JP5023610B2 - Data exchange method and system - Google Patents

Description

  The present invention relates to the technical field of encrypting and transferring data, and more particularly to a system and method that do not require the use of an encryption key when decrypting data.

In response to the problem of leakage of personal information, cases of encrypting data transmitted between computers and servers are increasing. When encrypting / decrypting data to be transmitted, it is common to encrypt / decrypt data using an encryption key according to a certain encryption algorithm. 1 is used, and a large amount of data is encrypted / decrypted using the security module.
JP-T-2006-512792

  However, depending on the other party who sends the data, there is a case where the data decryption function is not possessed. In such a case, even if the data encrypted by the data encryption function is sent, the data is received on the side receiving the data. It could not be decrypted.

  Therefore, the present invention provides a data transmission / reception method, a data transmission / reception system, a data encryption device, and a data decryption device capable of transmitting / receiving data encrypted by the data encryption function even if the other party does not have the data decryption function. The purpose is to provide.

A first invention for solving the above-described problem is a data transmission / reception method for transmitting / receiving data, which has a function of encrypting / decrypting data, and a security module installed on a data transmission side is transmitted / received. a first encryption key for encrypting the plaintext is data encrypted using the second encryption key for the security module, in said security module, registering the first encryption key encrypted encryption A key registration step, and the security module decrypts the first encryption key with the second encryption key inside the security module, and the plaintext as data to be encrypted is transferred to a block of a predetermined size from the top Using the first encryption key that is divided and decrypted in order, the plaintext is encrypted in units of blocks to generate the plaintext ciphertext, and the data An encryption step of transmitting said ciphertext generated on a computer installed on the side of signal, the ciphertext is divided sequentially from the head to the block of the same size as the plaintext, the value of each block for dividing the plaintext By referring to an encryption table in which a value encrypted using the first encryption key registered in the security module and a numerical value in units of blocks for dividing the plaintext are associated, the ciphertext in units of blocks is A decryption step of generating the plaintext of the received ciphertext by converting it into a numerical value in block units .

In the encryption key registration step according to the first aspect of the invention, the security module uses the second encryption key for the rearrangement data describing a rule for changing the order of characters in addition to the first encryption key. And the encrypted rearrangement data is registered in the security module, and in the encryption step , the security module encrypts the plaintext before encrypting the plaintext inside the security module . A scramble process that decrypts the ciphertext of the rearranged data using an encryption key and changes the order of each character included in the plaintext by using the rearranged data describing a rule for changing the order of the characters It is executed, and in the decoding step, the computer within said computer, by using the encryption table to decrypt the ciphertext Later, using the re-aligned data, the order of each included in the ciphertext decrypted, the encrypted process and it is desirable to descrambling processing of changing the reverse procedure is executed.

Further, the second invention is a data exchange system for exchanging data between computers, wherein a data encryption device that encrypts plaintext as data to be transmitted and generates a ciphertext, and the encryption generated by the data encryption device A data decryption device that decrypts a sentence and generates the plaintext, and the data encryption device encrypts a first encryption key that encrypts plaintext that is exchanged with a second encryption key. and internally stored in the hidden state was provided with a security module having a function for encrypting data, the security module decrypting the inside the first said first encryption key second encryption key of the security module and is divided sequentially from the head to the block size defined plaintext is data to be encrypted, the plaintext using the first encryption key decrypted Encrypted in block units, the plaintext to generate a ciphertext which is encrypted data, the data decoding device divides the ciphertext in order from the top blocks of the same size as the plaintext, dividing the plaintext A block unit numerical value obtained by encrypting a value obtained by encrypting a block unit numerical value using the first encryption key registered in the security module and a block unit numerical value for dividing the plaintext with reference to an encryption table. The plaintext of the ciphertext is generated by converting the ciphertext of a unit into a numerical value of a block unit .

In the second invention, the security module of the data encryption device converts the ciphertext of rearranged data describing a rule for changing the order of characters in addition to the first encryption key to the second encryption key. The encrypted text is stored in an encrypted state, and before the plaintext is encrypted, the second encrypted key is used to decrypt the rearranged data ciphertext, and the rearrangement in which the rules for changing the character arrangement order are described. Scramble processing is performed to change the order of each character included in the plaintext using data, and the data decryption device decrypts the ciphertext using the encryption table, and then the rearranged data It is preferable to execute a descrambling process for changing the order of arrangement of each decrypted ciphertext using the procedure reverse to that of the data encryption apparatus.

  According to the present invention described above, if the side receiving the ciphertext has the cipher table, the ciphertext encrypted by the data cipher function can be decrypted without having the data decryption function.

  Furthermore, before the plaintext is encrypted, it is more difficult to decrypt the plaintext from the ciphertext by using the rearrangement data to change the order of the characters included in the plaintext.

  From here, this invention is demonstrated in detail, referring a figure. FIG. 1 is a diagram for explaining a data exchange system to which a data exchange method according to the present invention is applied.

  The data transmission / reception system shown in FIG. 1 is a data transmission / reception system in which the change of PIN (Personal Identification Number) stored in the IC card 4a is plaintext, and plaintext is exchanged between two computers. A data encryption device 1 that is a computer for generation and a data decryption device 2 that is a computer for decrypting ciphertext are connected via a network 3.

  A security module 10 is connected to the data encryption device 1, and the data encryption device 1 receives data such as a PIN, a user ID number and an expiration date from the IC card terminal 4 as plain text, and receives the received data using the security module 10. These data are encrypted and transmitted to the data decryption apparatus 2. The data decryption device 2 decrypts the ciphertext transmitted from the data encryption device 1.

  FIG. 2 is a block diagram of the data exchange system shown in FIG. The security module 10 included in the data encryption device 1 encrypts a secret key 101 (hereinafter referred to as an “SM secret key”) of a public key cryptosystem that is secretly generated inside the security module 10 and a plaintext to be transmitted to the data decryption device 2. A common key 102 of a common key cryptosystem used sometimes and rearrangement data 103 in which rules for changing the arrangement order of plaintext characters are described are stored.

  The common key 102 and the rearranged data 103 are stored in the security module 10 in a state encrypted with the public key that forms a pair with the SM private key 101, and when the security module 10 is used, the security module 10 is decrypted using the SM private key 101.

  Further, the security module 10 includes a data encryption unit 100 that encrypts data to be transmitted to the data decryption apparatus 2 using the SM secret key 101, the secret key 102, and the rearrangement data 103. In the present embodiment, the data encryption unit 100 corresponds to two encryption methods, a public key encryption method and a common key encryption method.

  As shown in FIG. 2, the data decryption device 2 includes rearrangement data 21 having the same contents as the data encryption device 1, and an encryption table 22 used when decrypting the ciphertext transmitted from the data encryption device 1. Is stored, and the data decrypting unit 20 is used to decrypt the ciphertext transmitted from the data encryption device 1 using the rearrangement data 21 and the encryption table 22.

  Normally, when decrypting ciphertext transmitted between computers, the security module 10 is used, and the ciphertext is decrypted using an encryption key inside the security module 10, but as shown in FIG. There are cases where the security module 10 is not possessed depending on the other party to which the data is transmitted. In such a case, the security module 10 cannot be used to encrypt and transmit the data.

  On the other hand, according to the present invention, data encrypted by the security module 10 can be decrypted without using the security module 10 according to the contents described below.

  The data encryption unit 100 of the data encryption device 1 is realized by a program installed in the security module, and the data decryption unit 20 of the data decryption device 2 is realized by a program installed in the data decryption device 2.

  FIG. 3 is a diagram showing a procedure of an encryption process for encrypting plaintext, and this process is a process executed by the security module 10 of the data encryption device 1. As shown in FIG. 3, in the encryption process executed by the security module 10 of the data encryption device 1, first, the plaintext to be encrypted is scrambled, and the scrambled plaintext is encrypted to obtain the plaintext. Generate ciphertext for.

  FIG. 4 is a diagram for explaining the scramble process executed first in the encryption process. As shown in FIG. 4, the scramble process is a process of changing the order of each character included in the plain text by using rearranged data in which a rule for changing the order of characters is described.

  FIG. 5 is a diagram showing an example of the scramble process. A method for changing the order of characters is realized by various methods. In FIG. 5, the order of plaintext is changed by matrix operation.

  FIG. 5 (a) shows a matrix calculation formula. In FIG. 5 (a), x is a matrix of one column and n rows (n is the number of characters included in the plain text). The i-th character of is described. Further, in FIG. 5A, y is a matrix of 1 column and n rows (n is the number of characters included in the plaintext), and the character in the i-th row of this matrix corresponds to the i-th character in the scrambled plaintext. To do.

  Further, in FIG. 5A, A is rearrangement data, and here, the rearrangement data is an n-by-n matrix (n is the number of characters included in the plaintext), and an example of this matrix is shown in FIG. Shown in The i-th row of the matrix shown in FIG. 4 (5) indicates information related to the rearrangement of the i-th character in plain text. For example, in the matrix A shown in FIG. Since the value of 1 is 1, it is indicated that the first (first) character in the plaintext is placed at the eighth position by the scramble process.

  By the matrix operation shown in FIG. 5, as shown in FIG. 4, the plaintext “1234991234100101” is scrambled, and the scrambled plaintext, that is, the plaintext whose character arrangement order has been changed, becomes “3094310114092211”.

  FIG. 6 is a diagram for explaining the encryption process. As shown in FIG. 6, the encryption process is to scramble the plaintext into blocks of a predetermined size (here, 4 characters) and encrypt the plaintext in blocks using a common key. It means the process to turn.

  In this embodiment, a 4-character block is treated as a 2-byte hexadecimal number, and a 2-byte numerical value is encrypted using the common key 102. In FIG. 4, “0x3094” (x is hexadecimal notation) is encrypted to “0x3DE3”, “0x3101” is encrypted to “0x161D”, “0x1409” is encrypted to “0x1E9A”, and “0x2211” is encrypted to “0x8AD0”.

  As described above, the common key 102 for encrypting the plaintext in the encryption step is stored in the security module 10 in a state encrypted with the public key that is paired with the SM private key 101.

  For this reason, when executing the encryption process, the data encryption unit of the security module 10 decrypts the common key 102 with the SIM secret key 101 using the public key cryptosystem, and then decrypts using the common cryptosystem. The scrambled plaintext is encrypted using the common key 102.

  By executing the above-described encryption process in the data encryption device 1, as shown in FIG. 3, the plaintext “1234991234100101” is changed to “3094310114092211” by changing the character order by scramble processing, As shown in FIG. 5, “3094310114092211” is encrypted to “3DE3161D1E9A8AD0” by the encryption process, and transmitted from the data encryption device 1 to the data decryption device 2.

  From here, the content of the decryption process executed by the data decryption apparatus 2 to decrypt the ciphertext and generate the plaintext will be described. FIG. 7 is a diagram illustrating a procedure of a decoding process executed by the data decoding unit 20 of the data decoding device 2. As shown in FIG. 7, in the procedure of the decryption step, first, the ciphertext is decrypted, and then the decrypted ciphertext is descrambled to generate plaintext from the ciphertext.

  Generally, when decrypting ciphertext, an encryption key (here, common key 102) is used. However, in the present invention, when decrypting ciphertext, the encryption key (here, common key 102) is used instead. In addition, the encryption table 22 is used. By decrypting the ciphertext using the encryption table 22, the data decryption apparatus 2 does not need to include the security module 10 unlike the data encryption apparatus 1.

  FIG. 8 is a diagram showing an example of the encryption table 22. The encryption table 22 in FIG. 8 is an encryption table 22 when a 2-byte numerical value is encrypted with a common key stored in the security module 10, and the row of the encryption table 22 is the value of the upper byte, and the column is Indicates the value of the lower byte.

  According to the encryption table 22 of FIG. 8, for example, “0x0000” is shown to be encrypted to “0xEA4F”, and 4 characters that are 2-byte numerical values included in the ciphertext are searched from this encryption table. Then, a value obtained by decoding from the upper byte and the lower byte of the searched portion is obtained.

  For example, since the upper byte of the place where the ciphertext “0x3DE3” is described in the encryption table is “0x30” and the lower byte is “0x14”, “0x3DE3” is decrypted with the common key of the security module 10 It can be seen that the time value is “0x3014”.

  The data decryption device 2 refers to the encryption table 22 and identifies the character string obtained by decrypting the character string included in the ciphertext, thereby decrypting the ciphertext received from the data encryption device 1 without using the encryption key. it can. By this decryption processing, for example, the ciphertext “3DE3161D1E9A8AD0” shown in FIG. 5 is decrypted to “3094310114092211”.

  The encryption table 22 may be generated using the security module 10 of the data encryption device 1. When the encryption table 22 is generated using the security module 10, the encryption table 22 is generated if encryption is performed using the common key 102 for each overlapping permutation of a predetermined number of characters in the character set used in plain text. can do.

  The descrambling process executed after the decryption process is a process for performing a procedure reverse to the scramble process executed in the encryption process. In the descrambling process, the same sort data as when encrypted is used, and the characters of the decrypted ciphertext are rearranged in the reverse procedure of the scramble process.

  For example, when the scramble process is performed by the matrix operation shown in FIG. 5, the rearrangement data 21 included in the data decoding device 2 is converted to the inverse matrix of the matrix A shown in FIG. By multiplying 1 column n rows (n is the number of characters included in the plaintext) generated from the ciphertext, the descrambling process is executed, and the plaintext that is the basis of the ciphertext is generated.

  As described above, according to the present invention, the ciphertext encrypted using the security module 10 can be decrypted even by a partner who does not have the data decryption function, as long as the rearranged data and the encryption table are shared. It becomes like this.

  Note that an encryption key registration step of registering the rearrangement data 103 and the common key 102 in the security module 10 is executed before the above-described encryption step is executed.

  In this encryption key registration step, using the public key that is paired with the SM private key 101 on the side that owns the data decryption device 2 using the encryption software provided by the side that owns the data encryption device 1, The rearrangement data 103 and the common key 102 are encrypted, and these encrypted data are registered in the security module 10.

  Since the rearrangement data 103 and the common key 102 are encrypted on the side having the data decryption device 2 by being executed in the encryption key registration step, the rearrangement data 103 and the side having the data encryption device 1 are encrypted. It becomes difficult to decrypt the common key 102.

The figure for demonstrating a data transfer system. The block diagram of a data transfer system. The figure which showed the procedure of the encryption process. The figure for demonstrating a scramble process. The figure which showed an example of the scramble process. The figure for demonstrating an encryption process. The figure which showed the procedure of the decoding process. The figure which showed an example of the encryption table.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Data encryption apparatus 10 Security module 100 Data decryption part 101 SM private key, 102 Common key, 103 Rearrangement data 2 Data decryption apparatus 20 Data decryption part 21 Rearrangement data, 22 Encryption table 3 Network 4 IC card terminal

Claims (4)

A data exchange method for exchanging data, which has a function of encrypting / decrypting data, and a security module installed on a data transmitting side encrypts plain text as data to be exchanged the key is encrypted using a second encryption key for the security module, in said security module, the encryption key registration step of registering the first encryption key encrypted, the security module, the security In the module, the first encryption key is decrypted with the second encryption key, the plaintext, which is the data to be encrypted, is divided into blocks of a predetermined size in order from the top, and the decrypted first encryption key And encrypting the plaintext in units of blocks to generate the plaintext ciphertext and to a computer installed on the data receiving side An encryption step of transmitting said ciphertext form, wherein the ciphertext is divided sequentially from the head to the block of the same size as the plaintext, the the value of the block unit for dividing the plaintext has been registered in the security module By referring to an encryption table in which a value encrypted using the first encryption key is associated with a numerical value in block units that divides the plaintext, the ciphertext in block units is converted into numerical values in block units. And a decrypting step of generating the plaintext of the received ciphertext. 2. The data exchange method according to claim 1, wherein, in the encryption key registration step, the security module receives rearrangement data describing a change rule of a character arrangement order in addition to the first encryption key. And the encrypted rearranged data is registered in the security module, and in the encryption step , the security module encrypts the plaintext before encrypting the plaintext. In addition, the ciphertext of the rearranged data is decrypted using the second encryption key, and the rearrangement data describing the rules for changing the rearrangement order of the characters is used to arrange each character sequence included in the plaintext. run the scrambling process for changing the order, in the decoding step, the computer within said computer, using said encryption table After decrypting the ciphertext Te, by using the re-aligned data, the order of each included in the ciphertext decryption, executes descrambling processing for change in the reverse order from that of the encryption step A data exchange method characterized by this. A data exchange system for exchanging data between computers, which encrypts plaintext that is data to be transmitted and generates ciphertext, and generates the plaintext by decrypting the ciphertext generated by the data encryption device The data encryption device is configured to secretly store a first encryption key for encrypting plaintext, which is data to be exchanged, in a state encrypted with the second encryption key. And a security module having a function of encrypting data, the security module decrypting the first encryption key with the second encryption key and encrypting the data inside the security module. divided sequentially from the head to the block size defined plaintext, decoded the first encryption of the plaintext block using an encryption key To, the plaintext to generate a ciphertext which is encrypted data, the data decoding apparatus, the ciphertext is divided sequentially from the head to the block of the same size as the plaintext, the block unit for dividing the plaintext By referring to an encryption table in which a value obtained by encrypting a numerical value using the first encryption key registered in the security module and a numerical value in block units for dividing the plaintext are associated, the encryption in block units is referred to. A data exchange system, wherein the plaintext of the ciphertext is generated by converting a text into a numerical value in block units . 4. The data transmission / reception system according to claim 3, wherein the security module of the data encryption device receives, in addition to the first encryption key, a ciphertext of rearranged data describing a rule for changing a character arrangement order. The encrypted text is stored in the encrypted state, and before the plaintext is encrypted, the second encrypted key is used to decrypt the rearranged data ciphertext and describe the rules for changing the character order. Using the rearranged data, a scramble process for changing the order of the characters included in the plaintext is performed, and the data decryption device decrypts the ciphertext using the cipher table, and Data that performs re-scramble processing that uses reordering data to change the reordering order included in the decrypted ciphertext in the reverse procedure of the data encryption device Receiving system.

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