JP2013073257A - Mutual authentication system and mutual authentication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm authenticity of a device connected to a signal transmission line without providing an authentication engine in a master unit.SOLUTION: In a mutual authentication system for transmitting/receiving data between a plurality of devices and a host connected through a transmission line and having the host successively authenticate the plurality of devices, by making mutual authentication be executed between the devices connected to the transmission line and making the host authenticate the device connected to the transmission line on the basis of a result of the mutual authentication, the device connected to the transmission line is authenticated just by connecting one already authenticated device to the transmission line.

Description

  The present invention relates to a mutual authentication system and a mutual authentication method, and more particularly to a technique suitable for use by a host to authenticate a plurality of devices connected via an I2C bus.

  With the development of information processing technology, a large amount of information is communicated via a predetermined transmission path. In many transmission paths through which information is communicated, a third party (a person other than the sender and the receiver) can eavesdrop on the data being communicated.

  When communication is performed using such a transmission line without leaking information to a third party, encryption is often used. Even if the encrypted data can be eavesdropped by communicating the encrypted data using encryption, it is difficult for a third party to read the content of the communicated information from the data. .

  As an encryption method for generating such a cipher, a method for generating a cipher (data to be actually transmitted) from plain text (information to be transmitted) using a predetermined key is often used.

  There are two types of encryption using a key, common key encryption and public key encryption. In common key cryptography, the key for encryption (encryption key data) and the key for decryption (decryption key data) are the same. For example, a DES (Data Encryption Standard) method, which is one of Feistel ciphers, is often used as a common key cipher. On the other hand, in public key cryptography, encryption key data and decryption key data are different. Then, for the sender, the receiver publishes the encryption key data out of those keys, but hides the decryption key data without revealing it (that is, the decryption key data is stored in the receiver). Only know).

  However, in the above-described authentication method, a predetermined transmitter / receiver only authenticates other transmitter / receivers, and therefore, for example, the above-described authentication method is applied to a card system including a reader / writer device (master device) and an IC card. When the authentication method is applied, the reader / writer device can determine whether or not the communication partner is a regular IC card (authenticate the communication partner). / It has a problem that it is difficult to determine whether or not it is a writer device.

  In order to solve the above-described problems, for example, in Patent Document 1, a plurality of information processing apparatuses transmit plaintext to each other, receive transmitted plaintext, and encrypt the received plaintext. Encrypt and send the cipher to the device that sent the plaintext, receive the sent cipher and compare the plaintext that was decrypted with the plaintext that was sent first to authenticate each other Such an authentication method has been proposed.

Japanese Patent Laid-Open No. 10-020780

  In the authentication method described in Patent Document 1, the reader / writer device and the IC card authenticate each other. For this reason, it is necessary to provide the reader / writer device with a dedicated authentication engine.

In addition, the burden of developing the code for the control CPU software designated by the user for each user who uses the IC card, and the troublesome security management that occurs to disclose the developed code (confidentiality protection) Burden) was also a heavy burden.
In view of the above-described problems, an object of the present invention is to make it possible to confirm the authenticity of a device connected to a transmission path without the master unit having an authentication engine.

The mutual authentication system of the present invention is a mutual authentication system in which data is transmitted and received between a plurality of devices and a host connected via a transmission path, and the plurality of devices are sequentially authenticated by the host,
In the host, device determination means for determining a first device and a second device to be mutually authenticated among the plurality of devices connected via the transmission path;
In the host, first and second commands for instructing mutual authentication by designating the first and second devices determined by the device determination means, and mutual authentication from the first device Command generating means for generating a third command for instructing to read the result;
In the host, host side transmission means for transmitting the first command generated by the command generation means to the first and second devices via the transmission path;
In the first device, first device-side receiving means for receiving the first command transmitted by the host;
Second device-side receiving means for receiving the first command transmitted by the host in the second device;
First device-side random number data generating means for generating first random number data in the first device;
In the second device, second device-side random number data generating means for generating second random number data;
In the first device, the first and second devices commonly hold the first random number data in accordance with the first command received by the first device-side receiving means. First device side encryption means for generating first encrypted data by encrypting using one key data;
In the second device, in response to the first command received by the second device-side receiving means, the second random number data is converted into second encrypted data using the first key data. Second device side encryption means for generating
In the first device, first device-side transmission means for transmitting the first encrypted data to the host via the transmission path;
In the second device, second device side receiving means for receiving the first encrypted data transmitted by the first device;
In the second device, a second device-side decryption that obtains a first decryption result from the first encrypted data received by the second device-side receiving means using the first key data And
In the second device, a calculation is performed between the first decryption result obtained by the second device-side decryption means and the second random number data, and a second computation result is obtained. Device side computing means,
In the second device, second device-side transmission means for transmitting the second encrypted data generated by the second device-side encryption means to the host via the transmission path;
A first device-side receiving means for receiving the second encrypted data transmitted by the second device in the first device;
In the first device, the first device that decrypts the second encrypted data received by the first device-side receiving means using the first key data and obtains a second decryption result. Side decryption means;
In the first device, a calculation is performed between the second decoding result obtained by the first device-side decoding means and the first random number data, and a first calculation result is obtained. 1 device side computing means;
Host side transmission means for transmitting the second command generated by the command generation means in the host to the first and second devices via the transmission path;
First device-side receiving means for receiving the second command transmitted by the host in the first device;
Second device-side receiving means for receiving the second command transmitted by the host in the second device;
In the first device, the first and second devices commonly hold the first calculation result according to the second command received by the first device-side receiving unit. First device-side encryption means for generating third encrypted data by encrypting using the key data of
In the second device, in accordance with the second command received by the second device-side receiving means, the second calculation result is encrypted with the second key data, and the fourth device Second device side encryption means for generating encrypted data;
The first device transmits the third encrypted data to the host via the transmission path according to the second command received by the first device-side receiving unit. A device-side transmission means;
In the second device, second device-side receiving means for receiving the third encrypted data transmitted by the first device;
In the second device, a second device that obtains a third decryption result by decrypting the third encrypted data received by the second device-side receiving means using the second key data Side decryption means;
In the second device, a second device-side authentication unit that authenticates the first device by determining whether the third decryption result and the second calculation result match / mismatch,
In the second device, if the determination result by the second device-side authentication means is coincident, it is determined that the first device has been authenticated, and the fourth encrypted data is transmitted via the transmission path. To the host,
In the case of mismatch, it is determined that the first device has not been authenticated, and third random number data different from the second calculation result is generated by the second device-side random number data generation means, Using the second key data, the third random number data is encrypted by the second device side encryption unit according to the second command received by the second device side reception unit. Second device-side authentication result transmitting means for generating fifth encrypted data and transmitting the fifth encrypted data to the host via the transmission path;
In the first device, first device-side receiving means for receiving the fourth encrypted data or the fifth encrypted data transmitted by the second device;
In the first device, the fourth encrypted data or the fifth encrypted data received by the first device-side receiving means is decrypted by using the second key data to obtain a fourth First device side decoding means for obtaining a decoding result;
In the first device, first device side coincidence determining means for determining whether the fourth decoding result and the first calculation result match / do not match;
In the host, host-side transmission means for transmitting the third command generated by the command generation means to the first device via the transmission path;
In the first device, first device-side receiving means for receiving the third command transmitted by the host;
In the first device, the result determined in the first device-side coincidence determination stage in accordance with the third command received by the first device-side receiving means is transmitted via the transmission path. First device-side coincidence determination result transmission means for transmitting to the host;
In the host, host-side receiving means for receiving the determination result in the first device-side coincidence determining means transmitted from the first device;
A first device-side mutual authentication means for determining a mutual authentication result with the second device based on a result determined by the first device-side match determination means in the first device;
In the host, an authentication result determination unit that determines a mutual authentication result of the first and second devices based on a determination result of the first device side match determination unit received by the host side reception unit. It is characterized by having.

The mutual authentication method of the present invention is a mutual authentication method in which data is transmitted / received between a plurality of devices and a host connected via a transmission path, and the plurality of devices are sequentially authenticated by the host,
A device determining step of determining, by the device determining means, a first device and a second device to be mutually authenticated among the plurality of devices connected via the transmission path;
The host designates the first and second devices determined in the device determination step, and instructs to perform mutual authentication. From the first and second commands and the first device A command generation step of generating the third command by the command generation means, instructing to read a mutual authentication result;
In the host, the host-side transmission step of transmitting the first command generated in the command generation step to the first and second devices via the transmission path by the host-side transmission unit;
In the first device, in the host side transmission step, the first device side reception step of receiving the first command transmitted by the host by the first device side reception unit;
In the second device, in the host-side transmission step, the second device-side reception step of receiving the first command transmitted by the host by the second device-side reception unit;
In the first device, a first device-side random number data generation step of generating the first random number data by the first device-side random number data generation unit;
In the second device, a second device-side random number data generating step of generating the second random number data by the second device-side random number data generating means;
In the first device, the first and second devices commonly hold the first random number data according to the first command received in the first device-side receiving step. A first device-side encryption step of generating the first encrypted data by the first device-side encryption means using the first key data;
In the second device, in response to the first command received in the second device-side receiving step, the second random number data is converted into the second key data using the first key data. A second device side encryption step of generating the second encrypted data by the device side encryption means of
In the first device, a first device-side transmission step of transmitting the first encrypted data to the host via the transmission path by the first device-side transmission unit;
In the second device, the second device side that receives the first encrypted data transmitted by the first device in the first device-side transmission step by the second device-side receiving unit. Receiving process;
In the second device, the first encrypted data received in the second device-side receiving step is processed by the second device-side decrypting means using the first key data. A second device side decoding step of obtaining a decoding result of 1;
In the second device, calculation is performed by the second device side calculation means between the first decoding result obtained in the second device side decoding step and the second random number data. Performing a second device-side calculation step to obtain the second calculation result;
In the second device, a second device-side transmission step of transmitting the second encrypted data to the host via the transmission path by the second device-side transmission unit;
In the first device, in the second device-side transmission step, the first device receives the second encrypted data transmitted by the second device by the first device-side receiving unit. Side reception process;
In the first device, the second encrypted data received in the first device-side receiving step is decrypted by the first device-side decryption means using the first key data. A first device side decoding step for obtaining the second decoding result;
In the first device, calculation is performed by the first device-side calculation means between the second decoding result obtained in the first device-side decoding step and the first random number data. Performing a first device side calculation step for obtaining the first calculation result;
In the host, the host side transmission step of transmitting the second command generated in the command generation step to the first and second devices via the transmission path by the host side transmission means;
In the first device, in the host-side transmission step, the first device-side reception step of receiving the second command transmitted by the host by the first device-side reception unit;
In the second device, in the host-side transmission step, the second device-side reception step of receiving the second command transmitted by the host by the second device-side reception unit;
In the first device, the first and second devices commonly hold the first calculation result according to the second command received in the first device-side receiving step. A first device-side encryption step of generating the third encrypted data by the first device-side encryption means using the second key data;
In the second device, in accordance with the second command received in the second device side receiving step, the second operation result is converted into the second device by the second key data. A second device-side encryption step of generating the fourth encrypted data by encrypting with the side encryption means;
In the first device, the third encrypted data generated in the first device side encryption step is transmitted to the host via the transmission path by the first device side transmission means. A first device side transmission step to perform,
In the second device, the second device that receives the third encrypted data transmitted by the first device in the first device-side transmission step by the second device-side receiving unit. Side reception process;
In the second device, the second device-side decrypting means decrypts the third encrypted data received in the second device-side receiving step by using the second key data. A second device side decoding step for obtaining the third decoding result;
In the second device, the second device-side authentication means determines whether the third decryption result obtained in the second device-side decryption step matches or does not match the second calculation result. A second device-side authentication step for authenticating the first device;
In the second device, if the determination result by the second device-side authentication means in the second device-side authentication step is the same, it is determined that the first device has been authenticated, 4 encrypted data is transmitted to the host via the transmission path,
In the case of mismatch, it is determined that the first device has not been authenticated, and the third random number data different from the second calculation result is generated by the second device-side random number data generation means, In response to the second command received in the second device-side receiving step using the second key data, the third random number data is received by the second device-side encryption means, A second device-side authentication result transmitting step of generating the fifth encrypted data and transmitting the fifth encrypted data to the host via the transmission path by the second device-side authentication result transmitting means;
In the first device, in the second device-side authentication result transmission step, the second device generates and transmits the fourth encrypted data to the host via the transmission path, or A first device-side receiving step of receiving the fifth encrypted data by the first device-side receiving means;
In the first device, the fourth encrypted data or the fifth encrypted data received in the first device side receiving step is converted into the first device side by using the second key data. A first device side decoding step of decoding by a decoding means to obtain the fourth decoding result;
In the first device, whether or not the fourth decoding result obtained in the first device-side decoding step matches the first operation result is determined as the first device-side matching determination. A first device side coincidence determining step determined by means;
In the host, a host-side transmission step of transmitting the third command generated in the command generation step to the first device via the transmission path by the host-side transmission unit;
In the first device, a first device-side receiving step of receiving the third command transmitted by the host in the host-side transmitting step by the first device-side receiving unit;
In the first device, in accordance with the third command received in the first device-side receiving step, the determination result in the first device-side coincidence determining means is displayed on the first device side. A first device-side coincidence determination result transmission step of transmitting to the host via the transmission path by a coincidence result transmission unit;
In the host, in the first device side coincidence determination result transmission step, the determination result in the first device side coincidence determination unit that is transmitted from the first device is received by the host side reception unit. A host-side receiving process,
In the first device, a first device-side mutual authentication result step of determining a mutual authentication result with the second device based on a determination result in the first device-side coincidence determining unit;
In the host, based on the determination result in the first device-side coincidence determining unit received in the host-side receiving step, the mutual authentication result of the first and second devices is determined by the authentication result determining unit. An authentication result determination step for determining,
Devices that are not designated as the first and second devices by the first and second commands transmitted from the host do not participate in the mutual authentication operation and are on standby.

  According to the present invention, it is possible to confirm the authenticity of a device connected to a transmission path without the master unit having an authentication engine.

It is a figure which shows embodiment of this invention and shows the example of a whole structure of a mutual authentication system. It is a figure which shows embodiment of this invention and shows the structural example of a main | base station. It is a figure which shows embodiment of this invention and shows the structural example of a 1st device. It is a figure which shows embodiment of this invention and shows the structural example of a 2nd device. It is a timing chart which shows the embodiment of the present invention and explains the procedure of performing mutual authentication.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a mutual authentication system according to an embodiment of the present invention.
As shown in FIG. 1, in the mutual authentication system of the present embodiment, a plurality of devices A11, B12, C13... Are connected to a host (master unit) 10 through an I2C (Inter-Integrated Circuit) transmission path. 14 is connected.

  The host 10 determines whether the devices 11 to 13 connected to the transmission line 14 are true or false, and releases the access restriction only for the true devices. In order to determine whether or not a device connected to the transmission line 14 is a true device, generally, the host 10 includes a dedicated authentication engine for authentication, and between the host 10 and the device to be authenticated. Mutual authentication algorithm needs to be executed. In the present embodiment, the authenticity of the device connected to the transmission path 14 can be determined without providing the host 10 with a dedicated authentication engine for authentication.

  As shown in FIG. 1, a memory 11a is provided in the first device A11 of the present embodiment, and “first and second key data KA, KB” are stored in the memory 11a. In addition, the memory 12a is disposed in the second device B12, and “first and second key data KA, KB” are stored in the memory 12a. In addition, the memory 13a is disposed in the third device C13, and “first and second key data KA, KB” are stored in the memory 13a.

  However, since the host 10 of the present embodiment does not perform mutual authentication with the device connected to the transmission path 14, the memory 10a does not store "first and second key data KA, KB". . FIG. 2 shows a schematic configuration example of the host 10.

  As shown in FIG. 2, in the host 10, the control unit 21 performs various processes according to a built-in program. For example, the control unit 21 controls the command generation unit 23 to generate a command to be transmitted to a device that performs mutual authentication, and controls the generated command to be output to the transmission unit 24.

  The memory 22 stores data used for processing in the control unit 21. The transmission unit 24 transmits the command supplied from the command generation unit 23 to the device that performs mutual authentication via the I / F unit 25 and the transmission path 14.

  The reception unit 26 outputs the data transmitted by the device that performs mutual authentication to the authentication result determination unit 27 via the I / F unit 25.

  Under the control of the control unit 21, the authentication result determination unit 27 determines the authenticity of the authentication result transmitted from the device connected to the transmission path 14 based on the data supplied from the reception unit 26, and the determination result Is output to the control unit 21 or the data supplied from the reception unit 26 is output to the control unit 21 as it is.

FIG. 3 is a block diagram illustrating a configuration example of the first device according to the embodiment of the present invention.
In the first device, the control unit 31 performs various processes in accordance with commands supplied from the host 10. Specifically, a command from the host 10 is received from the receiving unit 36, processing corresponding to the command is performed, and random number data, calculation results, response data, and reading from the memory 32 generated corresponding to the processing result are read out. Data and the like are output to the encryption unit 33.

  The memory 32 includes a RAM (Random Access Memory) unit (and a ROM (Read Only Memory) unit. The RAM unit temporarily stores data used for processing in the control unit 31. On the other hand, a device address unique to the device and “first and second key data KA, KB” used for encryption or decryption are stored in advance in the ROM section.

The encryption unit 33 encrypts the data to be encrypted supplied from the control unit 31 with a predetermined key, outputs the encrypted data to the transmission unit 34, and does not encrypt the data supplied from the control unit 31. In this case, the data is output to the transmission unit 34 as it is.
The transmission unit 34 outputs the data supplied from the encryption unit 33 to the transmission path 14 via the I / F unit 35 and transmits the data to the host 10.

The receiving unit 36 receives the data sent via the transmission path 14 via the I / F unit 35 and outputs the data to the decoding unit 37.
The decryption unit 37 decrypts the data supplied from the reception unit 36 with a predetermined key according to the control of the control unit 21, and outputs the decrypted data to the control unit 31 or outputs it to the control unit 31 as it is. .

  FIG. 4 is a block diagram showing a configuration example of the second device according to the embodiment of the present invention. The configuration of the second device is exactly the same as the configuration of the first device shown in FIG. 3, but will be described separately in FIGS. 3 and 4 for easy understanding of the operation.

  Next, the outline of the process of the mutual authentication system of this embodiment will be described with reference to FIG. Note that data transmission performed in each step, which shows processing steps in FIG. 5, is performed via the transmission path 14.

(Step S1)
The host 10 designates the first and second device addresses to be mutually authenticated, further adds the first scrambled data X generated as random number data, and sends the first mutual authentication command 1 from the transmitting unit 24 to the I The data is transmitted to the transmission line 14 via the / F unit 25. For example, the first mutual authentication command 1 is transmitted by designating the first device A11 and the second device B12.

  In the present embodiment, it is confirmed in advance that the first device A11 is a true device. Therefore, mutual authentication is performed between the first device A11 and the second device B12 in accordance with the first to third mutual authentication commands 1 to 3, and the “first” stored in the memory 11a of the first device A11. 1 and second key data KA and KB ”and“ first and second key data KA and KB ”stored in the memory 12a of the second device B12 match, and the mutual authentication algorithm calculation is the same. In the case of correctly responding to the operation control, the second device B12 is authenticated by the host 10 as a true device. A device whose device address is not designated waits without participating in the mutual authentication operation.

The first device A <b> 11 receives the first mutual authentication command 1 transmitted from the host 10 to the transmission path 14 by the receiving unit 36 via the I / F unit 35.
The second device B 12 receives the first mutual authentication command 1 transmitted from the host 10 to the transmission path 14 by the receiving unit 46 via the I / F unit 45.

In the first device A11 whose device address is designated as the first device by the first mutual authentication command 1 transmitted from the host 10, the control unit 31 generates the first random number Ra.
In the second device B12 whose device address is designated as the second device by the first mutual authentication command 1 transmitted from the host 10, the control unit 41 generates the second random number Rb.
The first device A11 uses the “first key data KA” stored in the memory 11a and the first scrambled data X added to the first mutual authentication command 1 sent from the host 10. The first random number Ra is encrypted by the encryption unit 33 to obtain first encrypted data.
The second device B 12 receives the “first key data KA” stored in the memory 12 a and the first scrambled data X added to the first mutual authentication command 1 sent from the host 10. Then, the second random number Rb is encrypted by the encryption unit 43 to obtain second encrypted data.

(Step 2)
The first device A11 transmits the first encrypted data to the host 10 via the transmission unit 34, the I / F unit 35, and the transmission path 14.
The second device B 12 receives the first encrypted data transmitted from the first device A 11 to the host 10 via the transmission path 14 by the receiving unit 46 via the I / F unit 45.
The second device B12 performs a reverse operation in the decryption unit 47 using the “first key data KA” stored in its own memory 12a and the first scrambled data X, in the received first encrypted data. And decoding is performed to obtain first decoded data Ra ′.
In the second device B12, the control unit 41 performs a predetermined logical operation between the second random number Rb and the first decrypted data Ra ′ decrypted by performing the reverse operation in the decoding unit 47. 2 is obtained [Rb ◆ Ra '].
Furthermore, since the explanation is supplemented by a logical operation, an exchange law is established, and therefore there is a relation of [Rb ◆ Ra ′] = [Ra ′ ◆ Rb].
The logical operation is preferably performed by combining exclusive OR operation, bit shift, bit order rearrangement, data inversion of specific bits, and the like.

(Step S3)
The second device B 12 transmits the second encrypted data to the host 10 via the transmission unit 44, the I / F unit 45, and the transmission path 14.
The first device A11 receives the second encrypted data transmitted from the second device B12 to the host 10 via the transmission path 14 by the receiving unit 36 via the I / F unit 35.

The first device A11 decrypts the received second encrypted data using the “first key data KA” stored in the memory 11a and the first scrambled data X by the reverse operation by the decryption unit 37. The second decoded data Rb ′ is obtained.
In the first device A11, the control unit 31 performs a predetermined logical operation between the first random number Ra and the second decrypted data Rb ′ decrypted by performing the reverse operation in the decoding unit 37. 1 operation result [Ra <R> Rb '] is obtained.

(Step S4)
The host 10 again designates the first and second device addresses to be mutually authenticated, further adds the second scramble data Y generated as random number data, and sends the second mutual authentication command 2 to the I / F unit. 25 to the transmission line 14. A device whose address is not specified waits without participating in the mutual authentication operation.

The first device A11 receives the second mutual authentication command 2 transmitted from the host 10 to the transmission path 14 by the receiving unit 36 via the I / F unit 35.
The second device B 12 receives the second mutual authentication command 2 transmitted from the host 10 to the transmission path 14 by the receiving unit 46 via the I / F unit 45.
The first device A11 has sent the first operation result [Ra ◆ Rb ′] obtained by performing the logical operation from the host 10 and the “second key data KB” stored in the memory 11a. Using the first and second scrambled data X and Y added to the first and second mutual authentication commands 1 and 2, the encryption unit 33 encrypts the third encrypted data.
The second device B12 has received the second operation result [Rb ◆ Ra ′] obtained by performing the logical operation from the host 10 and the “second key data KB” stored in the memory 12a. Using the first and second scrambled data X and Y added to the first and second mutual authentication commands 1 and 2, encryption is performed by the encryption unit 43 to obtain fourth encrypted data.

(Step S5)
The first device A11 transmits the third encrypted data to the host 10 via the transmission unit 34, the I / F unit 35, and the transmission path 14.
The second device B 12 receives the third encrypted data transmitted from the first device A 11 to the host 10 via the transmission path 14 by the receiving unit 46 via the I / F unit 45.
The second device B12 uses the “second key data KB” stored in its own memory 12a and the first and second scrambled data X and Y to store the received third encrypted data in the decrypting unit 37. Then, the reverse operation is performed to perform decryption to obtain third decrypted data [Ra ◆ Rb ′] ′.
The second device B12 detects a match / mismatch between the second calculation result [Rb ◆ Ra ′] and the third decoded data [Ra ◆ Rb ′] ′.

(Step S6)
When the second operation result [Rb ◆ Ra ′] and the third decrypted data [Ra ◆ Rb ′] ′ match, the second device B12 sends the fourth encrypted data to the transmission unit 34, I The data is transmitted to the host 10 via the / F unit 35 and the transmission path 14.
Further, the second device B12 determines that mutual authentication has been established, and releases a predetermined access restriction for access to the second device B12.
The second device B12 generates a third random number Rc when the second calculation result [Rb ◆ Ra ′] and the third decrypted data [Ra ◆ Rb ′] ′ do not match.
Further, when the third random number Rc = second calculation result [Rb ◆ Ra ′] or when the third random number Rc = third decrypted data [Ra ◆ Rb ′] ′, The third random number Rc is generated again.
The second device B12 is sent in addition to the “second key data KB” stored in the memory 12a and the first and second mutual authentication commands 1 and 2 sent from the host 10. Using the first and second scrambled data X and Y, the third random number Rc is encrypted by the encryption unit 43 to obtain fifth encrypted data, and the fifth encrypted data is transmitted to the transmission unit 44, I / The data is transmitted to the host 10 via the F unit 45 and the transmission path 14.
In this case, the second device B12 determines that mutual authentication has not been established, and does not release a predetermined access restriction for access to the second device B12.

The first device A11 transmits the fourth encrypted data or the fifth encrypted data to be transmitted from the second device B12 to the host 10 via the transmission unit 44 and the I / F unit 45 transmission path 14. The signal is received by the receiving unit 36 via the F unit 35.
The first device A11 uses the received second encrypted data or fifth encrypted data in the memory 11a as the “second key data KB” and the first and second scrambled data X and Y. Then, the decoding unit 37 performs reverse calculation and decoding to obtain fourth decoded data [Rb ◆ Ra ′] ′ or Rc ′.
The first device A11 determines whether or not the fourth decoded data [Rb ′ ◆ Ra] ′ or Rc ′ and the first calculation result [Ra ◆ Rb ′] match or do not match to determine whether the first device matches. Data T is obtained.

(Step S7)
The host 10 designates the first device address, adds the third scramble data Z generated as random number data, and sends the third mutual authentication command 3 for inquiring the result of mutual authentication to the I / F unit 25. Via the transmission line 14. A device whose device address is not designated waits without participating in the mutual authentication operation.
The first device A11 receives the third mutual authentication command 3 transmitted from the host 10 to the transmission path 14 by the receiving unit 36 via the I / F unit 35.

(Step S8)
The first device A11 receives the first to third scrambled data X, Y, and Z added to the first, second, and third mutual authentication commands 1, 2, and 3 sent from the host 10. The first device side coincidence determination data T is scrambled and transmitted to the host 10 via the transmission unit 34, I / F unit 35, and transmission path 14.
The host 10 receives the first device-side coincidence determination data T that is scrambled and transmitted by the first device A11 via the I / F unit 25 and the receiving unit 26.

If the first device-side match determination data T indicates a match, the first device A11 determines that mutual authentication has been established, and releases a predetermined access restriction for access to the first device A11. To do.
Further, the first device A11 determines that mutual authentication has not been established when the first device-side match determination data T does not indicate a match, and restricts the predetermined access restriction for access to the first device A11. Do not open.

The host 10 sends the scrambled first device-side match determination data T received by the reception unit 26 to the authentication result determination unit 27.
The host 10 detects the first device-side coincidence determination data T using the first to third scramble data X, Y, and Z sent from the host 10 by the authentication result determination unit 27 and sends the first device-side match determination data T to the control unit 27. Based on the determination result, the mutual authentication result between the first device A11 and the second device B12 is determined, and the host 10 can access the restricted areas of the first device A11 and the second device B12. It is judged whether it became or is not possible.

  As described above, by performing mutual authentication between the first device A11 and the second device B12, the host 10 does not perform arithmetic processing for authenticating the authenticity of the second device B12. It can be reliably determined that the second device B12 is a true device.

  Thereby, the burden of the development cost of the host 10 can be reduced as compared with the case where the dedicated authentication engine is provided. Further, the control CPU of the host 10 can be responded to a request from a user who has already been developed or who wants to use the host 10 by taking over past assets. Furthermore, since the host 10 does not have “key data”, the troublesome security management can be eliminated. Furthermore, if the first device A11 is upgraded, various advantages can be obtained, such as updating to a new security system without imposing a burden on the control CPU of the host 10.

10 Host 10a Memory 11 First device A
11a Memory 12 Second device B
12a Memory 13 Third device C
13a memory 14 transmission path 21 host-side control unit 22 host-side memory 23 host-side command generation unit 24 host-side transmission unit 25 host-side I / F unit 26 host-side reception unit 27 host-side authentication result determination Units 31 and 41 Device side control units 32 and 42 Device side memory 33 and 43 Device side encryption units 34 and 44 Device side transmission units 35 and 45 Device side I / F units 36 and 46 Device side reception units 37, 47 Device-side decoding unit S1 to S8

Claims (4)

In a mutual authentication system in which data is transmitted and received between a plurality of devices and a host connected via a transmission path, and the plurality of devices are sequentially authenticated by the host,
In the host, device determination means for determining a first device and a second device to be mutually authenticated among the plurality of devices connected via the transmission path;
In the host, first and second commands for instructing mutual authentication by designating the first and second devices determined by the device determination means, and mutual authentication from the first device Command generating means for generating a third command for instructing to read the result;
In the host, host side transmission means for transmitting the first command generated by the command generation means to the first and second devices via the transmission path;
In the first device, first device-side receiving means for receiving the first command transmitted by the host;
A second device-side receiving means for receiving the first command transmitted by the host in the second device; and a first device-side random number for generating first random number data in the first device. Data generation means;
In the second device, second device-side random number data generating means for generating second random number data;
In the first device, the first and second devices commonly hold the first random number data in accordance with the first command received by the first device-side receiving means. First device side encryption means for generating first encrypted data by encrypting using one key data;
In the second device, in response to the first command received by the second device-side receiving means, the second random number data is converted into second encrypted data using the first key data. Second device side encryption means for generating
In the first device, first device-side transmission means for transmitting the first encrypted data to the host via the transmission path;
In the second device, second device side receiving means for receiving the first encrypted data transmitted by the first device;
In the second device, a second device-side decryption that obtains a first decryption result from the first encrypted data received by the second device-side receiving means using the first key data And
In the second device, a calculation is performed between the first decryption result obtained by the second device-side decryption means and the second random number data, and a second computation result is obtained. Device side computing means,
In the second device, second device-side transmission means for transmitting the second encrypted data generated by the second device-side encryption means to the host via the transmission path;
A first device-side receiving means for receiving the second encrypted data transmitted by the second device in the first device;
In the first device, the first device that decrypts the second encrypted data received by the first device-side receiving means using the first key data and obtains a second decryption result. Side decryption means;
In the first device, a calculation is performed between the second decoding result obtained by the first device-side decoding means and the first random number data, and a first calculation result is obtained. 1 device side computing means;
Host side transmission means for transmitting the second command generated by the command generation means in the host to the first and second devices via the transmission path;
First device-side receiving means for receiving the second command transmitted by the host in the first device;
Second device-side receiving means for receiving the second command transmitted by the host in the second device;
In the first device, the first and second devices commonly hold the first calculation result according to the second command received by the first device-side receiving unit. First device-side encryption means for generating third encrypted data by encrypting using the key data of
In the second device, in accordance with the second command received by the second device-side receiving means, the second calculation result is encrypted with the second key data, and the fourth device Second device side encryption means for generating encrypted data;
The first device transmits the third encrypted data to the host via the transmission path according to the second command received by the first device-side receiving unit. A device-side transmission means;
In the second device, second device-side receiving means for receiving the third encrypted data transmitted by the first device;
In the second device, a second device that obtains a third decryption result by decrypting the third encrypted data received by the second device-side receiving means using the second key data Side decryption means;
In the second device, a second device-side authentication unit that authenticates the first device by determining whether the third decryption result and the second calculation result match / mismatch,
In the second device, if the determination result by the second device-side authentication means is coincident, it is determined that the first device has been authenticated, and the fourth encrypted data is transmitted via the transmission path. To the host,
In the case of mismatch, it is determined that the first device has not been authenticated, and third random number data different from the second calculation result is generated by the second device-side random number data generation means, Using the second key data, the third random number data is encrypted by the second device side encryption unit according to the second command received by the second device side reception unit. Second device-side authentication result transmitting means for generating fifth encrypted data and transmitting the fifth encrypted data to the host via the transmission path;
In the first device, first device-side receiving means for receiving the fourth encrypted data or the fifth encrypted data transmitted by the second device;
In the first device, the fourth encrypted data or the fifth encrypted data received by the first device-side receiving means is decrypted by using the second key data to obtain a fourth First device side decoding means for obtaining a decoding result;
In the first device, first device side coincidence determining means for determining whether the fourth decoding result and the first calculation result match / do not match;
In the host, host-side transmission means for transmitting the third command generated by the command generation means to the first device via the transmission path;
In the first device, first device-side receiving means for receiving the third command transmitted by the host;
In the first device, the result determined in the first device-side coincidence determination stage in accordance with the third command received by the first device-side receiving means is transmitted via the transmission path. First device-side coincidence determination result transmission means for transmitting to the host;
In the host, host-side receiving means for receiving the determination result in the first device-side coincidence determining means transmitted from the first device;
A first device-side mutual authentication means for determining a mutual authentication result with the second device based on a result determined by the first device-side match determination means in the first device;
In the host, an authentication result determination unit that determines a mutual authentication result of the first and second devices based on a determination result of the first device side match determination unit received by the host side reception unit. And a mutual authentication system.   The mutual authentication system according to claim 1, wherein the first device is a previously authenticated device.   The mutual authentication system according to claim 1, wherein the transmission path is an I2C (Inter-Integrated Circuit) transmission line. A mutual authentication method in which data is transmitted and received between a plurality of devices and a host connected via a transmission path, and the host sequentially authenticates the plurality of devices,
A device determining step of determining, by the device determining means, a first device and a second device to be mutually authenticated among the plurality of devices connected via the transmission path;
The host designates the first and second devices determined in the device determination step, and instructs to perform mutual authentication. From the first and second commands and the first device A command generation step of generating the third command by the command generation means, instructing to read a mutual authentication result;
In the host, the host-side transmission step of transmitting the first command generated in the command generation step to the first and second devices via the transmission path by the host-side transmission unit;
In the first device, in the host side transmission step, the first device side reception step of receiving the first command transmitted by the host by the first device side reception unit;
In the second device, in the host-side transmission step, the second device-side reception step of receiving the first command transmitted by the host by the second device-side reception unit;
In the first device, a first device-side random number data generation step of generating the first random number data by the first device-side random number data generation unit;
In the second device, a second device-side random number data generating step of generating the second random number data by the second device-side random number data generating means;
In the first device, the first and second devices commonly hold the first random number data according to the first command received in the first device-side receiving step. A first device-side encryption step of generating the first encrypted data by the first device-side encryption means using the first key data;
In the second device, in response to the first command received in the second device-side receiving step, the second random number data is converted into the second key data using the first key data. A second device side encryption step of generating the second encrypted data by the device side encryption means of
In the first device, a first device-side transmission step of transmitting the first encrypted data to the host via the transmission path by the first device-side transmission unit;
In the second device, the second device side that receives the first encrypted data transmitted by the first device in the first device-side transmission step by the second device-side receiving unit. Receiving process;
In the second device, the first encrypted data received in the second device-side receiving step is processed by the second device-side decrypting means using the first key data. A second device side decoding step of obtaining a decoding result of 1;
In the second device, calculation is performed by the second device side calculation means between the first decoding result obtained in the second device side decoding step and the second random number data. Performing a second device-side calculation step to obtain the second calculation result;
In the second device, a second device-side transmission step of transmitting the second encrypted data to the host via the transmission path by the second device-side transmission unit;
In the first device, in the second device-side transmission step, the first device receives the second encrypted data transmitted by the second device by the first device-side receiving unit. Side reception process;
In the first device, the second encrypted data received in the first device-side receiving step is decrypted by the first device-side decryption means using the first key data. A first device side decoding step for obtaining the second decoding result;
In the first device, calculation is performed by the first device-side calculation means between the second decoding result obtained in the first device-side decoding step and the first random number data. Performing a first device side calculation step for obtaining the first calculation result;
In the host, the host side transmission step of transmitting the second command generated in the command generation step to the first and second devices via the transmission path by the host side transmission means;
In the first device, in the host-side transmission step, the first device-side reception step of receiving the second command transmitted by the host by the first device-side reception unit;
In the second device, in the host-side transmission step, the second device-side reception step of receiving the second command transmitted by the host by the second device-side reception unit;
In the first device, the first and second devices commonly hold the first calculation result according to the second command received in the first device-side receiving step. A first device-side encryption step of generating the third encrypted data by the first device-side encryption means using the second key data;
In the second device, in accordance with the second command received in the second device side receiving step, the second operation result is converted into the second device by the second key data. A second device-side encryption step of generating the fourth encrypted data by encrypting with the side encryption means;
In the first device, the third encrypted data generated in the first device side encryption step is transmitted to the host via the transmission path by the first device side transmission means. A first device side transmission step to perform,
In the second device, the second device that receives the third encrypted data transmitted by the first device in the first device-side transmission step by the second device-side receiving unit. Side reception process;
In the second device, the second device-side decrypting means decrypts the third encrypted data received in the second device-side receiving step by using the second key data. A second device side decoding step for obtaining the third decoding result;
In the second device, the second device-side authentication means determines whether the third decryption result obtained in the second device-side decryption step matches or does not match the second calculation result. A second device-side authentication step for authenticating the first device;
In the second device, if the determination result by the second device-side authentication means in the second device-side authentication step is the same, it is determined that the first device has been authenticated, 4 encrypted data is transmitted to the host via the transmission path,
In the case of mismatch, it is determined that the first device has not been authenticated, and the third random number data different from the second calculation result is generated by the second device-side random number data generation means, In response to the second command received in the second device-side receiving step using the second key data, the third random number data is received by the second device-side encryption means, A second device-side authentication result transmitting step of generating the fifth encrypted data and transmitting the fifth encrypted data to the host via the transmission path by the second device-side authentication result transmitting means;
In the first device, in the second device-side authentication result transmission step, the second device generates and transmits the fourth encrypted data to the host via the transmission path, or A first device-side receiving step of receiving the fifth encrypted data by the first device-side receiving means;
In the first device, the fourth encrypted data or the fifth encrypted data received in the first device side receiving step is converted into the first device side by using the second key data. A first device side decoding step of decoding by a decoding means to obtain the fourth decoding result;
In the first device, a match / mismatch between the fourth decryption result and the first calculation result obtained in the first device-side decryption step is determined as the first device-side mutual authentication. A first device side coincidence determining step determined by means;
In the host, a host-side transmission step of transmitting the third command generated in the command generation step to the first device via the transmission path by the host-side transmission unit;
In the first device, a first device-side receiving step of receiving the third command transmitted by the host in the host-side transmitting step by the first device-side receiving unit;
In the first device, in accordance with the third command received in the first device-side receiving step, the determination result in the first device-side coincidence determining means is displayed on the first device side. A first device-side coincidence determination result transmission step of transmitting to the host via the transmission path by a coincidence result transmission unit;
In the host, in the first device side coincidence determination result transmission step, the determination result in the first device side coincidence determination unit that is transmitted from the first device is received by the host side reception unit. A host-side receiving process,
In the first device, a first device-side mutual authentication result step of determining a mutual authentication result with the second device based on a determination result in the first device-side coincidence determining unit;
In the host, based on the determination result in the first device-side coincidence determining unit received in the host-side receiving step, the mutual authentication result of the first and second devices is determined by the authentication result determining unit. An authentication result determination step for determining,
A mutual authentication method characterized in that devices that are not designated as the first and second devices by the first and second commands transmitted from the host do not participate in the mutual authentication operation and are on standby.

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