored in the subkey storage unit 13 (step S205).

  In addition, the encryption device 2 executes the common key decryption process using the subkey stored in the subkey holding unit 13 in parallel with the encryption process of step S205 and executes the common key (also referred to as a second common key). ) Is decoded (step S206).

  Next, the encryption device 2 stores the second common key in the second common key holding unit 15 (step S207).

  Next, the encryption device 2 compares the first common key stored in the first common key holding unit 11 with the second common key stored in the second common key holding unit 15 (step S208).

  Then, when the first common key and the second common key match (Yes in step S209), the encryption device 2 outputs a ciphertext block (step S210).

  On the other hand, when the first common key and the second common key do not match (No in step S 209), the encryption device 2 detects an abnormality in the sub key, performs error processing, and discards the ciphertext block. (Step S211).

  The above is the description of an example of the operation of the encryption device 2 along the flowchart of FIG.

  As described above, when the subkey has been generated from the input common key, the encryption apparatus of the present embodiment executes the encryption process using the generated subkey. Therefore, according to the encryption apparatus of this embodiment, the key schedule process can be omitted as long as the common key does not change.

Third Embodiment
Next, an encryption apparatus according to a third embodiment of the present invention will be described with reference to the drawings. The encryption apparatus of the present embodiment differs from the first embodiment in that the common key is not generated but the common key is generated according to the encryption instruction. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description may be omitted.

  FIG. 5 is a block diagram showing an example of the configuration of the encryption device 3 of the present embodiment. As shown in FIG. 5, the encryption device 3 has a configuration in which a pseudo random number generation unit 31 and a common key generation unit 32 are added to the encryption device 1 of the first embodiment.

  An encryption instruction is input to the pseudo random number generation unit 31 (also referred to as a pseudo random number generation unit). The pseudo random number generation unit 31 generates a pseudo random number according to the encryption instruction. The pseudo random number generation unit 31 outputs the generated pseudo random number to the common key generation unit 32. The pseudo random number generation unit 31 may be configured to generate a pseudo random number at the timing when the plaintext block is input.

  The pseudo random number generated by the pseudo random number generation unit 31 is input to the common key generation unit 32 (also referred to as a common key generation unit). The common key generation unit 32 generates a common key using the input pseudo random number. The common key generation unit 32 stores the generated common key in the first common key holding unit 11 as a first common key.

  The other configuration is the same as that of the encryption device 1 of the first embodiment, and thus the detailed description is omitted.

  The above is the description of an example of the configuration of the encryption device 3. Next, an example of the operation of the encryption device 3 will be described with reference to the drawings.

(Operation)
FIG. 6 is a flowchart for explaining an example of the operation of the encryption device 3. That is, FIG. 6 is a flowchart showing the procedure of the encryption process performed by the encryption device 3. In the following description based on the flowchart of FIG. 6, the encryption device 3 will be described as the subject of the operation.

  In FIG. 6, first, when the encryption instruction is input, the encryption device 3 generates a pseudorandom number (step S301).

  Next, the encryption device 3 generates a common key using the generated pseudo random number (step S302).

  Next, the encryption device 3 stores the generated common key (also referred to as a first common key) in the first common key holding unit 11 (step S303).

  Next, the encryption device 3 generates a sub-key from the first common key stored in the first common key holding unit 11 by performing key scheduling according to a common key block encryption algorithm (step S304).

  Next, the encryption device 3 stores the generated sub key in the sub key storage unit 13 (step S305).

  The encryption device 3 encrypts the input plaintext block according to the common key block encryption algorithm using the subkey stored in the subkey storage unit 13 (step S306).

  In addition, the encryption device 3 executes a common key decryption process using the subkey stored in the subkey storage unit 13 in parallel with the encryption process of step S306 to obtain a common key (also referred to as a second common key). ) Is decoded (step S307).

  Next, the encryption device 3 stores the second common key in the second common key holding unit 15 (step S308).

  Next, the encryption device 3 compares the first common key stored in the first common key holding unit 11 with the second common key stored in the second common key holding unit 15 (step S309).

  Then, when the first common key and the second common key match (Yes in step S310), the encryption device 3 outputs a ciphertext block (step S311).

  On the other hand, when the first common key and the second common key do not match (No in step S310), the encryption device 3 detects an abnormality in the sub key, performs error processing, and discards the ciphertext block. (Step S312).

  The above is the description of an example of the operation of the encryption device 3 along the flowchart of FIG.

  As described above, the encryption apparatus of the present embodiment generates a common key according to the encryption instruction. Therefore, according to the encryption apparatus of the present embodiment, since the common key acquired from the outside is not used, encryption with the common key having the possibility of leakage or tampering is not performed, and the security of the ciphertext block And improve reliability.

Fourth Embodiment
Next, an encryption apparatus according to a fourth embodiment of the present invention will be described with reference to the drawings. The encryption apparatus according to the present embodiment is the first embodiment in that, when an abnormality is suspected in the sub key based on the comparison result of the common key, the sub key is regenerated from the first common key and re-encrypted. It is different from the form. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description may be omitted.

  FIG. 7 is a block diagram showing an example of the configuration of the encryption device 4 of the present embodiment. As shown in FIG. 7, the encryption device 4 has a configuration in which the retry determination unit 41 is added to the encryption device 1 of the first embodiment.

  The retry determination unit 41 (retry determination unit) receives the comparison result of the first common key and the second common key by the common key comparison unit 16. When it is suspected that there is an abnormality in the sub key based on the comparison result of the first common key and the second common key, the retry determination unit 41 re-generates the sub key from the first common key to the key scheduling unit 12. Give instructions to create.

  The key schedule unit 12 executes the key schedule using the first common key stored in the first common key holding unit 11 according to the instruction of the retry determination unit 41, and regenerates the sub key. The key scheduling unit 12 stores the re-created sub key in the sub key holding unit 13.

  The other configuration is the same as that of the encryption device 1 of the first embodiment, and thus the detailed description is omitted.

  The above is the description of an example of the configuration of the encryption device 4. Next, an example of the operation of the encryption device 4 will be described with reference to the drawings.

(Operation)
FIG. 8 is a flowchart for explaining an example of the operation of the encryption device 4. That is, FIG. 8 is a flowchart showing the procedure of the encryption process performed by the encryption device 4. In the following description following the flowchart of FIG. 8, the encryption device 4 will be described as the subject of the operation.

  In FIG. 8, first, when the common key is input, the encryption device 4 stores the common key (also referred to as a first common key) in the first common key holding unit 11 (step S401).

  Next, the encryption device 4 generates a sub-key from the first common key stored in the first common key holding unit 11 by performing key scheduling according to the common key block encryption algorithm (step S402).

  Next, the encryption device 4 stores the generated sub key in the sub key storage unit 13 (step S403).

  The encryption device 4 encrypts the input plaintext block by the common key block encryption algorithm using the subkey stored in the subkey holding unit 13 (step S404).

  In addition, the encryption device 4 executes the common key decryption process using the subkey stored in the subkey storage unit 13 in parallel with the encryption process of step S404 and calls the common key (also referred to as a second common key). ) Is decoded (step S405).

  Next, the encryption device 4 stores the decrypted second common key in the second common key holding unit 15 (step S406).

  Next, the encryption device 4 compares the first common key stored in the first common key holding unit 11 with the second common key stored in the second common key holding unit 15 (step S407).

  Then, when the first common key and the second common key match (Yes in step S408), the encryption device 4 determines that there is no abnormality in the sub key, and outputs a ciphertext block (step S409).

  On the other hand, when the first common key and the second common key do not match (No in step S408), the encryption device 4 determines that there is an abnormality in the sub key. At this time, the process returns to step S402, and the encryption device 4 generates a new sub key from the first common key stored in the first common key holding unit 11 by re-executing the key scheduling process.

  The above is the description of an example of the operation of the encryption device 4 along the flowchart of FIG.

  As described above, the encryption apparatus of the present embodiment re-generates the subkey using the first common key stored in the first common key holding unit when there is a suspicion of leakage or falsification in the subkey. Then, the encryption apparatus of this embodiment performs encryption using the re-created subkey. Therefore, according to the encryption apparatus of the present embodiment, it is possible to recover without stopping the operation of the system.

Fifth Embodiment
Next, an encryption apparatus according to a fifth embodiment of the present invention will be described with reference to the drawings. The encryption apparatus of this embodiment is different from the first embodiment in that the data scramble unit is duplicated and data abnormality is also detected. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description may be omitted.

(Constitution)
FIG. 9 is a block diagram showing an example of the configuration of the encryption device 5 of the present embodiment. As shown in FIG. 9, in the encryption device 1 of the first embodiment, the encryption device 5 duplicates the data scramble unit 17 into the first data scramble unit 51 and the second data scramble unit 52, and compares the encrypted blocks. It has the structure which added the part 53. FIG.

  The first data scramble unit 51 receives the subkey from the subkey holding unit 13 and also receives a plaintext block constituting the data to be encrypted. The first data scramble unit 51 encrypts the input plaintext block using the sub key. The first data scramble unit 51 outputs a ciphertext block (also referred to as a first ciphertext block), which is encrypted data, to the cipher block comparison unit 53.

  The second data scramble unit 52 receives the subkey from the subkey holding unit 13 and also receives a plaintext block constituting the data to be encrypted. The second data scramble unit 52 generates a ciphertext block by encrypting the input plaintext block using the sub key. The second data scramble unit 52 outputs the generated ciphertext block (also referred to as a second ciphertext block) to the cipher block comparison unit 53.

  The first ciphertext block is input from the first data scramble unit 51 and the second ciphertext block is input from the second data scramble unit 52 to the cipher block comparison unit 53 (also referred to as cipher block comparison unit). The cryptographic block comparison unit 53 compares the input first ciphertext block with the second ciphertext block. In addition to the comparison of the ciphertext blocks, the cipher block comparison unit 53 may apply the authentication-use cipher use mode.

  When the first ciphertext block and the second ciphertext block are different, the cipher block comparison unit 53 determines that at least one of the first ciphertext block and the second ciphertext block is abnormal. That is, when the first ciphertext block and the second ciphertext block are different, the cipher block comparison unit 53 determines that there is an abnormality in the ciphertext block or the plaintext block corresponding to the ciphertext block. If the cipher block comparison unit 53 determines that there is an abnormality in the ciphertext block or the plaintext block, the cipher block comparison unit 53 notifies the output determination unit 18 that there is an abnormality without outputting the ciphertext block.

  On the other hand, when the first ciphertext block and the second ciphertext block are the same, the cipher block comparison unit 53 determines that the first ciphertext block and the second ciphertext block are normal. That is, when the first ciphertext block and the second ciphertext block are the same, the cipher block comparison unit 53 determines that the ciphertext block is normal. If the cipher block comparison unit 53 determines that the ciphertext block is normal, it outputs either the first ciphertext block or the second ciphertext block as a ciphertext block to the output judgment unit 18.

  When receiving the notification that there is an abnormality from the encryption block comparison unit 53, the output determination unit 18 stops the output of the ciphertext block. For example, the output determination unit 18 may be configured to issue an instruction to display the notification result on a display device (not shown) or the like when receiving the notification that there is an abnormality.

  On the other hand, when acquiring the ciphertext block from the cipher block comparison unit 53, the output judgment unit 18 outputs the acquired ciphertext block.

  The other configuration is the same as that of the encryption device 1 of the first embodiment, and thus the detailed description is omitted.

  The above is the description of an example of the configuration of the encryption device 5. Next, an example of the operation of the encryption device 5 will be described with reference to the drawings.

(Operation)
FIG. 10 is a flowchart for explaining an example of the operation of the encryption device 5. That is, FIG. 10 is a flowchart showing the procedure of the encryption process performed by the encryption device 5. In the following description based on the flowchart of FIG. 10, the encryption device 5 will be described as the subject of the operation.

  In FIG. 10, first, when the common key is input, the encryption device 5 stores the common key (also referred to as a first common key) in the first common key holding unit 11 (step S501).

  Next, the encryption device 5 generates a sub-key from the first common key stored in the first common key holding unit 11 by performing key scheduling according to the common key block encryption algorithm (step S502).

  Next, the encryption device 5 stores the generated sub key in the sub key storage unit 13 (step S503).

  The encryption device 5 double encrypts the input plaintext block according to the common key block encryption algorithm using the subkey stored in the subkey storage unit 13 (step S504). That is, the encryption device 5 generates two encrypted blocks from the same plaintext block.

  Next, the encryption device 5 compares two ciphertext blocks generated from the same plaintext block (step S505).

  In addition, the encryption device 5 executes the common key decryption process using the subkey stored in the subkey storage unit 13 in parallel with the processing in step S504 and step S505, thereby generating the common key (also the second common key). Call) is decoded (step S506).

  Next, the encryption device 5 stores the decrypted second common key in the second common key holding unit 15 (step S507).

  Next, the encryption device 5 compares the first common key stored in the first common key holding unit 11 with the second common key stored in the second common key holding unit 15 (step S508).

  Then, when the first common key and the second common key match (Yes in step S509), the encryption device 5 outputs a ciphertext block (step S510).

  On the other hand, when the first common key and the second common key do not match (No in step S509), the encryption device 5 detects an abnormality in the sub key, performs error processing, and discards the ciphertext block. (Step S511).

  The above is the description of an example of the operation of the encryption device 5 along the flowchart of FIG.

  As described above, the encryption apparatus of this embodiment double encrypts the plaintext block to generate two encrypted blocks. Then, the encryption apparatus of the present embodiment can detect an abnormality in data by comparing two encrypted blocks.

Sixth Embodiment
Next, a decoding apparatus according to a sixth embodiment of the present invention will be described with reference to the drawings. The decryption apparatus of the present embodiment decrypts the ciphertext block output from the encryption apparatus of the first embodiment. The decryption apparatus of the present embodiment may be configured to decrypt a ciphertext block output from the encryption apparatus of the second to fifth embodiments.

(Constitution)
FIG. 11 is a block diagram showing an example of the configuration of the decoding device 6 according to the present embodiment. As shown in FIG. 11, the decryption device 6 includes a first common key holding unit 61, a key scheduling unit 62, a sub key holding unit 63, a common key decryption unit 64, a second common key holding unit 65, a common key comparison unit 66, A data descrambling unit 67 and an output determining unit 68 are provided.

  The first common key holding unit 61 (also referred to as a first common key holding unit) holds the input common key (hereinafter also referred to as a first common key). For example, the first common key holding unit 61 is realized by a register or a memory.

  The key schedule unit 62 (also referred to as a sub key generation unit) acquires the first common key held in the first common key holding unit 61. The key scheduling unit 62 generates a sub key from the acquired first common key. For example, the key scheduling unit 62 generates N subkeys used in all rounds from the first common key (N is a natural number). The key schedule unit 62 stores the generated sub key in the sub key holding unit 63.

  The sub key holding unit 63 (also referred to as a sub key holding unit) stores the sub key generated by the key scheduling unit 62. For example, the sub key holding unit 63 is realized by a register or a memory.

  The common key decryption unit 64 (also referred to as a common key decryption unit) decrypts the common key (hereinafter also referred to as a second common key) from the subkey stored in the subkey holding unit 63. For example, the common key decryption unit 64 decrypts the second common key from the N subkeys stored in the subkey holding unit 63 (N is a natural number). The common key decryption unit 64 causes the second common key holding unit 65 to hold the decrypted second common key.

  The second common key holding unit 65 (also referred to as a second common key holding unit) holds the second common key decrypted by the common key decryption unit 64. For example, the second common key holding unit 65 is realized by a register or a memory.

  The common key comparison unit 66 (also referred to as a common key comparison unit) compares the first common key held in the first common key holding unit 61 with the second common key held in the second common key holding unit 65. Do. The common key comparison unit 66 outputs the comparison result of the first common key and the second common key to the output determination unit 68.

  The data descrambling unit 67 (also referred to as a decryption unit) receives the subkey from the subkey holding unit 63 and receives the encrypted block. The data descrambling unit 67 decrypts the input encrypted block using the subkey. The data descrambling unit 67 outputs the decrypted plaintext block to the output determination unit 68.

  Output determination unit 68 (also referred to as output determination means) receives the plaintext block from data descrambling unit 67 and also receives the comparison result between the first common key and the second common key from common key comparison unit 66. Ru. Based on the comparison result by the common key comparison unit 66, the output determination unit 68 determines whether to output a plaintext block. If the first common key and the second common key are the same, the output judgment unit 68 judges to output a plaintext block. On the other hand, when the first common key and the second common key are different, the output determination unit 68 detects an abnormality (also referred to as an error) such as a failure or falsification in the sub key and discards the plaintext block without outputting it.

  The above is the description of the configuration of the decoding device 6. The operation of the decrypting device 6 may replace the encryption process (step S104) of the encrypting device of the first embodiment with the decrypting process, and thus the detailed description will be omitted.

  As described above, according to the decoding apparatus of the present embodiment, a large amount of data can be safely and quickly decoded without affecting the processing performance.

Seventh Embodiment
Next, a line encryption system according to a seventh embodiment of the present invention will be described with reference to the drawings. FIG. 12 is a block diagram showing an example of the configuration of the line encryption system 7 of the present embodiment. As shown in FIG. 12, the line encryption system 7 includes at least one encryption device 71 and at least one decryption device 72.

  The encryption device 71 corresponds to any of the encryption devices 1 to 5 of the first to fifth embodiments. For example, the encryption device 71 and the decryption device 72 are connected by at least one of a wired line and a wireless line. The encryption device 71 transmits the encrypted block generated by encrypting the input plaintext block to the decryption device 72.

  The decoding device 72 corresponds to the decoding device 6 of the sixth embodiment. The decryption device 72 receives the encrypted block from the encryption device 71. The decryption device 72 decrypts the plaintext block from the received encrypted block using the common key.

  As described above, according to the line encryption system of the present embodiment, it is possible to construct a communication system capable of transmitting and receiving a large amount of data safely and at high speed without affecting the processing performance.

(hardware)
Here, a hardware configuration for realizing the encryption apparatus or the decryption apparatus according to each embodiment of the present invention will be described by taking the computer 90 of FIG. 13 as an example. The computer 90 in FIG. 13 is a configuration example for realizing the encryption device or the decryption device according to each embodiment, and does not limit the scope of the present invention.

  As shown in FIG. 13, the computer 90 includes a processor 91, a main storage 92, an auxiliary storage 93, an input / output interface 95, and a communication interface 96. In FIG. 13, the interface is abbreviated as I / F (Interface). The processor 91, the main storage unit 92, the auxiliary storage unit 93, the input / output interface 95 and the communication interface 96 are communicably connected to each other via a bus 99. The processor 91, the main storage device 92, the auxiliary storage device 93, and the input / output interface 95 are connected to a network such as the Internet or an intranet via the communication interface 96.

  The processor 91 deploys the program stored in the auxiliary storage device 93 or the like in the main storage device 92, and executes the deployed program. In the present embodiment, a software program installed in the computer 90 may be used. The processor 91 executes processing by the encryption device or the decryption device according to the present embodiment.

  The main storage device 92 has an area in which a program is expanded. The main storage device 92 may be, for example, a volatile memory such as a dynamic random access memory (DRAM). In addition, a non-volatile memory such as a magnetoresistive random access memory (MRAM) may be configured and added as the main storage device 92.

  The auxiliary storage device 93 stores various data. For example, the auxiliary storage device 93 is configured by a local disk such as a hard disk or a flash memory. Note that various data may be stored in the main storage unit 92, and the auxiliary storage unit 93 may be omitted.

  The input / output interface 95 is an interface for connecting the computer 90 and peripheral devices. The communication interface 96 is an interface for connecting to an external system or device through a network such as the Internet or an intranet based on standards and specifications. The input / output interface 95 and the communication interface 96 may be common as an interface connected to an external device.

  The computer 90 may be configured to connect input devices such as a keyboard, a mouse, and a touch panel as necessary. Those input devices are used to input information and settings. Note that in the case where the touch panel is used as an input device, the display screen of the display device may serve as an interface of the input device. Data communication between the processor 91 and the input device may be performed by the input / output interface 95.

  The computer 90 may also be equipped with a display device for displaying information. When the display device is provided, the computer 90 is preferably provided with a display control device (not shown) for controlling the display of the display device. The display device may be connected to the computer 90 via the input / output interface 95.

  In addition, the computer 90 may be equipped with a disk drive as needed. The disk drive is connected to the bus 99. The disk drive mediates reading of a data program from the recording medium, writing of the processing result of the computer 90 to the recording medium, and the like between the processor 91 and a recording medium (program recording medium) (not shown). The recording medium can be realized by, for example, an optical recording medium such as a CD (Compact Disc) or a DVD (Digital Versatile Disc). Also, the recording medium may be realized by a semiconductor recording medium such as a Universal Serial Bus (USB) memory or a Secure Digital (SD) card, a magnetic recording medium such as a flexible disk, or another recording medium.

  The above is an example of the hardware configuration for enabling the encryption device or the decryption device according to each embodiment of the present invention. The hardware configuration in FIG. 13 is an example of the hardware configuration for executing the arithmetic processing of the encryption apparatus or the decryption apparatus according to each embodiment, and does not limit the scope of the present invention. Further, a program that causes a computer to execute a process related to the encryption device or the decryption device according to each embodiment is also included in the scope of the present invention. Furthermore, a program recording medium recording the program according to each embodiment is also included in the scope of the present invention.

  The components of the encryption device or decryption device of each embodiment can be arbitrarily combined. In addition, the components of the encryption device or decryption device of each embodiment may be realized by software or circuits.

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.
[Supplementary Note]
Some or all of the above embodiments may be described as in the following appendices, but is not limited to the following.
(Supplementary Note 1)
First common key holding means for holding the first common key;
Sub-key generation means for generating at least one sub-key from the first common key held in the first common key holding means according to a key schedule;
A subkey holding unit that holds the subkey generated by the subkey generation unit;
Common key decryption means for obtaining the subkey held in the subkey holding means and decrypting the second common key;
Second common key holding means for holding the second common key decrypted by the common key decryption means;
Common key comparison means for comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
An encryption unit that encrypts a plaintext block using the subkey stored in the subkey storage unit to generate a ciphertext block;
The comparison result between the first common key and the second common key by the common key comparison unit and the ciphertext block generated by the encryption unit are input, and based on the comparison result by the common key comparison unit And an output determination unit that determines whether to output the ciphertext block.
(Supplementary Note 2)
The output judging means
Outputting the ciphertext block if the first common key and the second common key are the same;
The encryption device according to appendix 1, wherein the ciphertext block is discarded when the first common key and the second common key are different.
(Supplementary Note 3)
Sub-key determination means for determining whether or not to generate the sub-key by comparing the input common key with the first common key held in the first common key holding means;
The sub key judging means
When the input common key and the first common key are different, the input common key is held as the first common key in the first common key holding unit, and the first common key holding unit is newly added Instructing the sub-key generation unit to generate the sub-key from the first common key held in
The encryption device according to claim 1 or 2, wherein the sub-key generation unit is not instructed to generate the sub-key when the input common key and the first common key are equal.
(Supplementary Note 4)
Pseudo-random number generation means for generating pseudo-random numbers according to the encryption instruction;
Common key generation means for generating a common key using the pseudo random number generated by the pseudo random number generation means, and holding the generated common key in the first common key holding means as the first common key The encryption device according to Appendix 1 or 2.
(Supplementary Note 5)
The apparatus further comprises retry determination means for determining whether or not the subkey is suspected to be abnormal based on the comparison result between the first common key and the second common key by the common key comparison means.
The retry determination means is
If it is suspected that the subkey is abnormal, the subkey generation means is instructed to regenerate the subkey;
The encryption device according to any one of appendices 1 to 4, wherein when it is not suspected that there is an abnormality in the sub key, the comparison result by the common key comparison means is output to the output determination means.
(Supplementary Note 6)
The encryption means is duplicated,
At least two of the ciphertext blocks generated from the same plaintext block by the duplexed encryption means are input, and provided with cipher block comparison means for comparing the at least two ciphertext blocks input.
The cipher block comparison means
If at least two of the input ciphertext blocks are different, it is determined that there is an abnormality, and the ciphertext block is not output to the output determination unit.
The encryption apparatus according to any one of appendices 1 to 5, wherein the encryption device is determined to be normal if the input at least two ciphertext blocks are equal, and the ciphertext block is output to the output determination unit.
(Appendix 7)
First common key holding means for holding the first common key;
Sub-key generation means for generating at least one sub-key from the first common key held in the first common key holding means according to a key schedule;
A subkey holding unit that holds the subkey generated by the subkey generation unit;
Common key decryption means for obtaining the subkey held in the subkey holding means and decrypting the second common key;
Second common key holding means for holding the second common key decrypted by the common key decryption means;
Common key comparison means for comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
Decryption means for decrypting a plaintext block from a ciphertext block using the subkey held in the subkey holding means;
The comparison result of the first common key and the second common key by the common key comparison unit and the plaintext block decrypted by the decryption unit are input, and the plaintext is input based on the comparison result by the common key comparison unit And a output determination unit that determines whether to output a block.
(Supplementary Note 8)
At least one subkey is generated from the first common key according to a key schedule, and a plaintext block is encrypted using the generated subkey to generate a ciphertext block, and the generated subkey is used to (2) An encryption apparatus that decrypts the common key and determines whether to output the ciphertext block based on the comparison result of the first common key and the second common key.
At least one subkey is generated from the first common key according to a key schedule, the plaintext block is decrypted from the ciphertext block using the generated subkey, and the subkey is generated using the generated subkey A decryption device that decrypts a second common key and determines whether to output the plaintext block based on a comparison result of the first common key and the second common key;
The encryption device is
Transmitting the ciphertext block obtained by encrypting the plaintext block to the decryption device;
The decoding device is
A line encryption system for decrypting the plaintext block from the ciphertext block received from the encryption device.
(Appendix 9)
Holding the first common key in the first common key holding means;
At least one sub-key is generated according to a key schedule from the first common key held in the first common key holding means,
The generated subkey is held in subkey holding means,
The second common key is decrypted using the subkey held in the subkey holding means,
Holding the decrypted second common key in second common key holding means;
Comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
The plaintext block is encrypted using the subkey held in the subkey holding means to generate a ciphertext block,
The encryption method for determining whether or not to output the ciphertext block based on the comparison result of the first common key and the second common key.
(Supplementary Note 10)
A process of holding the first common key in the first common key holding means;
A process of generating at least one sub-key from the first common key held in the first common key holding means according to a key schedule;
A process of holding the generated subkey in a subkey holding unit;
A process of decrypting a second common key using the subkey held in the subkey holding means;
A process of holding the decrypted second common key in second common key holding means;
A process of comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
A process of generating a ciphertext block by encrypting a plaintext block using the subkey held in the subkey holding means;
A program that causes a computer to execute processing of determining whether to output the ciphertext block based on the comparison result of the first common key and the second common key.
(Supplementary Note 11)
Holding the first common key in the first common key holding means;
At least one sub-key is generated according to a key schedule from the first common key held in the first common key holding means,
The generated subkey is held in subkey holding means,
The second common key is decrypted using the subkey held in the subkey holding means,
Holding the decrypted second common key in second common key holding means;
Comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
Decrypts plaintext data from a ciphertext block using the subkey held in the subkey holding means;
An encryption method for determining whether to output the plaintext data based on the comparison result of the first common key and the second common key.
(Supplementary Note 12)
A process of holding the first common key in the first common key holding means;
A process of generating at least one sub-key from the first common key held in the first common key holding means according to a key schedule;
A process of holding the generated subkey in a subkey holding unit;
A process of decrypting a second common key using the subkey held in the subkey holding means;
A process of holding the decrypted second common key;
A process of comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
A process of decrypting plaintext data from a ciphertext block using the subkey held in the subkey holding means;
A program that causes a computer to execute a process of determining whether to output the plaintext data based on the comparison result of the first common key and the second common key.

1, 2, 3, 4, 5 encryption device 6 decryption device 7 line encryption system 11 first common key holding unit 12 key schedule unit 13 sub key holding unit 14 common key decryption unit 15 second common key holding unit 16 common key Comparison unit 17 Data scramble unit 18 Output determination unit 21 Sub-key generation determination unit 31 Pseudorandom number generation unit 32 Common key generation unit 41 Retries determination unit 51 First data scramble unit 52 Second data scramble unit 53 Cipher block comparison unit 67 Data data Scrambler 71 Encryption device 72 Decryption device

Claims (10)

First common key holding means for holding the first common key;
Sub-key generation means for generating at least one sub-key from the first common key held in the first common key holding means according to a key schedule;
A subkey holding unit that holds the subkey generated by the subkey generation unit;
Common key decryption means for obtaining the subkey held in the subkey holding means and decrypting the second common key;
Second common key holding means for holding the second common key decrypted by the common key decryption means;
Common key comparison means for comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
An encryption unit that encrypts a plaintext block using the subkey stored in the subkey storage unit to generate a ciphertext block;
The comparison result between the first common key and the second common key by the common key comparison unit and the ciphertext block generated by the encryption unit are input, and based on the comparison result by the common key comparison unit And an output determination unit that determines whether to output the ciphertext block. The output judging means
Outputting the ciphertext block if the first common key and the second common key are the same;
The encryption device according to claim 1, wherein the ciphertext block is discarded when the first common key and the second common key are different. Sub-key determination means for determining whether or not to generate the sub-key by comparing the input common key with the first common key held in the first common key holding means;
The sub key judging means
When the input common key and the first common key are different, the input common key is held as the first common key in the first common key holding unit, and the first common key holding unit is newly added Instructing the sub-key generation unit to generate the sub-key from the first common key held in
3. The encryption device according to claim 1, wherein if the input common key and the first common key are equal, the sub-key generation unit is not instructed to generate the sub-key. Pseudo-random number generation means for generating pseudo-random numbers according to the encryption instruction;
Common key generation means for generating a common key using the pseudo random number generated by the pseudo random number generation means, and holding the generated common key in the first common key holding means as the first common key The encryption device according to claim 1. The apparatus further comprises retry determination means for determining whether or not the subkey is suspected to be abnormal based on the comparison result between the first common key and the second common key by the common key comparison means.
The retry determination means is
If it is suspected that the subkey is abnormal, the subkey generation means is instructed to regenerate the subkey;
The encryption device according to any one of claims 1 to 4, wherein when it is not suspected that there is an abnormality in the sub key, the comparison result by the common key comparison means is output to the output determination means. The encryption means is duplicated,
At least two of the ciphertext blocks generated from the same plaintext block by the duplexed encryption means are input, and provided with cipher block comparison means for comparing the at least two ciphertext blocks input.
The cipher block comparison means
If at least two of the input ciphertext blocks are different, it is determined that there is an abnormality, and the ciphertext block is not output to the output determination unit.
The encryption device according to any one of claims 1 to 5, wherein the encryption device is determined to be normal if the input at least two of the ciphertext blocks are equal, and the ciphertext block is output to the output determination unit. First common key holding means for holding the first common key;
Sub-key generation means for generating at least one sub-key from the first common key held in the first common key holding means according to a key schedule;
A subkey holding unit that holds the subkey generated by the subkey generation unit;
Common key decryption means for obtaining the subkey held in the subkey holding means and decrypting the second common key;
Second common key holding means for holding the second common key decrypted by the common key decryption means;
Common key comparison means for comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
Decryption means for decrypting a plaintext block from a ciphertext block using the subkey held in the subkey holding means;
The comparison result of the first common key and the second common key by the common key comparison unit and the plaintext block decrypted by the decryption unit are input, and the plaintext is input based on the comparison result by the common key comparison unit And a output determination unit that determines whether to output a block. At least one subkey is generated from the first common key according to a key schedule, and a plaintext block is encrypted using the generated subkey to generate a ciphertext block, and the generated subkey is used to (2) An encryption apparatus that decrypts the common key and determines whether to output the ciphertext block based on the comparison result of the first common key and the second common key.
At least one subkey is generated from the first common key according to a key schedule, the plaintext block is decrypted from the ciphertext block using the generated subkey, and the subkey is generated using the generated subkey A decryption device that decrypts a second common key and determines whether to output the plaintext block based on a comparison result of the first common key and the second common key;
The encryption device is
Transmitting the ciphertext block obtained by encrypting the plaintext block to the decryption device;
The decoding device is
A line encryption system for decrypting the plaintext block from the ciphertext block received from the encryption device. Holding the first common key in the first common key holding means;
At least one sub-key is generated according to a key schedule from the first common key held in the first common key holding means,
The generated subkey is held in subkey holding means,
The second common key is decrypted using the subkey held in the subkey holding means,
Holding the decrypted second common key in second common key holding means;
Comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
The plaintext block is encrypted using the subkey held in the subkey holding means to generate a ciphertext block,
The encryption method for determining whether or not to output the ciphertext block based on the comparison result of the first common key and the second common key. A process of holding the first common key in the first common key holding means;
A process of generating at least one sub-key from the first common key held in the first common key holding means according to a key schedule;
A process of holding the generated subkey in a subkey holding unit;
A process of decrypting a second common key using the subkey held in the subkey holding means;
A process of holding the decrypted second common key in second common key holding means;
A process of comparing the first common key held in the first common key holding means with the second common key held in the second common key holding means;
A process of generating a ciphertext block by encrypting a plaintext block using the subkey held in the subkey holding means;
A program that causes a computer to execute processing of determining whether to output the ciphertext block based on the comparison result of the first common key and the second common key.

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