JP2002330127A - Encryption device, decryption device and communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly secure communication system. SOLUTION: In encrypting and transmitting a file to be sent, a sending device 10 determines an encryption method based on encryption method tables 44-l and 44-2 stored in IC cards 40-1 and 40-2, respectively, which are decoded by an IC card reader 11. By employing the encryption method thus determined, the device 10 then encrypts the file to be sent to form an encrypted file and sends it by a sending part 18. In decrypting the encrypted file and outputting the original file to be sent, the receiving device 30 determines a decryption method based on decryption tables 44-3 and 44-4, stored in IC cards 40-3 and 40-4, respectively, which are decoded by an IC card reader. The device 30 decrypts the encrypted file by employing the decryption method thus determined and outputs the original file to be sent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a more secure encryption device, a more secure decryption and a more secure communication system.

[0002]

2. Description of the Related Art With the advance of information processing technology and communication technology,
2. Description of the Related Art Information can be easily and efficiently transmitted through a communication network, and accordingly, the amount of information transmitted through such a communication network has been dramatically increased. There are various forms of communication networks. For example, the Internet, in which a plurality of computer systems and networks are connected on a worldwide scale, has attracted attention in terms of its scale and communication cost, and is widely used. . By the way, via such a communication network, communication of data having various confidentialities is performed between individuals and companies.
As a general method of transmitting data requiring confidentiality in such data communication, a method of encrypting and transmitting confidential data has been used.

[0003]

However, in the conventional method, if the encryption method is leaked, the third party analyzes the encrypted data, specifies the encryption key, and decrypts the confidential data. May be done. Therefore, a method in which the encryption method is difficult to specify is desired.

Accordingly, it is an object of the present invention to provide an encryption device with higher security. Another object of the present invention is to provide a decryption device with higher security. Another object of the present invention is to provide a communication system with higher security.

[0005]

In order to solve the above-mentioned problems, an encryption apparatus according to the present invention stores an encryption method table for determining an encryption method for encrypting a file to be transmitted which is loaded. A reading unit that reads the stored encryption method table from the information storage device; and determines an encryption method based on the read encryption method table, and determines the transmission target based on the determined encryption method. Encryption means for encrypting the file and generating an encrypted file; control file generation means for generating a control file having at least information on the encryption method; and encrypting the encrypted file and the generated control file. Transmitting means for transmitting.

[0006] Further, the decryption apparatus according to the present invention comprises a receiving means for receiving an encrypted file obtained by encrypting a transmission target file and a control file having at least information on an encryption method, A reading unit that reads the stored decryption method table from an information storage device that stores a decryption method table that determines a decryption method for decrypting the received encrypted file; and the read decryption method table, Determining a decryption method based on information on an encryption method included in the received control file, decrypting the received encrypted file based on the determined decryption method, and outputting a transmission target file. Decoding means.

Further, the communication system according to the present invention is characterized in that an information storage device for storing an encryption system table for determining an encryption system for encrypting a file to be transmitted, which is to be loaded, is stored in the stored encryption system. Reading means for reading a table, an encryption method for determining an encryption method based on the read encryption method table, and encrypting the transmission target file based on the determined encryption method to generate an encrypted file. Means, a control file generating means for generating a control file having at least information on the encryption method, an encryption device having a transmission means for transmitting the encrypted file and the generated control file, An encrypted file that encrypts the file to be sent, and
A receiving unit that receives a control file having at least information on the encryption method, and an information storage device that stores a decryption method table for determining a decryption method for loading the received encrypted file.
Reading means for reading the stored decoding method table, and the read decoding method table;
A decryption method is determined based on information on the encryption method included in the received control file, and the received encrypted file is decrypted based on the determined decryption method, and a file to be transmitted is output. And a decoding device having decoding means.

[0008]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIGS. As an embodiment of the present invention, a communication system having a transmitting device and a receiving device that collectively transmit a plurality of desired data files via an arbitrary transmission path will be exemplified.

[0009] The operations of the transmitting device and the receiving device are respectively processed by an encryption application and a decryption application that are computer programs.
There are types of encryption application and decryption application that perform a series of different processes, and version numbers are determined correspondingly. For example, when one version number of the application is selected, a series of processing corresponding to the selected version number is performed. Here, a certain version number is set, and a corresponding encryption application is used.

FIG. 1 is a block diagram showing an overall configuration of a communication system 1 according to an embodiment of the present invention. The communication system 1 has a configuration in which a transmission device 10 and a reception device 30 are connected via a transmission path 20. The IC card 40-1 and the IC card 40-2 are loaded on the transmission device 10. The IC card 40-3 and the IC card 40-4 are
It is loaded on the receiving device 30. The embodiment of the present invention is based on the assumption that two persons, an administrator and a user (system operator and operator), are on the transmitting side for transmitting data, and two persons, an administrator and a user, are on the receiving side. It has a side user IC card 40-1, a transmitting side manager IC card 40-2, a receiving side user IC card 40-3, and a receiving side manager IC card 40-4.

FIG. 2 is a block diagram showing the configuration of the communication system 1 according to the embodiment of the present invention in detail. First, a schematic operation of each unit of the communication system 1 will be described. The transmission device 10 transmits a desired data file to be transmitted to
The data is converted into a predetermined format by performing various processes described later and transmitted to the transmission path 20. The transmission device 10 is a transmission-side user IC.
Card 40-1 and sending side manager IC card 40-2
Is loaded. Two ICs loaded in the transmission device 10
In the card 40-1 and the IC card 40-2, various data necessary when the transmitting device 10 performs a predetermined conversion on a desired data file to be transmitted and transmits the data file to the transmission path 20 is divided and stored. .

First, data stored in the IC card 40-1 and the IC card 40-2 will be described.
FIG. 3 is a block diagram showing data stored in the IC card 40-1. As shown in FIG. 3, the IC card 40-1 has a setting file 41-1, a partial division pattern table 42-1, an encryption key table 43-1 and an encryption method table 44-1.

The data elements stored in the transmitting-side user IC card 40-1 will be described. Configuration file 41
-1 is a user password, a card folder ID (ID
entity code), card folder name, user flag, manager flag, workgroup ID, card folder RSA (Rivest, Shamir, Ad)
leman encryption) private key, card folder RSA public key, administrator ID, administrator's name, receiver's ID, receiver's name, and receiver's RSA public key.

The user password is entered in the IC card 40-1.
Is a password for confirming the identity of the person possessing the password. The card folder ID is an ID number of a person holding the IC card 40-1. The name of the card folder is the name of the person who holds the IC card 40-1. The user flag is 1 in the case of a user IC card, and is 0 in other cases. The administrator flag is 1 in the case of an administrator IC card, and is 0 in other cases. The workgroup ID is an ID number of a workgroup to which the user and the administrator belong. The card folder RSA private key is the RSA private key of the holder of the IC card 40-1. The card folder RSA public key is stored in the IC card 40-
It is the RSA public key of one holder. The administrator ID is the ID number of the administrator on the transmission side. The name of the administrator is the name of the administrator on the transmission side. The ID on the receiving side is the ID number of the user on the receiving side. The name on the receiving side is the name of the user on the receiving side. The receiving-side RSA public key is the receiving-side user's RSA public key.

FIG. 4 is a diagram showing an example of the division pattern table. The partial division pattern table 42-1 is
As shown in FIG. 4, it is a part of a division pattern table used when dividing a data file to be transmitted. The data division unit 13 described later combines the partial division pattern table 42-1 and the partial division pattern table 42-2 to create a division pattern table, and divides the data file with reference to the division pattern table. Specifically, as shown in FIG.
The division pattern number and the corresponding division pattern are 16
It is a table arranged vertically. The partial division pattern table 42-1 is a table of the first to fourth columns of the division pattern table. Also, the partial division pattern table 4
2-2 is a table of the fifth to eighth columns of the division pattern table. 1B-F1 of pattern 1 in FIG. 4 means that 1-byte data is stored in file 1.

The encryption key table 43-1 is stored in the encryption unit 17
When generating an encryption key to be used by the
2 is a table referred to together with -2. More specifically, the encryption key table is 256-byte binary data obtained by random numbers.

FIG. 5 is a diagram showing an example of the encryption method table. The encryption method table 44-1 is a table for determining an encryption method in combination with the encryption method table 44-2 when the encryption unit 17 encrypts a file. Specifically, the encryption method table contains:
As shown in FIG. 5, data of the encryption method corresponding to the number is stored.

No. 1 DES (Data Encrypt)
ption Standard) encryption method is plain text,
This is a secret key block encryption system in which both the cipher text and the key are subjected to encryption processing in a 64-bit size.

No. The triple DES (1) encryption method is a secret key block encryption method that performs a series of DES encryption processes of encryption, decryption, and encryption using a plurality of keys.

No. The triple DES (2) encryption method is an encryption method in which a series of DES encryption processes of decryption, encryption, and decryption are performed using a plurality of keys.

No. MISTY 4 is a block encryption method in which the length of plaintext and ciphertext is 64 bits and the key size is 128 bits, and is an encryption method that is sufficiently secure against differential cryptanalysis and linear decryption. It is.

No. The RSA encryption method No. 5 is an encryption method in which the encryption key and the decryption key are different, and the encryption key is made public and the decryption key is kept secret. The difficulty of the factorization is used as the basis of the encryption strength.

The setting file 41-1 is referred to by the user / administrator transmitting / receiving side specifying unit 12 and the electronic signature unit 14,
The partial division pattern table 42-1 stores the data division unit 1
3 and the encryption key table 43-1 stores the encryption unit 1
7 and the encryption method table 44-1 is
Referenced by the encryption unit 17.

The data elements stored in the transmission-side manager IC card 40-2 correspond to the transmission-side user IC card 40-
1 is substantially the same as the data element stored in the setting file 41-2, the partial division pattern table 42-
2. It has an encryption key table 43-2 and an encryption method table 44-2.

Next, the transmitting device 1 of the communication system 1 of FIG.
Each element of 0 will be described. The transmitting device 10 includes an IC card reading unit 11, a user / administrator transmitting / receiving side specifying unit 12,
It has a data division unit 13, an electronic signature unit 14, a dummy file addition unit 15, a dummy data addition unit 16, an encryption unit 17, and a transmission unit 18.

FIG. 6 shows that the IC card reading unit 11 stores the transmitting user ID, the receiving user ID, the transmitting administrator ID and the receiving user stored in the IC card 40-1 and the IC card 40-2. It is the figure which read the side manager ID.
The IC card reading unit 11 includes an IC card 40-1 and an I card
It reads the data stored in the C card 40-2, performs the processing described below, and outputs the read data to predetermined components.

FIG. 7 shows a flowchart of a specific example of the processing of the IC card reading section 11. IC card reading unit 11
Requests the transmission side user and the transmission side administrator for a password as shown in FIG. 7 (S1101). I
The C card reading section 11 is configured to transmit the transmitting user IC card 40-
1 and the user password in the setting file 41-1 and the user password in the setting file 41-2 stored in the transmission-side manager IC card 40-2, respectively, and collates the input password with the read user password. (S1102). If the password is incorrect, the process ends (S1103).

In step S1103, if the passwords of the transmitting side user and the transmitting side administrator are verified, the IC card reading section 11 transmits the transmitting side user IC card 40-1 and the transmitting side administrator IC card. Card folder ID, card folder name, administrator flag, user flag, work group ID in the setting file 41-1 and the setting file 41-2 stored in 40-2
Then, the ID of the administrator is read out and output to the user / administrator transmitting / receiving side specifying unit 12 (S1104). The IC card reading unit 11 includes a user / administrator transmitting / receiving side specifying unit 1 described later.
If the transmitting-side user and the transmitting-side administrator are not specified in step 2, the process ends (S1105, S110).
3).

In step S1105, when the transmitting side user and the transmitting side administrator are specified, the storage is stored from the two transmitting side user IC cards 40-1 and 40-2. The setting file 41-1 and the setting file 41-2 are read and output to the electronic signature unit 14, and the partial division pattern table 42-
1 and the partial division pattern table 42-2 are read and output to the data division unit 13, and the encryption key table 43-
1 and the encryption key table 43-2 are read and output to the encryption unit 17, and the encryption method table 44-1 and the encryption method table 44-2 are read and output to the encryption unit 17 (S1106).

The user / administrator transmitting / receiving side specifying unit 12 reads the transmitting side user ID, the user flag, the transmitting side administrator ID, the administrator flag, and the work group ID read by the IC card reading unit 11 first. Based on the user /
Identify the sender and receiver of the administrator. This includes users, administrators,
This is to check whether the relationship between the workgroup and the user and the administrator is appropriate.

FIG. 8 shows a flowchart of a specific example of the processing of the user / administrator transmitting / receiving side specifying unit 12. As shown in FIG. 8, the user / administrator transmission / reception-side specifying unit 12 sends the transmission-side user ID, the user flag, the transmission-side administrator ID, the administrator flag, and the work group I from the IC card reading unit 11.
D data is received (S1201).

The user / administrator transmission / reception side specifying unit 12 checks that the user flag of the transmission side user setting file 41-1 is 1 (S1202). If the user flag is other than 1, the processing is stopped because the data of the setting file is not appropriate (S1203). Step S1
If the user flag is 1 in 202, it is checked that the administrator flag of the transmission-side administrator setting file 41-2 is 1 (S1204). If the administrator flag is other than 1, the process is stopped because the data of the setting file is not appropriate (S1203).

If the administrator flag is 1 in step S1204, the work group ID of the transmission-side user setting file 41-1 and the transmission-side administrator setting file 41-
It is checked whether the work group IDs of the second and third work groups are the same (S1205). If the workgroup IDs are different, the process is stopped because the data of the setting file is not appropriate (S1203).

In step S1205, if the work group IDs are the same, the user / administrator transmitting / receiving side specifying unit 12 determines the ID of the administrator in the transmitting side user setting file 41-1 and the transmitting side administrator setting file. It is checked whether the card folder ID of 41-2 is the same (S
1206). If not, the process is stopped because the hierarchical relationship between the user and the administrator is not appropriate (S1203). If the hierarchical relationship between the user and the administrator is appropriate in step S1206, it is determined that the transmitting user and the transmitting administrator have been identified, and the result is referred to as the IC card reading unit 1.
1 (S1207).

The data dividing unit 13 combines a plurality of input data files to be transmitted to generate one combined file, and divides the combined one combined file into seven temporary divided files. Two processes are performed.

FIG. 9 is a diagram showing a flowchart of a specific example of the combining process in the data dividing unit 13. As shown in FIG. 9, the data division unit 13 combines the number of data files to be transmitted, the size of each data file to be transmitted, and the data files to be transmitted, and generates a combined file (S1301). Combined file size is 512
If x7 = 3584 bytes or more, the data division unit 13 performs padding so that the combined file size is a multiple of 480 bytes (S1302, S130).
3). If the combined file size is 3584 bytes or less in step S1302, padding is performed to 3584 bytes (S1304). By the above processing, the data division unit 13 combines a plurality of data files to be transmitted and generates one combined file (S1305). The data division unit 13 calculates a hash value of the generated combined file, and outputs the calculated hash value to the electronic signature unit 14 (S1306).

The division process in which the data division unit 13 divides one combined file combined in the previous combining process and creates a temporary divided file will be described. As shown in FIG. 4, the data division unit 13 stores the partial division pattern table 4 read by the IC card reading unit 11 and stored in the IC card 40-1 and the IC card 40-2.
2-1 and the partial division pattern table 42-2 are combined to generate a division pattern table (S1307).
The data division unit 13 generates random numbers 1 to 16 and uses the generated values as division pattern numbers. Referring to the generated division pattern table, a division pattern corresponding to the previously generated division pattern number is determined (S1308). The combined file that has been combined first is successively added every 16 bytes,
According to the determined division pattern, the file is divided into seven temporary division files (S1309). The data dividing unit 13
The generated seven temporary division files are output to the dummy data adding unit 16 (S1310).

FIG. 10 is a diagram showing the structure of a digital signature. As shown in FIG. 10, the electronic signature has a hash value storage, a key storage, and a signature path storage. The electronic signature unit 14 includes the transmitting-side user IC card 40-1 read by the IC card reading unit 11 and the transmitting-side administrator I
The sender administrator RSA secret key, sender user RSA secret key, receiver administrator RSA public key in the setting files 41-1 and 41-2 of the C card 40-2,
As shown in FIG. 10, an electronic signature is created using the RSA public key of the receiving user, and the created electronic signature is output to the dummy file adding unit 15.

FIG. 11 is a diagram showing a flowchart of a specific example of the processing of the digital signature section 14. As shown in FIG. 11, the processing of the electronic signature unit 14 stores data in the hash value storage unit (S1410) and data storage in the key storage unit (S14).
1420), data storage in the signature path storage unit (S143)
0), digital signature generation (S1440) and output (S14)
50).

FIG. 12 is a diagram showing a flowchart of storing data in the hash value storage unit of the digital signature unit 14 (S1410). As shown in FIG. 12, the electronic signature unit 14
The hash value of the combined file is subjected to RSA encryption using the RSA secret key of the transmitting user (S1411). Using the RSA public key of the receiving side administrator, the hash value subjected to the RSA encryption processing is further subjected to the RSA encryption processing (S141).
2), it is recorded in the hash value storage unit (S1413).

FIG. 13 is a diagram showing a flowchart of data storage in the key storage unit of the digital signature unit 14. The key storage unit records an initial encryption key number created by an encryption unit 17 described later that has been subjected to RSA encryption processing.
As shown in FIG. 13, the electronic signature unit 14 performs an RSA encryption process on the initial encryption key number created by the encryption unit 17 described later using the RSA public key of the receiving side user (S
1421). Further, the electronic signature unit 14 stores the initial encryption key number subjected to the RSA encryption process in the RS
RSA encryption processing is performed using the A secret key (S1422),
It is recorded in the key storage (S1423).

FIG. 14 is a diagram showing a flowchart of data storage (S1430) of the digital signature section 14 in the signature path storage section. The signature path storage unit stores the ID of each person in the DES
It is made up of encrypted data. Electronic signature unit 1
4 combines the ID and name of the transmitting user, the ID and name of the receiving user, the ID and name of the transmitting administrator, and the ID and name of the receiving administrator as shown in FIG. 14 (S1).
431).

The data of the third, sixth, ninth and twelfth bytes of the hash value storage part are read, and the data of the second, fourth, sixth and eighth bytes of the key storage part are read, and the respective data are alternately connected. An initial value used in the encryption processing is generated (S1432). Next, the electronic signature unit 14 reads the data of the second, fifth, eighth, and eleventh bytes of the hash value storage unit, reads the data of the first, third, fifth, and seventh bytes of the key storage unit, and stores each data. The DES encryption keys are connected alternately and used in the DES encryption processing (S143).
3). The digital signature unit 14 performs DES encryption processing on the previously combined data string using the previously generated initial value and DES encryption key (S1434), and records it in the signature path storage unit (S1435).

As shown in FIG. 11, the electronic signature unit 14 combines the generated hash value storage unit, key storage unit and signature path storage unit to generate an electronic signature (S1440),
The generated digital signature is output to the dummy file adding unit 15 (S1450).

The dummy file adding unit 15 generates a temporary dummy file and outputs the generated temporary dummy file to the dummy data adding unit 16. FIG. 15 is a diagram in which a dummy file is added to a file to be transmitted. Dummy files are files that are unrelated to the split file,
As shown in FIG. 15, it is generated to make it difficult to specify the original file.

FIG. 16 is a flowchart showing a specific example of the processing of the dummy file adding section 15. The temporary dummy file has a signature, a division pattern number generated by the data division unit 13, and an initial value of the encryption process generated by the encryption unit 17. As shown in FIG. 16, the dummy file adding unit 15 divides the entire digital signature generated by the digital signature unit 14 into six blocks,
Block, third block and fifth block, total 3
A block is extracted and a signature is generated (S1501). The dummy file addition unit 15 combines the division pattern number generated by the data division unit 13, the initial value of the encryption process generated by the encryption unit 17 and the signature generated in step S1501 (S1502), and A file is generated (S1503). The generated temporary dummy file is output to the dummy data adding unit 16 (S150)
4).

The dummy data adding unit 16 stores an appropriate amount of dummy data in all or some temporary divided files generated by the data dividing unit 13 and the temporary dummy file generated by the dummy file adding unit 15. And outputs the generated padded temporary divided file and the padded temporary dummy file to the encryption unit 17.

Here, the appropriate amount is an amount such that the size of the file to be encrypted becomes a multiple of 8 bytes when the encrypting unit 17 performs the encrypting process. This is because the later encryption unit 17 uses the CBC (CipherBlock Chain) of the 8-byte block encryption algorithm.
ing; cipher block chaining) mode.
This is because the size of the file to be encrypted must be a multiple of 8 bytes per block.

FIG. 17 is a diagram showing that the dummy data adding unit 16 adds dummy data to a file. FIG. 18 is a diagram illustrating a flowchart of a specific example of the processing of the dummy data adding unit 16. As shown in FIG. 18, the temporary division file or the temporary dummy file is input to the dummy data adding unit 16 (S160).
1). The dummy data adding unit 16 adds 0x80 to the temporary division file (S1602) when the file size of the temporary division file is a multiple of 8 bytes-1 (S1603, S1604). In step S1603, if the file size of the temporary divided file is a multiple of 8 bytes-X (here, X = 2 to 8), padding is performed so as to start with 0x80 and continue with 0x00 for X-1 bytes (S1605). . The dummy data addition process is performed to generate a padded temporary division file (S1606), and the generated padded temporary division file is output to the encryption unit 17 (S1607).

In step S1602, the dummy data adding unit 16 replaces the temporary dummy file previously generated by the dummy file adding unit 15 with the same file size as the smallest file size of the seven padded temporary divided files. Dummy data is added so as to have the size (S1608). The value of the dummy data to be added is determined by a random number from 0x00 to 0xff. The padded temporary dummy file is generated (S160).
9), and outputs the result to the encryption unit 17 (S1607).

FIG. 19 is a diagram showing that the encryption unit 17 encrypts a file. The encryption unit 17 is an IC
Encryption method table 44 read by card reading unit 11
-1 and the encryption method 44-2 are determined to determine an encryption method, an encryption key is generated using the read encryption key table 43-1 and the read encryption key table 43-2, and the determined encryption method and generation are determined. The padded 7 generated by the dummy data adding unit 16 based on the
As shown in FIG. 18, one of the temporary divided files is selectively encrypted, and the seven divided files are output to the transmission unit 18.

The encryption unit 17 encrypts the temporary dummy file padded by the dummy data addition unit 16 with the file size of a multiple of 8 bytes, generates a dummy file, and generates the generated dummy file. Is output to the transmitting unit 18.

The encryption unit 17 combines the version number of the application, the encryption type, the hash value of the previously generated signature and the dummy file name, and the selected file name to be encrypted, and generates a control file. The transmitted control file is transmitted to the transmission unit 18.

FIG. 20 is a diagram showing a flowchart of a specific example of a process for creating a control file of the encryption unit 17.

The encryption unit 17 extracts the version number of the encryption application as shown in FIG.
1701). The version number of the encryption application is a preset value of the encryption application.
For example, specifically, it is set to 1.0.000. The encryption unit 17 extracts an encryption type, which is a number of an encryption method described later (S1702). The encryption method number is a number corresponding to the encryption method stored in the encryption method table.

The encryption unit 17 divides the entire digital signature generated by the digital signature unit 14 into six blocks, extracts a second block, a fourth block, and a sixth block, for a total of three blocks, and generates a signature. (S1703). The part written in the temporary dummy file is not written in the control file. The encryption unit 17 obtains a hash value of the dummy file name (S1704). This value is referred to when the receiving device 30 specifies the dummy file. The encryption unit 17 combines the version number of the application, the encryption type, the generated signature, and the hash value of the dummy file, generates a control file (S1705), and outputs the control file to the transmission unit 18 (S170).
6).

FIG. 21 is a flowchart showing a specific example of a process of selectively encrypting seven padded temporary divided files by the encrypting unit 17. As shown in FIG. 21, the encryption unit 17 determines the encryption type, which is the number for determining the encryption method, using a random number (S1).
711). The encryption unit 17 determines the encryption method based on the determined encryption type with reference to the read encryption method table 44-1 and the read encryption method table 44-2 (S1712). For example, specifically, when the encryption type is 1, the encryption method is the DES encryption method. The algorithm of the encryption scheme is programmed in the encryption application.

The encryption unit 17 generates an encryption key required for the determined encryption method. For example, specifically, when the encryption type is 1, an encryption key required for the DES encryption method is generated.

The encryption unit 17 obtains a random number from 0 to 255 eight times, and generates an initial value used in the DES encryption method (S1713). The initial value is output to the dummy file adding unit 15 (S1714). The encryption key is generated from the initial encryption key number. The initial encryption key number is 0 to 255
Is obtained and set as an initial encryption key number (S1715).
The initial encryption key number is output to the electronic signature unit 14 (S1716).

Next, the encryption key is obtained from the initial encryption key number. The encryption unit 17 performs a bit shift six times with respect to the initial encryption key number, and obtains six encryption key numbers (S1717). Four bytes are read from the encryption key table 43-1 of the transmission-side user IC card 40-1 using the seven encryption key numbers obtained up to the above processing as offset values. Further, 4 bytes are read from the encryption key table 43-2 of the transmission-side manager IC card 40-2 with the same offset value (S1718). The four bytes are combined and used as an encryption key (S1719). However, if the encryption key number is larger than 252 and 4 bytes cannot be read, the missing portion is read from the top of the encryption key tables 43-1 and 43-2.

Using the generated initial value and seven encryption keys, the encryption unit 17 selectively encrypts seven padded temporary division files in the CBC mode, and performs seven divisions. A file is generated (S1720), and the generated seven divided files are output to the transmission unit 18 (S1).
721). The name of the file to be encrypted is written to the control file.

The encrypting unit 17 includes a dummy data adding unit 16
The DES encryption process is performed on the padded temporary dummy file generated by the above, a dummy file is generated, and the generated dummy file is output to the transmission unit 18.

FIG. 22 is a diagram showing a flowchart of a specific example of a process of performing DES encryption on the padded temporary dummy file of the encryption unit 17. Encryption unit 1
7 obtains a hash value of 20 bytes of the generated control file as shown in FIG. 22 (S1731).
The value of the 5th to 12th bytes of the obtained hash value of 20 bytes is the initial value of 8 bytes, and the value of the obtained hash value of 20 bytes is 13 to
The value of the 20th byte is set to 8 bytes of the DES encryption key (S1
732). Using the generated initial value of 8 bytes and the DES encryption key of 8 bytes, the temporary dummy file padded in the CBC mode is subjected to DES encryption processing to generate a dummy file (S1733), and the generated dummy file is transmitted to the transmission unit. The data is output (S1734). The dummy file names have file names similar to the names of the seven divided files.

The transmitting unit 18 transmits the seven divided files, one dummy file, and the control file generated by the encrypting unit 17 to the receiving device 30 via the transmission path 20.

The data file to be transmitted as desired is transmitted to the transmission path 20 by the transmission device 10 having the above-described configuration. The operation of the transmitting device 10 at this time will be described collectively. FIG. 23 is a diagram illustrating a flow of processing of the transmission device. As shown in FIG. 23, a plurality of data files to be transmitted are input to the transmission device 10. The transmitting-side user loads the transmitting-side user IC card 40-1 into the transmitting device 10, and the transmitting-side manager sets the transmitting-side manager IC card 40-2.
Is loaded on the transmitting device 10, and the IC card reading unit 11
When the owners of the C card 40-1 and the IC card 40-2 are authenticated and authenticated correctly, the user / administrator transmitting / receiving side specifying unit 12 checks the relationship between the transmitting side user and the transmitting side administrator. . In the case of a proper relationship, the IC card reading unit 11 outputs the two IC cards 40-1 and I
The setting file 41-1 and the setting file 41-2 are read from the C card 40-2, output to the electronic signature unit 14, the partial division pattern table 42-1 and the partial division pattern table 42-2 are read, and the data division unit 1 is read.
3 and reads the encryption key table 43-1 and the encryption key table 43-2, outputs the same to the encryption unit 17, reads the encryption method table 44-1 and the encryption method 44-2, and Output to

The input plural data files to be transmitted become one combined file by the data dividing unit 13, are divided into seven temporary divided files by the data dividing unit 13, and dummy data is added by the dummy data adding unit 16. 7 and selectively encrypted by the encryption unit 17.
Divided files. At the time of division, two IC cards 40-1 and 2 stored in the IC card 40-1
The division is performed with reference to the two partial division tables 42-1 and 42-2. Two ICs for encryption
The two encryption key tables and the 43-1 encryption key table 43-2, the encryption method table 44-1 and the encryption method table 44-2 stored in the card 40-1 and the IC card 40-2 are referred to. Also, the hash value of the combined file, the initial encryption key number, and the ID and name of the transmitting side user, the transmitting side administrator, the receiving side user, and the receiving side administrator are processed by the electronic signature unit 35 and signed. Then, the dummy file adding unit 15 writes the division pattern number, the initial value of the encryption process, and half the information of the previous signature into the temporary dummy file. The temporary dummy file is added with dummy data by the dummy data adding unit 16 and is encrypted by the encryption unit 17 to become a dummy file. The information of the remaining half of the signature, the hash value of the dummy file name, the encryption type, the version number of the application, and the file name to be encrypted are written in the control file generated by the encryption unit 17. The generated eight files, that is, seven divided files and one dummy file, and the control file are transmitted to the transmission path 20 by the transmission unit 18.

The transmission line 20 is an arbitrary transmission line. In the present embodiment, transmitting apparatus 10 and receiving apparatus 30
It is assumed that various devices, computers and networks including the Internet are connected on a worldwide scale.

Next, the receiving device 30 of the communication system 1 will be described. The receiving device 30 receives the data file converted into a predetermined format sent from the transmitting device 10 via the transmission path 20, performs various processes described below, and decodes the original data file. The receiving device 30 receives the eight files transmitted by the transmitting device 10 as described above, that is, the seven divided files and one dummy file, and the control file, and restores and outputs the original data file. Therefore, the receiving device 30 has a configuration corresponding to each component of the transmitting device 10 described above.

The operation of the receiving device 70 is processed by a decoding application which is a computer program. The decryption application performs a series of processes corresponding to the version number as described above. A plurality of decryption applications having different version numbers are prepared, and a decryption process is performed only when the decryption application matches the version number of the encryption application.

The receiving device 30 has a receiving-side user IC card 40-3 and a receiving-side manager IC card 40-4. The two IC cards 40-3 and 40-4 loaded in the receiving device 30 perform various processings described below on the data file converted into a predetermined format and received by the receiving device 30 to obtain the original data. Various data necessary for decoding into a file are divided and stored.

First, the configuration of the IC card 40-3 and the IC card 40-4 will be described. IC card 40-
3 has a setting file 41-3, a partial combination pattern table 42-3, and a decryption key table 43-3. I
The C card 40-4 includes a setting file 41-4, a partial combination pattern table 42-4, and a decryption key table 43-
4. It has a decoding method table 44-3 and a decoding method table 44-4.

The contents of each component of the IC card 40-3 are almost the same as those of the IC card 40-1. The contents of each component of the IC card 40-4 are as follows.
The content is almost the same as 2. However, the setting file 41-
3 is the ID of the receiver, the name of the receiver, and the RS of the receiver.
Instead of the A public key, it has the ID of the sender, the name of the sender, and the RSA public key of the sender. The partial combination pattern table 42-3 is a part of a combination pattern table used when performing a process of combining seven divided files. Specifically, the partial combination pattern table 4
2-3 and the partial division pattern table 42-1 are tables having the same contents, and the partial combination pattern table 42-
4 is a table having the same contents as the partial division pattern table 42-2. The decryption key table 43-3 has the same content as the encryption key table 43-1. The decryption key table 43-4 has the same content as the encryption key table 43-2. Also, the decoding method table 44
-3 is a table having the same contents as the encryption method table 44-1, and the decryption method table 44-4 is a table having the same contents as the encryption method table 44-2.

Next, the receiving device 3 of the communication system 1 of FIG.
Each element of 0 will be described. The receiving device 30 includes a receiving unit 31, an IC card reading unit 32, a user / administrator transmitting / receiving side specifying unit 33, a dummy file removing unit 34, and an electronic signature unit 3.
5, a decoding unit 36, a dummy data removing unit 37, and a data integrating unit 38.

The receiving section 31 transmits the signal from the transmitting apparatus 10 to the transmission path 2
It receives the eight files transmitted through the "0", namely, the seven divided files and one dummy file, and the control file. The receiving unit 31 outputs the eight files and the control file to the dummy file removing unit 34.

The IC card reading section 32 has the same function as the IC card reading section 11 of the transmitting device 10. The reading time of the IC card 40-3 and the IC card 40-4 is measured. If the reading time is within a predetermined time, the password of the owner of the IC card 40-3 and the IC card 40-4 is requested, and Perform collation. When the collation is properly performed, the card folder ID, the card folder name, the manager flag, the user flag, and the work group ID in the setting files 41-3 and 41-4.
And the ID of the administrator is read out and output to the user / administrator transmitting / receiving side specifying unit 33.

When the user / administrator transmitting / receiving side specifying unit 33 specifies the receiving side user and the receiving side administrator, the IC card reading unit 32 sets the setting file 41-3 and the setting file 41-4. Is read, and the electronic signature unit 35 is read.
Output to Also, the partial combination pattern table 42-3
And the partial combination pattern table 42-4,
Output to the data integration unit 38. Also, the decryption key table 4
3-3 and the decryption key table 43-4 are read and output to the decryption unit 36. The decoding method table 44-
3 and the decoding method table 44-4 are read and output to the decoding unit 36.

The user / administrator transmitting / receiving side specifying unit 33 has substantially the same function as the user / administrator transmitting / receiving side specifying unit 12 of the transmitting apparatus 10. User / administrator transmitting / receiving side specifying unit 33
Is read by the IC card reading unit 32 first,
Receiving side user ID, user flag, receiving side administrator ID,
Based on the administrator flag and the workgroup ID, the user and the administrator on the receiving side are specified. The result is output to the IC card reading unit 32. The user / administrator transmitting / receiving side specifying unit 33 specifies the transmitting / receiving user and the administrator based on the ID of each person extracted from the electronic signature unit 35 described later. The result is output to the electronic signature unit 35.

FIG. 24 is a flowchart showing a specific example of a process for specifying the user and the manager on the transmitting / receiving side of the user / administrator transmitting / receiving side specifying unit 33. As shown in FIG. 24, the user / administrator transmission / reception-side specifying unit 33 transmits the transmission obtained by decrypting the signature path storage unit (S3301) input from the electronic signature unit 35 and the IC card reading unit 32 (S3301). It is checked whether the side manager ID matches the sender manager ID stored in the receiver manager IC card 40-4 (S3302). Recipient user ID of signature path storage unit and recipient user I of IC card 40-3
It is checked whether it matches D (S3303). It is checked whether the receiving side administrator ID in the signature path storage unit matches the receiving side administrator ID of the IC card 40-4 (S330).
4). It is checked whether the transmitting-side user ID in the signature path storage unit matches the transmitting-side user ID of the IC card 40-3 (S3305). If the user and the administrator on the transmitting and receiving sides are not identified by the above check, the process is stopped (S3306). If the user and the administrator on the transmitting and receiving sides are specified, the result is output to the electronic signature unit 35 (S3307).

The dummy file removing unit 34 includes the receiving unit 31
Then, the control file received is analyzed, and a dummy file is specified from the eight received files. The specified dummy file is output to the decoding unit 36. FIG. 25 is a diagram showing a flowchart of a specific example of the process of specifying the dummy file by the dummy file removing unit 34. The dummy file removing unit 34
As shown in (3), the hash values of the eight file names received by the receiving unit 31 are calculated (S3401), and a file having the same value as the hash value read from the control file is searched (S3402). As a result of the search,
A file having the same value is set as a dummy file (S340
3, S3405). If there is not the same value, the process ends assuming that the dummy file cannot be specified (S3404). The dummy file removing unit 34 outputs the specified one dummy file to the decoding unit 36, and outputs the remaining seven divided files to the decoding unit 34 (S3).
406).

The decoding unit 36 performs two processes, that is, a process for decoding a dummy file and a process for decoding a divided file. Here, the process of decoding the dummy file will be described. The process of decrypting the divided file will be described later.

The decryption unit 36 includes the dummy file removal unit 3
The decoding process is performed on the dummy file specified by step 4 to generate a padded temporary dummy file, and the generated padded temporary dummy file is output to the dummy file removing unit 34. FIG. 26 is a diagram illustrating a flowchart of a specific example of the processing of the decoding unit 36. The decryption unit 36 calculates the hash value of the control file as shown in FIG. 26 (S3601). The value of the 5th to 12th bytes of the obtained hash value is the initial value of 8 bytes, and the value of the 13th to 20th bytes of the obtained hash value is the DES decryption key 8B.
ye (S3602). Using the generated initial value of 8 bytes and the DES decryption key of 8 bytes, the dummy file received in the CBC mode is subjected to DES decryption processing to generate a padded temporary dummy file (S3603), and the generated padded dummy file. Is output to the dummy data removing unit 37 (S3604).

The dummy file removing unit 34 removes a dummy file irrelevant to the encrypted original data file. Also, the dummy file removing unit 34
6 extracts the division pattern number from the padded temporary dummy file decoded by the data integration unit 3
8 is output. Further, the dummy file removing unit 34 extracts an initial value of the DES encryption process from the padded temporary dummy file decrypted by the decrypting unit 36 and outputs the initial value to the decrypting unit 36. Furthermore, the dummy file removing unit 34 combines the contents of the temporary dummy file decrypted by the decrypting unit 36 and the content of the control file to generate an electronic signature, and outputs the electronic signature to the electronic signature unit 35.

FIG. 27 is a flowchart showing a specific example of a process of generating an electronic signature by the dummy file removing unit 34. As shown in FIG. 27, the dummy file removing unit 34 divides the signature data read from the temporary dummy file into three blocks (S3411), and then divides the signature data read from the control file into three blocks (S3411). In step S3412, the digital signatures are alternately arranged and combined to generate an electronic signature (S3413). The digital signature generated here is composed of a hash value storage, a key storage, and a signature path storage. Dummy file remover 3
4 outputs the generated digital signature to the digital signature unit 35 (S3414).

The digital signature section 35 is provided with the dummy data removal section 3
7 is performed on the digital signature output by the processing unit 7 to extract the hash value, the initial encryption key, and the signature path of the combined file. Further, the hash value of the extracted combined file is output to the data integration unit 38, the extracted initial encryption key is output to the decryption unit 36, and the extracted signature path is specified by the user / administrator transmission / reception side identification unit. 33.

The electronic signature unit 35 obtains the DES decryption key and the initial value from the hash value storage unit and the key storage unit.
After performing S decryption processing, the signature path storage unit is decrypted. FIG.
FIG. 8 is a diagram illustrating a flowchart of a specific example of a process of decrypting an electronic signature of the electronic signature unit 35. Electronic signature unit 35
As shown in FIG. 28, from the hash value storage unit,
The data of the sixth, ninth, and twelfth bytes are read, the data of the second, fourth, sixth, and eighth bytes of the key storage are read, and the respective data are alternately connected to generate an initial value used in the decryption processing. (S3501).

Next, from the hash value storage unit, 2, 5,
The data of the 8th and 11th bytes are read, and 1 and
The data of the third, fifth, and seventh bytes are read, and the respective data are alternately connected to generate a decryption key used in the decryption processing (S3502). Then, the digital signature unit 35 decrypts the signature path storage unit using the generated initial value and the decryption key, and transmits the ID and name of the transmitting user, the ID and name of the receiving user, The ID and name of the recipient and the ID and name of the administrator at the receiving side are obtained (S3503). The obtained signature path is output to the user / administrator transmitting / receiving side specifying unit 33 (S3504). The electronic signature unit 35 ends the process when the user / administrator transmission / reception-side identification unit 33 cannot identify each person (S3505, S350).
6). If each person is correctly specified, the following initial encryption key number is decrypted (S3507).

FIG. 29 is a flowchart showing a process for decrypting the initial encryption key number recorded in the key storage unit of the electronic signature unit 35. The electronic signature unit 35 is configured as shown in FIG.
As shown in FIG. 19, based on the sender manager ID obtained from the decrypted signature path storage, the sender manager RSA public key stored in the receiver manager IC card 40-4 is used. The key storage is decrypted (S3511). Based on the receiving user ID obtained from the signature path storage unit, an RSA decryption process is performed using the receiving user's RSA private key stored in the receiving user's IC card 40-3, and the initial encryption is performed. The key number is obtained (S3512). The electronic signature unit 35 outputs the extracted initial encryption key number to the decryption unit 36 (S3513).

Next, the hash value of the combined file stored in the hash value storage is decrypted. The hash value storage unit stores the hash value of the double-encrypted combined file. FIG. 30 is a diagram illustrating a flowchart of a process of decrypting the hash value of the combined file recorded in the key storage unit of the electronic signature unit 35. As shown in FIG. 30, the electronic signature unit 35 uses the RSA secret key of the recipient manager stored in the recipient manager IC card 40-4 to store the combined file stored in the hash value storage unit. Is decrypted (S3521). The hash value of the combined file is obtained by performing the RSA decryption using the RSA public key of the transmission side user stored in the reception side user IC card 40-3 (S3522). Electronic signature unit 35
Outputs the obtained hash value of the combined file to the data integration unit 38 (S3523).

The decoding unit 36 performs two processes, that is, the above-described process for decoding the dummy file and the process for decoding the divided file. Here, a process of decoding the divided file will be described. The decoding unit 36 performs a decoding process on the received seven divided files to generate seven temporary padded files, and outputs the generated temporary divided files to the dummy data removing unit 3.
7 is output.

FIG. 31 is a flowchart showing a specific example of a process in which the decoding unit 36 decodes a temporarily divided file. First, as shown in FIG. 31, the decryption unit 36 extracts the version number of the encrypted application from the control file (S3611), and determines whether or not it matches the version number of the decrypted application set in advance (S3612). . If the version numbers do not match, the decoding unit 36 ends the processing (S3
613). If the version numbers match in step S3612, the decryption unit 36 updates the read decryption method table 44-3 and the decryption method table 44-4 based on the encryption type extracted from the control file. The decoding method is determined with reference to (S361)
4). For example, specifically, when the encryption type is 1,
The decoding method is a DES decoding method.

The decryption unit 36 generates a decryption key required for the determined decryption method. For example, specifically, when the encryption type is 1, the decryption unit 36 sets the initial value extracted by the dummy file removal unit 34 as the initial value used for DES decryption (S3615). The decryption key is obtained from the initial encryption key number generated by the electronic signature unit 35.

The procedure for obtaining the decryption key will be described. First, the initial encryption key number is set as the initial decryption key number (S3616).
Bit shift is performed 6 times for the initial decryption key number, and 6
Two decryption key numbers are obtained (S3617). The following operation is performed for the above seven decryption key numbers. Four bytes are read from the decryption key table 43-3 of the reception-side user IC card 40-3, using each of the seven decryption key numbers obtained up to the above processing as an offset value. Also, with the same offset value, four bytes are read from the decryption key table 43-4 of the receiving manager IC card 40-4 (S3618). The four bytes are combined to form a decryption key (S361
9). However, if the decryption key number is larger than 252 and four bytes cannot be read, the missing part is read from the beginning of the decryption key table 40-3 and the decryption key table 40-4.

The decryption unit 36 determines the received seven divided files based on the previously determined decryption method, the seven decryption keys and the initial values, and the encrypted file name extracted from the control file. Then, a process of selective decoding is performed to generate seven padded temporary division files (S3620), and output to the dummy data removal unit 37 (S3621).

The dummy data removing section 37 is provided with the decoding section 36.
The dummy data removal process is performed on the seven padded temporary divided files generated by the above to generate a temporary divided file. The generated temporary division file is output to the data integration unit 38.

FIG. 32 is a diagram showing a flowchart of a specific example of a process in which the dummy data removing unit 37 removes dummy data. As shown in FIG. 32, the dummy data removing unit 37 acquires the file size of the padded temporary division file, reads data from the padded temporary division file, and writes the data up to the file size of -8 bytes in the temporary division file. (S3701). When writing the last 8 bytes of the file, read every byte from the last 8 bytes of the file and read 0x0
A search is made up to 0,..., 0x00, 0x80 (S3702). The dummy data removing unit 37 writes the portion up to the point before the found point in the temporary division file and generates a temporary division file (S3703). The dummy data removal unit 37 outputs the generated seven temporary division files to the data integration unit 38 (S3704).

The data integration unit 38 integrates the seven temporary division files generated by the dummy data removal unit 37 based on the connection pattern to generate one connection file, and one generated connection file. Of the splitting process for splitting a file and restoring it to the original multiple data files
Performs two processes.

FIG. 33 is a flowchart showing a specific example of a process in which the data integration unit 38 combines seven temporary divided files. As shown in FIG. 33, the data integration unit 38 uses the IC card reading unit 32 to
-3 and the partial connection pattern table 42-3 and the partial connection pattern table 42-4 stored in the IC card 40-4 are connected to generate a connection pattern table (S3801). The content of the generated combination pattern table is the same as the content of the above-described division pattern table.

The data integration unit 38 sets the division pattern number extracted from the temporary dummy file padded by the dummy file removal unit 34 as the combination pattern number (S3802). Then, by referring to the generated connection pattern table, a connection pattern corresponding to the previous connection pattern number is determined (S3803), and the seven temporary divided files are connected according to the determined connection pattern to generate one connection file. (S3804). From the above,
The seven temporarily divided files are combined and one combined file is generated.

The data integration unit 38 obtains a hash value from the combined file generated by the previous combining process (S
3805). The obtained hash value is matched with the hash value extracted by the dummy data removing unit 37 (S3806). If the hash values do not match, there is a possibility that proper combining processing has not been performed, so the generated file is deleted and the processing ends (S3).
807). If the hash values match in step S3806, the data integration unit 38 divides the combined file based on the original number of files, the original file name, and the original file size written at the beginning of the combined file. Then, a division process for restoring the original data files is performed (S3808). The data integration unit 38 outputs the restored plurality of original data files (S380).
9).

As described above, the receiving device 30
A plurality of original data files are restored and output from one divided file, one dummy file, and a control file.

The operation of receiving apparatus 30 at this time will be described together. FIG. 33 is a diagram showing a data flow of the receiving device. The receiving side user loads the receiving side user IC card 40-3 into the receiving device 30, and the receiving side administrator
When the receiving side administrator IC card 40-4 is loaded on the receiving device 30, the IC card reading unit 32 authenticates the owners of the IC card 40-3 and the IC card 40-4. / Administrator transmitting / receiving side specifying unit 33
Checks the relationship between the receiving user and the receiving administrator. If the relationship is appropriate, the IC card reading unit 32
The setting file 41-3 and the setting file 41-4 are read out from the two IC cards 40-3 and 40-4 and output to the electronic signature unit 35, and the partial division pattern table 42-3 and the partial division pattern table 42 are output.
-4, and outputs it to the data integration unit 38, reads out the decryption key table 43-3 and the decryption key table 43-4, outputs it to the decryption unit 36, and outputs the
3 and the decoding method table 44-4 are read and output to the decoding unit 36.

The eight files transmitted via the transmission path 20, ie, the seven divided files and one dummy file, and the control file are stored in the receiving device 30.
The dummy file received by the receiving unit 31 is a temporary dummy file that is specified by the dummy file removing unit 34 using the control file, subjected to the decoding process by the decoding unit 36, and padded. From the padded temporary dummy file and control file, the dummy file removing unit 34 extracts the signature, the division pattern number, and the initial value of the encryption process. From the extracted signature, the electronic signature unit 35 outputs a signature path,
The initial encryption key number and the hash value of the combined file are extracted. From the signature path, the user / administrator on the transmitting / receiving side is specified by the user / administrator transmitting / receiving side specifying unit 33.

For the seven divided files, the decryption unit 36 determines the decryption method based on the previously extracted encryption type with reference to the decryption method table 44-3 and the decryption method table 44-4. Then, a process of selectively decrypting is performed by using the decryption key obtained by converting the extracted initial value and the initial encryption key number, thereby forming seven padded temporary divided files. Performs the process of removing the dummy data, thereby forming seven temporary divided files, and the data integration unit 38 forms one combined file. The hash value of the generated combined file is compared with the extracted hash value, and if the hash value is the same, the combined file is divided by the data integration unit 38 and restored to a plurality of original data files.
Output from 0.

The overall operation of the communication system 1 will be described together. A plurality of data files to be transmitted are transmitted by the transmitting device 10 to the two IC cards 40-1 and I
Predetermined conversion is performed based on the encryption key table, the division pattern table, and the encryption method table stored in the C card 40-2, and the file is converted into eight files and control files, which are transmitted to the receiving device 30 via the transmission path 20. The transmitted eight files and the control file are transmitted to the two IC cards 4 by the receiving device 30.
A predetermined conversion is performed based on the decryption key table and the integrated pattern table stored in the IC card 40-3 and the IC card 40-4, and the original data files are restored and output.

As described above, in the communication system 1 of the present embodiment, the transmitting device 10 determines the encryption method based on the encryption method table stored in the IC card, and determines the determined encryption method. Encrypts the file to be transmitted. For this reason, the encryption method is hard to be specified as compared with the case where encryption is performed using one encryption method. Even if a file encrypted by a third party is intercepted, the encryption method is not used. It is very difficult to decipher because you do not know. Therefore, a desired file can be transmitted safely while maintaining high confidentiality.

The present invention is not limited to the above-described embodiment, and various suitable modifications are possible. In the above-described embodiment, the transmitting device and the receiving device operate using the encryption application and the decryption application that are computer programs, but the present invention is not limited to this mode. For example,
It may be constituted by an electronic circuit.

In the above-described embodiment, the encryption method table is stored in the IC card, and the algorithm of each encryption method is programmed in the encryption application. However, the present invention is not limited to this. For example, IC
Algorithms of a plurality of encryption schemes may be stored in the card, and the encryption application may read the algorithms and perform encryption.

In the above-described embodiment, the decoding method table is stored in the IC card, and the algorithm of each decoding method is programmed in the decoding application. However, the present invention is not limited to this embodiment. For example, IC
A plurality of decoding method algorithms may be stored in the card, and the decoding application may read the algorithms and perform the decoding.

In the above-described embodiment, the transmitting device and the receiving device are a computer device and two ICs.
Although the card drive is used, the present invention is not limited to this mode. For example, one IC card drive may be used.

In the above-described embodiment, the operation is performed using an IC card. However, the present invention is not limited to this embodiment. For example, a magnetic card may be used. Since magnetic cards are widely used, this system can be constructed using devices already used.

In the above-described embodiment, two I
Although the C card was used, it is not limited to this.
Three or more IC cards may be used. For example, higher security is realized by using three or more IC cards.

In the above-described embodiment, the division pattern table is divided into two. However, the division pattern table is not limited to this. For example, it may be arbitrarily divided into a plurality of parts and distributed in order.

In the above-described embodiment, the divided pattern table is stored in the IC card. However, the present invention is not limited to this. For example, the division method may be stored.

Further, in the above-described embodiment, the processing for dividing the file into seven is performed, but the processing is not limited to the processing for dividing into seven. For example, the file may be divided into arbitrary plural files.

Further, in the above-described embodiment, the process of dividing the combined file sequentially for each predetermined byte is performed. However, the method of dividing may not be the above-described embodiment. For example, you can split them randomly,
It does not have to be divided.

In the above-described embodiment, the encryption processing is performed on the data file to be transmitted using the secret key encryption method. However, the encryption method need not be the secret key encryption method. For example, a public key cryptosystem may be used.

Further, in the above-described embodiment, the DES encryption process is performed on the data file to be transmitted. However, the encryption method need not be the DES method. For example, FEAL (fast) using a more cryptographically strong Triple DES, 128-bit or 64-bit key
MISTY, RSA cryptography, elliptic curve cryptography utilizing the difficulty of the discrete logarithm problem, elliptic curve cryptography, elliptical ElGamal cryptography, elliptic RA
S encryption, stochastic encryption, Goldwasher-Mical
i-cipher, higher-order remainder encryption, OAEP encryption, Merkle-
It may be a Helman encryption, a McEliece encryption, a PGP encryption, a GPG encryption or the like.

In the above-described embodiment, the data file to be transmitted is encrypted. However, the present invention is not limited to the block encryption method. For example, a stream encryption method may be used.

In the above embodiment, the IC card is connected to the transmitting device and the receiving device.
It is not limited to this mode. For example, it may be remote via a network. A contact type IC card or a non-contact type IC card may be used.

In the above-described embodiment, the authentication is
Although this is performed using a password, the present invention is not limited to this mode. For example, a biometric characteristic of a person such as a fingerprint, a voiceprint, and a face type may be used as the authentication means. Alternatively, it may be performed using a zero-knowledge interactive proof that interactively proves one-bit information that certain information has a certain property without giving any other extra information.

In the above-described embodiment, the digital signature is used, but the present invention is not limited to this. For example, there may be no electronic signature. Further, the electronic signature may use another electronic signature method, for example, an ESIGN signature, an Elgamal signature, a DSA signature, or the like.

In the above-described embodiment, the dummy data and the dummy file are added and removed, but the method of adding the dummy file and the dummy data is not limited to this embodiment. It may be meaningful dummy data, random dummy data, a meaningful dummy file, or a completely random dummy file.

[0123]

As described above, according to the present invention, an encryption device with higher security can be provided. Also, according to the present invention, a decryption device with higher security can be provided. Further, according to the present invention, a communication system with higher security can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a communication system according to an embodiment of the present invention.

FIG. 3 is a block diagram showing data stored in a transmitting-side user IC card of the communication system shown in FIG. 2;

FIG. 4 is a diagram showing a division pattern table in the IC card shown in FIG. 3;

FIG. 5 is a diagram showing an encryption method table in the IC card shown in FIG. 3;

FIG. 6 is a diagram illustrating reading of IDs and names of users and managers on the transmitting and receiving sides stored from an IC card of the communication system illustrated in FIG. 2;

FIG. 7 is a flowchart of a process of an IC card reading unit of the communication system shown in FIG. 2;

FIG. 8 illustrates a user / user of the communication system shown in FIG.
It is a flowchart of the specific example of a process of the manager transmission / reception side identification part.

FIG. 9 is a flowchart of a specific example of a process in a data division unit of the communication system shown in FIG. 2;

FIG. 10 is a diagram illustrating a signature generated by an electronic signature unit of the transmission device of the communication system illustrated in FIG. 2;

FIG. 11 is a flowchart of a specific example of the process of the electronic signature unit of the communication system shown in FIG. 2;

FIG. 12 is a flowchart of data storage in a hash value storage unit of the electronic signature unit of the communication system shown in FIG. 2;

FIG. 13 is a flowchart of storing data in a key storage unit of the electronic signature unit of the communication system shown in FIG. 2;

FIG. 14 is a flowchart of data storage in a signature path storage unit of the electronic signature unit of the communication system shown in FIG. 2;

FIG. 15 is a diagram illustrating that a dummy file is added by a dummy file adding unit of the transmission device of the communication system illustrated in FIG. 2;

FIG. 16 is a flowchart of a specific example of a process of a dummy file adding unit of the communication system shown in FIG. 2;

FIG. 17 is a diagram showing that dummy data is added to a file by a dummy data adding unit of the transmission device of the communication system shown in FIG. 2;

FIG. 18 is a flowchart of a specific example of a process of a dummy data adding unit of the communication system shown in FIG. 2;

FIG. 19 is a diagram illustrating that a plurality of files are encrypted by an encryption unit of the transmission device of the communication system illustrated in FIG. 2;

FIG. 20 is a flowchart of a specific example of a process of creating a control file of the encryption unit of the communication system shown in FIG. 2;

FIG. 21 is a flowchart of a specific example of a process of encrypting a temporarily divided file of the encryption unit of the communication system shown in FIG. 2;

FIG. 22 is a flowchart of a specific example of a process of encrypting a temporary dummy file of the encryption unit of the communication system shown in FIG. 2;

FIG. 23 is a diagram illustrating a flow of data processing of the transmission device of the communication system illustrated in FIG. 2;

FIG. 24 is a flowchart of a specific example of a process for specifying a user and a manager on the transmitting / receiving side of the user / administrator transmitting / receiving side specifying unit of the communication system shown in FIG. 2;

FIG. 25 is a flowchart of a specific example of a process of specifying a dummy file in the dummy file removing unit of the communication system shown in FIG. 2;

FIG. 26 is a flowchart of a specific example of the processing of the decoding unit of the communication system shown in FIG. 2;

FIG. 27 is a flowchart of a specific example of a process of generating a digital signature of the dummy file removing unit of the communication system shown in FIG. 2;

FIG. 28 is a diagram illustrating a flowchart of a specific example of a process of decrypting an electronic signature of an electronic signature unit of the communication system illustrated in FIG. 2;

FIG. 29 is a flowchart of a process for decrypting an initial encryption key number recorded in a key storage unit of the electronic signature unit of the communication system shown in FIG. 2;

FIG. 30 is a flowchart of a process of decrypting a hash value of a combined file recorded in a hash value storage unit of the electronic signature unit of the communication system shown in FIG. 2;

FIG. 31 is a flowchart of a specific example of a process in which a decoding unit of the communication system illustrated in FIG. 2 decodes a divided file.

FIG. 32 is a flowchart of a specific example of a process of removing dummy data by a dummy data removing unit of the communication system shown in FIG. 2;

FIG. 33 is a flowchart of a specific example of a process in which the data integration unit of the communication system illustrated in FIG. 2 combines seven temporary division files.

FIG. 34 is a diagram explaining a flow of data processing of the receiving device of the communication system shown in FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Communication system 10 ... Transmission device 11 ... IC card reading part 12 ... User / administrator transmission / reception side specification part 13 ... Data division part, 14 ... Electronic signature part 15 ... Dummy file addition part, 16 ... Dummy data addition part DESCRIPTION OF SYMBOLS 17 ... Encryption part, 18 ... Transmission part 20 ... Transmission line 30 ... Receiving device 31 ... Receiving part, 32 ... IC card reading part 33 ... User / administrator transmission / reception side specification part, 34 ... Dummy file removal part 35 ... Data Integrating unit 36 Decoding unit 37 Dummy data removing unit 38 Data integrating unit 40-1 Transmitter user IC card 40-2 Transmitter manager IC card 40-3 Receiver user IC Card, 40-4 ... Receiving side administrator IC card 41-1 ... Transmission side user setting file 41-2 ... Transmission side administrator setting file 41-3 ... Receiving side user setting file 41-4 ... Receiving-side administrator setting file 42-1 ... Transmission-side user partial division pattern table 42-2 ... Transmission-side administrator partial division pattern table 42-3 ... Reception-side user partial combination pattern table 42-4 ... Reception-side administrator Partial combination pattern table 43-1 ... Sender user encryption key table 43-2 ... Sender administrator encryption key table 43-3 ... Reception side user decryption key table 43-4 ... Reception side administrator decryption key table 44- 1 ... Sender side user encryption method table 44-2 ... Sender side administrator encryption method table 44-3 ... Reception side user decryption method table 44-4 ... Reception side administrator decryption method table

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B017 AA03 BA07 CA16 5J104 AA09 AA16 DA03 JA28 KA01 LA06 NA02 NA05 NA07 NA12 NA35 NA37

Claims (7)

[Claims] A reading means for reading the stored encryption method table from an information storage device storing an encryption method table for determining an encryption method for encrypting a file to be transmitted to be loaded; An encryption unit that determines an encryption method based on the read encryption method table, encrypts the transmission target file based on the determined encryption method, and generates an encrypted file; and An encryption device comprising: a control file generation unit that generates a control file having at least information; and a transmission unit that transmits the encrypted file and the generated control file. 2. The apparatus according to claim 1, further comprising a dividing unit configured to divide the transmission target file to generate a divided file, wherein the encrypting unit selectively encrypts the divided file to generate an encrypted file. The control file further includes information on the encrypted file, and the transmission unit includes: a plurality of files including the encrypted file and the unencrypted divided file; and the control unit. The encryption device according to claim 1, which transmits the file. 3. The encryption unit according to claim 1, wherein said encryption unit is configured to encrypt the data based on a version number defining a type of a series of processing procedures in the read unit, the encryption unit, and the transmission unit, and the read encryption method table. The encryption method according to claim 1, wherein an encryption method is determined, the transmission target file is encrypted based on the determined encryption method to generate an encrypted file, and the control file further has the version number. apparatus. 4. A receiving means for receiving an encrypted file obtained by encrypting a file to be transmitted and a control file having at least information on an encryption method, and decrypting the received encrypted file loaded. A reading unit that reads the stored decoding method table from an information storage device that stores a decoding method table for determining a decoding method; and a reading unit that is included in the read decoding method table and the received control file. Decryption means for determining a decryption method based on information on the encryption method, decrypting the received encrypted file based on the determined decryption method, and outputting a transmission target file. apparatus. 5. The receiving means stores a plurality of files including an encrypted file obtained by dividing and encrypting a transmission target file and a non-encrypted divided file, and information on the encrypted file and information on an encryption method. Receiving at least a control file having the decryption means, the decryption means determines the decryption method based on the read decryption method table, and information on the encryption method included in the received control file, and the determined Combining means for decrypting the received plurality of files, combining the decrypted files, and outputting a file to be transmitted, based on information on a decryption method and an encrypted file included in the received control file. The decoding device according to claim 4, further comprising: 6. The receiving means receives an encrypted file obtained by encrypting a transmission target file, and a control file having at least information and a version number relating to an encryption method, and the decrypting means receives the encrypted file. The decryption method is determined based on the information on the method and the version number, and the encryption method table read by the reading unit, and the received encrypted file is decrypted based on the determined decryption method. The decryption device according to claim 4, wherein the decryption device outputs the file to be transmitted. 7. A reading means for reading the stored encryption method table from an information storage device for storing an encryption method table for determining an encryption method for encrypting a file to be transmitted which is loaded, and An encryption unit that determines an encryption method based on the read encryption method table, encrypts the transmission target file based on the determined encryption method, and generates an encrypted file; and Control file generating means for generating a control file having at least information; an encrypting apparatus having a transmitting means for transmitting the encrypted file and the generated control file; and the transmitted encrypted file and control Receiving means for receiving the file; and the received encrypted file being loaded. A reading unit that reads the stored decoding method table from an information storage device that stores a decoding method table that determines a decoding method for decoding a file; the read decoding method table; Decryption means for determining a decryption method based on information on an encryption method included in a control file, decrypting the received encrypted file based on the determined decryption method, and outputting a transmission target file And a decoding device having: