Communication system and communication method

The present invention relates to a communication system composed of a medium including an IC chip not equipped with a processor for cryptographic calculation and an information processing device for reading and writing data in the medium, and a communication method thereof.

Currently, a large amount of information is communicated between various media (IC cards, mobile phones, etc.) and information processing terminals via a predetermined transmission line. In the transmission line where information is communicated, a third party (a person other than the sender and the receiver) may eavesdrop or falsify the data being communicated.

Therefore, in order to enhance the security of data, a method of encrypting information is used. Even if the encrypted data can be eavesdropped by communicating the encrypted data, it is difficult for a third party to read the communicated information from the data.

As an encryption method, a method of generating encryption (data actually transmitted) from plain text (information to be transmitted) using a specific encryption method and key is often used. The recipient obtains the decrypted and transmitted information using the same encryption method and key.

There are two types of such encryption: common key cryptography and public key cryptography. In common key cryptography, the key for encryption (encryption key data) and the key for decryption (decryption data) are the same. On the other hand, in public key cryptography, the encryption key data and the decryption key data are different. The sender has two keys, a personal key and a public key, and sends the public key to the recipient. The sender uses the private key to encrypt, and the recipient uses the public key to decrypt.

FIG. 10 shows an example of secret communication using such a key. The sender 81 encrypts the information to be transmitted (plaintext M) into encryption C using the key K. Then, the sender 81 transmits the cipher C to the receiver 83 via a predetermined transmission line. The receiver 83 receives the cipher C, decrypts the cipher C using the same key K as the key K possessed by the sender 81, and acquires the information transmitted from the sender 81.

In this way, it is possible to ensure the confidentiality of the data by encrypting it, but it is also necessary to ensure that the transmitted data is not tampered with. Use the message digest for that. Message digest is a method of comparing calculation results using a special calculation formula. The sender calculates the calculation result using the calculation formula in plain text, encrypts it, and sends the calculation result and the encryption. After decoding, the recipient calculates using the same formula as the sender. If the calculation result and the transmitted calculation result are compared and match, it is assumed that the data has not been tampered with.

FIG. 11 shows an example of tampering detection using the message digest. The sender 85 calculates the plaintext M using the special formula X and obtains the calculation result A. The sender 85 sends the plaintext M and the calculation result A to the receiver 87. The receiver 87 calculates the plaintext M using the same formula X as the formula X possessed by the sender 85, and obtains the calculation result B. Comparing the calculation result A and the calculation result B, if they match, it is assumed that the plaintext M has not been tampered with.

Furthermore, by combining the above public key cryptography and the message digest, it is possible to prove that the data is transmitted by the person himself / herself. This is called an electronic signature, and the reliability of data is guaranteed during electronic commerce and online shopping.

In this way, in order to enhance the security of data transmission / reception between the non-contact medium and the information treatment terminal, an IC chip has come to be mounted on the medium (see Patent Document 1). Patent Document 1 discloses an IC card on which a processor device for cryptographic calculation is mounted on an IC chip, and performs authentication with a reader / writer, encrypted communication, and the like.

<patcit num="1"><text>Japanese Patent No. 3709946</text></patcit>

<p> However, recently, instead of the IC chip built in the IC card disclosed in Patent Document 1, an inexpensive IC chip that does not have a processor for cryptographic calculation or the like has appeared in order to reduce the cost. Conventional cryptographic processing and message digest cannot be performed on media with such an IC chip built-in. As a result, in addition to being unable to perform authentication and encrypted communication of a medium that prevents eavesdropping on the transmission line, it is not possible to detect even if the data stored in the medium is illegally rewritten.</p><p> The present invention has been made in view of such a situation, and an object of the present invention is that the data stored in a medium containing an IC chip not equipped with a processor for cryptographic calculation has been illegally rewritten. It is to provide a communication system and the like that can be detected.</p>

<p> In order to achieve the above-mentioned object, the first invention is a communication in which a medium having an IC chip not equipped with a processor for cryptographic calculation and an information processing device for reading and writing data in the medium communicate data. In the system, the medium includes a first storage means for storing the unique identification number as non-rewritable and a second storage means for storing data received from the information processing apparatus as rewritable. The information processing apparatus includes, a receiving means for receiving a unique identification number stored in the first storage means and data stored in the second storage means from the medium, and the first storage means. A fraudulent rewriting detection means for detecting whether or not the received data stored in the second storage means has been illegally rewritten based on the unique identification number stored in the storage means of the above. It is a communication system characterized by. By using the communication system according to the first invention, it is possible to detect that data has been illegally rewritten even in a medium having an IC chip not equipped with a processor for cryptographic calculation.</p><p> In the first invention, the information processing apparatus encrypts a ciphertext by concatenating a unique identification number and predetermined data, and decrypts the ciphertext to obtain the unique identification number and predetermined data. The receiving means further includes a decryption means for acquiring the data, and the receiving means receives the unique identification number stored in the first storage means and the ciphertext stored in the second storage means from the medium. Then, the fraudulent rewriting detection means compares the unique identification number obtained by decrypting the received ciphertext with the unique identification number stored in the first storage means received from the medium. If they do not match, it is desirable to determine that the ciphertext received from the medium has been illegally rewritten. The effect of this is as described above in the description of the first invention.</p><p> Further, in the first invention, the information processing apparatus further includes a signature generating means for generating a signature from a concatenation of a unique identification number and predetermined data, and the receiving means is the first storage means. The unique identification number stored in the second storage means and the signature and the plain text stored in the second storage means are received from the medium, and the fraudulent rewriting detecting means receives the unique identification number and the plain text from the received unique identification number and the plain text by the signature generating means. The generated signature is compared with the signature stored in the second storage means received from the medium, and if they do not match, it is determined that the plain text received from the medium has been illegally rewritten. Things are desirable. The effect of this is as described above in the description of the first invention.</p><p> Further, in the first invention, the information processing apparatus encrypts a key concatenated with a unique identification number transmitted from the medium to generate a derived key, and the derived key is used as the encryption means and the decryption. It is desirable to use it as a means of conversion. As a result, even if the derived key is decrypted, it will not be misused in other media and is safe.</p><p> Further, in the first invention, the information processing apparatus encrypts a key concatenated with a unique identification number transmitted from the medium to generate a derived key, and uses the derived key as the signature generation means. Things are desirable. As a result, even if the derived key is decrypted, it will not be misused in other media and is safe.</p><p> The second invention is a communication method in which a medium having an IC chip not equipped with a processor for cryptographic calculation and an information processing device for reading and writing data in the medium communicate data, and the medium is a communication method. It includes a first storage means for storing the unique identification number as non-rewritable and a second storage means for storing data received from the information processing apparatus as rewritable. The step of receiving the unique identification number stored in the first storage means and the data stored in the second storage means from the medium, and the step of the information processing apparatus storing in the first storage means. The communication method is characterized by comprising a step of detecting whether or not the received data stored in the second storage means is illegally rewritten based on the unique identification number. By using the communication method according to the second invention, it is possible to detect that data has been illegally rewritten even for a medium having an IC chip that does not have a processor for cryptographic calculation.</p>

<p> INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a communication system or the like capable of detecting that data stored in a medium containing an IC chip not equipped with a processor for cryptographic calculation has been illegally rewritten.</p>

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the first embodiment will be described. FIG. 1 is a diagram showing an example of communication system 1. As shown in FIG. 1, the communication system 1 is composed of a reader / writer 3, a medium 5, a computer 7, and the like. The medium 5 is, for example, an IC card, a mobile phone, or the like. The reader / writer 3 and the medium 5 send and receive data using electromagnetic waves. When the reader / writer 3 transmits a read command to the medium 5, the medium 5 receives the read command and transmits the data instructed by the read command to the reader / writer 3.

When the reader / writer 3 transmits data to the medium 5, the medium 5 receives the data and stores the received data in the built-in rewritable RAM (Random Access Memory) 45 (FIG. 5). ..

FIG. 2 is a block diagram showing the configuration of the reader / writer 3. The hardware configuration shown in FIG. 2 is an example, and various configurations can be taken depending on the application and purpose.

In the reader / writer 3, the control unit 11 performs various processes according to the built-in program. In addition, data is called from the memory 15 and the data is stored in the memory 15.

Further, the control unit 11 communicates with the computer 7 via the interface 13.

The memory 15 stores data used for processing in the control unit 11, a key used for encryption and decryption, and the like.

The encryption unit 17 encrypts the data supplied from the control unit 11 with a predetermined key, and outputs the encrypted data (encryption) to the transmission unit 19.

The transmission unit 19 modulates the data (encryption) supplied from the encryption unit 17 by a predetermined modulation method, and transmits the generated modulated wave to the medium 5 via the antenna unit 21.

The receiving unit 23 receives the modulated wave transmitted from the medium 5 via the antenna unit 21, demodulates it by a demodulation method corresponding to the modulated wave, and outputs the demodulated data (encryption) to the decoding unit 25.

FIG. 3 is a block diagram showing a configuration example of the encryption unit 17 of FIG. Key storage unit 29 Holds the key supplied by the control unit 11.

The data randomization unit 27 reads the key from the key storage unit 29, encrypts the data supplied from the control unit 11 with the key, and outputs the generated encryption to the transmission unit 19.

FIG. 4 is a block diagram showing a configuration example of the decoding unit 25 of FIG. The conversion unit 31 reads the key from the key storage unit 29, decrypts the data (encryption) supplied from the reception unit 23 with the key, and outputs the decrypted data to the control unit 11.

FIG. 5 is a block diagram showing the configuration of the medium 5, which is an embodiment of the present invention. The control unit 41 receives a command supplied by the reader / writer 3 via the antenna unit 49 and the receiving unit 51, and performs processing corresponding to the command. Then, the response data corresponding to the result of the processing is output to the transmission unit 47.

Further, the control unit 41 reads the unique identification number IDa stored in the ROM (Read Only Memory) 43 and the data stored in the RAM 45 in response to the command.

The ROM 43 is a non-volatile memory, and stores the unique identification number IDa determined for each medium 5 as non-rewritable.

The RAM 45 stores the data processed by the control unit 41 as rewritable.

Next, the details of the communication process according to the first embodiment will be described with reference to FIG.

FIG. 6 is a sequence diagram showing details of the communication process according to the first embodiment. As shown in FIG. 6, the reader / writer 3 and the medium 5 perform their own processing (indicated by a box) while exchanging messages (indicated by arrows) with each other. The specific data used for processing will be indicated by symbols.

The medium 5 receives the read command transmitted by the reader / writer 3 (S101), reads the unique identification number IDa stored in the ROM 43 (S102) in response to the command, and further stores the ciphertext stored in the RAM 45. Read statement C1 (S103). The read unique identification number IDa and ciphertext C1 are transmitted to the reader / writer 3 (S104).

The reader / writer 3 receives the IDa and C1 transmitted by the medium 5, and decrypts the ciphertext C1 into the plaintext V1 and the unique identification number ID1 by the decryption unit 25 (S105). The reader / writer 3 compares the IDa transmitted by the medium 5 with the ID1 obtained by decoding (S106), and if they match, determines that the data on the medium 5 has not been tampered with, and executes the business application. If IDa and ID1 do not match, the reader / writer 3 does not perform the processing after step S107. Here, the business application is, for example, an application that performs payment of electronic money, point addition of a point card, and the like.

The reader / writer 3 executes the business application and updates the plaintext V1 to the plaintext V2 (S107). The reader / writer 3 concatenates IDa and V2, encrypts them with the encryption unit 17, generates the ciphertext C2 (S108), and transmits C2 from the transmission unit (S109).

The medium 5 receives the encrypted C2 transmitted by the reader / writer 3 and writes the received C2 to the RAM 45 (S110).

In the first embodiment, encryption is used as a means (= fraudulent rewriting detection means) for detecting whether or not the data on the medium 5 is illegally rewritten. According to the first embodiment, it is possible to detect that the data has been illegally rewritten even for the medium 5 in which the IC chip not equipped with the processor for cryptographic calculation is built.

The reader / writer 3 has been described as performing encryption and decryption using the key stored in the memory 15, but the present invention is not limited to this. For example, the reader / writer 3 may perform encryption and decryption by using a derived key generated by concatenating the unique identification number IDa transmitted by the medium 5 and the key stored in the memory 15. .. As a result, even if the derived key is decrypted, there is no concern that it will be misused in other media 5.

Next, the second embodiment will be described. In the second embodiment, the signature is used as a means for detecting fraudulent rewriting. Hereinafter, the same elements as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 7 is a block diagram showing the configuration of the reader / writer 3. The signature generation unit 61 calculates the data supplied from the control unit 11 by a predetermined calculation formula, and outputs the generated signature to the transmission unit 19.

FIG. 8 is a block diagram showing a configuration example of the signature generation unit 61 of FIG. The key storage unit 63 stores the key required for signature generation, the signature generation unit 61 reads the key from the key storage unit 63, generates a signature with the data supplied from the control unit 11, and outputs the signature to the transmission unit 19. To do.

Next, the details of the communication process according to the second embodiment will be described with reference to FIG.

FIG. 9 is a sequence diagram showing details of the communication process according to the second embodiment. The reader / writer 3 transmits a read command to the medium 5 (S111). The medium 5 receives the command transmitted by the reader / writer 3, and reads the unique identification number IDa from the ROM 43 in response to the command (S112). In addition, the plaintext V1 and signature T1a are read from RAM45 (S113). The medium 5 transmits IDa, V1, and T1a to the reader / writer 3 (S114). The reader / writer 3 concatenates V1 and IDa to generate the signature T1b (S115). The reader / writer 3 compares the T1a transmitted by the medium 5 with the generated T1b (S116), and if they match, determines that the data on the medium 5 has not been tampered with and executes the business application. If they do not match, the processing after step S117 is not performed. The reader / writer 3 executes the business application and updates the plaintext V1 to the plaintext V2 (S117). IDa and V2 are concatenated to generate a signature T1c (S118), and V2 and T1c are transmitted to medium 5 (S119).

The medium 5 receives V2 and T1c transmitted by the reader / writer 3 and stores them in the RAM 45 (S120).

In the second embodiment, the signature is used as a means for detecting fraudulent rewriting. According to the second embodiment, it is possible to detect whether or not the data has been tampered with even in the medium 5 incorporating an IC chip that does not have a processor for cryptographic calculation or the like.

The reader / writer 3 has explained that the signature process is performed using the key stored in the memory 15, but the present invention is not limited to this. For example, the reader / writer 3 may perform signature processing by using a derived key generated by concatenating the unique identification number IDa transmitted by the medium 5 and the key stored in the memory 15 and encrypting the key. As a result, even if the derived key is decrypted, there is no concern that it will be misused in other media 5.

Further, the reader / writer 3 may perform both the encryption process in the first embodiment and the signature process in the second embodiment. Then, the reader / writer 3 may execute the business application only when it is determined that the data on the medium 5 has not been tampered with in both processes. This increases the accuracy of detecting unauthorized rewriting.

Further, in the embodiment of the present invention, it has been described that the reader / writer 3 alone detects unauthorized rewriting and executes a business application as an information processing device, but the present invention is not limited to this. For example, the reader / writer 3 may only send and receive data to and from the medium 5, and the computer 7 may detect unauthorized rewriting and execute a business application. In this case, the reader / writer 3 and the computer 7 are integrated to form an information processing device.

Although preferred embodiments of the communication system 1 and the like according to the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modified examples or modified examples within the scope of the technical idea disclosed in the present application, and these also naturally belong to the technical scope of the present invention. Understood.

<figref num="1">The figure which shows an example of the communication system 1.</figref><figref num="2">The figure which shows the structure of the reader / writer 3 which performs the encryption process.</figref><figref num="3">Block diagram showing a configuration example of the encryption unit 17</figref><figref num="4">Block diagram showing a configuration example of the decoding unit 25</figref><figref num="5">Block diagram showing a configuration example of medium 5</figref><figref num="6">A sequence diagram showing details of communication processing according to the first embodiment</figref><figref num="7">The figure which shows the structure of the reader / writer 3 which performs a signature process.</figref><figref num="8">Block diagram showing a configuration example of the signature generation unit 61</figref><figref num="9">A sequence diagram showing details of communication processing according to the second embodiment</figref><figref num="10">Block diagram showing an example of communication using secret encryption</figref><figref num="11">Block diagram showing an example of communication using message digest</figref>

Code description

1 ......... Communication system 3 ......... Reader / Writer 5 ......... Medium 7 ......... Computer 11 ......... Control unit 13 ......... Interface 15 ......... Memory 17 ......... Cryptography 19 ......... Transmitter 21 ......... Antenna part 23 ......... Receiver 25 ......... Decoding part 27 ......... Data Randomization Department 29 ......... Key storage 31 ......... Conversion unit 41 ......... Control unit 43 ......... ROM 45 ......... RAM 47 ......... Transmitter 49 ......... Antenna part 51 ......... Receiver 61 ......... Signature generator 63 ......... Key storage