JP2013062691A - Information processing device and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information processing device capable of automatically selecting an arithmetic algorithm to calculate an error detection code to verify integrity of data, depending on a data length of the data as a target of integrity verification.SOLUTION: An information processing device 1 comprises: data holding means 13 for holding data 130 having an error detection code added thereto; error detection code calculating means 12 having a plurality of calculating sections 120 corresponding to arithmetic algorithms of different error detection codes, respectively, and a reference table 121 for associating ranges of data lengths with the calculating sections 120, for, when data to be calculated is specified, referring the reference table 121 to select the calculating section 120 corresponding to the data length of the data to be calculated to calculate an error detection code; and data matching verifying means 10 for using the error detection code calculated by the error detection code calculating means 12 to verify integrity of the data 130 held in the data holding means 13.

Description

  The present invention relates to a technique for calculating data error detection codes and verifying data integrity.

  When an information processing device such as an IC card or a personal computer verifies the integrity of data stored in the memory of the information processing device or data received from the outside, as described in Patent Document 1, a predetermined arithmetic algorithm is used. It is common to use an error detection code calculated by the above.

  When the information processing apparatus verifies the integrity of data received from the outside, as described in Patent Document 1, the apparatus for verifying the error detection code calculated by the information processing apparatus may be the information processing apparatus itself, Although an external device may be used, when the information processing device verifies the integrity of the data stored in the memory of the information processing device, the device that verifies the error detection code is the information processing device itself, and the information In order to verify the integrity of the data stored in the memory of the information processing device, the processing device stores the data in the memory in a form to which an error detection code calculated by a predetermined calculation algorithm is added. When the integrity is verified, the error detection code of the data calculated by a predetermined calculation algorithm is collated with the error detection code of the data stored in the memory.

  There are multiple calculation algorithms used for calculation of error detection codes, such as a calculation algorithm using a value obtained by performing NOT of logical operation on data as an error detection code, and a checksum, CRC, SHA1, DES, etc. However, when the information processing apparatus verifies the integrity of data received from the outside, it is common for the calculation algorithm used for calculation of the error detection code to be determined in advance with the apparatus on the data transmission side. It is.

  On the other hand, when the information processing apparatus verifies the integrity of the data stored in the memory of the information processing apparatus, the arithmetic algorithm used for the calculation of the error detection code added to the data stored in the memory is the information processing apparatus. Can be arbitrarily determined on the side.

  A problem in using an error detection code for verifying the integrity of data stored in the memory of the information processing apparatus is a reduction in the calculation time of the error detection code.

  FIG. 5 is a diagram for explaining the relationship between the data length and the calculation time of the error detection code. Naturally, as shown in FIG. 5, if the same calculation algorithm is used, the calculation time becomes longer as the data length becomes longer. Depends on data length.

  For example, if the data length of the data to be calculated is shorter than the length L, the calculation time of the error detection code is shorter when the calculation algorithm A is used than when the calculation algorithm B is used, but the data length is L If it is longer, the calculation time of the error detection code is longer when the calculation algorithm A is used than when the calculation algorithm B is used.

  In particular, in a platform type operating system equipped with a virtual machine (VM) such as Java (registered trademark), when an application on the platform type operating system calculates an error detection code, the data to be calculated by the error detection code Since the access and the interpretation / execution of the intermediate code are repeatedly executed according to the data length of the data to be calculated, the above-described property appears remarkably.

JP 2006-350738 A

  When considering reducing the time required for verifying the integrity of data stored in the memory of the information processing apparatus, if the data stored in the memory of the information processing apparatus is of a fixed length, for example, FIG. With reference to such a graph, it is possible to uniquely determine the calculation algorithm used for the calculation of the error detection code. However, when the data has a variable length, as shown in FIG. Since the short calculation algorithm is changed according to the data length, it is desirable that the calculation algorithm used for calculating the error detection code can be determined according to the data length.

  Accordingly, the present invention provides an information processing apparatus and a computer program that can automatically select an arithmetic algorithm according to the data length of data to be verified for integrity, calculate an error detection code, and verify data integrity. The purpose is to do.

  The first invention for solving the above-described problem is that the data holding means for holding the data to which the error detection code is added, and different errors so that the calculation algorithm can be changed according to the data length of the data to be calculated. A plurality of calculation units corresponding to the calculation algorithm of the detection code, a reference table that associates the data length range and the calculation unit, and when the data to be calculated is specified, the reference table is referred to, An error detection code calculation means for selecting the calculation section corresponding to the data length of the data to be calculated and calculating an error detection code, and an instruction for verifying the integrity of the data held in the data holding means The error detection code of the indicated data is calculated by the error detection code calculation means, and the error detection code added to the indicated data and the error detection code Calculating means is an information processing apparatus characterized by comprising a data integrity verification means for checking the error detection code computed is.

  Further, in the second invention, when an update of the error detection code added to the data held in the data holding means is instructed, the error detection code of the updated data is updated after the indicated data is updated. Error detection code update means for updating the error detection code added to the updated data to the error detection code calculated by the error detection code calculation means. This is the information processing apparatus described in the first invention.

  Furthermore, the third invention has a plurality of calculation units corresponding to different calculation algorithms for error detection codes, a reference table in which the range of data length is associated with the calculation unit, and data to be calculated is designated. Then, referring to the reference table, the error detection code calculation means for calculating the error detection code by selecting the calculation unit corresponding to the data length of the data to be calculated, and held in the data holding means When the instruction for verifying the integrity of the received data is received, the error detection code calculating means calculates the error detection code of the specified data, and the error detection code added to the specified data and the error detection code calculation A computer program for causing a computer to function as data integrity verification means for collating error detection codes calculated by the means.

  Thus, according to the present invention, an information processing apparatus capable of automatically selecting an arithmetic algorithm and calculating an error detection code to verify data integrity according to the data length of data to be integrity verified, and A computer program can be provided.

3A and 3B illustrate functions included in an information processing device. 6A and 6B illustrate an operation of an information processing device. The figure explaining the hardware constitutions of the IC chip mounted in the IC card of an Example. The figure explaining the reference table in an Example. The figure explaining the relationship between data length and the calculation time of an error detection code.

  Now, a preferred embodiment of an information processing apparatus according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications and changes can be made.

  FIG. 1 is a diagram illustrating functions of the information processing apparatus 1 according to the present embodiment. The information processing apparatus 1 of the present embodiment is an apparatus realized using a computer. Preferably, the information processing apparatus 1 of the present embodiment is an IC card on which a platform type operating system is mounted. It may be a personal computer or a smartphone.

  As illustrated in FIG. 1, the information processing apparatus 1 according to the present embodiment includes a data holding unit 13 that holds data 130 to which an error detection code is added, and an error that calculates an error detection code of data 130 to be calculated. The detection code calculation means 12 includes a plurality of calculation units 120 corresponding to different calculation algorithms for error detection codes, and a reference table 121 that associates the data length range with the calculation unit 120. If the data 130 to be calculated is designated, the reference table 121 is referred to, and the calculation unit 120 corresponding to the data length of the data 130 to be calculated is selected to calculate the error detection code.

  Further, the information processing apparatus 1 according to the present embodiment instructs to verify the integrity of the data 130 held in the data holding unit 13 so that the integrity of the data 130 held in the data holding unit 13 can be verified. The error detecting code of the indicated data 130 is calculated by the error detecting code calculating means 12, and the error detecting code added to the indicated data 130 and the error detecting code calculated by the error detecting code calculating means 12 are received. The data complete verification means 10 is provided.

  Furthermore, the information processing apparatus 1 according to the present embodiment instructs to update the error detection code added to the data 130 so that the error detection code can be updated when the data 130 held in the data holding unit 13 is updated. Then, the error detection code of the updated data 130 is calculated by the error detection code calculation means 12, and the error detection code calculated by the error detection code calculation means 12 is added to the updated data 130. An error detection code updating means 11 for updating to is provided.

  In the present embodiment, the reference table 121 provided in the information processing apparatus 1 is table format data, and the data holding unit 13 is connected to the memory mounted in the information processing apparatus 1 or the information processing apparatus 1. Each means of the information processing apparatus 1 is realized by a computer program installed in the information processing apparatus 1.

  FIG. 2 is a diagram for explaining the operation of the information processing apparatus 1. When the information processing apparatus 1 calculates an error detection code, first, the data 130 that is the target of the error detection code operation is calculated from the data 130 stored in the data storage unit 13 with respect to the error detection code calculation unit 12. It is designated by other means of the information processing apparatus 1 (S1).

  In this embodiment, an identifier for identifying each data 130 is added to the data 130 held in the data holding means 13, and the data 130 to be calculated is designated by this identifier. When verifying the integrity of the data 130, the data integrity verifying unit 10 of the information processing apparatus 1 designates the data 130 to be subjected to the integrity verification, and the data retaining unit 13 holds the data 130. When the updated data 130 is updated, the error detection code update unit 11 of the information processing apparatus 1 designates the updated data 130.

  When the data 130 to be calculated is designated, the error detection code calculating unit 12 of the information processing apparatus 1 acquires the data length of the data 130 to be calculated from the data holding unit 13 using the identifier of the data 130. After (S2), referring to the reference table 121, the calculation unit 120 corresponding to the data length of the calculation target data 130 is selected as the calculation unit 120 used for calculation of the error detection code of the calculation target data 130. (S3).

  In the present embodiment, the reference table 121 of the error detection code calculation unit 12 is provided with a record for each calculation unit 120 included in the error detection code calculation unit 12, and an identifier for identifying each calculation unit 120 is included in the record. The range of the data length when using the calculation unit 120 in association with is described.

  For example, the identifier of the calculation unit 120 associated with the data length range from 1 byte to 31 bytes is “01”, and the identifier of the calculation unit 120 associated with the data length range from 32 bytes to 63 bytes is When the identifier of the calculation unit 120 associated with “02” and a data length range of 64 bytes or more is “03”, if the data length of the data 130 to be calculated is 16 bytes, the identifier is “01”. If a certain calculation unit 120 is selected and the data length of the data 130 to be calculated is 56 bytes, the calculation unit 120 with the identifier “02” is selected, and the data length of the data 130 to be calculated is 256. If it is a byte, the computing unit 120 whose identifier is “03” is selected.

  When the error detection code calculation unit 12 of the information processing apparatus 1 selects the calculation unit 120 corresponding to the data length of the data 130 to be calculated, the error detection code calculation unit 12 acquires the data 130 to be calculated from the data holding unit 13 and calculates The error detecting code of the data 130 to be calculated is calculated by the selected calculation unit 120 (S4). The error detection code calculated by the selected calculation unit 120 is stored in a predetermined location in the memory, so that the error detection code calculated by the selected calculation unit 120 is stored in the means for designating the data 130 to be calculated. Delivered.

  The means specifying the data 130 to be calculated is processed using the error detection code delivered from the error detection code calculation means 12 (S5), and this procedure ends.

  When the means for designating the data 130 to be calculated is the data integrity verification means 10, the data integrity verification means 10 uses the error detection code added to the data 130 for integrity verification as the data holding means 13. The integrity of the data 130 designated as the operation target is verified by collating the acquired error detection code with the error detection code delivered from the error detection code calculation means 12.

  When the means for designating the data 130 to be calculated is the error detection code update means 11, the error detection code update means 11 uses the error detection code added to the updated data 130 as the error detection code calculation means. 12 is updated to the error detection code delivered from 12.

  From here, an example when the information processing apparatus 1 is an IC card will be described. FIG. 3 is a diagram illustrating the hardware configuration of the IC chip mounted on the IC card 2 of the embodiment. As shown in FIG. 3, the IC chip mounted on the IC card 2 has a CPU 21 (Central Processing Unit) for controlling the IC chip, and this CPU 21 has an I / O for data communication with an external device. O interface 20, RAM (Random Access Memory) 22 as volatile memory, EEPROM (Electrically Erasable Programmable Read-Only Memory) 23 as electrically rewritable nonvolatile memory, and nonvolatile memory for storing programs and the like A certain ROM (Read-Only Memory) 24 is connected. Note that the hardware configuration of the IC chip shown in FIG. 4 is merely an example, and other hardware such as a coprocessor specialized for cryptographic operations and a timer for measuring time is generally mounted. It is.

  In the IC card 2 of the embodiment, the EEPROM 23 is used as the data holding means 13 of the information processing apparatus 1, and the CPU 20 as the error detection code calculation means 12, the data integrity verification means 10 and the error detection code update means 11 of the information processing apparatus 1. Modules for operating the are stored in the ROM 24.

  The module functioning as the data integrity verification means 10 is a module called by a command that uses data stored in the EEPROM 23 such as a READ command for reading out data stored in the EEPROM 23, and as the error detection code update means 11. The functioning module is a module called by a command for rewriting data stored in the EEPROM 23, such as an UPDATE command for updating data stored in the EEPROM 23.

  In addition, the IC card 2 of the embodiment includes a calculation module that calculates a checksum and a calculation module that calculates a CRC (Cyclic Redundancy Check) as a calculation module that functions as the calculation unit 120. Whether to use is determined by the reference table 121 of the IC card 2 of the embodiment.

  FIG. 4 is a diagram illustrating the reference table 121a in the embodiment. As shown in FIG. 4, in the embodiment, when the data length range is 1 byte or more and 31 bytes or less, a checksum is used for calculation of the error detection code, and when the data length range is 32 bytes or more, an error occurs. CRC (Cyclic Redundancy Check) is used for calculation of the detection code.

  According to FIG. 4, when data stored in the EEPROM 23 is read by the READ command, the integrity of the read data is verified by the module functioning as the data integrity verification means 10 and the data length of the data to be read is 32. If it is greater than or equal to bytes, CRC is used to calculate the error detection code and the data integrity is verified. Otherwise, the checksum is used to calculate the error detection code and the data integrity is verified. The

  When the data stored in the EEPROM 23 is updated by the UPDATE command, the error detection code added to the updated data is also updated by the module functioning as the error detection code update means 11, and the data data after the update is updated. If the length is 32 bytes or more, CRC is used to calculate the error detection code, and otherwise, the checksum is used to calculate the error detection code.

DESCRIPTION OF SYMBOLS 1 Information processing apparatus 10 Data integrity verification means 11 Error detection code update means 12 Error detection code calculation means 120 Operation part 121 Reference table 13 Data holding means 130 Data

Claims (3)

  A data holding means for holding data to which an error detection code is added; a plurality of calculation units corresponding to different calculation algorithms for error detection codes; and a reference table in which a range of data length is associated with the calculation unit When the data to be calculated is designated, the error detection code calculation means for calculating the error detection code by referring to the reference table and selecting the calculation unit corresponding to the data length of the data to be calculated; When receiving an instruction to verify the integrity of data held in the data holding means, the error detection code calculating means calculates the error detection code of the indicated data, and an error added to the indicated data An information processing apparatus comprising data integrity verification means for collating a detection code with an error detection code calculated by the error detection code calculation means.   When the update of the error detection code added to the data held in the data holding means is instructed, after updating the indicated data, the error detection code of the updated data is sent to the error detection code calculating means. 2. The error detection code update means for calculating and updating an error detection code added to the updated data to an error detection code calculated by the error detection code calculation means. Information processing device. A plurality of calculation units corresponding to different calculation algorithms for error detection codes, and a reference table in which a range of data length and the calculation unit are associated with each other. The error detection code calculation means for calculating the error detection code by selecting the calculation section corresponding to the data length of the data to be calculated, and the integrity of the data held in the data holding means is verified. When the instruction is received, the error detecting code calculating means calculates the error detecting code of the indicated data, and the error detecting code added to the indicated data and the error detecting code calculated by the error detecting code calculating means are A computer program for causing a computer to function as data integrity verification means for collation.

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