JP2006325269A - Encryption method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encryption method which allows modification of a secret key B with a control software D of secret information protection system implemented outside of the secret information protection system. <P>SOLUTION: In the encryption method which has a cipher decoding circuit 1b for encoding or decoding secret information A that is a key or a contents required to be protected into or from an encrypted secret information Enc (A, B) with a secret key B for encoding or decoding the secret information A, a secret key C is input into a shift register 2a and a rotation is applied to the secret key C to generate a secret key B. The rotation bit count of the shift register 2a can be modified with a selection signal configured by the control software D. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an encryption method used for encryption or decryption of confidential information.

  In the conventional encryption method (see Patent Document 1 below), one secret key C is mounted on the secret information protection system, and the secret key B used by the encryption / decryption circuit 1b for encrypting or decrypting the secret information A is a secret key. The key C was used as it was. FIG. 8 is a diagram of an encryption method described in Patent Document 1. In FIG.

In FIG. 8, the encryption method uses a secret key C1a and an encryption / decryption circuit 1b. The secret key C1a is directly input to the encryption / decryption circuit 1b, and the secret information B is used as the secret key B used in the encryption / decryption circuit 1b to encrypt or decrypt the secret information A into the encrypted secret information Enc (A, B).
Japanese Patent Laid-Open No. 09-326166

  However, in such a conventional encryption scheme configuration, when the secret key B is hacked, there is no way to invalidate the hacked secret key B from outside the secret information protection system.

  Alternatively, in order to invalidate the hacked secret key B, it is necessary to change the confidential information protection system itself in which the secret key C is mounted, and an increase in cost is expected.

  Or, in order to prevent damage caused by hacking to a minimum, when the secret key B is changed and installed in advance for each device, the secret key C is changed and installed for each secret information protection system of each device, which increases the cost. is expected.

  Accordingly, an object of the present invention is to realize a means for changing the secret key B by the control software D of the confidential information protection system that is implemented outside the confidential information protection system. It is an object of the present invention to realize an encryption method that can invalidate a hacked secret key B only by changing the setting of the control software D even when the key B is hacked.

  Alternatively, in order to prevent damage caused by hacking to a minimum, when the secret key B is changed and installed for each device in advance, an encryption method that can change the secret key B only by changing the setting of the control software D is realized. Let it be an issue.

  In order to solve the above-described problem, the present invention provides several secret key B generation means having different embodiments, and uses the secret key generated by the generation means as the secret key B used in the encryption / decryption circuit in the encryption / decryption circuit. You are typing.

The encryption method according to claim 1 encrypts confidential information into encrypted confidential information by using a first confidential key for encrypting or decrypting confidential information with respect to confidential information that is a key or content that needs to be protected. Alternatively, an encryption method provided with an encryption / decryption means for decoding,
Generating means for generating a first secret key by performing an operation by performing a bit rotation on the second secret key by a shift register;
The generating means is a selection signal from the outside, and the first secret key can be changed by changing the calculation method of the calculation by the selection signal based on the hacking information on whether or not the confidential information is hacked. It is what.

The encryption method according to claim 2 encrypts or decrypts confidential information into encrypted confidential information with a confidential key for encrypting or decrypting the confidential information with respect to confidential information that is a key or content that needs to be protected. An encryption method provided with encryption / decryption means,
There is a generation means for generating a secret key by dividing the secret key into bits and performing the reverse operation of the calculation used to generate the modified key from the modified key that has been operated by changing the order of each divided unit. And
The generation means is a selection signal from the outside, and the secret key can be changed by changing the calculation method of the reverse operation by the selection signal based on the hacking information on whether or not the confidential information is hacked. Is.

  According to the encryption method of the first aspect, the secret key B is generated by performing an operation by performing a bit rotation on the secret key C installed in the secret information protection system by a shift register. By making the generated calculation contents changeable by the control software D of the confidential information protection system implemented outside the confidential information protection system, the setting of the control software D and the encrypted confidential information implemented outside the confidential information protection system It is possible to invalidate the hacked secret key B only by changing Enc (A, B), or to prevent damage due to hacking of the secret key B to a minimum.

  According to the encryption method of the second aspect, the secret key B is divided into bits, and the modified key that is operated by changing the order for each divided unit is mounted inside the secret information protection system, and the secret key B The secret key B is reorganized from the modified key by performing the inverse operation of the above, and the reorganization method of the secret key B can be changed by the control software D of the confidential information protection system installed outside the confidential information protection system. For this reason, the same effect as that of claim 1 is obtained.

(Embodiment 1)
FIG. 1 is a diagram showing an encryption method according to the first embodiment of the present invention. In FIG. 1, the same components as those in FIG.

  In FIG. 1, the encryption method is realized by a secret key C1a, a shift register 2a for rotating the secret key C1a as a key operation circuit, a selection signal 2b for setting the number of rotation bits (bits), and an encryption / decryption circuit 1b. The

  In this embodiment, the secret key C1a is input to the shift register 2a, the secret key C1a is rotated by the shift register 2a, and is input to the encryption / decryption circuit 1b as the secret key B used in the encryption / decryption circuit 1b. A selection signal 2b for setting the number of rotation bits is input to the shift register 2a, and the control software D sets the selection signal 2b. When the secret key B is hacked, setting the control software D and implementing it outside the confidential information protection system without changing the confidential information protection system by changing the number of rotation bits in the shift register by changing the setting of the control software D The secret key B hacked can be revoked only by changing the encrypted secret information Enc (A, B). Alternatively, by setting the setting value of the control software D and the encrypted confidential information Enc (A, B) installed outside the confidential information protection system for each device in advance, damage caused when the confidential key B is hacked can be reduced. Can be kept to a minimum.

  In this embodiment, a shift register is used as a circuit for performing an operation. However, not only the shift register but also a plurality of circuits for performing an operation on the secret key C1a are prepared, and these circuits are continuously used for the secret key C1a. It is also possible to perform calculation, input the selection signal 2b to each circuit, and the control software D to set the calculation method of each circuit. Alternatively, a method may be employed in which a plurality of secret keys C1a are prepared, and one of them is selected by a selector and input to the shift register 2a.

As described above, the encryption method of the first embodiment uses the confidential information A by the confidential key B for encrypting or decrypting the confidential information A with respect to the confidential information A that is a key or content that needs to be protected. Is encrypted into encrypted confidential information Enc (A, B),
The confidential information A can be obtained by decrypting the encrypted confidential information Enc (A, B) implemented outside the confidential information protection system with the confidential key B,
A secret key C, which is a key for generating the secret key B, is implemented inside the confidential information protection system,
A secret key B is generated by applying a logical operation or arithmetic operation or a combination of logical operation and arithmetic operation to the secret key C,
The secret key B can be changed by changing the calculation method for generating the secret key B from the secret key C by the control software D of the secret information protection system installed outside the secret information protection system.
By changing the encrypted confidential information Enc (A, B) in accordance with the change of the secret key B due to the change of the control software D, the confidential information A can be decrypted even after the control software D is changed.

(Embodiment 2)
FIG. 2 is a diagram showing an encryption method according to the second embodiment of the present invention. In FIG. 2, the same components as those in FIG.

In FIG. 2, the encryption method is to divide one secret key C1a into m divided keys 3a ′ having the same bit width (hereinafter, the m divided keys in the secret key C1a are sequentially assigned K1, K2,. .., Km), and a modified key 3a formed by replacing the m divided keys 3a '(hereinafter, the divided keys in the modified key are represented by Ki1, Ki2,. )When,
Index conversion table for storing an index conversion method for split keys for reorganization from the modified key 3a ({Ki1, Ki2,..., Kim}) to the secret key C1a ({K1, K2,..., Km}). A key reorganization circuit 3b having 3c and a key storage register 3d;
A selection signal 3e for changing the contents of the index conversion table 3c;
This is realized by the encryption / decryption circuit 1b.

  In the present embodiment, each split key 3a ′ of the modified key 3a is input to the key reorganization circuit 3b in order from Ki1, and an index before replacement of the split key is obtained by the index conversion table 3c, and the index is stored in the key storage register 3d. The split key is stored in the location indicated by. By performing this operation for all m split keys 3a ′ of the modified key 3a, the modified key 3a is reorganized to the confidential key C1a before the modification, and is input to the encryption / decryption circuit 1b as the secret key B used in the encryption / decryption circuit 1b. . A selection signal 3e for changing the contents of the index conversion table 3c is input to the key reorganization circuit 3b, and the control software D sets the selection signal 3e. When the secret key B is hacked, the contents of the index conversion table 3c are changed by changing the setting of the control software D, so that the setting of the control software D and the outside of the confidential information protection system are implemented without changing the confidential information protection system. The secret key B hacked can be revoked only by changing the encrypted secret information Enc (A, B). Alternatively, by setting the setting value of the control software D and the encrypted confidential information Enc (A, B) installed outside the confidential information protection system for each device in advance, damage caused when the confidential key B is hacked can be reduced. Can be kept to a minimum.

  In the present embodiment, a splitting method in which the lengths of the split keys are not equal may be adopted for the splitting method of m split keys forming one modified key. Alternatively, a method may be adopted in which a plurality of modification keys 3a are prepared, and one of them is selected by a selector and input to the key reorganization circuit. Alternatively, when a plurality of modification keys are prepared, the value of m may be different for each modification key.

As described above, the encryption method of the second embodiment is such that the confidential information A is encrypted with the confidential key B for encrypting or decrypting the confidential information A with respect to the confidential information A that is a key or content that needs to be protected. Is encrypted into encrypted confidential information Enc (A, B),
The confidential information A can be obtained by decrypting the encrypted confidential information Enc (A, B) implemented outside the confidential information protection system with the confidential key B,
Generate a modified key by performing a logical operation or arithmetic operation or a combination of logical operation and arithmetic operation on the secret key B, and implement the modified key inside the confidential information protection system.
The secret key B can be obtained from the modified key by performing the inverse operation of the operation used to generate the modified key,
The secret key B can be changed by changing the calculation method for obtaining the secret key B from the altered key by the control software D of the secret information protection system implemented outside the secret information protection system,
By changing the encrypted confidential information Enc (A, B) in accordance with the change of the secret key B due to the change of the control software D, the confidential information A can be decrypted even after the control software D is changed.

(Embodiment 3)
FIG. 3 is a diagram showing an encryption method according to the third embodiment of the present invention. In FIG. 3, the same components as those in FIG.

  In FIG. 3, the encryption method is formed by arranging m secret keys 4a that are formed by arranging n secret keys C1a and m dummy keys 4b that are spare secret keys when the secret key B is hacked. This is realized by a dummy key bundle 4c, a selector 4d, a selection signal 4e for selecting one secret key B from the secret key bundle 4a and the dummy key bundle 4c, and the encryption / decryption circuit 1b.

  In the present embodiment, the secret key bundle 4a and the dummy key bundle 4c are input to the selector 4d which is a generation unit, and one secret key B is selected from the secret key bundle 4a and the dummy key bundle 4c. However, in the initial state (state in which the secret key B is not hacked), no dummy key is selected in the selector 4d. The output of the selector 4d is input to the encryption / decryption circuit 1b as the secret key B used in the encryption / decryption circuit 1b. The selector 4d receives the selection signal 4e, and the control software D sets the selection signal 4e. When the initial secret key B is hacked, the dummy key 4b is selected by changing the setting of the control software D, so that the setting of the control software D and the outside of the confidential information protection system can be performed without changing the confidential information protection system. It is possible to invalidate the hacked secret key B only by changing the encrypted confidential information Enc (A, B).

As described above, the encryption method of the third embodiment is such that the confidential information A is encrypted with the confidential key B for encrypting or decrypting the confidential information A with respect to the confidential information A that is a key or content that needs to be protected. Is encrypted into encrypted confidential information Enc (A, B),
The confidential information A can be obtained by decrypting the encrypted confidential information Enc (A, B) implemented outside the confidential information protection system with the confidential key B,
A secret key bundle formed by arranging n secret keys and a dummy key bundle formed by arranging m dummy keys that are spare secret keys when secret key B is hacked inside the confidential information protection system Implement,
The secret key B is one selected from n + m secret keys obtained by adding the secret key ring and the dummy key ring.
It is possible to change the selection of the secret key B from the secret key ring and the dummy key ring by the control software D of the confidential information protection system implemented outside the confidential information protection system,
By changing the encrypted confidential information Enc (A, B) in accordance with the change of the secret key B due to the change of the control software D, the confidential information A can be decrypted even after the control software D is changed.

(Embodiment 4)
FIG. 4 is a diagram showing an encryption method according to the fourth embodiment of the present invention. In FIG. 4, the same components as those in FIG.

In FIG. 4, the encryption method is a generated key formed by forming a generated key 5a divided into m divided generated keys 5a ′ for each kbit (bit) for one secret key and arranging n generated keys 5a. A bundle 5b (hereinafter, m divided generation keys in the i-th generation key are expressed as Ki1, Ki2,..., Kim in order from the top),
The split generation key selector 5d that selects one split generation key Krici from the generation key bundle 5b, and the ri in each selection when selecting m split generation keys Krici from the generation key bundle 5b using the split generation key selector 5d. a key generation circuit 5c having an index acquisition table 5e for storing the value of ci, and a shift register 5f for connecting the selected divided generation keys to generate a secret key B used in the encryption / decryption circuit 1d;
A selection signal 5g for changing the contents of the index acquisition table 5e;
This is realized by the encryption / decryption circuit 1b.

  The index acquisition table 5e associates the split generation key with m indexes, and the corresponding split generation key is selected by designating each index. When changing the contents of the table, there is a change in only one or both of ri (Row) and ci (Column) in each index.

  In the present embodiment, the generated key bundle 5b is input to the key generation circuit 5c, and the key generation circuit 5c refers to the contents of the index acquisition table 5e to extract the values of ri and ci in the current selection of the split generation key Krici. Then, Krici is selected from the generated key bundle 5b using the split generated key selector 5d, and is input to the shift register 5f for shifting. This is repeated m times, and the selected Krici is concatenated in order to generate one secret key from the plurality of split generation keys 5a 'and input it to the encryption / decryption circuit 1b as the secret key B used in the encryption / decryption circuit 1b. A selection signal 5g for changing the contents of the index acquisition table 5e is input to the key generation circuit 5c, and the control software D sets the selection signal 5g.

  When the secret key B is hacked, the contents of the index acquisition table 5e are changed by changing the setting of the control software D, so that the control software D is set and installed outside the secret information protection system without changing the secret information protection system. The secret key B hacked can be revoked only by changing the encrypted secret information Enc (A, B). Alternatively, by setting the setting value of the control software D and the encrypted confidential information Enc (A, B) installed outside the confidential information protection system for each device in advance, damage caused when the confidential key B is hacked can be reduced. Can be kept to a minimum.

  Note that it is also possible to change the contents of the table by preparing a plurality of tables as a modified form and selecting from among them.

As described above, the encryption method of the fourth embodiment is such that the confidential information A is encrypted with the confidential key B for encrypting or decrypting the confidential information A with respect to the confidential information A that is the key or content that needs to be protected. Is encrypted into encrypted confidential information Enc (A, B),
The confidential information A can be obtained by decrypting the encrypted confidential information Enc (A, B) implemented outside the confidential information protection system with the confidential key B,
A generated key is formed by dividing a secret key into divided generated keys that are divided into m pieces for each kbit for one secret key, and a generated key bundle formed by arranging n generated keys. Implement inside the confidential information protection system,
Select m from n × m split generation keys in the generated key bundle, and generate a secret key B by concatenating them,
It is possible to change the secret key B by changing the selection of m divided generation keys from the generated key bundle by the control software D of the confidential information protection system installed outside the confidential information protection system,
By changing the encrypted confidential information Enc (A, B) in accordance with the change of the secret key B due to the change of the control software D, the confidential information A can be decrypted even after the control software D is changed.

(Embodiment 5)
FIG. 5 is a diagram showing an encryption method according to the fifth embodiment of the present invention. 5, the same components as those in FIGS. 8 and 1 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 5, the encryption method includes a secret key C1a, a shift register 2a for rotating the secret key C1a, a selection signal 2b for setting the number of rotation bits in the shift register, an encryption / decryption circuit 1b, A hash function 6a device for generating a hash value using the signal 2b and the secret key C1a rotated by the shift register 2a as input, a hash value Hash2 generated by the hash function 6a device, and a confidential information protection system This is realized by a comparator 6b for comparing the hash value Hash1 mounted outside and a mask 6c for validating or invalidating the secret key B based on the comparison result.

  In this embodiment, the secret key C1a is input to the shift register 2a, and the secret key C1a is rotated by the shift register 2a to generate the secret key B.

  In order to confirm that the secret key B and the control software D have not been tampered with, the hash value Hash1 generated in advance using the setting values of the secret key B and the control software D as the input of the hash function 6a is implemented outside the secret information protection system. In the confidential information protection system, the hash value Hash2 is calculated using the rotation result and the set value of the control software D as the input of the hash function 6a, and Hash1 and Hash2 are compared by the comparator 6b. When Hash1 and Hash2 are different, it is assumed that the secret key B or the control software D has been tampered with, and the secret key B cannot be used when the secret key B or the control software D has been tampered with by masking with the mask 6c Can be made. When Hash1 and Hash2 are equal, the result obtained by rotating the secret key C1a is input to the encryption / decryption circuit 1b as the secret key B used in the encryption / decryption circuit 1b.

  A selection signal 2b for setting the number of rotation bits is input to the shift register 2a, and the control software D sets the selection signal 2b. When the secret key B is hacked, the number of rotation bits in the shift register 2a is changed by changing the setting of the control software D, so that the setting of the control software D and the outside of the confidential information protection system can be performed without changing the confidential information protection system. The hacked secret key B can be invalidated only by changing the encrypted confidential information Enc (A, B) to be implemented. Alternatively, by setting the setting value of the control software D and the encrypted confidential information Enc (A, B) installed outside the confidential information protection system for each device in advance, damage caused when the confidential key B is hacked can be reduced. Can be kept to a minimum.

  In the embodiment, the means for generating the secret key B of the first embodiment is used. However, the means for generating the second to fourth embodiments or a combination thereof (the eighth embodiment) is used. May be.

As described above, the encryption method of the fifth embodiment is a hash generated using a hash function from the set value of the secret key B and the control software D of the secret information protection system installed outside the secret information protection system. Hold the value 1 outside the confidential information protection system,
After the secret key B is generated inside the confidential information protection system according to the setting value of the control software D, the hash value 2 is generated from the generated secret key B and the control software D using the hash function, and generated inside the confidential information protection system. By comparing the hash value 2 with the hash value 1 held outside the confidential information protection system to determine whether the secret key B and the control software D have been tampered with,
After confirming that the secret key B and the control software D have not been tampered with, the secret information A can be decrypted by the secret key B.

(Embodiment 6)
FIG. 6 is a diagram showing an encryption method according to the sixth embodiment of the present invention. In FIG. 6, the same components as those in FIGS. 8, 1 and 5 are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 6, the encryption method includes a secret key C1a, a shift register 2a for rotating the secret key C1a, a selection signal 2b for setting the number of rotation bits in the shift register 2a, a secret key B, and control software. A means for generating a check value 7a, an encryption / decryption circuit 1b, a selection signal 2b, and a secret key rotated by the shift register 2a are installed in the confidential information protection system to confirm that D is not falsified. A hash function hash device 6a for generating a hash value Hash having C1a and a check value 7a as inputs, a hash value Hash2 generated by the hash function device 6a, and a hash value Hash1 implemented outside the confidential information protection system And the secret key B is validated or invalidated according to the above comparison result. It is realized by the order of mask 6c.

  In this embodiment, the secret key C1a is input to the shift register 2a, and the secret key C1a is rotated by the shift register 2a to generate the secret key B.

  In order to confirm that the secret key B and the control software D have not been tampered with, the secret key B, the set value of the control software D, and the hash value Hash1 generated using the check value 7a as the input of the hash function are used as the secret information protection system. As a result of external rotation and rotation inside the confidential information protection system, the hash value Hash2 is calculated using the set value of the control software D and the check value 7a as the input of the hash function 6a, and the hash values Hash1 and Hash2 are compared. Compare with 6b. When the hash values Hash1 and Hash2 are different, the secret key B or the control software D is assumed to be falsified, and the secret key B is used when the secret key B or the control software D is falsified by masking using the mask 6c. You can make it impossible. When the hash values Hash1 and Hash2 are equal, the result obtained by rotating the secret key C1a is input to the encryption / decryption circuit 1b as the secret key B used in the encryption / decryption circuit 1b.

  A selection signal 2b for setting the number of rotation bits is input to the shift register 2a, and the control software D sets the selection signal 2b. When the secret key B is hacked, setting the control software D and implementing it outside the confidential information protection system without changing the confidential information protection system by changing the number of rotation bits in the shift register by changing the setting of the control software D The secret key B hacked can be revoked only by changing the encrypted secret information Enc (A, B). Alternatively, the secret key B is hacked by setting the setting value of the control software D and the encrypted confidential information Enc (A, B) installed outside the confidential information protection system or the check value 7a differently for each device. Damage can be minimized.

  In the embodiment, the means for generating the secret key B of the first embodiment is used. However, the means for generating the second to fourth embodiments or a combination thereof (the eighth embodiment) is used. May be.

As described above, in the sixth embodiment, in the first to fourth embodiments, the confidential key B or the control software D of the confidential information protection system implemented outside the confidential information protection system is falsified. A check value 7a for guaranteeing that there is no data is held inside the confidential information protection system,
A hash value Hash1 generated by using a hash function device from the set value of the secret key B and the control software D and the check value 7a is held outside the secret information protection system,
After generating the secret key B in the confidential information protection system according to the setting value of the control software D, the hash function device is obtained from the generated secret key B, the setting value of the control software D and the check value 7a held in the confidential information protection system. Using this, the hash value Hash2 is generated, and the hash value 2 generated inside the confidential information protection system is compared with the hash value 1 held outside the confidential information protection system to determine whether the secret key B and the control software D have been tampered with. And
After confirming that the secret key B and the control software D have not been tampered with, the secret information A can be decrypted by the secret key B.

(Embodiment 7)
FIG. 7 is a diagram showing an encryption method according to the seventh embodiment of the present invention. 7, the same components as those in FIGS. 8 and 1 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 7, the encryption method includes a secret key C1a, a shift register 2a for rotating the secret key C1a, a selection signal 2b for setting the number of rotation bits in the shift register 2a, an encryption / decryption circuit 1b, This is realized by an ID number E8a input from the removable medium and an adder 8b.

  In this embodiment, the secret key C1a is input to the shift register 2a, the secret key C1a is rotated by the shift register 2a, and is input to the encryption / decryption circuit 1b as the secret key B used in the encryption / decryption circuit 1b. The result of adding the value of the selection signal 2b and the ID number E8a input from the removable medium by the adder 8b is the number of rotation bits in the shift register 2a, and the control software D sets the selection signal 2b.

  Since a different secret key B is generated for each removable medium, damage when the secret key B is hacked can be minimized. Alternatively, when the secret key B is hacked, the control software D can be set without changing the confidential information protection system by changing the number of rotation bits in the shift register 2a by changing the setting of the control software D. It is possible to invalidate the hacked secret key B only by changing the encrypted confidential information Enc (A, B).

  Although this embodiment is applied to the first embodiment, the only difference is that the signal of ID number E is added to the selection signal of the first embodiment, and the other embodiments are also different. Applicable. The selection signal and the ID number E are input to the generating means through the adder 8b. However, the secret key B may be changed by adding both the selection signal and the ID number E to the generating means.

  As described above, in this embodiment, in the system in which the confidential information protection system and the removable medium communicate, the ID unique to the removable medium held by the removable medium is determined as a factor for determining the secret key B generation method together with the control software D. A different secret key B is generated for each removable medium, and can be applied to each of the above embodiments.

(Embodiment 8)
As an eighth embodiment, the confidential information A is encrypted with the confidential key B for encrypting or decrypting the confidential information A, and the confidential information Enc (A , B) encryption method,
A secret key B is generated by combining a plurality of secret key B generation methods described in the first to fourth embodiments,
It is possible to change each generation method combined by the control software D of the confidential information protection system implemented outside the confidential information protection system and change the secret key B,
By changing the encrypted confidential information Enc (A, B) in accordance with the change of the secret key B due to the change of the control software D, the confidential information A can be decrypted even after the control software D is changed.

  For example, the secret key B input to the encryption / decryption circuit 1b is selected by the selecting means from the secret key B obtained by the first to fourth embodiments, or the second to fourth embodiments. The secret key B is used as the secret key C of the first embodiment, the secret key B of the first, third and fourth embodiments is used as the modified key of the second embodiment, or the first, first The secret key B of the second and fourth embodiments is made one of the secret keys in the secret key bundle of the third embodiment, or the secret key B of the first, second and third embodiments is used. It can be considered to be one of the generated keys in the generated key bundle of the fourth embodiment.

  As described above, when the secret key B is hacked by using the encryption method of the present invention, the secret key B is generated by changing the setting of the control software D of the secret information protection system installed outside the secret information protection system. By changing the method, it is possible to invalidate the hacked secret key B without changing the confidential information protection system, and it is possible to reduce the cost required to invalidate the hacked secret key B. Alternatively, by setting the setting value of the control software D and the encrypted confidential information Enc (A, B) installed outside the confidential information protection system for each device in advance, damage caused when the confidential key B is hacked can be reduced. Can be kept to a minimum.

  The encryption method of the present invention has an effect that the hacked secret key can be invalidated only by changing the setting of the control software even when the secret key is hacked, and is useful as an encryption method used for encryption or decryption of confidential information. It is.

It is a block diagram which shows the encryption system in the 1st Embodiment of this invention. It is a block diagram which shows the encryption system in the 2nd Embodiment of this invention. It is a block diagram which shows the encryption system in the 3rd Embodiment of this invention. It is a block diagram which shows the encryption system in the 4th Embodiment of this invention. It is a block diagram which shows the encryption system in the 5th Embodiment of this invention. It is a block diagram which shows the encryption system in the 6th Embodiment of this invention. It is a block diagram which shows the encryption system in the 7th Embodiment of this invention. It is a block diagram which shows the conventional encryption system.

Explanation of symbols

A Confidential information B Confidential key Enc (A, B) Encrypted confidential information 1a Confidential key C
1b Encryption / Decryption Circuit 2a Shift Register 2b Selection Signal 3a Modified Key 3a 'Split Key 3b Key Reorganization Circuit 3c Index Conversion Table 3d Key Storage Register 3e Selection Signal 4a Secret Key Bundle 4b Dummy Key Bundle 4d Selector 4e Selection Signal 5a Generation Key 5a 'split generation key 5b generation key bundle 5c key generation circuit 5d split generation key selector 5e index acquisition table 5f shift register 5g selection signal 6a hash function 6b comparator 6c mask 7a check value 8a ID number E
8b Adder

Claims (2)

Encryption / decryption means for encrypting or decrypting the confidential information into the encrypted confidential information with the first confidential key for encrypting or decrypting the confidential information with respect to the confidential information that is a key or content that needs to be protected An encryption method provided,
Generating means for generating the first secret key by performing an operation by performing bit rotation on the second secret key by a shift register;
The generation means is a selection signal from the outside, and the first secret key can be changed by changing a calculation method of the calculation by a selection signal based on hacking information regarding whether or not the confidential information is hacked. An encryption method characterized by that. Encryption with encryption / decryption means for encrypting or decrypting the confidential information into encrypted confidential information with a confidential key for encrypting or decrypting the confidential information with respect to confidential information that is a key or content that needs to be protected A method,
Generating the secret key by dividing the secret key into bits and performing the inverse operation of the calculation used to generate the altered key from the altered key obtained by performing an operation by changing the order of each divided unit. Having means,
The generation means is a selection signal from the outside, and the secret key can be changed by changing the reverse calculation method by a selection signal based on hacking information on whether or not the confidential information is hacked. An encryption method characterized by

Images