JP5602602B2 - Communication apparatus, control method, and program - Google Patents

Description

  The present invention relates to a communication device, a control method, and a program.

  When performing wireless communication in a wireless LAN compliant with the IEEE802.11 standard series, it is necessary to set many setting items before using each communication device.

  Specifically, various communication parameters required for performing wireless communication, such as SSID (Service Set Identifier) as a network identifier, an encryption method, an encryption key, an authentication method, an authentication key, and the like can be given. Conventionally, these setting items are all manually set by the user, which is very complicated for the user.

  On the other hand, in recent years, Wi-Fi Protected Setup (hereinafter referred to as WPS, see Non-Patent Document 1) has been standardized as an industry-standard automatic setting method that allows various communication parameters to be easily set in a communication device. Currently, it is being installed in communication devices.

  FIG. 8 is a sequence of communication parameter automatic setting processing by WPS between communication apparatus A (communication apparatus functioning as a receiving apparatus) and communication apparatus B (communication apparatus functioning as a providing apparatus) disclosed in WPS. Is shown briefly. Each message from WSC-Start (F805) to WSC-Done (F814) shown in FIG. 8 is transmitted / received based on the EAP protocol defined by RFC3748 Extensible Authentication Protocol.

  Details of the format of each message of WSC-M1 (F806), WSC-M2 (F807), and WSC-M3 (F808) shown in FIG. 8 are shown in FIGS.

  As shown in FIG. 9, the WSC-M1 message (F806) includes WPS version information (Version) 901 as an element in addition to the EAP header. Furthermore, a receiving device's random number 902 and a receiving device's public key 903 are provided as elements.

  Also, as shown in FIG. 10, the WSC-M2 message (F806) includes WPS version information (Version) 1001 and a random number (Enrolle Nonce) 1003 of the receiving device as elements. Furthermore, a provision device random number 1004, a public key 1005 of the providing device, and a message authentication code 1006 are provided as elements.

  It should be noted that the receiving device random number 1003 included in the WSC-M2 message (F807) needs to be the same value as the receiving device random number 902 included in the WSC-M1 message (F806).

  A message authentication code (Authenticator) 1006 is a hash value calculated from the message received immediately before (here, the WSC-M1 message) and the message transmitted this time (here, the WSC-M2 message). The hash value can be verified by the communication device A functioning as a receiving device, and information such as whether the message transmitted / received by using the hash value has not been falsified or partially destroyed is used. Can be confirmed.

  As shown in FIG. 11, the WSC-M3 message (F808) includes WPS version information (Version) 1101 and a random number (Register Nonce) 1103 of the providing device as elements. Further, a message authentication code (Authenticator) 1104 is provided as an element.

  Note that the random number (Register Nonce) 1103 of the providing apparatus included in the WSC-M3 message (F808) needs to be the same value as the random number (Registrar Nonce) 1004 of the providing apparatus included in the WSC-M2 message (F807). A message authentication code (Authenticator) 1104 is a hash value calculated from the message received immediately before (here, WSC-M2 message) and the message transmitted this time (here, WSC-M3 message).

  In the WSC-M8 message (F813) shown in FIG. 8, communication parameters are transmitted from the communication apparatus A (providing apparatus) to the communication apparatus B (receiving apparatus). It is encrypted using a common key calculated from the public key and random number.

  As described above, in the communication parameter automatic setting process by WPS, the public key of the public key cryptosystem and the random number specific to each communication device are transmitted to each other, and the common key between the communication devices is calculated. Thereby, a safer mechanism can be provided in transmitting communication parameters from the communication device A (providing device) to the communication device B (receiving device).

“Wi-Fi Protected Setup Specification”, Version 1.0h, December, 2006

  However, the calculation process of the common key is complicated and takes a long calculation time. However, in the case of a communication device equipped with a low-performance CPU such as various embedded devices such as a compact digital camera, a high calculation capability is expected. It is not possible.

  On the other hand, while the communication device is executing the common key calculation process, the opposing communication device determines whether there is a response from the communication device to the message transmitted by the own device. For this reason, if the common key calculation process takes time and there is no response within a predetermined time, the timeout process is activated, and as a result, the communication parameter automatic setting process does not end normally.

  FIG. 12 is a sequence diagram of automatic setting processing for explaining such a situation in detail. In the description, it is assumed that the communication device B (providing device) and the communication device A (receiving device) are connected to the same network. In the processes from F1202 to F1206, it is assumed that messages are exchanged in accordance with the specification of the communication parameter automatic setting process by the WPS.

  In FIG. 12, the WSC-M1 message (F1206) includes the public key of the communication device A (receiving device) as described above. For this reason, the communication device B (providing device) that has received the WSC-M1 message (F1206) executes a common key calculation process based on the private key held inside and the received public key ( F1207).

  At this time, since the communication device B (providing device) executes the common key calculation processing (F1207) by the low-performance CPU, it takes time to complete the processing. For this reason, in the communication apparatus A (reception apparatus) that transmitted the WSC-M1 message (F1206), a state in which a subsequent message is not transmitted from the opposite communication apparatus B continues, and a timeout occurs (F1208).

  When timeout occurs, the communication device A (reception device) retransmits the WSC-M1 message (F1209). At this time, the retransmitted WSC-M1 message (F1209) is different from the previously transmitted WSC-M1 message (F1206) in the random number (Enrolle Nonce) of the receiving device.

  On the other hand, the communication device B (providing device) transmits a WSC-M2 message (F1210) when the common key calculation process (F1207) ends. Along with this, the communication device A (reception device) receives the WSC-M2 message (F1210). At this time, the WSC-M2 message (F1210) is not a retransmitted WSC-M1 message (F1209) but a message constructed based on the previously transmitted WSC-M1 message (F1206).

  For this reason, the communication device A (reception device) ignores the WSC-M2 message (F1210) and retransmits the WSC-M1 message (F1211) because it is different from the message to be received. The communication device B (providing device) that has received the WSC-M1 message (F1211) performs the common key calculation process again based on the WSC-M1 message (F1211) (F1212).

  At this time, the common key calculation process (F1212) executed in the communication apparatus B (providing apparatus) takes time until the process is completed, similar to the previous common key calculation process (F1207). For this reason, the communication device A (reception device) again generates a timeout (F1213) and retransmits the WSC-M1 message (F1213).

  Thus, in the case of a communication apparatus that requires a long processing time for the common key calculation process, there is a problem that the communication parameter automatic setting process by WPS does not end normally.

  The present invention has been made in view of the above problems, and an object of the present invention is to allow communication parameter automatic setting processing to be completed normally even if it takes time to calculate a common key. .

In order to achieve the above object, a communication apparatus according to the present invention has the following configuration, for example. That is,
A communication device,
Receiving means for receiving a message including a public key and a random number from another communication device;
Calculating means for calculating a common key using the public key included in the message received by the receiving means and a secret key held in advance by the communication device;
Between the start and completion of the calculation of the common key by the calculation means, the reception means receives the message from the other communication device a plurality of times, and the public key included in each of the plurality of messages is the same In this case, the receiving unit includes a transmitting unit that transmits a message including a random number included in the message received last to the other communication device.

  According to the present invention, even if it takes time to calculate a common key, it is possible to normally complete communication parameter automatic setting processing.

It is a figure which shows an example of the network formed by the communication apparatus which concerns on one Embodiment of this invention. It is a figure which shows the hardware constitutions of the communication apparatus which concerns on one Embodiment of this invention. It is a figure which shows the function structure of the communication apparatus which concerns on one Embodiment of this invention. It is a sequence diagram which shows the flow of the communication parameter automatic setting process by the communication apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of the communication parameter automatic setting process in the communication apparatus which concerns on one Embodiment of this invention. It is a sequence diagram which shows the flow of the communication parameter automatic setting process in the communication apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of the communication parameter automatic setting process in the communication apparatus which concerns on one Embodiment of this invention. FIG. 10 is a sequence diagram showing a flow of communication parameter automatic setting processing by WPS disclosed in Non-Patent Document 2. It is a figure which shows the message format of WSC-M1 currently disclosed by the nonpatent literature 2. FIG. It is a figure which shows the message format of WSC-M2 currently disclosed by the nonpatent literature 2. FIG. It is a figure which shows the message format of WSC-M3 currently disclosed by the nonpatent literature 2. FIG. It is a sequence diagram which shows the flow of the communication parameter automatic setting process by WPS in the communication apparatus carrying low-performance CPU.

  Hereinafter, communication devices according to embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the case where the present invention is applied to a wireless LAN compliant with the IEEE 802.11 series will be described. However, the application destination of the present invention is not necessarily limited to the wireless LAN compliant with IEEE 802.11.

[First Embodiment]
<1. Network configuration>
First, a network formed by a communication apparatus according to an embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a network A formed by a communication device B according to an embodiment of the present invention and a communication device A facing the communication device B.

  As illustrated in FIG. 1, in the network A, the communication device A functions as the reception device 101, and the communication device B functions as the providing device 102. Note that the network A may be an infrastructure network or an ad hoc network.

<2. Hardware configuration of communication device>
Next, the hardware configuration of the communication device A and the communication device B that form the network A will be described. In the present embodiment, the communication device A and the communication device B have the same hardware configuration, and therefore only the hardware configuration of the communication device B will be described here with reference to FIG.

  In FIG. 2, reference numeral 201 denotes a control unit that controls the entire communication apparatus by executing a control program stored in the storage unit 202. The control unit 201 executes communication parameter automatic setting processing with another communication device (communication device A).

  A storage unit 202 stores a control program executed by the control unit 201 and various types of information such as communication parameters. The communication parameter automatic setting process, which will be described later, is realized by reading out a control program stored in the storage unit 202 and executing it in the control unit 201.

  Reference numeral 203 denotes a wireless unit for performing wireless communication in a wireless LAN compliant with the IEEE 802.11 series. A display unit 204 performs various displays, and can output visually recognizable information such as an LCD or LED, or can output sound such as a speaker. That is, the display unit 204 has a function of outputting at least one of visual information and sound information.

  Reference numeral 205 denotes a setting button for giving a trigger for starting communication parameter automatic setting processing. When the setting button 205 is operated, communication parameter automatic setting processing is started. When the control unit 201 detects an operation of the setting button 205 by the user, the control unit 201 performs an automatic setting process described later.

  Reference numeral 206 denotes an antenna control unit, and 207 denotes an antenna. Reference numeral 208 denotes an input unit for the user to make various inputs.

<3. Functional configuration of communication device>
Next, a communication parameter automatic setting function realized in the control unit 201 of the communication device A and the communication device B forming the network A will be described with reference to FIG. In the present embodiment, it is assumed that the control unit 201 of the communication device A and the control unit 201 of the communication device B each have a common automatic setting function as a communication parameter automatic setting function.

  In FIG. 3, reference numeral 301 denotes an automatic setting control unit that performs overall control of communication parameter automatic setting processing such as control of the setting button 205 and control of the input unit 208 and the display unit 204.

  Reference numeral 302 denotes a packet receiving unit that executes processing for analyzing packets received through the wireless unit 203. A packet transmission unit 303 assembles packets necessary for communication parameter automatic setting processing and transmits packets to the opposite communication device.

  An encryption key calculation unit 304 executes a common key calculation process using a public key encryption method. Reference numeral 305 denotes a hash calculator, which executes a process for calculating a message authentication code (Authenticator).

  Reference numeral 306 denotes a communication parameter reception unit. When the communication device functions as a reception device, the communication parameter is received from the opposite communication device (communication device functioning as a providing device), and the validity of the received communication parameter is confirmed. Etc.

  Reference numeral 307 denotes a communication parameter providing unit. When the communication device functions as a providing device, the communication parameter is transmitted to the opposite communication device (communication device functioning as a receiving device).

  Reference numeral 308 denotes a communication parameter storage unit. When the communication device functions as a providing device, the communication parameter is extracted from the communication parameter storage unit 308 and transmitted to the opposite communication device (receiving device). On the other hand, when the communication device functions as a receiving device, the communication parameter received by the communication parameter receiving unit 306 is stored.

  Note that all functional blocks have a mutual relationship in terms of software or hardware. Further, the above functional block is an example, and a plurality of functional blocks may be configured by one functional block, or any one functional block may be further divided into a plurality of functional blocks. .

<4. Communication Parameter Automatic Setting Processing by Communication Device A and Communication Device B>
Next, the flow of communication parameter automatic setting processing by the communication device A and the communication device B will be described with reference to the sequence diagram shown in FIG. As illustrated in FIG. 4, the communication device A that functions as a receiving device executes connection processing (F401) with the communication device B that functions as a providing device. Thereby, the communication device A and the communication device B are connected to the same network A.

  Of the subsequent processes, the processes (F402) to (F406) are general packet transmission / reception processes in accordance with the specification of the communication parameter automatic setting process by WPS. Omitted.

  As described above, the WSC-M1 message (F406) includes the public key of the communication apparatus A functioning as a receiving apparatus. Then, the communication device B that has received the WSC-M1 message (F406) calculates a common key based on the private key held inside and the public key included in the received WSC-M1 message (F406). The common key calculation process is executed.

  The common key calculation process (F407) takes time to complete in the communication apparatus B in which the low-performance CPU is mounted. Therefore, in the communication device A that has transmitted the WSC-M1 message (F406), a state in which a subsequent message is not transmitted from the communication device B continues, and a timeout occurs.

  When a timeout occurs, the communication device A retransmits the WSC-M1 message (F408). At this time, the WSC-M1 message (F408) to be transmitted is different from the previously transmitted WSC-M1 message (F406) in the random number (Enrolle Nonce) of the receiving device.

  On the other hand, the communication apparatus B constructs a WSC-M2 message when the common key calculation process (F407) is completed. At this time, the communication apparatus B receives a new WSC-M1 message (F408) while the common key calculation process (F407) is being executed.

  Therefore, the communication apparatus B replaces the random number (Enrolle Nonce) and message authentication code (Authenticator) of the receiving apparatus with respect to the constructed WSC-M2 message, and reconstructs the WSC-M2 message. The other elements are left in the already constructed message format.

  The communication device B reconstructs the WSC-M2 message and then transmits the WSC-M2 message to the communication device A (F409). A value corresponding to the latest WSC-M1 message (F408) is stored in the random number (Enrolle Nonce) and message authentication code (Authenticator) of the WSC-M2 message (F409) transmitted at this time. For this reason, in the communication apparatus A, subsequent processing can be normally executed.

  As a result, the processing (F410 to F417) is executed in accordance with the specification of the communication parameter automatic setting processing by the WPS, and the communication parameter automatic setting processing is normally completed.

<5. Flow of communication parameter automatic setting process in communication apparatus B>
Next, communication parameter automatic setting processing in the communication apparatus B will be described. FIG. 5 is a flowchart showing a flow of communication parameter automatic setting processing in the communication apparatus B. Here, for simplification of description, the flow of processing from reception of the WSC-M1 message (F406) to transmission of the WSC-M2 message (F409) will be described.

  In step S501, the communication apparatus B receives the WSC-M1 message (F406) from the communication apparatus A. In step S502, the WSC-M1 message (F406) received in step S501 is analyzed.

  In step S503, as a result of the analysis in step S502, the public key (Public Key) of the receiving device included in the WSC-M1 message (F406) and the secret key held internally by the communication device B are used. The key (DH-Key) is calculated. The common key (DH-Key) is information serving as a basis of a key used for encryption processing when transmitting communication parameters and calculation processing of a message authentication code, as defined in the WPS specification.

  As described above, in the communication apparatus B equipped with a low-performance CPU, it takes time to complete the calculation process of the common key (DH-Key).

  When the calculation process of the common key (DH-key) in step S503 ends, the communication apparatus B constructs a WSC-M2 message in step S504. The format of the WSC-M2 message is as described with reference to FIG.

  After constructing the WSC-M2 message in step S504, it is confirmed in step S505 whether a new WSC-M1 message (F408) has been received.

  If it is confirmed in step S505 that the message has not been received, the process proceeds to step S510, and the WSC-M2 message constructed in step S504 (the first constructed WSC-M2 message) is transmitted to the communication apparatus A.

  On the other hand, if it is confirmed in step S505 that a new WSC-M1 message (F408) has been received, the process proceeds to step S506.

  In step S506, the new WSC-M1 message (F408) confirmed to be received in step S505 is analyzed. In step S507, as a result of the analysis in step S506, it is determined whether there is a difference between the previously received WSC-M1 message (F406) and the newly received WSC-M1 message (F408).

  Specifically, whether or not there is a difference between the newly received WSC-M1 message (F408) and the random number (Enrolle Nonce) of the receiving device included in the previously received WSC-M1 message (F406). judge.

  If it is determined in step S507 that there is no difference in the random number (Enrolle Nonce) of the receiving apparatus, the process proceeds to step S510. In step S510, the WSC-M2 message constructed in step S504 (the first constructed WSC-M2 message) is transmitted to communication apparatus A.

  On the other hand, if it is determined in step S507 that there is a difference with respect to the random number of the receiving device (Enrolle Nonce), the process proceeds to step S508.

  In step S508, it is determined whether the public key (Public Key) included in the previously received WSC-M1 message (F406) is different from the newly received WSC-M1 message (F408).

  If it is determined in step S508 that there is a difference with respect to the public key (public key), the process returns to step S503 to recalculate the common key (DH-Key).

  On the other hand, if it is determined in step S508 that there is no difference (the same) with respect to the public key (public key), the process proceeds to step S509. In step S509, the common key (DH-Key) calculated in step S503 is used as it is to reconstruct the WSC-M2 message. That is, only the random number (Enrolle Nonce) and the message authentication code (Authenticator) of the receiving device are recalculated to reconstruct the WSC-M2 message.

  Specifically, the random number of the receiving device (Enrolle Nonce) is changed from the value set in step S504 to the random number acquired in step S506 (that is, the random number included in the last message among the messages received a plurality of times). replace. Note that since the message authentication code (Authenticator) is only hash calculation, the operation of the communication apparatus A is not affected even when the CPU of the communication apparatus B has a low calculation capability.

  When the WSC-M2 message is reconstructed in step S509, the reconstructed WSC-M2 message (F409) is transmitted to the communication apparatus A in step S510. Thereafter, the automatic setting process is normally executed according to the sequence diagram described with reference to FIG.

  As is clear from the above description, in the communication device (providing device) according to the present embodiment, when the same message is retransmitted during the execution of the common key calculation process, only the necessary part is replaced, The message is reconstructed and sent.

  As a result, the communication parameter automatic setting process is normally completed even when the CPU of the communication apparatus B functioning as the providing apparatus has a low calculation capability and the common key calculation process using the public key cryptography takes time. It became possible.

[Second Embodiment]
In the first embodiment, the case has been described in which the common key calculation process is executed in the communication apparatus B as the providing apparatus. However, the present invention is not limited to this. For example, contrary to the first embodiment, when the CPU of the communication device A that is the receiving device has a low calculation capability and the communication device A that is the receiving device performs the common key calculation process. Is the same.

  Therefore, in the present embodiment, a case will be described in which a common key calculation process is executed in the communication apparatus A having a low CPU computing power. The configuration of the network A, the hardware configuration of the communication device, and the functional configuration of the communication device have already been described with reference to FIGS.

<1. Communication Parameter Automatic Setting Processing by Communication Device A and Communication Device B>
First, a communication parameter automatic setting process performed by the communication apparatus A (communication apparatus functioning as a receiving apparatus) and a communication apparatus B (communication apparatus functioning as a providing apparatus) facing the communication apparatus A according to the present embodiment. This will be described with reference to the sequence diagram shown in FIG.

  As illustrated in FIG. 6, the communication device A that functions as a receiving device executes connection processing (F601) with the communication device B that functions as a providing device. Thereby, the communication device A and the communication device B are connected to the same network A.

  Of the processes after being connected, the processes (F602) to (F607) are general packet transmission / reception processes in accordance with the specification of the communication parameter automatic setting process by WPS. The detailed explanation is omitted.

  As described above, the WSC-M2 message (F607) includes the public key of the communication apparatus B that functions as the providing apparatus. Then, in the communication apparatus A that has received the WSC-M2 message (F607), the common key is calculated based on the secret key held therein and the public key included in the received WSC-M2 message (F607). The process is executed (F608).

  The common key calculation process (F608) takes a long time to complete in the communication apparatus A in which a low-performance CPU is mounted, as in the communication apparatus B (providing apparatus) in the first embodiment. Therefore, in the communication device B that has transmitted the WSC-M2 message (F607), a state in which a subsequent message is not transmitted from the communication device A continues, and a timeout occurs.

  When a timeout occurs, the communication apparatus B retransmits the WSC-M2 message (F609). At this time, the transmitted WSC-M2 message (F609) differs from the previously transmitted WSC-M2 message (F607) in the random number (Registrar Nonce) of the providing device.

  On the other hand, the communication apparatus A constructs a WSC-M3 message when the common key calculation process (F608) ends. At this time, the communication device A receives a new WSC-M2 message (F609) while the common key calculation process (F608) is being executed.

  Therefore, the communication apparatus A replaces the random number (Registrar Nonce) and the message authentication code (Authenticator) of the providing apparatus with respect to the constructed WSC-M3 message, and reconstructs the WSC-M3 message. The other elements are left in the already constructed message format.

  The communication apparatus A transmits the WSC-M3 message to the communication apparatus B after reconstructing the WSC-M3 message (F610). In the WSC-M3 (F610) and the message authentication code (Authenticator) transmitted at this time, values corresponding to the latest WSC-M2 message (F609) are stored. For this reason, in the communication apparatus B, the subsequent processing can be normally executed.

  As a result, the processing (F611 to F617) is executed in accordance with the specification of the communication parameter automatic setting processing by the WPS, and the communication parameter automatic setting processing is normally completed.

<2. Flow of communication parameter automatic setting processing in communication apparatus A>
Next, communication parameter automatic setting processing in the communication apparatus A will be described. FIG. 7 is a flowchart showing a flow of communication parameter automatic setting processing in the communication apparatus A. Here, for simplification of description, the flow of processing from the transmission of the WSC-M1 message (F606) to the transmission of the WSC-M3 message (F610) will be described.

  In step S701, the communication apparatus A transmits a WSC-M1 message (F606) to the communication apparatus B. In response to the transmission of the WSC-M1 message (F606) in step S701, the communication apparatus B transmits a WSC-M2 message (F607), and the communication apparatus A receives the WSC-M2 message (F607). In step S703, the WSC-M2 message (F607) received in step S702 is analyzed.

  In step S704, as a result of the analysis in step S703, based on the public key (Public Key) included in the WSC-M2 message (F607) and the private key held internally by the communication device A, the common key (DH -Key) is calculated. The common key (DH-Key) is information serving as a basis of a key used for encryption processing when transmitting communication parameters and calculation processing of a message authentication code, as defined in the WPS specification.

  As described above, in the communication device A in which the low-performance CPU is mounted, it takes time to complete the calculation process of the common key (DH-Key).

  When the calculation process of the common key (DH-key) in step S704 ends, the communication apparatus A constructs a WSC-M3 message in step S705. The format of the WSC-M3 message is as described with reference to FIG.

  After constructing the WSC-M3 message in step S705, it is confirmed in step S706 whether a new WSC-M2 message (F609) has been received.

  If it is confirmed in step S706 that it has not been received, the process proceeds to step S711, and the WSC-M3 message constructed in step S705 (the first constructed WSC-M3 message) is transmitted to the communication apparatus B.

  On the other hand, if it is confirmed in step S706 that a new WSC-M2 message (F609) has been received, the process proceeds to step S707.

  In step S707, the new WSC-M2 message (F609) confirmed to have been received in step S706 is analyzed. In step S708, as a result of the analysis in step S707, it is determined whether there is a difference between the previously received WSC-M2 message (F607) and the newly received WSC-M2 message (F609).

  Specifically, whether or not there is a difference between the newly received WSC-M2 message (F609) and the random number (Registrar Nonce) of the providing device included in the previously received WSC-M2 (F607) message. judge.

  If it is determined in step S708 that there is no difference in the random number (Registrar Nonce) of the providing apparatus, the process proceeds to step S711. In step S711, the WSC-M3 message constructed in step S705 (the first constructed WSC-M3 message) is transmitted to the communication apparatus B.

  On the other hand, if it is determined in step S708 that there is a difference in the random number of the providing device, the process proceeds to step S709.

  In step S709, it is determined whether the public key (Public Key) included in the previously received WSC-M2 message (F607) is different from the newly received WSC-M2 message (F609).

  If it is determined in step S709 that there is a difference in the public key (public key), the process returns to step S704 to recalculate the common key (DH-Key).

  On the other hand, if it is determined in step S709 that there is no difference (same) as to the public key (public key), the process proceeds to step S710. In step S710, the common key (DH-Key) calculated in step S704 is used as it is to reconstruct the WSC-M3 message. That is, only the random number (Registrar Nonce) and the message authentication code (Authenticator) of the providing device are recalculated to reconstruct the WSC-M3 message.

  Specifically, the random number of the providing apparatus (Registrar Nonce) is changed from the value set in step S705 to the random number acquired in step S707 (that is, the random number included in the last message among the messages received a plurality of times). replace. Since the message authentication code (Authenticator) is only hash calculation, the operation of the communication device B is not affected even if the CPU of the communication device A has a low calculation capability.

  When the WSC-M3 message is reconstructed in step S710, the reconstructed WSC-M3 message (F610) is transmitted to the communication apparatus B in step S711. Thereafter, the automatic setting process is normally executed according to the sequence diagram described with reference to FIG.

  As is clear from the above description, in the communication device (receiving device) according to the present embodiment, when the same message is retransmitted during the execution of the common key calculation process, only the necessary part is replaced, The message is reconstructed and sent.

  As a result, the communication parameter automatic setting process is normally completed even when the CPU of the communication apparatus A functioning as a receiving apparatus has a low calculation capability and it takes a long time to calculate the common key using the public key cryptosystem. It became possible.

[Third Embodiment]
In the first and second embodiments, the case where the present invention is applied to a wireless LAN system compliant with IEEE 802.11 has been described. However, the present invention is not limited to this, and may be applied to other wireless systems such as wireless USB, MBOA, Bluetooth (registered trademark), UWB, and ZigBee. Moreover, you may apply to wired communication systems, such as wired LAN.

  In addition, MBOA here is an abbreviation for Multi Band OFDM Alliance. UWB includes wireless USB, wireless 1394, WINET, and the like.

  In the first and second embodiments, the network identifier, the encryption method, the encryption key, the authentication method, the authentication key, and the like have been exemplified as communication parameters. However, the present invention is not limited to this, and other settings are possible. It may be an item. Alternatively, the other setting items may be included in addition to the communication parameters.

[Other Embodiments]
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

Claims (5)

A communication device,
Receiving means for receiving a message including a public key and a random number from another communication device;
Calculating means for calculating a common key using the public key included in the message received by the receiving means and a secret key held in advance by the communication device;
Between the start and completion of the calculation of the common key by the calculation means, the reception means receives the message from the other communication device a plurality of times, and the public key included in each of the plurality of messages is the same In this case, the communication device further comprises: a transmission unit that transmits a message including a random number included in the message last received by the reception unit to the other communication device.   When the receiving unit receives the message including a different public key from the other communication device between the start and completion of the calculation of the common key by the calculating unit, the calculating unit The communication apparatus according to claim 1, wherein a common key is calculated using   Between the start and completion of the calculation of the common key by the calculation means, the reception means receives the message from the other communication device a plurality of times, and the public key included in each of the plurality of messages is the same When the random numbers are also the same, the transmission unit transmits a message including a random number included in a message first received by the reception unit to the other communication device. The communication apparatus according to 1. A communication device control method comprising:
A receiving step for receiving a message including a public key and a random number from another communication device;
A calculating step in which a calculating unit calculates a common key using the public key included in the message received in the receiving step and a secret key held in advance by the communication device;
The transmission means receives the message from the other communication device a plurality of times in the reception step between the start and completion of the calculation of the common key in the calculation step, and is included in each of the plurality of messages. And a transmission step of transmitting, to the other communication device, a message including a random number included in the message received last in the reception step when the public keys are the same. . In the communication device, the computer
A receiving step of receiving a message including a public key and a random number from another communication device;
A calculation step of calculating a common key using the public key included in the message received in the reception step and a secret key held in advance by the communication device;
Between the start and completion of the calculation of the common key in the calculation step, the message is received a plurality of times from the other communication device in the reception step, and the public key included in each of the plurality of messages is the same In this case, a program for executing a transmission step of transmitting a message including a random number included in the message received last in the reception step to the other communication device.

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