JP2009278565A - Communication apparatus and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a communication apparatus for realizing high-security cryptographic communication. <P>SOLUTION: A communications apparatus 10A at authenticating side applies authentication process to a communications apparatus to be authenticated by generating random numbers; transmitting unique data and random numbers for identifying the own apparatus itself to a communication apparatus 10B to be authenticated; generating a first random number and a second random number from such random numbers; generating a temporary key with the cryptographic process by using the unique data, the first random number, and a master key shared among the apparatuses; generating a first verifying data by encrypting the second random number with the temporary key; and comparing, for verification, the first verifying data with a second verifying data generated and transmitted by the communication apparatus 10B to be authenticated, on the basis of the unique data and the random numbers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication device and a communication system that perform cryptographic communication.

  Conventionally, various cryptographic communication systems have been proposed. For example, in Patent Document 1 below, the unique information is IV, the challenge data is raw, an encryption key is generated, the challenge data is encrypted with the encryption key, verification data is created, and the encryption key is used using the public communication network. Is informed.

JP 2006-339963 A

  In the technique disclosed in Patent Document 1, the encryption information is generated with the unique information set to IV and the challenge data set to raw, and neither the specific information nor the challenge data is secret information. For this reason, there has been a problem that the encryption key generation method is estimated and the encryption key may be stolen.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a communication device and a communication system that can provide more secure encrypted communication.

  In order to solve the above-described problems and achieve the object, the present invention is a communication device that performs cryptographic communication with a communication device on the authenticated side, and identifies itself from an authentication-side random number generation unit that generates a random number. And transmitting the unique information and the random number to the communication device on the authenticated side, generating a first random number and a second random number by performing a predetermined process on the random number, and generating the unique information and the first random number. Authentication-side control means for generating a temporary key by encryption processing using a random number and a master key shared between devices, and authentication for generating first verification data by encrypting the second random number with the temporary key Side authentication processing means, wherein the authentication side control means is further configured to send the second verification data and the second data generated and sent based on the unique information and the random number by the authentication side communication device. Compare with validation data By certifying, and performs authentication processing for the authenticated side of the communication device.

  According to the present invention, data used for key generation and encryption processing is difficult to grasp from the outside of the apparatus, and it is possible to provide more secure encrypted communication. Also, since the temporary key is created from the concatenated unique information and the random number, the temporary key for creating the verification data changes every time, so it becomes possible to improve the resistance to selective plaintext attacks, etc. In addition, it is possible to provide highly secure encrypted communication.

  Embodiments of a communication apparatus and a communication system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a communication device according to the present invention. 1 includes a communication unit 1, a control unit 2 including a CPU, a logic circuit, and a sequence ROM, a non-volatile memory 3, a random number generation unit 4, and an encryption processing unit 5. Yes. The communication unit 1 is a functional unit that transmits and receives communication data. For example, a contact interface for smart cards, a non-contact interface, a parallel interface, a serial interface, a wired interface such as IEEE1394 or USB, infrared communication / Bluetooth, etc. / Wireless interfaces such as wireless LAN / DSRC / cell phones are used.

  The control unit 2 controls the entire communication device 10, analyzes communication data received by the communication unit 1, and creates communication data transmitted by itself. The non-volatile memory 3 holds unique information used at the time of encryption processing, secret information such as a master key, and the like. Here, the unique information is information such as the individual number or ID of the communication device 10 and is not particularly secret information. The master key is shared between the devices in advance. The random number generator 4 generates a random number. The encryption processing unit 5 encrypts or decrypts communication data.

  Here, the operation of the authentication process using the communication apparatus configured as described above will be described. The communication device that performs authentication is the communication device 10A, and the communication device that is authenticated is the communication device 10B. The communication devices 10A and 10B both have the same configuration as the communication device 10.

  FIG. 2 is a sequence diagram showing the mutual authentication operation of the communication devices (communication devices 10A and 10B) in the present embodiment. The control unit 2 of the communication device 10A reads unique information from the non-volatile memory 3 (step S1) and performs conversion of a format for transmission. Next, the control unit 2 issues a random number generation command to the random number generation unit 4, and the random number generation unit 4 that has received this generates a random number (step S <b> 2) and outputs the random number to the control unit 2. Then, the control unit 2 concatenates the unique information and the random number, and transmits them to the communication device 10B via the communication unit 1 (step S3).

  In addition, the control unit 2 of the communication device 10A divides the random number generated in step S2 into two parts to be a random number # 1 and a random number # 2, concatenating the unique information and the random number # 1, and the random number # 2. And get.

  An image in which unique information and random numbers are concatenated is shown for various examples of random number division. FIG. 3A is a diagram illustrating a state in which the unique information and the random number are concatenated as they are. FIG. 3B is a diagram illustrating an example in which a random number bit string is divided into two. FIG. 3C is a diagram illustrating an example in which random number # 2 and random number # 1 are arranged in this order as another example in which a random number bit string is divided into two. FIG. 3-4 is a diagram illustrating an example where the random number # 1 and the random number # 2 are divided without using some bits of the random number. FIG. 3-5 is a diagram illustrating an example in which some bits of the random number are used for both the random number # 1 and the random number # 2. Thus, the random number can be divided in various ways. The division method is set in advance in each communication device, and may be fixed or may vary according to a predetermined rule.

  Next, the control unit 2 of the communication device 10 </ b> A reads the master key from the nonvolatile memory 3. Then, a temporary key is created using the connected unique information and random number # 1 as plain text and the master key as an encryption key (step S4). FIG. 4 is a diagram for explaining a method for creating a temporary key.

  Next, the control unit 2 of the communication device 10 </ b> A notifies the encryption processing unit 5 of the temporary key and the random number # 2 created above and the encryption processing instruction. The encryption processing unit 5 that has received the instruction performs a cryptographic operation using the random number # 2 as plain text and the notified temporary key as an encryption key, creates verification data # 1 (step S5), and outputs the verification data # 1 to the control unit 2 .

  On the other hand, when the communication unit 1 of the communication device 10B receives the unique information and the random number from the communication device 10A, the control unit 2 of the communication device 10B converts the random number into the random number # 1 in the same process as the control unit 2 of the communication device 10A. And random number # 2 (step S6).

  Next, the control unit 2 and the encryption processing unit 5 of the communication device 10B create a temporary key and verification data by the same process as the communication device 10A. That is, the control unit 2 reads out the master key from the nonvolatile memory 3, creates a temporary key using the concatenated unique information and the random number # 1 as plain text, and the master key as an encryption key (step S7). Also, the cryptographic processing unit 5 performs cryptographic computation using the random number # 2 as plain text and the generated temporary key as a new cryptographic key, creates verification data # 2 (step S8), and outputs it to the control unit 2. And the control part 2 transmits verification data to 10 A of communication apparatuses using the communication part 1 (step S9).

  When the control unit 2 of the communication device 10A receives the verification data # 2 from the communication device 10B via the communication unit 1 (step S10), the control unit 2 itself (the communication device 10A) creates the verification data # 1 and the authenticated side ( A verification process for comparing the verification data # 2 transmitted from the communication device 10B) is performed (step S11). Specifically, when the control unit 2 determines that both pieces of verification data match, the control device 2 determines that the communication device 10B is a valid communication device. On the other hand, when it is determined that they do not match, the communication device 10B is not recognized as a valid communication device, and thereafter, the processing with the communication device 10B is not performed.

  When the communication device 10A recognizes the communication device 10B as a valid communication device, the communication device 10B then authenticates the communication device 10A (step S12). The processing procedure is the same as described above. When the communication device 10B authenticates the communication device 10A as a valid communication device, mutual authentication is completed, and thereafter, data communication can be performed.

  As described above, in the present embodiment, a random number is used for encryption processing, and the random number portion is divided and used to create an encryption key. As a result, the data used for key generation and encryption processing is difficult to grasp from the outside of the apparatus, and it is possible to provide more secure encryption communication. Moreover, since the temporary key is created from the connected unique information and the random number, the temporary key for creating the verification data changes every time. As a result, it is possible to improve resistance to selective plaintext attacks and the like, and it is possible to provide highly secure encrypted communication.

  In the above embodiment, no limitation is imposed on the created temporary key. For example, the created temporary key or the SUM value of the temporary key is recorded and is the same as the one created in the past. If the temporary key is created again, the authentication process may be performed again without generating verification data. By doing so, the temporary key always changes, and security can be improved.

  In the above embodiment, the temporary key is created as shown in FIG. 4, but other methods may be adopted. FIG. 5 is a diagram for explaining another temporary key creation method (part 2). The master key and the cryptographic calculation method used in the creation method of FIG. 5 are the same as in the above embodiment. In this creation method, (unique information | random number # 1) is incremented, a cryptographic operation is performed each time, and the obtained result is concatenated with "C0 | C1 | ... | Cn". Then, a hash calculation is performed on the connected result to obtain a temporary key. The number “n” of increments may be determined in advance, or may be variable such as the number of lower 4 bits of the random number # 1.

  In this case, the relationship between the connected unique information and the random number # 1 and the temporary key becomes complicated, and it is possible to make estimation of the temporary key more difficult.

Embodiment 2. FIG.
In the first embodiment, a random number divided and encrypted in multiple stages is used as verification data for authentication between communication apparatuses. In the present embodiment, a case will be described in which a communication device on the authentication side further generates a random number, processes verification data using the random number, and transmits the processed verification data.

  Continuing from the first embodiment, the communication terminal 10A will be described as an authentication side, and the communication device B as the authentication target side. FIG. 6 is a sequence diagram showing the mutual authentication operation of the communication devices (communication devices 10A and 10B) in the present embodiment.

  Compared with the operation in the first embodiment, the operation in the present embodiment generates a random number separately from the random number received from the authentication communication device 10A and verifies the random number. The difference is that the data is transmitted while being connected.

  In FIG. 6, when the communication unit 1 of the communication device 10B receives the unique information and the random number transmitted from the communication device 10A, the processes of steps S6 to S8 are performed as described above. Next, the control unit 2 of the communication device 10B issues a notification instructing the random number generation unit 4 to generate a random number. Receiving this, the random number generation unit 4 generates a random number (step S13) and outputs it to the control unit 2, and the control unit 2 concatenates the newly generated random number to the already created verification data # 2. And the control part 2 transmits (verification data # 2 | random number) to the communication apparatus 10A via the communication part 1 (step S14).

  When the control unit 2 of the communication device 10A receives (verification data # 2 | random number) from the communication device 10B, it performs a verification data reception process (step S15). Specifically, the connection between the verification data # 2 and the random number is removed. Here, the connected parts are shared between the communication apparatuses by being set in advance.

  Next, as described above, the control unit 2 of the communication device 10A compares the verification data # 1 created by itself (the communication device 10A) with the verification data # 2 transmitted from the authenticated side (the communication device 10B). A verification process is performed (step S11). Specifically, when the control unit 2 determines that both pieces of verification data match, the control device 2 determines that the communication device 10B is a valid communication device. On the other hand, when it is determined that they do not match, the communication device 10B is not recognized as a valid communication device, and thereafter, the processing with the communication device 10B is not performed.

  As described above, in the present embodiment, the authenticated side also generates a random number and transmits it in connection with the created verification data. This makes it difficult to extract verification data from the outside. That is, a communication device with higher safety can be obtained by simple means.

  In the above embodiment, the verification data is concatenated with a random number, but the verification data may be masked with a random number (exclusive OR), and the result and the random number may be concatenated and sent to the authentication side. Good. In this case, the authentication side can obtain verification data by removing the connected random number from the received data and removing the mask using the random number, so that the safety can be further improved.

  As described above, the communication device according to the present invention is useful for a communication device that performs mutual authentication, and is particularly suitable for a communication device that performs mutual authentication using encrypted data.

It is a figure which shows the structural example of Embodiment 1 of the communication apparatus concerning this invention. FIG. 6 is a sequence diagram showing a mutual authentication operation of the communication device in the first embodiment. It is a figure which shows the state which connected the specific information and the random number as it was. It is a figure which shows the example which divided the bit string of the random number into two. It is a figure which shows the example which divided the bit string of the random number into two. It is a figure which shows the example which divided | segmented the random number, without using the one part bit of a random number. It is a figure which shows the example which used some bits of the random number for both random number # 1 and random number # 2. It is a figure which shows an example of the creation method of a temporary key. It is a figure which shows an example of the creation method of a temporary key. FIG. 11 is a sequence diagram showing a mutual authentication operation of a communication device in the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication part 2 Control part 3 Non-volatile memory 4 Random number generation part 5 Cryptographic processing part 10, 10A, 10B Communication apparatus

Claims (23)

A communication device that performs cryptographic communication with a communication device on the authenticated side,
An authenticating random number generating means for generating a random number;
The unique information for identifying itself and the random number are transmitted to the authentication-side communication device, and a predetermined process is performed on the random number to generate a first random number and a second random number, and the unique information and Authentication-side control means for generating a temporary key by an encryption process using the first random number and a master key shared between devices;
Authentication-side cryptographic processing means for generating first verification data by encrypting the second random number with the temporary key;
With
The authentication-side control means further compares and verifies the first verification data and the second verification data generated and transmitted based on the unique information and the random number by the communication device on the authenticated side. Thus, an authentication process is performed on the authentication-side communication device.   When the second verification data is received in a state where it is concatenated with a random number generated by the authenticated communication device, the second verification data is separated by separating the received data at a predetermined position. The communication device according to claim 1, wherein the communication device is obtained.   When the second verification data is masked with a random number generated by the authenticated communication device and the second verification data is received in a state where the mask data and the random number are concatenated, the received data is The second verification data is obtained by separating mask data and a random number by separating at a predetermined position, and unmasking the mask data using the random number. The communication apparatus according to 1.   The authentication-side control means, as the predetermined processing, divides a part or all of the random number into two, one as a first random number, and the other as a second random number. 2. The communication device according to 2 or 3.   4. The communication apparatus according to claim 1, wherein the authentication-side control unit generates a first random number and a second random number sharing a part of the random number as the predetermined process. 5. .   When it is determined that the temporary key generated by the authentication side control unit is the same as the temporary key generated in the past, the authentication side cryptographic processing unit stops generating the first verification data. The communication device according to any one of claims 1 to 5.   The authentication side control means encrypts the unique information and the first random number using the master key, and uses the result as a temporary key. The communication device described.   The authentication-side control means increments a data series obtained by concatenating the unique information and the first random number over a predetermined number of times, and encrypts each data series before and after the computation using the master key. The communication apparatus according to claim 1, wherein a hash operation is further performed on a data series obtained by concatenating each encrypted data and the result is used as a temporary key. A communication device that performs cryptographic communication with an authentication-side communication device that operates as the communication device according to claim 1,
When receiving the unique information and the random number sent from the authentication side communication device, the random number is subjected to predetermined processing to generate a third random number and a fourth random number, and the unique information and the fourth random number are generated. Authentication-side control means for generating a temporary key by an encryption process using a random number and a master key shared between devices;
An authenticated-side encryption processing means for generating second verification data by encrypting the fourth random number with the temporary key;
With
The authentication-side control unit further transmits the second verification data to the authentication-side communication device. A communication device that performs cryptographic communication with an authentication-side communication device that operates as the communication device according to claim 1,
When the unique information and the random number sent from the authentication side communication device are received, the random number is subjected to predetermined processing to generate a third random number and a fourth random number, and the unique information and the fourth random number are generated. Authentication-side control means for generating a temporary key by an encryption process using a random number and a master key shared between devices;
An authenticated-side encryption processing means for generating second verification data by encrypting the fourth random number with the temporary key;
An authenticated-side random number generation means for generating a random number;
With
The authenticated side control means transmits a transmission sequence generated based on the second verification data and the random number generated by the authenticated side random number generating means to the communication apparatus on the authentication side. apparatus.   11. The communication apparatus according to claim 10, wherein the transmission sequence is generated by concatenating the second verification data and the random number generated by the authenticated-side random number generation unit.   11. The transmission sequence is generated by masking the second verification data with a random number generated by the authenticated-side random number generation means and concatenating the mask data and the random number. The communication apparatus as described in.   The authenticated-side control means divides a part or all of a random number sent from the authenticating-side communication device into two as the predetermined processing, one as a third random number, and the other as a fourth random number The communication device according to any one of claims 9 to 12, wherein the communication device is configured as follows.   The authenticated-side control unit generates a third random number and a fourth random number sharing a part of a random number sent from the authentication-side communication device as the predetermined process. Item 13. The communication device according to any one of Items 9 to 12.   When it is determined that the temporary key generated by the authenticated-side control unit is the same as the temporary key generated in the past, the authenticated-side cryptographic processing unit stops generating the second verification data The communication device according to any one of claims 9 to 14.   16. The authentication-side control unit encrypts the unique information and the third random number using the master key, and uses the result as a temporary key. The communication apparatus as described in.   The authenticated-side control means increments the data series obtained by concatenating the unique information and the third random number over a predetermined number of times, and encrypts each data series before and after the computation using the master key, The communication apparatus according to any one of claims 9 to 15, wherein a hash operation is further performed on a data series obtained by connecting the obtained encrypted data, and the result is used as a temporary key. The function of the communication device according to claim 1;
The function of the communication device according to claim 9,
Have
A communication apparatus capable of operating as an authentication side or an authenticated side. The function of the communication device according to claim 2,
The function of the communication device according to claim 11,
Have
A communication apparatus capable of operating as an authentication side or an authenticated side. The function of the communication device according to claim 3,
The function of the communication device according to claim 12,
Have
A communication apparatus capable of operating as an authentication side or an authenticated side. An authentication-side communication device that operates as the communication device according to claim 1;
An authentication-side communication device that operates as the communication device according to claim 9;
A communication system comprising: An authentication-side communication device that operates as the communication device according to claim 2;
An authentication-side communication device that operates as the communication device according to claim 11;
A communication system comprising: An authentication-side communication device that operates as the communication device according to claim 3;
An authentication-side communication device that operates as the communication device according to claim 12;
A communication system comprising:

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