JP2005295408A - Enciphering device, decoding device, enciphering and decoding system, and key information updating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise the security of independent information such as individual information stored or to be stored in a storage medium, etc., without performing a complicated enciphering processing, and to easily decode encipher data which is enciphered by the enciphering processing. <P>SOLUTION: A manufacturer, etc., previously generates an encipher key for enciphering data, based on intrinsic identification information (an identification code, etc.,) attached to each storage medium such as a radio IC tag and based on a prescribed common key. The data is enciphered with the use of the encipher key. The enciphered encipher data is stored in the storage medium in a state where the common key, etc., is added. The encipher data is decoded with the use of a decoding key which is generated in the same procedure as that of the encipher key, based on the common key, etc., added to the encipher data and based on the intrinsic identification information. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an encryption technology and a decryption technology for preventing falsification, leakage, and eavesdropping of individual information stored in a storage medium, and in particular, ensures high security of encrypted individual information and the like. In addition, the present invention relates to an encryption technique and a decryption technique that can realize high-speed encryption processing and decryption processing.

In recent years, in a data writing / reading system including a reader / writer having an antenna and a controller and a storage medium such as a wireless IC tag with a built-in memory, a wireless communication is performed between the reader / writer and the wireless IC tag. Wireless non-contact solid-state recognition (RFID) that performs authentication of data exchanged by communication has come to be used. Unlike a contact-type reading system such as a barcode, this RFID can read and write data without contact by wireless communication, so it is not easily affected by dirt, dust, etc. In addition, there are various features such as data communication via obstacles. Utilizing such characteristics, the RFID is widely used in various fields such as a revolving sushi settlement system, a system for preventing unauthorized take-out at a CD shop, a bookstore and the like, and a distribution management system.
In particular, as interest in information security increases socially, personal information such as employee ID cards and entry / exit permits embedded with the above-mentioned wireless IC tags is read and authenticated by a gate antenna connected to a reader / writer. Use of RFID technology for systems that manage individual information such as personal information such as security systems, anti-counterfeiting devices (immobilizers) for cars, etc., and IC card ticket systems recently introduced by railway companies Needs are growing.

Today, with the progress of networking, information has a great value. In particular, individual information such as personal information has a great meaning from the viewpoint of information security. Along with this, in recent years, advanced security technology relating to the encryption of the individual information has been required. Therefore, in the above-described system using individual information such as personal information, the personal information stored in the storage medium such as the wireless IC tag or the like is concealed to prevent falsification, leakage, etc. of the individual information. The individual information is encrypted and stored in the storage medium. On the other hand, an encryption technology that encrypts IC key data used when performing authentication processing between an IC used for personal authentication or the like and an authentication device, and prevents unauthorized alteration or leakage of the IC key data is patented. It is proposed in Document 1.
JP 2002-359614 A

However, although high security is ensured for personal information and the like by the encryption technique described in Patent Document 1 or a conventionally known encryption technique, the encryption of information (data) is enhanced as the security becomes higher. Tend to be complicated. If the encryption process and the decryption process become complicated in this way, there arises a problem that the throughput (processing speed) of the reader / writer or the like that executes the process is lowered. On the other hand, it is possible to improve the throughput by using a high-speed CPU, a high-performance LSI, or the like for the reader / writer, but this is not practical because it leads to an increase in the scale of the apparatus and an increase in the unit price of the apparatus. .
Therefore, the present invention has been made in view of the above circumstances, and its purpose is to provide security for individual information such as personal information stored in or stored in a storage medium without performing complicated encryption processing. It is to improve the performance and to easily decrypt the encrypted data encrypted by the encryption process.

In order to achieve the above object, the present invention provides an individual identification information acquisition means for acquiring individual identification information of a storage medium in an encryption apparatus for encrypting the digital data and storing the encrypted digital data in the storage medium. And the individual identification information acquired by the individual identification information acquisition means, and a decryption key for decrypting the encrypted digital data as well as used for generating an encryption key for encrypting the digital data. Using the encryption key generated by the encryption key generating means, the encryption key generating means for generating the encryption key for encrypting the digital data based on the common key information used when generating, Encryption means for encrypting at least the digital data based on a predetermined encryption rule, encrypted digital data encrypted by the encryption means, A data storage means for associating and storing the common key specifying information for specifying the common key information in the storage medium. Item 1).
As described above, in the encryption device according to the present invention, the encryption key is generated from the individual identification information and the common key information, and therefore, an encryption key that is difficult to illegally decrypt is generated. Since digital data is encrypted by this encryption key and encryption rules (encryption algorithms) such as DES, 3DES, and AES, even if the encrypted digital data is leaked or wiretapped, it cannot be easily decrypted. It is possible to ensure high security for data. In addition, since the encryption key is generated by a simple process of combining the individual identification information of the storage medium and the common key information based on a predetermined rule, the burden of encryption processing is reduced, and the processing speed (throughput) is reduced. Can be improved.
In this case, it is desirable that the encryption key generating means generates the encryption key by combining the bit array of the individual identification information and the bit array of the common key information based on a predetermined rule (claims). Item 2).

Further, the present invention provides a first unique information generating means for generating unique information of digital data before encryption based on the digital data, and the pre-encryption information generated by the first unique information generating means. It may be configured as an encryption device further comprising unique information storage means for storing unique information of digital data in the storage medium.
With this configuration, in the decryption device that decrypts the encrypted digital data, it is possible to perform data verification using the unique information of the digital data before encryption. Thereby, it can be determined whether or not the data has been tampered with.
In this case, it can be considered that the first unique information generating means generates a fixed-length pseudorandom number from document data included in the digital data before encryption.

Further, the unique information storage means associates the unique information of the digital data before encryption generated by the first unique information generation means with the encrypted digital data and the common key specifying information in the storage medium. If it is stored (claim 5), it becomes easy to distinguish the unique information corresponding to the encrypted digital data stored in the storage medium.
Further, if the encryption means integrally encrypts the unique information of the digital data before encryption generated by the first unique information generation means together with the digital data (claim 6), It is possible to prevent leakage and eavesdropping of the specific information.

Furthermore, the present invention is configured to further comprise key information storage means for storing the common key information and key information update means for updating the common key information stored in the key information storage means. It may be a thing. In this case, the encryption key generation unit generates the encryption key based on the individual identification information acquired by the individual identification information acquisition unit and the updated common key information updated by the key information update unit. (Claim 7).
As a result, the common key information is updated to new common key information provided from the key information management device that manages the common key information, and an encryption key is generated using the updated common key information. Therefore, data security can be further improved.

  The present invention further includes encryption rule changing means for changing an encryption rule used for encryption based on the number of updates of the common key information updated by the key information updating means, and the encryption means includes If the digital data is encrypted according to the encryption rule changed by the encryption rule changing means (Claim 8), the security and confidentiality of the encrypted encrypted data are further enhanced, and more advanced information is obtained. Security can be realized.

  The present invention also provides individual identification information of the storage medium in a decryption apparatus that reads the encrypted digital data encrypted by the encryption apparatus and stored in the storage medium and decrypts it into the digital data before encryption. Generating individual identification information acquisition means, the encrypted digital data stored in the storage medium, and an encryption key for encrypting the digital data stored in the storage medium in association with the encrypted digital data And means for reading out encrypted data, etc., for reading common key specifying information for specifying common key information used for generating a decryption key for decrypting encrypted encrypted digital data , The individual identification information acquired by the individual identification information acquisition means, and the common key identification read by the reading means such as the encrypted data Using the decryption key generation means for generating the decryption key for decrypting the encrypted digital data based on the common key information specified by the information, and the decryption key generated by the decryption key generation means, The present invention can be regarded as a decryption device comprising decryption means for decrypting the encrypted digital data into digital data before encryption (claim 9). As a result, the decryption key can be generated by the same method as the encryption key, and as a result, the encrypted digital data can be decrypted.

  Further, the decryption device according to the present invention is based on a plurality of key information storage means for storing one or more different common key information and the common key specifying information read by the encryption data reading means. It may further comprise key information extracting means for specifying and extracting one common key information stored in the plural key information storing means. This makes it possible to decrypt data encrypted with the encryption key generated with the latest version of the common key information in the encryption device. In this case, the decryption key generation means generates the decryption key based on the individual identification information acquired by the individual identification information acquisition means and the common key information extracted by the key information extraction means. (Claim 10). When the common key information is updated, the common key information used when generating the encryption key in the encryption device may not match the common key information used when generating the decryption key in the decryption device. Can occur. Therefore, the old version of the common key information was used for encryption, but this common key information is then updated in each device, and the new version of the common key information is used for decryption. If this happens, there is a problem that the encrypted data cannot be decrypted. In order to solve such problems, all or a part of the common key information used in the past and the latest common key information are accumulated and stored, so that the common key information after encryption is stored. It is possible to cope with the case where the encrypted digital data is decrypted thereafter.

Further, the decoding device according to the present invention includes second unique information generating means for generating unique information of the decoded digital data based on the digital data decoded by the decoding means, Unique information of unencrypted digital data stored in the storage medium together with the digital data at the time of encryption, unique information of the decrypted digital data generated by the second unique information generating means, and , And a unique information collating unit that collates the data (Claim 11).
As a result, even if the encrypted digital data is wiretapped and the contents are changed, it is possible to determine whether the data has been altered by checking the unique information before encryption and the unique information after decryption. It becomes possible.
In this case, it is desirable that the second unique information generating means generates a fixed-length pseudo-random number from the document data included in the decrypted digital data.

  Furthermore, the present invention can be understood as an encryption / decryption system configured to include the encryption device and the decryption device. That is, an encryption device that encrypts digital data and stores the encrypted digital data in a storage medium, and an encryption device that reads the encrypted digital data stored in the storage medium and decrypts it into digital data before encryption In the encryption / decryption system configured with the encryption device, the encryption device includes the individual identification information acquired by the individual identification information acquisition means for acquiring the individual identification information of the storage medium, and the digital data. And encrypting the digital data based on common key information used when generating a decryption key for decrypting the encrypted digital data. An encryption key generating means for generating an encryption key to be converted, and an encryption key generated by the encryption key generating means. Data storage for storing in the storage medium the encryption means for encrypting data, the encrypted digital data encrypted by the encryption means, and the common key specifying information for specifying the common key information in association with each other Means for reading out the encrypted digital data stored in the storage medium by the data storage means and the common key specifying information, and the individual identification Decryption for generating a decryption key for decrypting the encrypted data based on the individual identification information acquired by the information acquisition means and the common key specifying information read by the read means such as the encrypted data Decrypting the encrypted digital data into digital data before encryption using a key generation means and a decryption key generated by the decryption key generation means And the step can be regarded as an encryption decryption system characterized in that it comprises a (claim 13).

  Here, the encryption apparatus includes a first unique information generation unit that generates unique information of the digital data before encryption based on the digital data, and the encryption generated by the first unique information generation unit. And a unique information storage means for storing the unique information of the digital data before decryption in the storage medium, wherein the decryption device performs the decryption based on the digital data decrypted by the decryption means. Second unique information generating means for generating unique information after decryption of the digital data, and unique information of the digital data before encryption stored in the storage medium together with the digital data at the time of encryption, It may be configured to further include unique information collating means for collating the unique information of the decrypted digital data generated by the second unique information generating means. (Claim 14).

The present invention also provides an encryption device for encrypting digital data and storing the encrypted digital data in a storage medium, and reading the encrypted digital data stored in the storage medium into digital data before encryption. An encryption device for decryption, and a decryption key used for generating an encryption key for encrypting the digital data by the encryption device and for decrypting the encrypted digital data by the decryption device In a key information update system configured to include a key information management device that issues common key information used when generating the key, the key information management device periodically issues the common key information. Key information issuance / transmission means for transmitting to the encryption device and / or the decryption device, and the encryption device and / or the decryption device includes the common key information. Key information storage means for storing, and key information update means for updating the common key information stored in the key information storage means to new common key information transmitted by the key information issuing and transmitting means. It can also be understood as a key information update system characterized by the above (claim 15).
In this case, the key information storage means provided in the decryption apparatus is a plurality of key information storage means for storing one or more different common key information, and is updated before the key information update means is updated. It is desirable to store and store common key information.
Further, if the pseudo random number is a hash value generated based on a hash function (claim 17), even if the hash value is wiretapped or leaked during data writing or reading, Since the original data is not reproduced, the confidentiality of the data can be protected.
As the storage medium, a wireless non-contact type IC memory is conceivable, but a storage medium such as a contact type memory card may also be used.

As described above, according to the present invention, the illegal decryption generated by the individual identification information of the storage medium and the common key information used in common for encryption and decryption provided from the key information management device is performed. Since data is encrypted with a difficult encryption key, data leakage and tampering are prevented, and data security is improved. In addition, the encryption key is generated by a simple process of combining the individual identification information of the storage medium and the common key information based on a predetermined encryption rule (encryption algorithm), and the decryption key is generated by the reverse process. , The throughput of the encryption process and the decryption process can be improved.
The encryption key and decryption key are generated based on new common key information periodically issued from the key information management device, that is, the common key used for generating the encryption key and decryption key. Since the key information is updated periodically, it is possible to achieve a higher level of information security.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: It is not the thing of the character which limits the technical scope of this invention.
1 is a system block diagram showing a schematic configuration of a security system X according to an embodiment of the present invention, FIG. 2 is an enlarged detailed view of an RFID tag used in the security system X, and FIG. FIG. 4 is a flowchart for explaining an example of the procedure of the encryption process executed by the reader / writer controller used. FIG. 4 shows an example of the procedure of the decryption process executed by the reader / writer controller used in the security system X. FIG. 5 is a flowchart for explaining an example of a procedure of a common key update process executed between the reader / writer used in the security system X and the management server, and FIG. 6 is a reader / writer used in the security system X. Encryption circuit executed with the management server It is a flowchart illustrating an example of a processing procedure for selecting.

First, an outline of a security system X (hereinafter abbreviated as system X) according to an embodiment of the present invention will be described using the system block diagram of FIG.
As shown in FIG. 1, the system X stores digital data (hereinafter abbreviated as data) such as personal information and confidential data or encrypted digital data (hereinafter abbreviated as encrypted data) obtained by encrypting the data. The RFID tag 30 (an example of a storage medium) and the above-described data stored in the RFID tag 30 as well as functioning as an encryption device that encrypts the data and stores the encrypted encrypted data in the RFID tag 30 An encryption / decryption system A according to the first embodiment of the present invention (hereinafter referred to as a system) is configured to include a reader / writer 20 that functions as a decryption device that reads encrypted data and decrypts the data before encryption (Abbreviated as A)). The system A may include the RFID tag 30 and other reader / writers 20-1 and 20-2.
The system X includes the reader / writer 20 (or other reader / writers 20-1 and 20-2), a common key described later, and common key specifying information for specifying the common key (for example, the common key). Key information according to the second embodiment of the present invention configured to include a management server 10 (an example of a key information management device) that issues (provides (distributes)) information to the reader / writer 20. An update system B (hereinafter abbreviated as system B) is constructed. The common key is used when generating an encryption key for encrypting data and common key information used when generating a decryption key for decrypting encrypted encrypted data. It is an example.
In the present embodiment, the common key specifying information is described as being provided to the reader / writer 20 by the management server 10. However, the present invention is not limited to this, and the common key provided from the management server 10 in the reader / writer 20 is not limited thereto. An embodiment in which the common key specifying information is generated based on a key may be used. The reader / writer 20 is described as having both functions of an encryption device and a decryption device. However, the reader / writer 20 may be a system in which the encryption device and the decryption device are independently configured.

First Embodiment Here, basic configurations of the RFID tag 30 and the reader / writer 20 constituting the system A according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. . 2A is an enlarged detailed view of the RFID tag 30, and FIG. 2B is a block diagram showing a schematic configuration of an IC chip 32 built in the RFID 30. As shown in FIG.
The RFID tag 30 is a card-type wireless IC memory card, and is a non-contact type storage medium in which data is read and written by performing wireless communication with the reader / writer 20. Individual identification information (individual identification information) is provided (stored) in advance in the RFID tag 30 in order to avoid confusion with other RFID tags. The RFID tag 30 does not have a battery and uses an electromotive force induced by electromagnetic induction as a power source. Therefore, as shown in FIGS. 2A and 2B, the RFID tag 30 includes a memory circuit 32-1, a rectifier circuit 32-2, a data transmission circuit 32-3, a data reception circuit 32-4, and the like. A coil antenna that receives the radio wave transmitted from the IC chip (integrated circuit) 32 and the reader / writer 20 and transmits the radio wave that propagates the data stored in the storage circuit 32-1 to the reader / writer 20. 31 and so on. When a radio wave is received by the coil antenna 31, an electromotive force is induced in the coil antenna 31, and power is supplied to the IC chip 33 and the like.

On the other hand, the reader / writer 20 is a device that writes data to the RFID tag 30 or reads data stored in the RFID tag 30 by performing wireless communication with the RFID tag 30. The reader / writer 20 performs data read processing and data write processing on the RFID tag 30, and propagates predetermined signals and data to the controller 22 that controls the system A and the RFID tag 30. A gate antenna 21 and the like for transmitting radio waves and receiving radio waves from the RFID tag 30 are schematically configured.
The controller 22 includes a CPU 23 (central processing unit), a memory 24 (an example of key information storage means) that stores various data such as a predetermined program and the common key, and an encryption key generated by an encryption key generation process described later. A conventionally known encryption circuit 25 (an example of encryption means) that encrypts data using a key based on a predetermined algorithm (encryption rule) such as DES, 3DES, and AES, and is generated by a decryption key generation process described later. Conventionally known decryption circuit 26 (decryption) that decrypts encrypted data encrypted using the decryption key into data before encryption based on the predetermined algorithm (decryption rule) used at the time of encryption An example of the converting means). In the present system A, encrypted data encrypted by the controller 22 is transmitted and received between the reader / writer 20 and the RFID tag in order to prevent data leakage and wiretapping. In the first embodiment, the encryption circuit 25 and the decryption circuit 26 will be described as an example of the encryption means and the decryption means, but the encryption circuit is replaced with the encryption circuit. The present invention may be an embodiment that encrypts and decrypts data using an encryption program that realizes the functions of 25 and a decryption program that realizes the functions of the decryption circuit 26.
The memory 24 stores the common key issued by the management server 10 and provided to the reader / writer 20 and the common key specifying information. For this reason, the memory 24 stores and stores the old common key group issued in the past and the latest common key together with the common key specifying information. That is, as described above, the memory 24 in which one or more common keys that are different (that is, different in version) at the time of revision (update) are stored corresponds to a plurality of key information storage means.

Here, the principle of wireless communication in the system A will be briefly described. For example, in a procedure for writing encrypted data, a radio wave including the encrypted data encrypted by the reader / writer 20 and a data write signal is transmitted from the gate antenna 21, and this radio wave is transmitted to the coil of the RFID tag 30. When received by the antenna 31, an electromotive force is generated in the coil antenna 31 by electromagnetic induction. The IC chip 32 is activated in response to this electromotive force. In the IC chip 32, the encryption data included in the radio wave is received by the reception circuit 32-4 based on the data write signal, and then the encryption data is stored in the storage circuit 32-1.
In the encrypted data reading procedure, when the radio wave including the data read signal is transmitted from the reader / writer 20 from the gate antenna 21 and received by the coil antenna 31 of the RFID tag 30, the above-described procedure is performed. As described above, in the IC chip 32 activated by receiving the electromotive force generated by the coil antenna 31, the encrypted data is read from the storage circuit 32-1 based on the data read signal included in the radio wave, and the data The read encrypted data is transmitted from the transmission circuit 32-3 to the reader / writer 20 through the coil antenna 31.

Next, referring to the flowchart of FIG. 3, the encryption process (including data writing process) executed by the controller 22 (CPU 23) of the reader / writer 20 when functioning as an encryption apparatus according to a predetermined program. An example of the procedure will be described. In the figure, S10, S20,... Indicate processing procedure (step) numbers. The process starts from step S10.
When the RFID tag 30 is moved to a range where radio waves transmitted from the reader / writer 20 can be received (range where radio waves reach), and thereafter, individual identification information of the RFID tag 30 is transmitted from the RFID tag 30. In step S10, the controller 22 receives (acquires) the transmitted individual identification information of the RFID tag 30 (individual identification information acquisition processing), and then stores the received individual identification information in the memory 24. (S20).
When the individual identification information received in step S20 is stored in the memory 24, then in step S30, the individual identification information stored in the memory 24 and the latest common information previously stored in the memory 24 are stored. Based on a key (a common key provided in advance from the management server 10), an encryption key generation process is executed for generating an encryption key for encrypting data to be written (stored) in the RFID tag 30. This processing is performed by, for example, combining a bit array of 64-bit digital data indicating the individual identification information and a bit array of 256-bit digital data indicating the common key based on a predetermined rule, thereby generating a 320-bit encryption key. Is a process for generating The common key may be used in common for all RFID tags that can be used in the reader / writer 20. For example, the common key is provided by the management server 10 individually for each RFID tag. In an embodiment in which the encryption key is generated using a key, it is considered that the encryption key is more difficult to decrypt.
In this way, since the individual identification information and the common key are used for generating an encryption key, an encryption key that is difficult to illegally decrypt is generated.

  When the encryption key is generated, in step S40, unique information unique to the write data is generated based on the data before encryption written to the RFID tag 30 (hereinafter referred to as write data). The first unique information generation process is executed. Specifically, a fixed-length pseudorandom number is generated from document data (plaintext data) included in the write data. As this pseudo-random number, a hash value calculated from the document data according to a hash function can be considered. The hash function is a one-way function, that is, a function having a property that it is almost impossible to reproduce or infer the original text from the hash value. Therefore, the hash value before writing and the hash value after data reading are collated to determine whether the decrypted data has been tampered with (described later in steps S190 to S210 in the flowchart of FIG. 4). It is possible to determine whether or not the data has been altered before and after the data writing process and the data reading process. As described above, since the unique information obtained by the first unique information generation process is information used when the falsification determination process is executed, the falsification determination process is executed at the time of decoding. In the embodiment that is not performed, it is not necessary to perform the first unique information generation process.

Subsequently, in step S50, the write data written to the RFID tag 30 is encrypted using the generated encryption key. This encryption is performed by a known encryption circuit 25 provided in the controller 22 according to an algorithm (encryption rule) such as DES (Data Encryption Standard), 3DES (Triple DES), or AES (Advanced Encryption Standard). Done. Of course, the present invention is not limited to these algorithms, and the write data may be encrypted according to other algorithms. In the first embodiment, an example in which only write data is encrypted will be described. For example, in order to prevent leakage of specific information and to realize higher information security, It is also conceivable to encrypt the unique information and the write data together.
Thereafter, in step S60, the encrypted data (data encrypted by the encryption circuit 25) associated with (added to) the above-described common key specifying information, the unique information, and a data write signal to be described later is stored in the above-described manner. Data storage processing (also referred to as data writing processing) stored in the RFID tag 30 is performed. Specifically, the encrypted data is transmitted to the RFID tag 30 via the gate antenna 21 of the reader / writer 20. In the RFID tag 30 that has received the data, the encrypted data received according to the data write signal, the common key specifying information, and the unique information are associated with each other and stored in the storage circuit 32-1 of the RFID tag 30 (stored). ) The data storage process is also a unique information storage process for storing the unique information in the RFID tag 30. Here, the data write signal is a command signal for causing the RFID tag 30 to store the write data in the storage circuit 32-1, and is a signal generated in the reader / writer 20. It is. The common key specifying information is for specifying and extracting a common key used when generating a decryption key from a plurality of common keys stored in the memory 24. In the management server 10 to be described later, Information issued and provided (distributed) to the reader / writer 20. Although it is possible to transmit the common key itself without using the common key specifying information and store it in the RFID tag 30 together with the encrypted data, from the viewpoint of preventing leakage of the common key and wiretapping, As described in S60, it is desirable that the common key specifying information is transmitted to the RFID tag 30 in association with the encrypted data. In the first embodiment, an example in which the common key information is transmitted (stored) to the RFID tag 30 in association with encrypted data will be described. For example, all reader / writers 20 always use a common key. When encryption is performed, it is not necessary to store the common key information in the RFID tag 30.
As described above, since the write data is encrypted by the difficult-to-decrypt encryption key generated by the individual identification information and the common key, the encryption data is temporarily stored in the RFID tag 30 when the encryption data is stored. Even if the encrypted data is leaked, illegally obtained, or eavesdropped, the confidentiality of the data can be protected. As a result, data security can be improved. Further, for the same reason, falsification of data stored in the RFID tag 30 can be prevented.

Next, referring to the flowchart of FIG. 4, a decryption process (data) executed by the controller 22 (CPU 23) of the reader / writer 20-1 (see FIG. 1) when functioning as a decryption apparatus according to a predetermined program. An example of the procedure (including the reading process) will be described. The process starts from step S110. Since the reader / writer 20-1 is configured in substantially the same manner as the reader / writer 20, the components of the reader / writer 20-1 are denoted by the same reference numerals as those of the reader / writer 20. . Further, detailed description of the processing procedure that is substantially the same as the procedure described in the above-described encryption processing (see the description of the flowchart of FIG. 3) is omitted.
When the RFID tag 30 is moved to a range where radio waves transmitted from the reader / writer 20-1 can be received, and then individual identification information of the RFID tag 30 is received (acquired) in step S110, The received individual identification information is stored in the memory 24 (S120).
Thereafter, the controller 22 receives the encrypted data transmitted (read) from the RFID 30 in accordance with the data read signal transmitted from the controller 22 to the RFID tag 30 (S130). At this time, it is determined whether or not the common key specifying information associated with the encrypted data and stored in the RFID tag 30 when the encryption of step S50 is performed is received together with the encrypted data (S140). . If it is determined that the common key specifying information is received together with the encrypted data (Yes side of S140), the process proceeds to step S150. If it is determined that the common key specifying information has not been received (No in S140), the process proceeds to step S220, and a predetermined error process is performed. The data read signal is a command signal for reading out and wirelessly transmitting the encrypted data stored in the storage circuit 32-1 to the RFID tag 30, and in the reader / writer 20-1. This is a signal to be generated. Further, the process in step S130 corresponds to a process for reading out encrypted data and the like.

  When the process proceeds to step S150, here, the controller 22 performs key information extraction processing for identifying and extracting one common key stored in the memory 24 based on the received common key specifying information. That is, it is searched whether the common key specified by the common key specifying information is stored in the memory 24. Thereafter, if it is determined in step S160 that the common key specified by the common key specifying information is stored in the memory 24 as a result of the search, the process proceeds to step S170. If it is determined that the common key is not stored (No in S160), the process proceeds to step S220, and a predetermined error process is performed. The error process in step S220 may be, for example, a process of outputting a display or warning indicating that “encrypted data has been read but the encrypted data cannot be decrypted”. Note that after the error processing, a series of decryption processing ends without decrypting the encrypted data.

If it is determined in step S160 that the common key is in the memory 24 and the common key is specified, then in step S170, the individual identification information of the RFID tag 30 stored in the memory 24 and the specification are specified. A decryption key generation process for generating a decryption key for decrypting the encrypted data transmitted from the RFID tag 30 based on the common key (see S160) is executed. That is, the process of step S170 is substantially the same process as the encryption key generation process (S30) described above, and the encryption key used when the encrypted data is encrypted is obtained by performing this process. Generated as a decryption key. Therefore, for example, when data encryption is performed on an RFID tag using the encryption key generated by the encryption key generation process, decryption of the encryption data stored in the RFID tag is as follows: By performing a decryption key generation process based on the same algorithm as the encryption key generation process, a decryption key having the same structure as the encryption key is generated.
Thereafter, using the generated decryption key, the encrypted data received from the RFID tag 30 is decrypted into data (write data) before being encrypted (S180). Note that this decryption is performed in accordance with the same algorithm as that used for encryption in the conventionally known decryption circuit 26 provided in the controller 22.

By performing the above-described steps S110 to S180, the decryption processing for decrypting the encrypted data is completed, but the following steps S190 to S210 (falsification determination processing) are further executed. Thus, it can be determined whether or not the decrypted data has been tampered with. By including such a processing procedure in the decryption process, the identity between the data before encryption and the data after decryption is protected, and higher-level information security is realized.
That is, first, in step S190, when the encrypted data is received (S130), it is determined whether the unique information of the data before encryption (hereinafter referred to as unique information before encryption) is also received. Here, if it is determined that the pre-encryption unique information has been received, then the unique information of the data decrypted by the process of step S170 (hereinafter referred to as post-decryption unique information) is generated. 2 is executed (S200). This second unique information generation process is substantially the same as the first unique information generation process described above, and generates a fixed-length pseudo-random number from document data (plain text data) included in the decrypted data. It is processing.
If it is determined that the unique information before encryption has not been received (No in S190), the series of decryption processing ends without matching the unique information.
If the unencrypted unique information and the unencrypted data are encrypted together, whether or not the unencrypted unique information exists when the encrypted data is decrypted in step S180. This is determined in step S190.

  Subsequently, in step S210, the controller 22 executes a unique information matching process for matching the pre-encrypted unique information with the decrypted unique information generated by the second unique information generation process. In this way, it is possible to determine whether or not the data has been tampered with by comparing the unique information before encryption with the unique information after decryption. That is, if it is determined that the unique information matches by the unique information collating process (Yes in S210), it means that the data has not been tampered with, and a series of decryption processes are completed. If it is determined that the unique information does not match (No in S210), then error processing in step S220 is performed. In this case, for example, the error processing may be to output a display and warning that “data has been tampered with”.

Second Embodiment Next, an example of a common key update processing procedure executed in the system B according to the second embodiment of the present invention will be described using the flowchart of FIG. The process starts from step S310. Note that the reader / writer 20 configuring the system B is as already described in the first embodiment. The management server 10 (key information management device) constituting the system B is an information processing device such as a conventionally known personal computer that is connected to the reader / writer 20 so as to be communicable by wire or wirelessly. The detailed description of is omitted. In the second embodiment, the common key update process is described as being executed between the reader / writer 20 and the management server 10 based on a publicly known public key cryptosystem. Therefore, as a premise that the common key update process is executed, the reader / writer 20 stores the public key provided (issued) from the management server 10 and the signature information of the management server 10 in the memory 24 or the like. In the management server 10, a secret key corresponding to the public key provided to the reader / writer 20 and signature information of the reader / writer 20 are stored in a memory or the like in the management server 10. And However, if the secret state in the communication path between the management server 10 and the reader / writer 20 is sufficiently secured, that is, if the safety, reliability, confidentiality, etc. of the communication path are high, it goes without saying. There is no need to use public key cryptography.

First, in step S305, the reader / writer 20 determines whether or not a predetermined update setting time has been counted by a timer or the like provided in the reader / writer 20 after the previous common key was updated. The In the second embodiment, a description will be given of a process example in which the update process of the common key is performed when the update setting time has elapsed. For example, the update process is periodically performed at predetermined intervals. It may be an embodiment to be performed. Further, even when the update instruction signal output from the management server 10 (signal output from the management server 10 by the user or the like at an arbitrary timing) is received, the common key update process is performed. It doesn't matter.
The update setting time is stored in advance in the memory 24, and can be changed by accessing the controller 22 from the management server 10, for example.
When the update instruction signal is received, a temporary encryption key is subsequently generated by the controller 22 (S310). The temporary encryption key is for encrypting a new common key transmitted from the management server 10 by the processing described later, common key specifying information for specifying the common key, and signature information of the management server 10. This is a disposable encryption key that is newly generated every time the common key is updated. Since this temporary encryption key is generated by a known method using random numbers or the like on the reader / writer 20 side, detailed description thereof will be omitted.
When the temporary encryption key is generated, the signature information of the reader / writer 20 and the temporary encryption key are encrypted using the public key (S320), and then the encrypted signature information is encrypted. Then, a key update request signal with a temporary encryption key (hereinafter referred to as “digital signature etc.”) attached to the header area etc. is transmitted to the management server 10 (S330). Thereafter, the controller 22 waits for reception of data transmitted from the management server 10.

On the management server 10 side, after the update instruction signal is transmitted, it is determined in step S410 whether or not the key update request signal transmitted from the reader / writer 10 has been received. Here, if it is determined that the key update request signal has been received, the digital signature or the like attached to the received key update request signal is subsequently changed to a secret corresponding to the public key used in step S320. Decryption processing is performed using the key (S420). Thereafter, the signature information of the reader / writer 20 obtained by decryption by the process of step S420 is collated with the signature information of the management server 10 stored in advance in the management server 10 (S430). This is a process performed to determine whether the reader / writer that has transmitted the key update request signal is under the management of the management server 10.
Subsequently, in step S440, when it is determined that the collation in step S430 matches, the process proceeds to step S450. If it is determined that they do not match, the process proceeds to step S490, and after a predetermined error process is performed, a series of key update processes are completed without transmitting a new common key to the reader / writer 20. .

When the process proceeds to step S450, it is determined here whether a new common key has been issued. For this determination, for example, the common key currently used in the reader / writer 20 is identified by referring to the signature information of the reader / writer 20, the common key update history of the reader / writer 20, and the like. , By comparing with the latest common key issued by the management server 10. If it is determined that there is a new common key, then in step S460, the new common key, the common key specifying information for specifying the common key, and the signature information of the management server 10 are obtained. A process of encrypting using the temporary encryption key transmitted from the reader / writer 20 and obtained by the decryption of step S420 is performed, and then the process proceeds to step S480. If it is determined that a new common key does not exist, then in step S470, data indicating that no new common key exists and the signature information of the management server 10 are used for the temporary encryption key. Then, the encryption process is performed, and then the process proceeds to step S480.
When the process proceeds to step S480, the data encrypted in step S460 or S470 is transmitted to the reader / writer 20 here.

When the data transmitted from the management server 10 is received by the reader / writer 20 (S340), the controller 22 of the reader / writer 20 generates the received data (received data) in step S310. A process of decrypting using the temporary encryption key is executed (S350).
Thereafter, in step S360, the signature information of the management server 10 obtained by the decryption in step S350 is collated with the signature information of the management server stored in advance in the memory 24 or the like. This is a process performed to determine whether the management server that transmitted the data (data encrypted using the temporary encryption key) in step S480 is correct. If it is determined in step S370 that the collations in S360 match, the process proceeds to step S380. If it is determined that the collations do not match, the process proceeds to step S400, and after a predetermined error process is performed, a series of key update processes is terminated without updating the common key.
When the process proceeds to step S380, it is determined here whether or not the data obtained by decrypting in step S350 includes a new common key. Here, if it is determined that there is no new common key, the fact is displayed and output based on the data indicating that there is no new common key included in the decrypted data, and then A series of processing ends without updating the common key. If it is determined that there is a new common key, the process proceeds to step S390, and the new common key obtained by decrypting the common key stored in the memory 24 of the controller 22 in step S350 is obtained. The controller 22 executes the process of updating to At this time, the common key specifying information for specifying the new common key is also stored in the memory 24.
As described above, the common key update process updates the common key used to generate the encryption key and the decryption key, so that it is possible to further improve data security. .

  In the above-described embodiment, a system for encrypting data written to the RFID tag 30 which is an example of a wireless contactless IC memory, or reading and decrypting encrypted data stored in the RFID tag 30 will be described. However, the storage medium to which the encrypted data is written or read is not limited to the wireless non-contact type IC memory. For example, the present invention can be applied to a storage medium such as a contact-type memory card or a prepaid card.

Further, as described above, the encryption executed in step S50 in the flowchart of FIG. 3 is performed according to an encryption algorithm (encryption rule) such as DES, 3DES, AES, etc., but the confidentiality of the encrypted encrypted data is not limited. In order to further increase the RFID tag 30 according to the encryption algorithm (the encryption rule used for encryption) changed based on the number of updates of the common key used in the encryption key generation process of step S30 in the flowchart of FIG. An embodiment in which write data to be written is encrypted can be considered. Here, a process for changing the encryption algorithm based on the number of times of updating the common key will be briefly described with reference to the flowchart of FIG.
First, if it is determined on the management server 10 side that a new common key has been issued in step S450 (FIG. 5), an update in which the number of times the common key has been updated by the reader / writer 20 is set in advance. It is determined whether or not the set number is exceeded (S510). As the number of times of update, for example, an update completion notification (a signal indicating that the update of the common key has been completed) transmitted from the reader / writer 20 to the management server 10 after the common key update process in step S390 has been performed. The number of times received can be considered. The management server 10 is provided with a counting unit such as a counter (not shown) and a count storage unit for storing a count value counted (counted) by the counting unit. The count value (that is, the number of times the update completion notification has been received) is stored in the count storage unit. Therefore, the determination in step S510 is performed by comparing the number of times of reception of the update completion notification stored in the count storage unit with the number of update settings stored in advance in the memory or the like in the management server 10. . It is preferable that the set value of the update setting number can be arbitrarily changed by an operation from the management server 10. Therefore, depending on the set value, for example, every time the common key is updated or every time it is updated twice, the algorithm used for encryption is updated. Since the update process of the common key is performed every update setting time as described above, it can be said that the number of updates indicates an update interval (update time). Note that the number of updates is not limited to the number of times the update completion notification is received. For example, data including a new common key (data encrypted with a temporary encryption key) in step S480 (FIG. 5) is used. The number of times of transmission may be assumed to be the above update number.

If it is determined in step S510 that the number of updates is greater than or equal to the update setting, then in step S520, processing for transmitting changed algorithm identification information (described later) to the reader / writer 20 is performed. On the other hand, if it is determined in step S510 that the update count is less than the update set count, then in step S521, processing for transmitting the current algorithm specifying information to the reader / writer 20 is performed. In any of the transmission processes in steps S520 and S521, the changed algorithm specifying information is further added to the new common key, the common key specifying information, and the signature information of the management server 10 in step S460 (FIG. 5). This is a process of encrypting data integrally and then transmitting the data encrypted in step S480. The algorithm specifying information is an encryption algorithm used on the reader / writer 20 side when data is encrypted using an encryption key generated using a new common key transmitted to the reader / writer 20. Information for specifying (specifically, an encryption circuit or an encryption program), that is, information for specifying an encryption algorithm corresponding to the transmitted new common key.
When the transmission process of step S520 is performed, the number of updates stored in the count storage unit is reset (S530). When the transmission process of step S521 is performed, the number of updates stored in the count storage unit is updated. Incremented.

On the reader / writer 20 side, the controller 22 of the reader / writer 20 determines whether or not the algorithm specifying information transmitted by the transmission processing of steps S520 and S521 has been received (S540). Here, if it is determined that the algorithm specifying information has been received, then, in step S550, an algorithm correspondence table (not shown) is updated (table update processing). The algorithm correspondence table is table data including a plurality of common key specifying information for specifying a plurality of common keys and the algorithm specifying information corresponding to each of the plurality of common key specifying information. This is table data for specifying the algorithm used (or used). This algorithm correspondence table is stored in the memory 24 of the controller 22. Normally, when the common key is updated, the above algorithm correspondence table does not include information indicating the encryption algorithm corresponding to the new common key after the update. Therefore, the encryption circuit and encryption program used for encryption are not included. In order to identify the table, the table update process in step S550 is executed.
When the algorithm correspondence table is updated, the encryption algorithm used for the encryption in step S50 (FIG. 3) is subsequently extracted from the updated algorithm correspondence table. Specifically, the algorithm specifying information corresponding to the common key to be used is extracted from the algorithm correspondence table, and an encryption circuit or an encryption program corresponding to the extracted algorithm specifying information is selected.

As described above, the encryption circuit or encryption program corresponding to the algorithm specifying information transmitted in step S520 is selected, whereby the encryption algorithm used for the encryption in step S50 is changed. Note that even if the current algorithm specifying information transmitted in step S521 is received, the encryption algorithm used for the encryption in step S50 is not changed.
In this way, the encryption algorithm can be changed by changing the encryption circuit used for encryption. Needless to say, when a plurality of encryption programs for encrypting data according to a plurality of algorithms such as DES, 3DES, and AES are used in place of the plurality of encryption circuits, the selection function allows the One encryption program used for encryption is selected from the memory 24 of the reader / writer 20 in which a plurality of encryption programs are stored, according to the number of times the common key is updated, etc. Can be changed.
Since the encryption circuit or the encryption program is changed in this way, the data is encrypted by the changed encryption circuit or encryption program, thereby improving the confidentiality of the encrypted data. Therefore, it is possible to realize higher information security.
Note that the decryption of the encrypted data executed in step S180 in the flowchart of FIG. 4 is performed according to the decryption algorithm (decryption rule) corresponding to the encryption algorithm used in the above-described encryption or the same as the encryption algorithm. Done. In this case, the encryption circuit or encryption program used for encryption (that is, the encryption algorithm) must be known at the time of decryption, but the common key used at the time of encryption together with the encrypted data The encryption algorithm used for encryption is specified at the time of decryption by referring to the common key specification information stored in the ID tag 30 and the algorithm correspondence table. Is possible.

  Further, in the transmission process of data (data encrypted using the temporary encryption key) performed in step S480 in the flowchart of FIG. 5, the use of a new common key is restricted together with the transmitted data. An embodiment for transmitting a limiting signal is conceivable. As the restriction signal, the use of the new common key is restricted when the encryption key generation process for generating the encryption key in step S30 is executed, that is, the encryption key is generated using the new common key. An encryption key generation restriction signal for restricting this can be considered. For example, when the key update process (FIG. 5) is performed simultaneously between the management server 10 and a plurality of reader / writers, a new common key is updated after the common key is updated in all the plurality of reader / writers. It is desirable to be used. Therefore, in this case, first, the encryption key generation restriction signal is transmitted to all of the plurality of reader / writers together with the data encrypted using the temporary encryption key, and the key update processing is executed in all the reader / writers. In addition, after receiving the update completion notification from all the reader / writers, a process of transmitting a use permission signal for permitting the use of the new common key in the encryption key generation process (S30) from the management server 10 It is possible to consider an embodiment in which the restriction on the use of the new common key is canceled by performing the above. In this case, until the use permission signal is transmitted, use of the new common key may be permitted only when the reader / writer executes the decryption key generation process (S180 in FIG. 4). By doing so, even if there is encrypted data encrypted with an encryption key generated using a new common key, the encrypted data can be decrypted.

  The present invention provides a security system for encrypting and storing individual information to be protected, such as personal information and billing information, in a storage medium, or decrypting the encrypted individual information, and encrypting and storing the individual information. The present invention can be applied to an encryption device that performs the decryption and a decryption device that reads and decrypts the encrypted individual information.

1 is a system block diagram showing a schematic configuration of a security system X according to an embodiment of the present invention. FIG. 3 is an enlarged detailed view of an RFID tag used in the security system X. 6 is a flowchart for explaining an example of a procedure of encryption processing executed by a controller of a reader / writer used in the security system X. The flowchart explaining an example of the procedure of the decoding process performed by the controller of the reader / writer used for the said security system X. The flowchart explaining an example of the procedure of the common key update process performed between the reader / writer used for the said security system X, and a management server. 7 is a flowchart for explaining an example of a processing procedure for selecting an encryption circuit executed between a reader / writer and a management server used in the security system X.

Explanation of symbols

X ... Security system A ... Encryption / decryption system B ... Key information update system 10 ... Management server (an example of a key information management device)
20. Reader / writer (an example of an encryption device and a decryption device)
21 ... Gate antenna 22 ... Controller 23 ... CPU
24 ... Memory (an example of key information storage means, multiple key information storage means)
25. Encryption circuit (an example of encryption means)
26: Decoding circuit (an example of decoding means)
30... RFID tag (an example of a storage medium)
31 ... Coil antenna 32 ... IC chip

Claims (18)

In an encryption device that encrypts digital data and stores the encrypted digital data in a storage medium,
Individual identification information acquisition means for acquiring individual identification information of the storage medium;
Used when generating the individual identification information acquired by the individual identification information acquisition means and the encryption key for encrypting the digital data, and generating a decryption key for decrypting the encrypted digital data Encryption key generation means for generating an encryption key for encrypting the digital data based on common key information used at the time,
Encryption means for encrypting at least the digital data based on a predetermined encryption rule using the encryption key generated by the encryption key generation means;
Data storage means for associating the encrypted digital data encrypted by the encryption means with the common key specifying information for specifying the common key information in the storage medium;
An encryption device comprising:   2. The encryption key according to claim 1, wherein the encryption key generation means generates the encryption key by combining the bit array of the individual identification information and the bit array of the common key information based on a predetermined rule. apparatus. First unique information generating means for generating unique information of digital data before encryption based on the digital data;
3. The encryption apparatus according to claim 1, further comprising unique information storage means for storing unique information of the digital data before encryption generated by the first unique information generation means in the storage medium. .   4. The encryption apparatus according to claim 3, wherein the first unique information generating means generates a fixed-length pseudo-random number from document data included in digital data before encryption.   The unique information storage means stores the unique information of the digital data before encryption generated by the first unique information generation means in association with the encrypted digital data and the common key specifying information in the storage medium. The encryption device according to claim 3 or 4, wherein the encryption device is a device.   6. The encryption unit according to claim 1, wherein the encryption unit integrally encrypts the unique information of the digital data before encryption generated by the first unique information generation unit together with the digital data. The encryption device described. Key information storage means for storing the common key information;
Key information update means for updating the common key information stored in the key information storage means,
The encryption key generation means generates the encryption key based on the individual identification information acquired by the individual identification information acquisition means and the updated common key information updated by the key information update means. The encryption device according to claim 1. A cryptographic rule changing means for changing a cryptographic rule used for encryption by the encryption means based on the number of updates of the common key information updated by the key information updating means;
8. The encryption apparatus according to claim 1, wherein the encryption means encrypts the digital data in accordance with the encryption rule changed by the encryption rule change means. In a decryption device that reads encrypted digital data encrypted by an encryption device and stored in a storage medium, and decrypts the encrypted digital data before encryption.
Individual identification information acquisition means for acquiring individual identification information of the storage medium;
The encryption digital data stored in the storage medium and the encryption digital data stored in the storage medium in association with the encryption digital data are used when generating an encryption key for encrypting the digital data and are encrypted. A means for reading out encrypted data, etc., for reading out common key specifying information for specifying common key information used in generating a decryption key for decrypting the encrypted digital data;
The encrypted digital data based on the individual identification information acquired by the individual identification information acquisition means and the common key information specified by the common key specifying information read by the reading means such as the encrypted data. Decryption key generation means for generating a decryption key for decrypting
Decryption means for decrypting the encrypted digital data into digital data before encryption using the decryption key generated by the decryption key generation means;
A decoding device comprising: A plurality of key information storage means for storing one or more different common key information;
Key information extracting means for specifying and extracting one common key information stored in the plurality of key information storage means based on the common key specifying information read by the encryption data reading means,
10. The decryption key generation unit generates the decryption key based on the individual identification information acquired by the individual identification information acquisition unit and the common key information extracted by the key information extraction unit. The decoding device according to 1. Second unique information generating means for generating unique information of the decoded digital data based on the digital data decoded by the decoding means;
Unique information of unencrypted digital data stored in the storage medium together with the digital data at the time of encryption, unique information of the decrypted digital data generated by the second unique information generating means, and Unique information matching means for matching,
The decoding device according to claim 9 or 10, further comprising:   12. The decoding device according to claim 11, wherein the second unique information generating means generates a fixed-length pseudo-random number from document data included in the decrypted digital data. An encryption device for encrypting digital data and storing the encrypted digital data in a storage medium, and an encryption device for reading the encrypted digital data stored in the storage medium and decrypting the digital data before encryption And an encryption / decryption system comprising:
The above encryption device
Used to generate the individual identification information acquired by the individual identification information acquisition means for acquiring the individual identification information of the storage medium and the encryption key for encrypting the digital data, and decrypt the encrypted digital data Encryption key generation means for generating an encryption key for encrypting the digital data based on common key information used when generating a decryption key to be converted,
Encryption means for encrypting at least the digital data using the encryption key generated by the encryption key generation means;
Data storage means for associating and storing the encrypted digital data encrypted by the encryption means and the common key specifying information for specifying the common key information in the storage medium,
The decoding device is
Means for reading out the encrypted digital data and the common key specifying information stored in the storage medium by the data storage means;
A decryption key for decrypting the encrypted data based on the individual identification information acquired by the individual identification information acquiring means and the common key specifying information read by the reading means such as the encrypted data. A decryption key generating means for generating;
Decryption means for decrypting the encrypted digital data into digital data before encryption using the decryption key generated by the decryption key generation means;
An encryption / decryption system comprising: The above encryption device
First unique information generating means for generating unique information of digital data before encryption based on the digital data;
Unique information storage means for storing the unique information of the digital data before encryption generated by the first unique information generation means in the storage medium;
The decoding device is
Second unique information generating means for generating unique information after decoding the decrypted digital data based on the digital data decrypted by the decryption means;
Unique information of unencrypted digital data stored in the storage medium together with the digital data at the time of encryption, unique information of the decrypted digital data generated by the second unique information generating means, and Unique information matching means for matching,
The encryption / decryption system according to claim 13, further comprising: An encryption device for encrypting digital data and storing the encrypted digital data in a storage medium, and an encryption device for reading the encrypted digital data stored in the storage medium and decrypting the digital data before encryption And used when the encryption device generates an encryption key for encrypting the digital data, and also used when the decryption device generates a decryption key for decrypting the encrypted digital data. A key information update system configured to include a key information management device for issuing common key information
The key information management device
Key information issuance / transmission means for issuing the common key information and transmitting it to the encryption device and / or the decryption device;
The encryption device and / or the decryption device are:
Key information storage means for storing the common key information;
A key information updating means for updating the common key information stored in the key information storage means with new common key information transmitted by the key information issuing / transmitting means; Information update system.   The key information storage means provided in the decryption device is a plurality of key information storage means for storing one or more different common key information, and the common key before being updated by the key information update means 16. The key information update system according to claim 15, which stores and stores information.   The encryption device according to claim 4 or the decryption device according to claim 12, wherein the pseudo-random number is a hash value generated based on a hash function.   The encryption device according to claim 1, the decryption device according to claim 9, and the encryption / decryption according to claim 13 or 14, wherein the storage medium is a wireless contactless IC memory. A key information update system according to claim 15 or 16.

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