JP2013134414A - Key encryption device, key decryption device, key encryption method, key decryption method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a key encryption device, a key decryption device, a key encryption method, a key decryption method, and a program to which a key encryption algorithm is applied of which efficiency of processing is enhanced compared to conventional ones by reducing the number of times of encryption/decryption processing by a common key encryption algorithm for verifying key authenticity.SOLUTION: A key encryption device 10 comprises: a fixed length data calculation unit 11 which, in decrypting an encrypted data key, calculates fixed length data to be used for verifying authenticity of the decrypted data key from the data key by using a one-way function; a coupling unit 12 which couples the calculated fixed length data and the data key; and an encryption unit 13 which encrypts the data key coupled with the calculated fixed length data with a key encryption key, and generates key encrypted data.

Description

  The present invention relates to a key encryption device, a key decryption device, a key encryption method, a key decryption method, and a program for encrypting a key.

  In general, content that is sold and distributed via a network has a method of encrypting the content, and further encrypting the key (content key) used for encrypting the content with a different key (user key) for each user. It is used. By using this method, it is possible to prevent content from leaking for reasons such as wiretapping on the network or secondary distribution unintended by the content right holder. Further, by using the content key, it is not necessary to individually encrypt a large content with the user key, and the processing can be performed efficiently.

  A key encryption algorithm for encrypting a key used for encrypting such data with another key is composed of a key encryption algorithm and a decryption algorithm. It is also possible to verify the validity of the key at the time of decryption.

  The key encryption algorithm includes, for example, AES Key Warp (for example, see Non-Patent Document 1) designed to encrypt an encryption key using AES, which is proposed by NIST, and TWKW (for example, non-patent document). Patent Document 2), AKW1 and AKW2 (for example, see Non-Patent Document 3).

Microsoft, “Security Algorithm Suite Class”, http: // msdn. Microsoft. com / en-us / library / system. servicemodel. security. securityalgorithmsuite. aspx [retrieved on November 8, 2011] J. et al. Schaad, R.A. Houseley “Advanced Encryption Standard (AES) Key Wrap Algorithm”, Request for Comments: 3394, http: // tools. ietf. org / html / rfc3394 [retrieved on November 4, 2011] "Request for Review of Key Wrap Algorithms.", Http: // eprint. iacr. org / 2004/340. pdf [retrieved on November 4, 2011]

  However, for example, AES Key Warp encrypts / decrypts a 128-bit key to encrypt / decrypt the key itself and to verify the validity of the encrypted key at the time of decryption. At the same time, encryption / decryption by AES must be performed six times, and in other key encryption algorithms, when a 128-bit key is encrypted / decrypted, it is encrypted by a common key encryption algorithm. / There was a problem that the decoding had to be performed a plurality of times. In addition, the key encryption algorithm is subject to analysis by an attacker who wants to obtain content without a legitimate right. However, once the algorithm is analyzed, the algorithm cannot be used again. .

  Therefore, the present invention has been made in view of the above-described problems, and reduces the number of times of encryption / decryption processing by a common key encryption algorithm performed for verifying the validity of the key. It is an object of the present invention to provide a key encryption device, a key decryption device, a key encryption method, a key decryption method, and a program to which a key encryption algorithm with improved processing efficiency is applied. It is another object of the present invention to provide a key encryption algorithm that can change the algorithm.

  The present invention proposes the following matters in order to solve the above problems. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.

  (1) The present invention is a key encryption device that encrypts a data key used for data encryption, and verifies the validity of the decrypted data key when decrypting the encrypted data key. Fixed-length data calculating means (for example, equivalent to the fixed-length data calculating unit 11) that calculates fixed-length data used for the above-mentioned data key using a one-way function, the calculated fixed-length data and the data key A combining means (for example, corresponding to the combining unit 12), and an encryption means (for example, a key encryption key) for encrypting a data key combined with the calculated fixed-length data with a key encryption key (for example, , Corresponding to the encryption unit 13).

  According to the present invention, the fixed-length data detector calculating stage converts the fixed-length data used for verifying the validity of the decrypted data key from the data key in one-way direction when decrypting the encrypted data key. Calculate using a function. The combining means combines the calculated fixed-length data and the data key. The encryption unit encrypts a data key combined with the calculated fixed-length data with a key encryption key, and generates key-encrypted data. Therefore, encryption processing is performed once, and processing for generating fixed length data used for verifying the validity of the data key encrypted by the key encryption key is performed once using a one-way function. Thus, it is possible to construct a key encryption device to which a key encryption algorithm whose processing is more efficient than the conventional one is applied.

  (2) The present invention proposes a key encryption device in which the one-way function is a hash function or a MAC function with respect to the key encryption device of (1).

  According to the present invention, the one-way function is a hash function or a MAC function. Therefore, fixed-length data for verifying the validity of the key encrypted by the key encryption key can be generated by the hash function and the MAC function. In order to verify the validity of the data key by using a hash function or a MAC function instead of the conventional common key encryption algorithm for generating fixed-length data used for verifying the validity of the data key. It is possible to remove the restriction on the data length of the fixed length data used for the data.

  (3) The present invention relates to the key encryption device according to (1) or (2), wherein the encryption unit executes a predetermined process a plurality of times and uses a data key combined with the calculated fixed-length data. It is composed of a round function (for example, corresponding to FIG. 3) for generating the key encrypted data, and the round function has a portion where the algorithm is variable according to bit information of the input algorithm key. A key encryption device is proposed.

  According to the present invention, the encryption means is composed of a round function that executes predetermined processing a plurality of times and generates key encrypted data from the data key combined with the calculated fixed-length data. The round function has a portion where the algorithm varies according to the bit information of the input algorithm key. Therefore, since the encryption means is composed of a round function that can change a specific part of the algorithm, the algorithm of the key encryption device can be made variable.

  (4) According to the present invention, in the key encryption device of (1) to (3), the fixed length data calculation means performs a predetermined process on each of a plurality of data groups obtained by dividing the data key into predetermined bits. A round function processing means (for example, equivalent to the round function processing unit 100 in FIG. 2) to be executed a plurality of times and a plurality of data groups that have been processed by the round function processing means Terminal processing means (for example, corresponding to the terminal processing section 200 in FIG. 2) for generating the fixed-length data, and the round function processing means according to the input bit information of the second algorithm key A key encryption device characterized by having a variable algorithm part has been proposed.

  According to the present invention, the round function processing means has a portion in which the algorithm varies according to the bit information of the input second algorithm key, and each of the plurality of data groups in which the data key is divided into predetermined bits. The predetermined process is executed a plurality of times. The termination processing unit performs an exclusive OR operation on the plurality of data groups processed by the round function processing unit to generate fixed-length data. Therefore, the fixed-length data calculation means includes the round function processing means that can change the specific part of the algorithm, and the termination processing means, thereby ensuring the unidirectionality of the fixed-length data and the key encryption device. The algorithm can be variable.

  (5) The present invention provides a key encryption key that combines a data key used for data encryption and fixed-length data that is coupled to a predetermined position of the data key and used to verify the validity of the data key. A key decryption device for decrypting the key-encrypted data encrypted by the decryption means for decrypting the key-encrypted data with the key-encryption key (for example, corresponding to the decryption unit 21 in FIG. 7) The data key is extracted from the key-encrypted data based on the position of the fixed-length data and the key length of the data key, and the fixed-length data is calculated from the extracted data key using a one-way function Fixed-length data calculation means (for example, equivalent to the fixed-length data calculation unit 22 in FIG. 7), and the remaining data excluding the extracted data key from the decrypted key-encrypted data were calculated. Compare with fixed-length data, Verification means for verifying the validity of the issued data key (e.g., corresponding to a verification unit 23 of FIG. 7) proposes a key decryption device, characterized in that it comprises a, a.

  According to this invention, the decrypting means encrypts the data key used for data encryption and the fixed-length data that is coupled to a predetermined position of the data key and used to verify the validity of the data key. Key encrypted data encrypted with the key is decrypted with the key encryption key. The fixed length data calculation means extracts a data key from the decrypted key encryption data based on the position of the fixed length data and the key length of the data key, and uses a one-way function from the extracted data key, Calculate fixed length data. The verification means compares the remaining data excluding the extracted data key in the decrypted key-encrypted data with the calculated fixed-length data, and verifies the validity of the extracted data key. Therefore, the decryption process is performed once, and the process of generating fixed-length data used for verifying the validity of the data key encrypted by the key encryption key is performed once by using the one-way function. Thus, it is possible to construct a key decryption device to which a key encryption algorithm whose processing is more efficient than the conventional one is applied.

  (6) The present invention proposes a key decryption device characterized in that the one-way function is a hash function or a MAC function with respect to the key decryption device of (5).

  According to the present invention, the one-way function is a hash function or a MAC function. Therefore, fixed length data for verifying the validity of the data key encrypted by the key encryption key can be generated by the hash function and the MAC function. In order to verify the validity of the data key, a hash function or a MAC function is used instead of the conventional common key encryption algorithm for generation of fixed-length data used for verifying the validity of the data key. It is possible to remove the restriction on the data length of the fixed length data used for the data.

  (7) According to the present invention, in the key decryption device according to (5) or (6), the decryption unit performs a predetermined process a plurality of times, and uses a data key in which the fixed-length data is combined at the predetermined position. It is composed of a round function (e.g., corresponding to FIG. 3) generated from the key encrypted data, and the round function has a portion where the algorithm is variable according to the bit information of the input third algorithm key. A key decryption device is proposed.

  According to this invention, the decryption means is constituted by a round function that executes a predetermined process a plurality of times and generates a data key in which fixed-length data is combined at a predetermined position from the key encrypted data. The round function has a portion where the algorithm varies according to the bit information of the input third algorithm key. Therefore, since the decryption means is composed of a round function that can vary the specific part of the algorithm, the algorithm of the key decryption device can be made variable.

  (8) The present invention provides the key decryption device according to (5) to (7), wherein the fixed-length data calculation means has a predetermined data amount for each of a plurality of data groups obtained by dividing the extracted data key into predetermined bits. Round function processing means (for example, equivalent to the round function processing unit 100 in FIG. 2) that executes processing a plurality of times, and exclusive OR operation on a plurality of data groups that have been processed by the round function processing means Termination processing means (for example, corresponding to the termination processing unit 200 in FIG. 2) that executes the fixed-length data, and the round function processing means converts the bit information of the input fourth algorithm key In response to this, a key decryption device is proposed in which the algorithm has a variable part.

  According to the present invention, the round function processing means has a portion in which the algorithm varies according to the bit information of the input fourth algorithm key, and a plurality of data obtained by dividing the extracted data key into predetermined bits A predetermined process is executed a plurality of times for each group. The termination processing unit performs an exclusive OR operation on the plurality of data groups processed by the round function processing unit to generate fixed-length data. Accordingly, the fixed-length data calculation means includes the round function processing means that can change a specific part of the algorithm, and the termination processing means, thereby ensuring the unidirectionality of the fixed-length data and the algorithm of the key decryption device. Can be made variable.

  (9) The present invention is a key encryption method in a key encryption apparatus that includes a fixed-length data calculation unit, a combination unit, and an encryption unit, and encrypts a data key used for data encryption. The fixed-length data calculating means calculates fixed-length data used for verifying the validity of the decrypted data key using the one-way function when decrypting the encrypted data key. A first step (for example, corresponding to step S1 in FIG. 6) and a second step (for example, in step S2 in FIG. 6) in which the combining means combines the calculated fixed-length data and the data key. And the encryption means encrypts the data key combined with the calculated fixed-length data with the key encryption key to generate key encrypted data (for example, step S3 in FIG. 6). Equivalent to It has proposed a key encryption method which is characterized the door.

  According to this invention, first, in the first step, the fixed-length data calculation means uses the fixed-length data used for verifying the validity of the decrypted data key when decrypting the encrypted data key. Calculate from the data key using a one-way function. Next, in the second step, the combining unit combines the calculated fixed length data and the data key. Next, in a third step, the encryption unit encrypts the data key combined with the calculated fixed-length data with the key encryption key to generate key encrypted data. Therefore, encryption processing is performed once, and processing for generating fixed length data used for verifying the validity of the data key encrypted by the key encryption key is performed once using a one-way function. Thus, it is possible to provide a key encryption method to which a key encryption algorithm that is more efficient than the conventional method is applied.

  (10) The present invention includes a decryption unit, a fixed-length data calculation unit, and a verification unit, and is coupled to a data key used for data encryption and a predetermined position of the data key. A key decryption method in a key decryption device for decrypting key-encrypted data obtained by encrypting fixed-length data used for verifying validity with a key encryption key, wherein the decryption means converts the key-encrypted data into A first step of decrypting with the key encryption key (e.g., corresponding to step S11 in FIG. 8), and the fixed length data calculating means, from the decrypted key encrypted data, the position of the fixed length data and the A second step of extracting the data key based on the key length of the data key and calculating fixed-length data from the extracted data key using a one-way function (for example, corresponding to step S12 in FIG. 8) And the above test The means compares the remaining data excluding the extracted data key in the decrypted key-encrypted data with the calculated fixed-length data, and verifies the validity of the extracted data key And a third step (e.g., corresponding to steps S13 to S15 in FIG. 8).

  According to this invention, first, in the first step, the decryption means is combined with the data key used for data encryption and a predetermined position of the data key, and used to verify the validity of the data key. Key encrypted data obtained by encrypting fixed-length data with a key encryption key is decrypted with a key encryption key. Next, in the second step, the fixed length data calculation means extracts a data key from the decrypted key encrypted data based on the position of the fixed length data and the key length of the data key, and the extracted data key From the above, fixed length data is calculated using a one-way function. Next, in the third step, the verification means extracts the extracted key-encrypted data by comparing the remaining data excluding the extracted data key with the calculated fixed-length data. Verify the validity of the data key. Therefore, the decryption process is performed once, and the process of generating fixed-length data used for verifying the validity of the data key encrypted by the key encryption key is performed once by using the one-way function. Therefore, it is possible to provide a key decryption method to which a key encryption algorithm whose processing is more efficient than the conventional one is applied.

  (11) The present invention provides a computer with a key encryption method in a key encryption apparatus that includes a fixed-length data calculation unit, a combination unit, and an encryption unit, and encrypts a data key used for data encryption. A program to be executed, wherein the fixed-length data calculation means uses fixed-direction data used for verifying the validity of the decrypted data key in one direction from the data key when decrypting the encrypted data key. A first step (for example, corresponding to step S1 in FIG. 6) calculated using a sex function, and a second step (for example, the combining unit combines the calculated fixed-length data and the data key). 6 corresponds to step S2 in FIG. 6 and the encryption means encrypts a data key combined with the calculated fixed-length data with a key encryption key to generate key-encrypted data (for example, And equivalent) in step S3 in FIG. 6, it proposes a program for executing a computer.

  According to this invention, first, in the first step, the fixed-length data calculation means uses the fixed-length data used for verifying the validity of the decrypted data key when decrypting the encrypted data key. Calculate from the data key using a one-way function. Next, in the second step, the combining unit combines the calculated fixed length data and the data key. Next, in a third step, the encryption unit encrypts the data key combined with the calculated fixed-length data with the key encryption key to generate key encrypted data. Therefore, encryption processing is performed once using a one-way function, and processing for generating fixed-length data used for verifying the validity of a data key encrypted with a key encryption key is performed once. Therefore, it is possible to provide a program to which a key encryption algorithm whose processing is more efficient than the conventional one is applied.

  (12) The present invention includes a decryption unit, a fixed-length data calculation unit, and a verification unit, and is coupled to a data key used for data encryption and a predetermined position of the data key. A program that causes a computer to execute a key decryption method in a key decryption device that decrypts key-encrypted data obtained by encrypting fixed-length data used for verifying validity with a key encryption key, and the decryption means includes: A first step (for example, corresponding to step S11 in FIG. 8) for decrypting the key encrypted data with the key encryption key, and the fixed length data calculating means, from the decrypted key encrypted data, A second step of extracting the data key based on the position of the long data and the key length of the data key, and calculating fixed-length data from the extracted data key using a one-way function (for example, FIG. And the verifying unit compares the remaining data excluding the extracted data key with the calculated fixed-length data in the decrypted key-encrypted data, and A program for causing a computer to execute a third step (for example, corresponding to steps S13 to S15 in FIG. 8) for verifying the validity of the extracted data key is proposed.

  According to this invention, first, in the first step, the decryption means is combined with the data key used for data encryption and a predetermined position of the data key, and used to verify the validity of the data key. Key encrypted data obtained by encrypting fixed-length data with a key encryption key is decrypted with a key encryption key. Next, in the second step, the fixed length data calculation means extracts a data key from the decrypted key encrypted data based on the position of the fixed length data and the key length of the data key, and the extracted data key From the above, fixed length data is calculated using a one-way function. Next, in the third step, the verification means extracts the extracted key-encrypted data by comparing the remaining data excluding the extracted data key with the calculated fixed-length data. Verify the validity of the data key. Therefore, the decryption process is performed once, and the process of generating fixed-length data used for verifying the validity of the data key encrypted by the key encryption key is performed once by using the one-way function. Therefore, it is possible to provide a program to which a key encryption algorithm whose processing is more efficient than the conventional one is applied.

  According to the present invention, the number of processes is reduced by performing the encryption / decryption process by the common key encryption algorithm, which has been performed for verifying the validity of the key to be encrypted, with a one-way function. It is possible to provide a key encryption device, a key decryption device, a key encryption method, a key decryption method, and a program to which a key encryption algorithm whose processing is more efficient than that of the above is applied. A key encryption device, a key decryption device, a key encryption method, a key decryption method, and a key encryption algorithm applied to a program by making at least one algorithm of one-way function processing or encryption processing variable Can be made variable.

It is a figure which shows the function structure of the key encryption apparatus which concerns on this embodiment. It is a figure which shows the function structure of the algorithm variable type fixed length data calculation part which concerns on this embodiment. It is a figure which shows the function structure of the algorithm variable encryption part which concerns on this embodiment. It is a figure which shows the encryption process which concerns on this embodiment which has 128 bit class security using a variable encryption algorithm. It is a figure which shows the encryption process which concerns on this embodiment which has 256-bit class safety | security using a variable encryption algorithm. It is a figure which shows the flow of the key encryption process in the key encryption apparatus which concerns on this embodiment. It is a figure which shows the function structure of the key decryption apparatus which concerns on this embodiment. It is a figure which shows the flow of the key decryption process in the key decryption apparatus which concerns on this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the components in the present embodiment can be appropriately replaced with existing components and the like, and various variations including combinations with other existing components are possible. Therefore, the description of the present embodiment does not limit the contents of the invention described in the claims.

<Functional configuration of key encryption device>
FIG. 1 is a diagram showing a functional configuration of a key encryption device 10 according to the present embodiment. The key encryption device 10 is a device for encrypting a key used for data encryption (hereinafter referred to as a target key). As shown in FIG. 1, a fixed length data calculation unit 11 and a combining unit 12 are used. And the encryption unit 13.

  The fixed length data calculation unit 11 calculates fixed length data from the target key using a one-way function. The fixed length data calculated by the fixed length data calculation unit 11 verifies the validity of the decrypted target key when the target key encrypted by the encryption unit 13 described later is decrypted by the key decryption device 20 described later. Used to do.

  As the one-way function, for example, a hash function or a MAC function can be used. Conventionally, fixed-length data used to verify the validity of the decrypted target key was generated using a common key encryption algorithm, so the data length was limited by the block length of the common key encryption algorithm. . However, in the present embodiment, since the fixed-length data used for verifying the validity of the decrypted target key is generated using a one-way function, the data length of the fixed-length data is not limited and is arbitrary. Can be of length. Conventionally, fixed-length data is generated by performing encryption by a common key encryption algorithm a plurality of times. In the present embodiment, the fixed-length data is generated by performing processing by a one-way function once. be able to.

  The fixed length data calculation unit 11 may be a variable algorithm type in which the algorithm changes by applying the method described in Japanese Patent Application No. 2011-239651 filed earlier by the applicant. Here, the fixed length data calculation unit 11 that provides the method described in Japanese Patent Application No. 2011-239651 will be briefly described with reference to FIG. FIG. 2 illustrates a case where 256-bit fixed length data is generated from a 512-bit target key.

  The fixed-length data calculation unit 11 includes a round function processing unit 100 having a variable algorithm and a termination processing unit 200 that performs an exclusive OR operation for ensuring unidirectionality. The round function processing unit 100 includes cyclic shift units N1 to N4, exclusive OR operation units 110a to 110f, switches S1 to S6, and stirring units C1 to C4.

  Cyclic shift units N1 to N4 perform cyclic shift of bits determined according to bit information of the input algorithm key on each of a plurality of blocks obtained by dividing the target key every predetermined bit. Here, the algorithm key is a key for determining the algorithm of the round function processing unit 100, and is a MAC key when the one-way function is a MAC function, and an arbitrary fixed value when the one-way function is a hash function. .

  The exclusive OR operation units 110a to 110f execute an exclusive OR operation on the two input data. The switches S1 to S6 determine opening and closing according to the bit information of the algorithm key, and control whether or not the exclusive OR operation units 110c to 110f execute the operation. The agitation units C1 to C4 perform nonlinear processing on the calculation results of the exclusive OR calculation units 110a to 110f.

  As described above, based on the input algorithm key, the switches S1 to S1 that control the number of bits to be cyclically shifted in the cyclic shift units N1 to N4 and whether or not the exclusive OR calculation units 110a to 110f perform the calculation. By determining whether to open or close S6, the algorithm of the round function processing unit 100 can be made variable, and the algorithm of the fixed length data calculation unit 11 can be made variable.

  Returning to FIG. 1, the combining unit 12 combines the fixed-length data calculated by the fixed-length data calculating unit 11 with the target key. Specifically, fixed-length data is combined at a predetermined position of the target key, for example, at the beginning or end of the target key.

  The encryption unit 13 encrypts the target key combined with the fixed-length data by the combining unit 12 using a key encryption key with a common key encryption algorithm, and generates key encrypted data. The key encryption key is generated for each user by using a random number or information unique to the user. The encryption unit 13 can use AES or the like as a common key encryption algorithm. In addition, the encryption unit 13 can use a method described in Japanese Patent Application No. 2011-30553 filed earlier by the applicant and use an algorithm variable common key encryption algorithm in which the algorithm changes. Here, the encryption unit 13 to which the method described in Japanese Patent Application No. 2011-30553 is applied will be briefly described with reference to FIG. FIG. 3 illustrates a case where a 128-bit target key is encrypted.

  The encryption unit 13 includes a round function. As shown in FIG. 3, the encryption unit 13 has cyclic shift units N5 and N6, exclusive OR operation units 120a and 120b, operation determination units 130a and 130b, It comprises non-linear function units L1 and L2.

  Cyclic shift units N5 and N6 replace blocks obtained by dividing input data into predetermined bits according to bit information of the input algorithm key. Specifically, it is assumed that 128-bit input data is cyclically shifted to the right by a multiple of 4 bytes, for example. Here, the algorithm key is a key for determining the algorithm of the encryption unit 13.

  The exclusive OR operation units 120a and 120b execute an exclusive OR operation on the two input data.

  The operation determination units 130a and 130b determine whether or not the operation is performed in the exclusive OR operation units 120a and 120b connected to the cyclic shift units N5 and N6 according to the key bit information. Specifically, it is determined whether to apply “0” or “1” to the data according to the key bit, and the execution of the operation is controlled in the exclusive OR operation units 120a and 120b.

  The non-linear function units L1 and L2 are functions composed of non-linear replacement and linear transformation, and perform non-linear processing on the calculation results of the exclusive OR calculation units 120a and 120b.

  As described above, based on the input algorithm key, the operation determination unit that controls the number of bits to be cyclically shifted in the cyclic shift units N5 and N6 and whether or not the exclusive OR operation units 120a and 120b perform the operation. The common key encryption algorithm of the encryption unit 13 can be made variable by determining the processing of 130a and 130b and making the round function algorithm variable.

  An encryption process in the encryption unit 13 when the key encryption device 10 has 128-bit class security using the algorithm variable type common key encryption algorithm described above will be described with reference to FIG. Note that the key length and block length are 256 bits, and an algorithm variable type common key encryption algorithm is used.

  Since the key encryption device 10 has 128-bit class security, the target key is 128 bits, but the key length and block length of the common key encryption algorithm of the encryption unit 13 are 256 bits. Is padded with 0 to 256 bits. Then, the 256-bit target key is input to the encryption unit 13. The encryption unit 13 determines a common key encryption algorithm using an algorithm key having an arbitrary length, encrypts a 256-bit target key using the determined common key encryption algorithm, and uses a 256-bit encryption Generate sentence 1.

  On the other hand, 256-bit data generated from the target key is used as fixed-length data. The fixed length data is, for example, a 256-bit hash value generated using SHA-256. Since the fixed-length data is 256 bits, it is input to the encryption unit 13 as it is. As in the case of the target key, the encryption unit 13 determines a common key encryption algorithm using an arbitrary-length algorithm key, and uses the determined common key encryption algorithm to use 256-bit fixed-length data using the key encryption key. Is encrypted and 256-bit ciphertext 2 is generated.

  Next, encryption processing in the encryption unit 13 when the key encryption device 10 has 256-bit class security using a variable algorithm type common key encryption algorithm will be described with reference to FIG. In this case, since the target key is 256 bits, it is input to the encryption unit 13 as it is. Then, the encryption unit 13 determines a common key encryption algorithm using an algorithm key having an arbitrary length, and generates a 256-bit ciphertext 3 using the key encryption key using the determined common key encryption algorithm.

  On the other hand, 512-bit data generated from the target key is used as fixed-length data. The fixed length data is, for example, a 512-bit hash value generated using SHA-512. Since the fixed-length data is 512 bits, the encryption unit 13 performs encryption by 256 bits. Specifically, the encryption unit 13 determines a common encryption algorithm using an algorithm key having an arbitrary length, and encrypts fixed-length data 256 bits at a time using the key encryption key based on the determined common encryption algorithm. And 256-bit ciphertext 4 and ciphertext 5 are generated.

<Key encryption processing>
FIG. 6 is a diagram showing a key encryption processing flow in the key encryption device 10 according to the present embodiment. When the target key is input to the key encryption device 10, the process starts.

  First, in step S1, the fixed length data calculation unit 11 calculates fixed length data from the target key using a one-way function.

  Next, in step S2, the combining unit 12 combines the fixed length data calculated in step S1 with the target key.

  Next, in step S3, the encryption unit 13 encrypts the target key combined with the fixed-length data in step S2 with a common key encryption algorithm using the key encryption key to generate key encrypted data. To do.

<Functional configuration of key decryption device>
FIG. 7 is a diagram illustrating a functional configuration of the key decryption apparatus 20 according to the present embodiment. The key decryption device 20 decrypts the key encrypted data encrypted by the key encryption device 10 described above, and acquires the target key. As illustrated in FIG. 7, the key decryption device 20 includes a decryption unit 21, a fixed length data calculation unit 22, and a verification unit 23.

  The decrypting unit 21 decrypts the key encrypted data using a common key encryption algorithm using the key encryption key. The decrypted key-encrypted data is a target key combined with fixed-length data. The decryption unit 21 can use AES or the like as a common key encryption algorithm. In addition, the decryption unit 21 can use a method described in Japanese Patent Application No. 2011-30553 filed earlier by the applicant and use an algorithm variable type common key encryption algorithm in which the algorithm changes. The decryption unit 21 to which the method described in Japanese Patent Application No. 2011-30553 is applied, the cyclic shift units N5 and N6 of the encryption unit 13 to which the method described in Japanese Patent Application No. 2011-30553 described with reference to FIG. It can be realized by using the inverse function as the non-linear function of the non-linear function units L1 and L2 with the circulation direction as the reverse direction.

  The fixed length data calculation unit 22 extracts the target key from the decrypted key encryption data. Specifically, since fixed length data is combined with a predetermined position of the target key, the position of the target key is obtained from the predetermined position of the fixed length data, and the obtained position of the target key and the key length of the target key are obtained. And the target key itself is extracted from the decrypted key-encrypted data. For example, when fixed-length data is combined at the beginning of the target key, data for the key length of the target key is obtained from the decrypted key-encrypted data from the end of the decrypted key-encrypted data. The target key itself can be acquired.

  Then, the fixed length data calculation unit 22 calculates fixed length data from the extracted target key using a one-way function. As the one-way function, a hash function or a MAC function can be used as in the fixed-length data calculation unit 11 of the key encryption device 10. Similarly to the fixed length data calculation unit 11 of the key encryption device 10, the fixed length data calculation unit 22 of the key decryption device 20 is also disclosed in Japanese Patent Application No. 2011-239651 filed by the applicant previously described with reference to FIG. By applying the described method, an algorithm variable type in which the algorithm changes can be obtained.

  The verification unit 23 calculates the remaining data excluding the target key from the decrypted key encrypted data, that is, the fixed length data included in the decrypted key encrypted data and the fixed length data calculation unit 22. The validity of the target key of the decrypted key-encrypted data is verified by comparing with the fixed-length data. If both match and the validity of the target key is confirmed, the target key is output. On the other hand, if they do not match and the validity of the target key cannot be confirmed, an error is output.

<Key decryption process>
FIG. 8 is a diagram showing a key decryption process flow in the key decryption apparatus 20 according to the present embodiment. Processing starts when key-encrypted data is input.

  First, in step S11, the decryption unit 21 decrypts the key encrypted data using the common key encryption algorithm using the key encryption key.

  Next, in step S12, the fixed length data calculation unit 22 extracts a target key from the key encrypted data decrypted in step S11, and calculates fixed length data from the extracted target key using a one-way function. .

  Next, in step S13, the verification unit 23 compares the fixed length data included in the decrypted key encrypted data with the fixed length data calculated in step S12, and verifies the validity of the target key. If they match and the validity of the target key is confirmed, the process proceeds to step S14. On the other hand, if they do not match and the validity of the target key cannot be confirmed, the process proceeds to step S15.

  Next, in step S14, the verification unit 23 outputs the target key extracted in step S12.

  Next, in step S15, the verification unit 23 outputs an error.

  As described above, according to the present embodiment, the encryption / decryption processing by the common key encryption algorithm, which has been performed for verifying the validity of the encryption target key, is performed by a one-way function. It is possible to provide a key encryption device, a key decryption device, a key encryption method, a key decryption method, and a program to which a key encryption algorithm that reduces the number of processing times and makes the processing more efficient than the conventional method is applied. Also, the key encryption algorithm can be made variable by making at least one algorithm of the one-way function processing or encryption processing variable.

  The processing of the key encryption device and the key decryption device is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read by the key encryption device and the key decryption device and executed. The key encryption device and the key decryption device can be realized. The computer system here includes an OS and hardware such as peripheral devices.

  Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW (World Wide Web) system is used. The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  The embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes designs and the like that do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Key encryption apparatus 11 Fixed length data calculation part 12 Connection part 13 Encryption part

Claims (12)

A key encryption device for encrypting a data key used for data encryption,
Fixed-length data calculating means for calculating fixed-length data used for verifying the validity of the decrypted data key from the data key using a one-way function when decrypting the encrypted data key;
Coupling means for coupling the calculated fixed-length data and the data key;
An encryption means for encrypting a data key combined with the calculated fixed-length data with a key encryption key and generating key-encrypted data;
A key encryption device comprising:   The key encryption apparatus according to claim 1, wherein the one-way function is a hash function or a MAC function. The encryption means includes a round function that executes a predetermined process a plurality of times and generates the key encrypted data from a data key combined with the calculated fixed-length data,
The key encryption apparatus according to claim 1, wherein the round function includes a portion where the algorithm is variable according to bit information of the input algorithm key. The fixed length data calculation means is
Round function processing means for executing a predetermined process a plurality of times for each of a plurality of data groups obtained by dividing the data key into predetermined bits;
Termination processing means for performing exclusive OR operation on a plurality of data groups processed by the round function processing means, and generating the fixed-length data;
With
4. The key encryption device according to claim 1, wherein the round function processing unit includes a portion in which the algorithm is variable according to bit information of the input second algorithm key. 5. . Key encryption in which a data key used for data encryption and fixed-length data that is combined with a predetermined position of the data key and used to verify the validity of the data key are encrypted with a key encryption key A key decryption device for decrypting data,
Decryption means for decrypting the key encrypted data with the key encryption key;
From the decrypted key encrypted data, the data key is extracted based on the position of the fixed-length data and the key length of the data key, and the fixed-length data is converted from the extracted data key using a one-way function. Fixed length data calculating means for calculating;
Verification means for comparing the remaining data excluding the extracted data key in the decrypted key-encrypted data with the calculated fixed-length data and verifying the validity of the extracted data key When,
A key decryption device comprising:   The key decryption apparatus according to claim 5, wherein the one-way function is a hash function or a MAC function. The decryption means includes a round function that executes a predetermined process a plurality of times and generates a data key in which the fixed-length data is combined at the predetermined position from the key-encrypted data,
The key decryption apparatus according to claim 5 or 6, wherein the round function has a portion in which the algorithm varies according to bit information of the input third algorithm key. The fixed length data calculation means is
Round function processing means for executing a predetermined process a plurality of times for each of a plurality of data groups obtained by dividing the extracted data key into predetermined bits;
Termination processing means for performing exclusive OR operation on a plurality of data groups processed by the round function processing means, and generating the fixed-length data;
With
8. The key decryption device according to claim 5, wherein the round function processing unit includes a portion in which the algorithm varies according to bit information of the input fourth algorithm key. 9. A key encryption method in a key encryption apparatus, comprising a fixed length data calculation means, a combination means, and an encryption means, and encrypts a data key used for data encryption,
The fixed-length data calculation means calculates fixed-length data used for verifying the validity of the decrypted data key using the one-way function when decrypting the encrypted data key. A first step;
A second step in which the combining means combines the calculated fixed-length data and the data key;
A third step in which the encryption means encrypts a data key combined with the calculated fixed-length data with a key encryption key, and generates key-encrypted data;
A key encryption method comprising: A decryption unit, a fixed-length data calculation unit, and a verification unit, coupled to a data key used for data encryption and a predetermined position of the data key, for verifying the validity of the data key; A key decryption method in a key decryption device for decrypting key-encrypted data obtained by encrypting fixed-length data to be used with a key encryption key,
A first step in which the decryption means decrypts the key encrypted data with the key encryption key;
The fixed-length data calculation means extracts the data key from the decrypted key-encrypted data based on the position of the fixed-length data and the key length of the data key, and uses the one-way function from the extracted data key A second step of calculating fixed length data using
The verification means compares the remaining data excluding the extracted data key in the decrypted key-encrypted data with the calculated fixed-length data, and the validity of the extracted data key A third step of verifying
Including a key decryption method. A program for causing a computer to execute a key encryption method in a key encryption device that includes a fixed length data calculation unit, a combination unit, and an encryption unit, and encrypts a data key used for data encryption,
The fixed-length data calculation means calculates fixed-length data used for verifying the validity of the decrypted data key using the one-way function when decrypting the encrypted data key. A first step;
A second step in which the combining means combines the calculated fixed-length data and the data key;
A third step in which the encryption means encrypts a data key combined with the calculated fixed-length data with a key encryption key, and generates key-encrypted data;
A program that causes a computer to execute. A decryption unit, a fixed-length data calculation unit, and a verification unit, coupled to a data key used for data encryption and a predetermined position of the data key, for verifying the validity of the data key; A program that causes a computer to execute a key decryption method in a key decryption device that decrypts key-encrypted data obtained by encrypting fixed-length data to be used with a key encryption key,
A first step in which the decryption means decrypts the key encrypted data with the key encryption key;
The fixed-length data calculation means extracts the data key from the decrypted key-encrypted data based on the position of the fixed-length data and the key length of the data key, and uses the one-way function from the extracted data key A second step of calculating fixed length data using
The verification means compares the remaining data excluding the extracted data key in the decrypted key-encrypted data with the calculated fixed-length data, and the validity of the extracted data key A third step of verifying
A program that causes a computer to execute.

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