JP2005277588A - System and method for electronic data transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic data transmission system and an electronic data transmission method capable of transmitting data more safely in the electronic data transmission system and the electronic data transmission method for concealing data. <P>SOLUTION: In the electronic data transmission system for transmitting and receiving plaintext data by encryption and decryption, a transmission side comprises a data dividing means 21 for dividing plaintext data D-0 into N (N>2) data; a feature point extraction means 22 for extracting the feature points of the division data D-1; an encrypting means 23 for encrypting each of the division data D-1; a data editing means 24 for editing the Nth data of the encrypted data D-4 and an encryption key D-3 in those other than the one used for encrypting the Nth data in the encryption into one transmitting data D-5, by referring to the feature point D-2 of the divided Nth data; and a data transmission means 25 for transmitting the transmission data D-5 to the reception side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic data transmission system and an electronic data transmission method for transmitting data between terminals, and more particularly, to reduce the risk of data being wiretapped, tampered with, or decrypted with respect to data exchanged between terminals. The present invention relates to an electronic data transmission system and an electronic data transmission method.

  In recent years, in data communication via the Internet, such as e-mail exchanged between terminals, data encryption technology has become widespread and widely used particularly for safely transmitting and receiving confidential data.

  However, even encrypted data may be stolen in the middle of transmission by a cracker or the like and the decryption of the encrypted data may result in leakage of confidential data transmitted after encryption. There was a problem that there was.

  Therefore, in Patent Document 1 below, by transmitting encrypted data on one line, if the encryption rule in the encryption device leaks to the outside, confidential data can be easily taken out, such as crackers, etc. In order to solve the problem of being susceptible to infringement, an external cracker that extracts confidential data from the line by encrypting a series of communication data sent from the sending side and then dividing and transmitting it over multiple lines An encrypted transmission method that can prevent infringement of the above has been disclosed.

More specifically, as shown in FIG. 8, the data sent from the transmission-side terminal 111 is subjected to f conversion (predetermined encryption processing) in the encryption device 121, encrypted, and then a communication circuit. The data is divided and transmitted on 150 lines. The small pieces of data transmitted over a plurality of lines are corrected for delays caused by transmission over the lines by a delay correction buffer 160 prepared for the lines, and are rearranged in the original order again by the line concentrator 132 and decrypted. After being restored by the conversion of f ⁻¹ by the device 122, it is transmitted to the receiving side terminal 112.

  According to the method disclosed in Patent Document 1, in addition to encryption, the encrypted data is further divided into small pieces of data, transmitted over a plurality of lines, and transmitted to the receiving side. Infringement of external crackers, etc. can be prevented.

Japanese Patent Laid-Open No. 03-108830 (FIG. 1, second page, lower right row, second to twelfth lines)

  However, in Patent Document 1, since data is divided into a plurality of small pieces of data and transmitted over a plurality of lines, it is safer than transmitting one piece of data encrypted with one line as in the prior art. There is only one encryption key necessary for decryption of the data. Therefore, if one of the small pieces of data is decrypted, all other small pieces of data can be decrypted, so that a sufficient security environment is still secured. Absent.

  In view of the above problems, the present inventor has conducted various studies on an electronic data transmission system and an electronic data transmission method that more reliably prevent infringement of crackers and the like without increasing the number of keys required for decryption, After dividing the data into a plurality of small pieces of data, each piece of small piece of data is encrypted using a different encryption key, and further encrypted multiple pieces of small piece data, and an encryption key obtained by encrypting the plurality of pieces of small piece data, , By embedding the encryption key in small pieces of data that are different from the small pieces of data encrypted by the encryption key, and dividing and transmitting the data, it is possible to perform data transmission with higher security. It is a thing.

  That is, a first object of the present invention is to provide an electronic data transmission system and an electronic data transmission method capable of performing safer data transmission.

In the invention of the electronic data transmission system according to claim 1 of the present application, the plaintext data on the sender side is encrypted with a predetermined encryption, transmitted to the receiver, and the data encrypted on the receiver side In an electronic data transmission system that transmits and receives plaintext data by combining
The transmission side includes data dividing means for dividing the plaintext data into N pieces (N> 2),
Feature point extracting means for extracting feature points of the N divided data;
Encryption means for encrypting each of the N divided data by a predetermined encryption method;
The N-th of the encrypted data and an encryption key other than the one used for the N-th encryption at the time of encryption are referred to the characteristic points of the divided N-th data, and a predetermined method And data editing means for editing to one transmission data with,
Data transmission means for transmitting N pieces of transmission data edited by the transmission data editing means to the receiving side;
It is characterized by comprising.

  The invention according to claim 2 of the present application is the electronic data transmission system according to claim 1, wherein the electronic data transmission system further generates an encryption key used in the encryption means. The encryption key generation unit generates an encryption key for encrypting each of the N pieces of data divided by the division unit, and performs encryption.

  According to a third aspect of the present invention, in the electronic data transmission system according to the first aspect, when the transmission unit transmits N pieces of transmission data edited by the data editing unit, the data is first transferred. After transmitting data indicating the start of transmission, the N transmission data are transmitted in random order using one line or a plurality of lines, and data indicating the end of data transmission is transmitted after transmitting the N transmission data. It is characterized by that.

  According to a fourth aspect of the present invention, in the electronic data transmission system according to the first aspect, the feature point of the divided data extracted by the feature point extracting means is a data capacity of each of the divided data. It is characterized by.

  According to a fifth aspect of the present invention, in the electronic data transmission system according to the first or fourth aspect, the plurality of encryption keys generated by the encryption key generation unit is a predetermined data in the data editing unit. It is characterized by being unified in capacity and edited in transmission data.

  The invention according to claim 6 of the present application is the electronic data transmission system according to claim 1, wherein the data editing means converts the first encrypted data and the Nth encryption key into the first divided data. The X (2 ≦ X ≦ N) th encrypted data and the X−1th encryption key are edited with reference to the feature points of the Xth divided data. It is characterized by that.

The invention of the electronic data transmission method according to claim 7 of the present application encrypts plaintext data on the sender side and transmits it to the receiver, and decrypts the encrypted data on the receiver side. An electronic data transmission method for performing transmission and reception, wherein the transmission side
Dividing plaintext data into a plurality of data;
Extracting feature points of the divided data;
Encrypting each of the divided data using different encryption keys;
Editing one of the encryption keys used for encryption and one of the divided data different from the divided data encrypted by the one encryption key based on the feature points extracted from the divided data And creating transmission data,
Transmitting the transmission data;
It is characterized by comprising.

  The electronic data transmission system of the present invention has the following excellent effects. In other words, according to the first aspect of the present invention, the plaintext data is divided into a plurality of parts and then encrypted, and the encrypted data and the encryption key are edited in a combination different from the encrypted combination. By transmitting as one piece of data, illegal eavesdropping / falsification of crackers and the like can be well prevented. Further, since the feature points of the divided data are used when editing, even if the data is falsified, it can be detected.

  According to a second aspect of the present invention, the electronic data transmission system has encryption key generation means to divide plaintext data into a large number of divided data, and a plurality of encryption keys are required. Furthermore, in the electronic data transmission system of the present invention, since the user of the transmission / reception side terminal does not need to know the code of the encryption key, there is no problem even if the encryption key is automatically created. Therefore, it is possible to save time and trouble between users, and to perform good use.

  Further, according to the invention of claim 3, it is difficult to easily decode even if the data is wiretapped by a cracker or the like by transmitting a plurality of transmission data in random order regardless of the order of the data, and further dividing the data. If data is transmitted using multiple lines, there is little risk of eavesdropping on all of the transmitted data, and since the combination of encryption key data differs only for each transmitted data, it is difficult to decrypt It becomes difficult.

  According to the invention of claim 4, the feature point data can be obtained from the transmission data received on the receiving side by using the feature point data as the feature points of the divided data. It is no longer necessary to exchange data between senders and receivers.

  Further, according to the invention of claim 5, even when the encryption key is an encryption method using a variable length encryption key such as RC4 (Ron's Code 4), the encryption key is used. By unifying the data capacity in the editing means, the data capacity that increases by being edited by the data editing means becomes the same for each of the divided encrypted data, so that it becomes easier to obtain the feature points of the divided data. .

  According to the sixth aspect of the present invention, when the combination of the encrypted data and the encryption key is determined in advance, the edited transmission data is separated into the encryption key and the encrypted data. The combination of the encryption key and the encrypted data can be easily understood, and the decryption process can be performed better.

  According to the invention of claim 7, the plaintext data is divided into a plurality of pieces, the divided pieces of data are encrypted with different encryption keys, and the plurality of encrypted data and the encryption key are further encrypted. Are edited with a combination different from the encrypted combination by referring to the feature points of the divided data, and it becomes possible to perform data transmission with a high security strength, and an illegal An electronic data transmission method capable of preventing eavesdropping / tampering can be provided.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies an electronic data transmission system for embodying the technical idea of the present invention, and is not intended to specify the present invention to this electronic data transmission system. Other embodiments within the scope of the claims are equally applicable.

  FIG. 1 is a schematic explanatory diagram showing an outline of an electronic data transmission system according to a first embodiment of the present invention, and FIG. 2 is a block diagram illustrating in detail the configuration of a transmission side terminal of the electronic data transmission system of FIG. FIG. 3 is a flowchart for explaining the data transmission processing steps of the transmission side terminal.

  As shown in FIG. 1, the electronic data transmission system 1 of the present invention creates transmission data obtained by encrypting plaintext data D-0 created by the transmission side terminal 2 via the encryption device 20, and transmits the data. Data transmitted to the receiving terminal 3 by preventing wiretapping / falsification of data by a third party such as a cracker in the transmission process of the unit 4 is transmitted to the receiving terminal 3, and the transmission data encrypted using the decryption device 30 in the receiving terminal 3 Is obtained by decoding plaintext data D-0.

Data transfer by the electronic data transmission system of the present invention will be described in detail below with reference to FIGS.
The plain text data D-0 created by the transmission side terminal 2 that transmits data by the electronic data transmission system 1 of the present invention is encrypted by the encryption device 20 and transmitted to the reception side terminal 3. The encryption device 20 includes a data dividing unit 21, a feature amount extracting unit 22, an encryption key generating unit 23, an encrypting unit 24, a data editing unit 25, and a data transmitting unit 26. Each part will be described below.

  The data dividing means 21 divides the plaintext data D-0 created by the transmission side terminal 2 into N (N ≧ 2) pieces of divided data, and the division method divides the data equally. Alternatively, the plaintext data is divided into N pieces of divided data D-1 by using a known division method such as dividing the divided data so that the data length is different.

  The feature quantity extraction means 22 extracts the set feature point data from each of the divided N pieces of divided data D-1, and the N pieces of extracted feature point data D-2 are respectively For example, it is the data capacity of the divided data D-1, and as a feature point other than the data capacity, any data can be used as long as it can be read from the transmission data (D-5) transmitted from the transmission side terminal.

  The encryption key generation means 23 generates N encryption keys D-3 used when the encryption means 24 encrypts each of the N pieces of divided data D-1, and the generation thereof. As a method, the user using the transmission side terminal may set as appropriate, and when the divided data number N is large, an appropriate code is extracted from the random number generator in the encryption key generation unit 23. However, in the electronic data transmission system 1 of the present invention, since the user on the transmission side and the reception side do not need to know the code of the encryption key, the random number generator automatically It is preferable to set to.

  The encryption unit 24 performs encryption using N different encryption keys D-3 for each of the N pieces of divided data D-1, and a common key (also referred to as a secret key) encryption is used as an encryption method. Encryption is performed by an encryption method, for example, DES (Data Encryption Standard), RC4 (Ron's Code 4), etc. in which the capacity of input / output data does not change. By the way, when performing encryption using a common key encryption method that outputs encrypted data different from the input data capacity, especially data after encryption processing (encrypted data) to data before encryption processing (divided data) Those that cannot obtain the feature points are not used here.

  The data editing means 25 extracts feature amounts of the N encrypted data D-4 encrypted by the encrypting means 24 and the N encrypted keys D-3 generated by the encryption key generating means 23. Editing is performed with reference to the N feature point data D-2 extracted by the means 22, and more specifically, the Xth encrypted data is encrypted into the X (1 ≦ X ≦ N) th encrypted data. One of the encryption keys other than the X-th encryption key used for conversion is edited with reference to the X-th feature point data. One transmission data D-5 is created by embedding an encryption key having a predetermined data length (for example, 256 bits) in D-4 bit by bit, and the embedding position of the encryption key D-3 Using the feature point data D-2 extracted from the divided data D-1. Is that no so as to determine Te.

  In the data editing unit 25, the encryption key D-3 generated by the encryption key generation unit 23 is unified to a predetermined data length such as 256 bits. However, there is a common key encryption method in which the data length of the encryption key is determined in advance (for example, DES is fixed to 56 bits (originally 64 bits)), and such a method does not need to be unified. In the case where the key data length is variable as in the RC series or the like, for example, when the maximum data length in the N encryption keys D-3 is 256 bits, a predetermined 256-bit character string is used. By embedding, the data length of the encryption key is unified.

  The combination of the encrypted data D-4 and the encryption key D-3 to be edited refers to the first encrypted data and the Nth encryption key with reference to the characteristic points of the first divided data. It is preferable to edit and edit the X (2 ≦ X ≦ N) th encrypted data and the X−1th encryption key with reference to the feature points of the Xth divided data. By doing so, the combination of the encryption key and the encrypted data can be easily understood, so that it is not necessary to create extra data such as data relating to the combination of the encryption key and the encrypted data. However, the combination of the encryption key and the encrypted data may be out of order, and the data indicating the combination may be transmitted to the receiver together with the transmission data D-5.

  The data transmission means 26 is a part for transmitting N pieces of transmission data D-5 edited by the data editing means 25 to the receiving side terminal 3 through the data transmission unit 4, and uses one line or a plurality of lines. N pieces of transmission data D-5 are randomly selected and transmitted by a transmission control table provided inside. The transmission procedure will be described in detail later, and the description is omitted here.

With reference to FIG. 3, the electronic data transmission processing process of the transmission side terminal of the first embodiment will be described in detail below. In the present embodiment, the feature points extracted from the divided data D-1 are described as the data capacity of each divided data D-1, and the encryption method is RC4. However, other feature points or encryption methods may be used. It can be appropriately changed depending on the usage situation.
When the transmission processing of the plain text data D-0 created by the transmission side terminal 2 is started, the plain text data D-0 sent to the data dividing means 21 in step S01 is first divided into at least two or more pieces of divided data D-1. Divided. Here, the plaintext data D-0 is divided into N pieces of divided data D-1, and the data length of each divided data D-1 is determined by the encryption method used by the encryption means 24. It is preferable to divide the input block into such a length that two or more input blocks are formed.

  Next, in step S02, the data capacity of N pieces of divided data D-1 is extracted as each feature point data D-2 of the divided data D-1 divided into N pieces in step S01. Thereafter, in step S03, the N pieces of divided data D-1 are encrypted with the N pieces of encryption keys D-3 generated by the encryption key generation unit 23, thereby creating encrypted data D-4. The N encryption keys D-3 generated by the encryption key generator 23 are assumed to have different data lengths, and the encryption key having the maximum data length is 256 bits (32 bytes). .

  In step S04, the data volume D-2 extracted by the feature point extraction means 22 in step S02 is referred to, and the encryption key D-3 is embedded and edited in the encrypted data D-4. The editing method is as follows. First, N encryption keys D-3 ′ having a uniform data length embedded in a predetermined 256-bit (32-byte) character string are encrypted data using a hash function, for example. The position of embedding in D-4 is determined. More specifically, the feature data D-2 is used as an input of a hash function, and an output is obtained. The input to the hash is repeated until the output becomes larger than the file capacity of the encrypted data D-4 (when the feature point data D-2 is a character string output, it is converted into a number). When the file capacity is exceeded, it is repeatedly drawn until it becomes smaller than the file capacity. If the result is x bytes, the first 1 byte in the 32-byte character string of the encryption key D-3 'is embedded in the x byte from the beginning of the file. Next, x of x bytes is input to the random number generator, and the same operation is repeated to embed all of the 32-byte character string of the encryption key D-3 '. The above processing is performed N times, which is the number of divided data. By editing in this way, the transmission data D-5 created by the data editing means 25 has extra data (data of the encryption key D-3 ′) in the encrypted data D-4. Since it is embedded, it cannot be decrypted uniquely, improving the encryption strength.

  In step S05, the transmission data D-5 edited by the data editing means 25 is transmitted to the receiving terminal 3 by the data transmitting means 26. The data transmission means 26 has a transmission control table therein, and N transmission data D-5 are selected at random in the transmission control table and transmitted. At this time, the data indicating the start of data transmission and the data indicating the end of data transmission are transmitted at the beginning and end of the data transmission, so that it is possible to prevent data reception omission when received. .

  Next, the configuration of the receiving terminal according to the electronic data transmission system of the present invention will be described with reference to the drawings. FIG. 4 is a block diagram illustrating in detail the configuration of the receiving terminal of the electronic data transmission system of FIG. 1, and FIG. 5 is a flowchart illustrating the data reception processing steps of the receiving terminal.

  The receiving side terminal 3 includes a decoding device 30, and the decoding device 30 includes a data receiving unit 31, a feature amount extracting unit 32, a data decomposing unit 33, a decoding unit 34, and a data integration unit 35. This can be obtained by decrypting the plain text data D-0 encrypted by the transmission side terminal 2.

  The data reception means 31 receives data transmitted from the transmission side terminal 2, and converts the received data to the original transmission data D-5 according to the transmission method set by the data transmission means 26 of the transmission side terminal 3. It also has a function for changing to the same state as. The feature quantity extraction unit 32 extracts feature point data similar to the feature point data D-2 extracted by the transmission side terminal 3 from the transmission data D-5 sent from the data reception unit 31.

  The data decomposing means 33 converts the transmission data D-5 formed by editing the encrypted data D-4 and the encryption key D-3 by the data editing means 25 on the transmission side into the original encryption key D- 3 and the encrypted data D-4. The dividing method refers to the feature point data D-2, and decomposes the data by means of the reverse of the editing process performed by the data editing means 25.

  The decrypting means 34 rearranges the encryption key D-3 and the encrypted data D-4 that have been decomposed by the data decomposing means 33 into a paired combination, and then performs encryption at the transmitting terminal 2. Data is decrypted using the same encryption method as that described above. At this time, the combination of the encrypted data D-4 and the encrypted key D-3 may be edited with a combination determined in advance between the sender and the receiver, or the transmission side separately transmits data indicating the combination. You may make it rearrange with reference to data. The data integration means 35 is a part that integrates a plurality of pieces of decomposed data D-1 decrypted by the decryption means 34 as one plaintext data D-0.

Processing steps when the receiving terminal 3 receives the encrypted transmission data will be described below with reference to FIG.
When the receiving side terminal 3 receives the data, as shown in FIG. 5, first, in step S11, transmission data D-5 transmitted by the transmitting side terminal 2 is created. That is, for example, when transmission data D-5 is transmitted out of order when transmitted from the transmission side terminal 2, the contents of the data received by the data receiving means 31 and the original arrangement order are identified and transmitted. Transmission data D-5 similar to that created on the side is created from the received data. However, this step S11 can be omitted if it is not always necessary to perform some processing during transmission.

  Next, in step S12, the feature point data D-2 used by the encryption device 20 is extracted from the received transmission data D-5. In this case, since the feature point that can be recognized from the transmission data D-5 is used as the feature point data D-2, for example, if it is an encryption process and an editing process as performed in the transmission side terminal 2 described above, In other words, if the encryption key capacity is unified and the encryption method uses the same data capacity before and after encryption, the feature point is the data capacity of each divided data. The capacity can be easily obtained from the transmission data D-5.

  When the feature point data D-2 is acquired in step S12, in step S13, the data decomposition means 33 converts the transmission data D-5 from the feature point data D-2 to the encryption key D-3 and the encrypted data D-4. And decompose. As a decomposition method, data may be decomposed by performing a process opposite to the editing process performed by the data editing unit 25 of the transmission side terminal 2, and the description thereof is omitted.

  In step S14, a combination of the encryption key D-3 and the encrypted data D-4 decomposed in step S13 is selected. With regard to the combination, the combination may be selected by referring to data indicating the combination acquired from the transmission side terminal 2 in advance, or a method defined in advance regarding the combination, for example, the transmission side terminal 3 is 1 The Nth encryption data and the Nth encryption key are edited with reference to the feature points of the first divided data, and the X (2 ≦ X ≦ N) th encryption data and the X−1th encryption data are edited. When editing the encryption key with reference to the feature point of the Xth divided data, the combination of the encryption key D-3 and the encrypted data D-4 is selected without referring to the data indicating the combination. be able to.

  In step S15, the encrypted data D-4 is decrypted by the decrypting means 34 using the encryption key D-3 and the encrypted data D-4 whose combination is selected in step S14. Then, the divided data D-1 obtained by the decryption is integrated into one data by the data integration means 35 in step S16 to obtain plain text data D-0.

  Next, specific examples of transmission processing and reception processing according to the present invention will be described below with reference to the drawings. FIG. 6 is a flowchart showing a specific example of the transmission processing step by the data transmission unit of the transmission side terminal, and FIG. 7 is a flowchart showing a specific example of the reception processing step by the data reception unit of the reception side terminal.

First, when the transmission process of the transmission data D-5 is started, transmission start data for notifying the reception side that data transmission is started is transmitted in step S31. Next, in step S32, the total number N of transmission data D-5 is recognized and stored as the number of untransmitted data N ′. In step S33, one transmission data D-5 is randomly selected from the untransmitted transmission data D-5. Select ₁ . The selection is made by a known method such as selection using a random number generator.

Next, in step S34, the transmission data D-5 ₁ selected in step S33 is to recognize whether an ordinal number of the data in all the transmission data D-5, is recorded as the data of the data number. Then transmits the transmission data D-5 ₁ said selected at step S35 to the receiving side. At this time, it is preferable to add a time stamp at the time of transmission to the data to be transmitted. By adding the time stamp, it is possible to know a more accurate transmission order and to easily rearrange the data at the receiving terminal. become.

  When the data transmission is completed, in step S36, the number N 'of untransmitted data acquired in step S32 is rewritten to N'-1. When the rewriting of N 'is completed, in step S37, it is identified whether or not the number N' of untransmitted data is N '> 0. If N ′> 0, that is, if untransmitted data still remains, the process returns to step S33 to repeat each process, and it is determined in step S37 that N ′ ≦ 0 (actually N ′ = 0). Then, in step S38, data D-6 having the data number recorded in the order in which the data numbers are acquired (that is, the order in which the data is transmitted) is transmitted. Incidentally, the data D-6 indicating the data number may be transmitted separately from the transmission data.

  When the data transmission of the transmission data D-5 and the data number data D-6 is completed, in step S39, transmission end data indicating the end of data transmission is transmitted to the receiving side, and the transmission process is terminated.

  Transmission data D-5 and data number data D-6 transmitted in this way are encrypted even if a part of the transmission data D-5 is intercepted by a cracker or the like. Since the encryption key D-3, which is data irrelevant to the encrypted data D-4, is embedded inside, it is difficult to decrypt it uniquely. Further, the encryption key D-3 and the encrypted data D Since the combination of -4 is different, even if a part of the transmission data D-5 of the present invention is wiretapped, it is difficult to decrypt the data, so that high security strength can be achieved. If the transmission data D-5 and the data number data D-6 are transmitted using a single line or a plurality of lines and are transmitted using a plurality of lines, the transmission data D- The risk of eavesdropping on all the data of 5 is reduced, and higher security strength can be achieved.

A reception processing step of the reception side terminal 3 that receives data transmitted from the transmission side terminal 2 by the above-described method will be described below with reference to FIG.
The receiving side terminal 3 is generally in a standby state in a receivable state. When the transmission start data of the transmission data encrypted by the transmission side terminal 2 is received by the data reception means 31 of the reception side terminal 3 in step S51, first, the identification code of the transmission start data is acquired in step S52. The identification code here is used to identify a plurality of transmission data D-5 or data number data D-6 to be received later based on the type of transmission data, transmission source information, etc. Any data can be used as long as the data can be identified. Here, such identifiable elements are collectively referred to as an identification code.

  After receiving the transmission start data, the data reception means 31 of the transmission side terminal 3 further enters a standby state for data reception (see step S53). When data reception is confirmed here, it is recognized whether the received data is the same as the identification code of the transmission start data received in step S51. If the identification code is different from the transmission start data, the data is irrelevant to the transmission start data received in step S51. Therefore, after normal reception is performed in step S55, the process returns to step S53 again, and the identification code is changed. If it is similar, the process proceeds to step S56.

  If it is determined in step S54 that the identification codes are the same, it is determined in step S56 whether or not the received data is transmission end data indicating the end of data transmission. If it is determined that the data is the transmission end data, the data reception process is terminated. If it is determined that the data is not the transmission end data, the process proceeds to step S57. In step S57, the data indicates the data D- indicating the data number. 6 is determined. If it is determined that the data number is data D-6, it is temporarily stored as data number data D-6 in step S58, and then the process returns to step S53 to continue receiving data. If it is determined that there is no data, the data is stored in the order of transmission as transmission data D-5 divided and transmitted in step S59, and then the process returns to step S53 to continue data reception.

  The data obtained by the above reception processing steps is stored in the order in which it was transmitted, but it is preferable to obtain an accurate transmission order by referring to the time stamp given to the data when it is transmitted. Like that. Then, the transmission data D-5 stored in the transmission order is replaced with the original arrangement order by referring to the data number data D-6, and the decoding process shown in FIG. 5 is performed.

  As described above, in the electronic data transmission system and the electronic data transmission method of the present invention, the plaintext data is divided into a plurality of parts and then encrypted, and the encrypted data and the encryption key are further encrypted. It is possible to satisfactorily prevent illegal eavesdropping / falsification of a cracker or the like by editing with a combination different from the combination into one data and further dividing and transmitting. Further, since the feature points of the divided data are used when editing, even if the data is falsified, it can be detected.

  Furthermore, the electronic data transmission system and the electronic data transmission method of the present invention can be used for decryption even though encryption is performed using different encryption keys for each of the divided data pieces. Since it is not necessary to prepare an encryption key in advance, and a plurality of encryption keys can be used without increasing the number of tools necessary for decryption, high security strength can be easily achieved.

FIG. 1 is a schematic explanatory diagram showing an outline of an electronic data transmission system according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating in detail the configuration of the transmission side terminal of the electronic data transmission system of FIG. FIG. 3 is a flowchart for explaining a data transmission processing process of the transmission side terminal. 4 is a block diagram illustrating in detail the configuration of the receiving terminal of the electronic data transmission system of FIG. FIG. 5 is a flowchart for explaining the data reception process of the receiving terminal. FIG. 6 is a flowchart showing a specific example of the transmission processing step by the data transmission means of the transmission side terminal; FIG. 7 is a flowchart showing a specific example of the reception processing step by the data receiving means of the receiving terminal. FIG. 8 is a block diagram showing the encrypted transmission method of Patent Document 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic data transmission system 2 Transmission side terminal 3 Reception side terminal 4 Data transmission part 20 Encryption apparatus 21 Data division means 22 Feature quantity extraction means 23 Encryption key generation means 24 Encryption means 25 Data editing means 30 Decryption apparatus 31 Data Reception means 32 Feature quantity extraction means 33 Data decomposition means 34 Decryption means 35 Data integration means D-0 Plain text data D-1 Division data D-2 Feature point data D-3 Encryption key D-4 Encryption data D-5 Send data

Claims (7)

Electronic data transmission that sends and receives plaintext data by encrypting the plaintext data on the sender side, encrypting it, sending it to the receiver, and decrypting the encrypted data on the receiver side In the system,
The transmission side includes data dividing means for dividing the plaintext data into N pieces (N> 2),
Feature point extracting means for extracting feature points of the N divided data;
Encryption means for encrypting each of the N divided data by a predetermined encryption method;
The N-th of the encrypted data and an encryption key other than the one used for the N-th encryption at the time of encryption are referred to the characteristic points of the divided N-th data, and a predetermined method And data editing means for editing to one transmission data with,
Data transmission means for transmitting N pieces of transmission data edited by the transmission data editing means to the receiving side;
An electronic data transmission system comprising:   The electronic data transmission system further includes an encryption key generating means for generating an encryption key used by the encryption means, and an encryption key for encrypting each of the N pieces of data divided by the dividing means 2. The electronic data transmission system according to claim 1, wherein the encryption key is generated by the encryption key generation means and encryption is performed.   When transmitting the N pieces of transmission data edited by the data editing unit, the transmission unit first transmits data indicating the start of data transmission, and then transmits the N pieces of data using one line or a plurality of lines. The electronic data transmission system according to claim 1, wherein transmission data is transmitted in random order, and data indicating the end of data transmission is transmitted after transmitting N pieces of transmission data.   2. The electronic data transmission system according to claim 1, wherein the feature point of the divided data extracted by the feature point extracting means is a data capacity of each of the divided data.   5. The electronic device according to claim 1, wherein the plurality of encryption keys generated by the encryption key generation unit are unified to a predetermined data capacity by the data editing unit and edited into transmission data. Data transmission system.   The data editing means edits the first encrypted data and the Nth encryption key with reference to the feature point of the first divided data, and X (2 ≦ X ≦ N) th encrypted data. 2. The electronic data transmission system according to claim 1, wherein the X-1th encryption key is edited with reference to a feature point of the Xth divided data. An electronic data transmission method for transmitting and receiving plaintext data by encrypting plaintext data on the sender side and transmitting the encrypted data to the receiver, and decrypting the encrypted data on the receiver side.
Dividing plaintext data into a plurality of data;
Extracting feature points of the divided data;
Encrypting each of the divided data using different encryption keys;
Editing one of the encryption keys used for encryption and one of the divided data different from the divided data encrypted by the one encryption key based on the feature points extracted from the divided data And creating transmission data,
Transmitting the transmission data;
An electronic data transmission method comprising:

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