JP2008109612A - Radio communication method and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication method and system capable of securing confidentiality of communication data relayed in a multi-hop network. <P>SOLUTION: A base station public key A1 corresponding to a decoding key A0 is transmitted from a base station 5 having the decoding key A0 through a radio terminal A, and a radio terminal B acquires the base station public key A1. The radio terminal B encodes certificate K containing a shared key G shared between the base station 5 by using the base station public key A1 and transmits the encoded certificate K to the base station 5 through the radio terminal A. The shared key G is shared between the radio terminal B and the base station 5, to perform encryption communication with the shared key G. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radio communication method and a radio communication system for enhancing the security of data communication in a radio communication system having a multi-hop communication function, for example.

  In a system in which one or more wireless terminals communicate wirelessly, such as a mobile communication system, a wireless LAN system, or a wireless access system, there is a method in which a wireless terminal performs communication by relaying traffic for another wireless terminal. Such a communication function is called, for example, a multi-hop communication function, and a network having the multi-hop function is called a multi-hop network.

  The multihop network is configured to include a base station and one or more wireless terminals. Specifically, the wireless terminal has a transmission function, a reception function, and a relay function, and the base station communicates with the wireless terminal via a wireless line, and a signal is transmitted between the wireless terminal and the wired network. Relay.

In such a wireless communication system using a multi-hop network, a technique for improving the safety of the system is desired. Conventionally, for example, wireless terminals constituting a multi-hop network are wiretapped from outside the network. In order to prevent this, a technique has been considered in which common secret information (key) is shared and communication data is encrypted / decrypted using this secret information (see, for example, Patent Document 1 or 2).
JP 2005-236951 A JP 2005-278044 A

  However, since the conventional method described above is configured so that all wireless terminals constituting the multi-hop network share secret information, there is no secrecy against unauthorized intruders from outside the multi-hop network. However, in the multi-hop network, since the wireless terminal as a relay station can decrypt the encrypted communication data that relays the wireless terminal using the shared secret information, There exists a problem that communication data will be exploited by the wireless terminal.

  Then, an object of this invention is to provide the radio | wireless communication method and radio | wireless communications system which can ensure the secrecy of the communication data relayed within a multihop network in view of said subject.

  In order to achieve the above object, a first feature of the present invention is that a first wireless communication device (base station) is connected to a third wireless communication device (wireless terminal A) via a second wireless communication device (wireless terminal A). In the wireless communication method for transmitting / receiving data to / from the terminal B), the first corresponding to the first decryption key transmitted from the first wireless communication apparatus having the decryption key (base station secret key) The step of acquiring the encryption key (base station public key: encryption key) by the second wireless communication device and the data transmitted and received between the first wireless communication device and the second wireless communication device Generating a first common key (a key shared between the base station and the wireless terminal A: a common key for the terminal A) for encryption and decryption, and a second wireless communication apparatus, A step of encrypting and transmitting the first common key using the acquired first encryption key; A communication device that receives the encrypted first common key, decrypts it with the first decryption key, and obtains the first common key; a second wireless communication device and a third wireless communication; A second common key (a key shared between the wireless terminal A and the wireless terminal B: a common key for the terminal A-B) for encrypting and decrypting data transmitted and received with the device The step of sharing, the step of the third wireless communication device acquiring the first encryption key from the second wireless communication device, and the transmission and reception between the third wireless communication device and the first wireless communication device Generating a third common key for encrypting and decrypting the data to be transmitted, and the third wireless communication apparatus using the first encryption key to generate a third common key (wireless with the base station). The key shared with the terminal B), and the encrypted third common key is used as the second wireless communication device. And transmitting to the first wireless communication device via the first wireless communication device, the first wireless communication device receiving the encrypted third common key, decrypting it with the first decryption key, and One of the first wireless communication apparatus and the third wireless communication apparatus encrypts data using the third common key, and the first wireless communication apparatus transmits the first wireless communication via the second wireless communication apparatus. And a step of transmitting to the other of the communication device and the third wireless communication device.

  The present invention is particularly applicable to multi-hop network systems and ad hoc network systems.

  According to such a wireless communication method, communication data encrypted by one of the first wireless communication device or the third wireless communication device using the third common key is transmitted via the second wireless communication device. Even in the case of transmission to the other side, since the second wireless communication device cannot decrypt the transmitted encrypted communication data in the first place, communication between the first wireless communication device and the third wireless communication device is not possible. Confidentiality can be secured.

  In the wireless communication method according to the first feature, the third common key is different from the second common key (second feature).

  According to this wireless communication method, the second common key is shared between the second wireless communication device and the third wireless communication device, but the second common key and the third common key are different. Therefore, even if communication between the first wireless communication device and the third wireless communication device is performed via the second wireless communication device, confidentiality can be reliably ensured.

  In the wireless communication method according to the first feature or the second feature, a certificate used by the first wireless communication device for authentication of the first wireless communication device together with the first encryption key is used. The method further comprises a step of transmitting to the second wireless communication device, and in the step of acquiring the first encryption key by the second wireless communication device, the first wireless key is used together with the first encryption key. A certificate used for authentication of the communication device is acquired, and the second wireless communication device uses the acquired certificate used for authentication of the first wireless communication device together with the first encryption key. A step of transmitting to the wireless communication device, wherein the third wireless communication device obtains the first encryption key from the second wireless communication device together with the first encryption key. , A certificate used for authentication of the first wireless communication device A certificate used for authentication of the acquired first wireless communication device, and the third wireless communication device receives the encrypted third common key in the second In the step of transmitting to the first wireless communication device via the wireless communication device, a certificate used for authentication of the third wireless communication device is used with the first encryption key together with the third common key. In the step of encrypting and transmitting to the first wireless communication apparatus, and the first wireless communication apparatus obtaining the third common key, the encrypted third common key and third wireless Receiving the certificate used for authentication of the communication device, decrypting the certificate with the decryption key, and holding the decrypted certificate used for authentication of the third wireless communication device, the third wireless communication device Is directly or with the first wireless communication device or the fourth wireless communication device. When transmitting and receiving data via the first wireless communication device, the authentication processing of the first wireless communication device is executed using the stored certificate used for authentication of the first wireless communication device, and the first wireless communication device is authenticated. The wireless communication device further includes a step of executing an authentication process using a certificate used for authentication of the held third wireless communication device (third feature).

  According to this wireless communication method, when data is transmitted and received between the first wireless communication device and the third wireless communication device, the first wireless communication device and the third wireless communication device When the mutual certificate as the transmission / reception destination is acquired, the certificate is held, and therefore it is not necessary to exchange a new certificate when switching the wireless communication path. For this reason, at the time of switching between wireless communication devices, it is possible to efficiently perform authentication processing using the held certificate, and the processing burden on the wireless communication device can be reduced.

  In the wireless communication method according to the third feature, the third wireless communication apparatus transmits information (hops) transmitted from the first wireless communication apparatus and indicating a communication state of the first wireless communication apparatus. Information indicating the number, communication quality (QoS: Quality of service, and so on), and / or information indicating the communication state of the fourth wireless communication device transmitted from the fourth wireless communication device Acquiring information indicating the communication state of the second wireless communication device transmitted from the second wireless communication device, and the acquired communication state of the first wireless communication device And / or information indicating the communication state of the fourth wireless communication device and information indicating the communication state of the second wireless communication device, and the first wireless communication device Between or directly to the fourth radio A step of determining whether or not to transmit / receive data via a communication device, wherein the third wireless communication device directly communicates with the first wireless communication device in the determination. Alternatively, when it is determined that data transmission / reception is performed via the fourth wireless communication device, the third wireless communication device uses a certificate used for authentication of the held first wireless communication device. The first wireless communication device executes authentication processing, and the first wireless communication device executes authentication processing using the stored certificate used for authentication of the third wireless communication device. It is characterized by that.

  According to this wireless communication method, information indicating the communication state such as the number of hops and communication quality is acquired and compared to determine whether to switch the wireless communication path for transmitting and receiving data. For example, it is necessary to compare the information indicating the communication state, determine the switching despite the slight difference, and perform mutual authentication with the wireless communication device that is the transmission / reception destination of new data. There is no problem. For this reason, it becomes possible to reduce the processing burden at the time of switching the wireless communication path.

  In addition, the present invention provides a wireless communication system in which a first wireless communication device transmits and receives data to and from a third wireless communication device via a second wireless communication device. A decryption key storage unit that stores a decryption key; and a first transmission unit that transmits a first encryption key corresponding to the decryption key to the second wireless communication device side, the second wireless The communication device generates a first common key for encrypting and decrypting data transmitted and received between the first wireless communication device and the second wireless communication device. A generator, a first encryption unit that encrypts the first common key using the first encryption key acquired from the first wireless communication device, and encryption by the first encryption unit And a second transmitter that transmits the first common key that has been converted to a first common key. Receiving the encrypted first common key and decrypting with the decryption key, and obtaining the first common key based on the decryption by the decryption unit A common key acquisition unit, and the second wireless communication device and the third wireless communication device are transmitted to and received from the second wireless communication device and the third wireless communication device. Means for sharing the second common key for encrypting and decrypting the data to be transmitted, and the third wireless communication apparatus transmits the data transmitted to and received from the first wireless communication apparatus. A third common key generation unit for generating a third common key for encryption and decryption, and a first encryption key from the base station are acquired, and the first encryption key is used to obtain the first encryption key. The third common key is encrypted, and the encrypted third common key is transmitted via the second wireless communication device. A second transmitter for transmitting to the first wireless communication device, wherein the first wireless communication device further receives the encrypted third common key and receives the decryption key. And a third common key acquisition unit that acquires the third common key based on the decryption, the first wireless communication device and the third wireless communication device One of the devices encrypts data using the third common key and transmits the data to the other of the first wireless communication device and the third wireless communication device via the second wireless communication device. The gist of the present invention is a wireless communication system.

  According to the present invention, even when encrypted communication data is transmitted / received between the first wireless communication device and the third wireless communication device via the second wireless communication device, The encrypted communication data is not decrypted by the second wireless communication apparatus. Therefore, confidentiality of communication can be ensured.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic.

(First embodiment)
FIG. 1 is a system configuration diagram showing a radio communication system according to the first embodiment of the present invention, and FIG. 2 is a block diagram showing a main configuration of an example of the radio communication system. FIG. 3 is a sequence diagram showing processing for establishing confidentiality in the wireless communication system. The wireless communication system includes an authentication server (CA) 1 connected to a mobile communication network, a base station 5 (first wireless communication device) connected to the authentication station 1 via the network 3, a base station 5, for example, a wireless terminal A (20) (second wireless communication device) composed of a mobile phone or a card terminal, and a base station via the wireless terminal A (20) (relay) And a wireless terminal B (40) (third wireless communication device) that transmits and receives communication data to and from the wireless communication device 5. The wireless terminal B (40) is composed of a mobile phone or a card terminal, like the wireless terminal A (20).

  As shown in FIGS. 2 and 3, the authentication server 1 stores (stores) the base station 5, the wireless terminal A (20), and the wireless terminal B (40) in advance (the memory will be described later). The public key X is updated when the base station 5, the wireless terminal A (20), and the wireless terminal B (40) are connected to each other. Processing such as updating is performed by the CA public key management unit 7. Done.

  The base station 5 includes at least a first communication unit 9 that communicates with the authentication server 1 via the network 3, a second communication unit 11 that communicates wirelessly with the wireless terminal A (20), and a first memory 13. Authentication of the first encryption unit 15 for creating the encrypted data, the first decryption unit 17 for decrypting the encrypted data, and the wireless terminal A (20) and the wireless terminal B (40). A first certificate generation unit 21 that generates a base station certificate B including a first authentication unit 19 to be performed and a base station public key (first encryption key) A1 signed by the authentication server 1 and a base station RSA signature. And a control unit 23 for controlling the whole.

  Here, as data to be stored in the first memory 13, a CA public key X, a base station secret key (decryption key) A0, and a terminal A common key (described later) transmitted from the wireless terminal A (20) ( And a common key (first common key) C to be shared between the base station 5 and the wireless terminal A (20).

 The wireless terminal A (20) creates at least a third communication unit 25 that performs wireless communication with the base station 5 and the wireless terminal B (40), a second memory 27, and encrypted data. The second encryption unit 29, the second decryption unit 31 for decrypting the encrypted data, the second authentication unit 33 for authenticating the base station 5 and the wireless terminal B (40), and the authentication server 1 A certificate including the signed common key for the wireless terminal A (20) (the common key between the base station 5 and the wireless terminal A (20): the first common key) C and the RSA signature of the wireless terminal A (20) Certificate D, a second certificate that generates a certificate F including a public key (terminal A public key: second encryption key) E of the wireless terminal A (20) signed by the authentication server 1 and a base station RSA signature A generator 35, a data transmitted / received between the wireless terminal A (20) and the base station 5 For encrypting and decrypting data, and a first common key generation unit 37 that generates the common key C terminal A, a control unit 39 for controlling the whole, a.

 Here, as data stored in the second memory 27, the CA public key X, the base station public key A1 transmitted from the base station 5, and the common for terminal A generated by the first common key generation unit 37 are used. The key C and the private key (terminal A private key) I of the wireless terminal A (20) corresponding to the public key E of the wireless terminal A (20) are included.

 The wireless terminal B (40) creates at least a fourth communication unit 41 that performs wireless communication with the wireless terminal A (20) and the base station 5, a third memory 43, and encrypted data. The third encryption unit 45, the second decryption unit 47 that decrypts the encrypted data, the third authentication unit 49 that authenticates the base station 5 and the wireless terminal A (20), and the authentication server 1 Between the second common key generation unit 51 that generates the signed common key for terminal AB (second common key) G, and the common key for terminal B (base station 5 and wireless terminal B (40)) Common key: third common key) a third common key generation unit 53 for generating J, and a control unit 55 for controlling the whole.

 The data stored in the third memory 43 includes the CA public key X, the base station public key A1, the terminal A-B common key G generated by the second common key generation unit 51, the first 3 and the common key J for terminal B generated by the common key generator 53 of FIG.

 Next, a process for establishing confidentiality in the wireless communication system according to the first embodiment of the present invention will be described with reference to FIGS. 3 and 4.

(Processing between base station and wireless terminal A (20))
In the present embodiment, when a wireless communication channel used in normal communication is established between the base station 5 and the wireless terminal A (20), the base station 5 first stores it in the first memory 13. The base station certificate B (including the base station public key A1) encrypted using the existing CA public key X is transmitted to the wireless terminal A (20) (S1).

  Next, the wireless terminal A (20) that has received the encrypted base station certificate B uses the CA public key X stored in the second memory 27 to obtain the encrypted base station certificate B. Decryption (S2), the base station RSA signature of the base station certificate B obtained by the decryption is confirmed by the second authentication unit 33, and after the confirmation, the base station public key A1 is obtained (S3).

  The wireless terminal A (20) creates encrypted data to be transmitted to the base station 5 using the acquired base station public key A1. Specifically, the wireless terminal A (20) generates the terminal A common key C by the first common key generation unit 37, and obtains the certificate D including the terminal A common key C as the second certificate. After being generated by the certificate generation unit 35, the certificate D is encrypted with the base station public key A1, and then the encrypted certificate D is transmitted to the base station 5 (S4).

  The base station 5 that has received the encrypted certificate D decrypts the encrypted certificate D using the base station private key A0 stored in the first memory, and the certificate obtained by the decryption. The RSA signature of the terminal A of the certificate B is confirmed by the first authenticating unit 19 and, after the confirmation, the common key C for the terminal A is acquired. Thereby, the common key C for terminal A is shared between the base station 5 and the wireless terminal A (20) (S5).

(Processing between wireless terminal A and wireless terminal B)
A case where the wireless terminal B (40) communicates with the wireless terminal A (20) while the terminal A common key C is shared between the base station 5 and the wireless terminal A (20) (S5). (When so-called multi-hop communication is performed), the wireless terminal A (20) and the wireless terminal B (40) share the common key G for the terminal A-B. The same processing as that up to S5 is performed.

  That is, the wireless terminal A (20) first uses the second certificate generation unit 35 to public key (terminal A public key: second encryption key) of the wireless terminal A (20) signed by the authentication server 1. E and the certificate F including the base station RSA signature are generated, the certificate F is encrypted using the base station public key A1 decrypted in S3 described above, and transmitted to the wireless terminal B (40) ( S6).

  Next, the wireless terminal B (40) that has received the encrypted certificate F decrypts it using the base station public key A1 stored in the third memory 43 (S7), and obtains it by the decryption. The third authentication unit 49 confirms the RSA signature of the terminal A of the certificate F to be obtained. After confirmation, the public key E of the wireless terminal A (20) is acquired (S8).

  The wireless terminal B (40) generates the terminal A-B common key G signed by the authentication server 1 by the second common key generation unit 51 and the third certificate generation unit (not shown) A certificate H including the AB common key G is generated, and the certificate H is encrypted using the public key E of the wireless terminal A (20) acquired in S8, so that the wireless terminal A (20) (S9).

  The wireless terminal A (20) decrypts the encrypted certificate H with the private key I of the wireless terminal A (20) stored in the second memory 27, and based on the decryption, the terminal AB The common key G is acquired. Thereby, the common key G for terminal AB is shared between the wireless terminal A (20) and the wireless terminal B (40) (S10).

(Processing between wireless terminal B and base station)
As described above, the common key C for terminal A is shared between the base station 5 and the wireless terminal A (20), and the terminal A− is shared between the wireless terminal A (20) and the wireless terminal B (40). In a state where the B common key G is shared, the following processing is performed.

  First, when the wireless terminal A (20) acquires the base station certificate B in S1, the wireless terminal A (20) uses the CA public key X stored in the second memory 27 to The certificate B is encrypted and transmitted to the wireless terminal B (40) side by broadcast (S11).

  Next, the wireless terminal B (40) decrypts the received encrypted base station certificate B using the CA public key X stored in the third memory unit 43 (S12), and performs the decryption. The RSA signature of the terminal A in the certificate B obtained by the authentication is confirmed by the third authenticating unit 49, and after the confirmation, the base station public key A1 is obtained (S13).

  Then, the wireless terminal B (40) uses the terminal B common key (common key used between the wireless terminal B (40) and the base station 5) J signed by the authentication server 1 as the third common key. A certificate K including a common key J for terminal B is generated by a third certificate generator (not shown) and generated by the generator 53, and the certificate K is obtained from the base station public key A1 acquired in S13. And is transmitted to the wireless terminal A (20) side (S14). The encrypted certificate K transmitted to the wireless terminal A (20) side is transmitted to the base station 5 via the wireless terminal A (20) (S15).

  The terminal B common key J generated by the third common key generation unit 53 is generated by a general reversible encryption method (AES, 3DES, DES, etc.). The key J is generated so as to be different from the common key G for the terminal AB. Accordingly, when the wireless terminal B (40) transmits and receives data to and from the base station 5 via the wireless terminal A (20), the wireless terminal A (20) encrypts the terminal common key. Since J cannot be decrypted, the confidentiality of communication between the wireless terminal B (40) and the base station 5 is reliably ensured.

  Next, when the base station 5 receives the encrypted certificate K transmitted from the wireless terminal A (20), the base station 5 uses the base station private key A0 stored in the first memory 13 to perform the encryption. The certificate K is decrypted, and the terminal B common key J is obtained based on the decryption. Thereby, the terminal B common key J is shared between the wireless terminal B (40) and the base station 5 (S16).

  Thus, when the terminal B common key J is shared between the wireless terminal B (40) and the base station 5, as shown in FIG. 4A, the base station 5 and the wireless terminal A ( 20) between the wireless terminal A (20) and the wireless terminal B (40), and the shared key G for the terminal AB between the wireless terminal A (20) and the wireless terminal B (40). The terminal B common key J is shared with the base station 5, and encrypted communication with high secrecy is performed using each common key.

  In the present embodiment, the wireless terminal A (20) has been described as a relay station. However, the present invention is not limited to this, and the wireless terminal B (40) is a relay station, and the wireless terminal A (20) is the wireless station. The present invention can also be applied when data is transmitted / received to / from the base station 5 via the terminal B (40) (see {b} in FIG. 4).

  As described above, according to the present embodiment, since the wireless terminal A (20) does not have the base station secret key A0, the wireless terminal A (20) is encrypted from the wireless terminal B (40) with the base station public key A1. Even if the certificate K including the common key J is transmitted to the base station 5 via the wireless terminal A (20), the wireless terminal A (20) cannot decrypt the encrypted certificate K. For this reason, since the wireless terminal A (20) cannot acquire the terminal B common key J, the confidentiality of data transmission / reception between the wireless terminal B (40) and the base station 5 via the wireless terminal A (20) is determined. Is secured.

(Second Embodiment)
When wireless terminals that constitute a multi-hop network frequently move, the communication connection state frequently changes. For this reason, mutual authentication or the like needs to be performed again between wireless terminals due to changes in the communication connection state. In such a case, for example, the processing load on the wireless terminals during handover should not be increased. Is desirable.

  In response to such a request, conventionally, when mutual authentication is performed between wireless terminals due to a change in communication connection state in a multi-hop network caused by movement of wireless terminals, multiple Determine whether there is common secret information (key) shared within the hop network, and then determine whether to perform authentication by using the common secret information (key) or authentication using a public key. A technique for reducing the processing load on the wireless terminal by simplifying the processing of the wireless terminal at the time of authentication is also considered.

  However, in this case, since different authentication is performed by determining whether there is secret information (key) to be held, if any of secret information (key) shared in the network is stolen, the stolen secret Using information makes it easy to authenticate with a wireless terminal in the network.

  In addition, at the time of mutual authentication, different secret information held by other wireless terminals other than the secret information (key) used for authentication from the wireless terminals performing mutual authentication but not held by the own wireless terminal Since the (key) is exchanged and held, different secret information (key) other than the stolen secret information (key) can be easily obtained, and it is impossible to improve security.

  Therefore, in the second embodiment, in addition to the first embodiment described above, a method and a wireless communication system that can appropriately avoid the above-described problems are shown.

  FIG. 5 is a block diagram showing a main configuration of an example of a radio communication system according to the second embodiment of the present invention. The base station 5, the wireless terminal A (20), and the wireless terminal B (40) configuring the wireless system in FIG. 5 are as follows in addition to the components configured in the wireless communication system according to the first embodiment described above. The configuration is provided. Specifically, the base station 5 further includes a first communication state information generation unit 57 that generates information (details will be described later) indicating the communication state of the base station 5. The second communication state in which the wireless terminal A (20) generates information indicating the communication state of the wireless terminal A (20) based on the information indicating the communication state of the base station 5 acquired from the base station 5 An information generation unit 59 is included. The wireless terminal B (40) generates the information indicating the communication state of the wireless terminal B (40) based on the information indicating the communication state acquired from the base station 5 or the wireless terminal A (20). A state information generation unit 61 is included.

  The data stored in the first memory 13 of the base station 5 includes a CA public key X, a base station secret key A0, a common key C for terminal A, and a certificate (for example, certificate) used for authentication of the wireless terminal. Letter D, K).

  As data stored in the second memory 27 of the wireless terminal A (20), in addition to the CA public key X, the base station public key A1, the common key C for terminal A, and the secret key I, authentication of the base station 5 is performed. A certificate to be used (certificate B) and a certificate to be used for authentication of the wireless terminal B (40) (certificate H) are included. Further, information indicating the communication state of the base station 5 acquired from the base station 5 is also included.

  As data stored in the third memory 43 of the wireless terminal B (40), in addition to the CA public key X, the base station public key A1, the terminal AB common key G, and the terminal B common key J, A certificate used for authentication of the base station 5 (certificate B) and a certificate used for authentication of the wireless terminal A (20) (certificate F) are included. Moreover, the information which shows the communication state of the radio | wireless terminal A (20) acquired from the radio | wireless terminal A (20) is also contained.

  In addition, the control unit 55 compares information indicating the communication state acquired from the base station or each wireless terminal stored in the third memory 43, and determines switching of the wireless communication path for transmitting and receiving data.

(Authentication process when switching wireless communication path of wireless terminal in wireless communication system)
Next, referring to FIG. 5, FIG. 6, and FIG. 7, a process for maintaining the confidentiality established in advance while efficiently authenticating at the time of switching the wireless communication path caused by the movement of the wireless terminal or the like. explain.

  The base station 5 shares the wireless terminal B (40) and the common key J for the terminal B through the processing from S1 to S16, and establishes the confidentiality of the wireless communication path (from the base station 5 to the wireless terminal A (20 ) Through the wireless communication path to the wireless terminal B (40) (see FIG. 3)). In the process of establishing the secrecy, the base station 5 obtains the certificate D including the RSA signature of the wireless terminal A (20) and the certificate K including the RSA signature of the wireless terminal B (40) from the wireless terminal A (20 ) Includes a certificate B including the RSA signature of the base station 5 and a certificate B including the RSA signature of the wireless terminal B (40). The wireless terminal B (40) transmits the wireless terminal A from the wireless terminal A (20). The certificate F including the RSA signature of (20) and the certificate B including the RSA signature of the base station 5 are acquired and held.

  Each wireless terminal (at least wireless terminal A (20), wireless terminal B (40)) holds the certificate B of the base station 5 by the process of establishing confidentiality, and the base station 5 Certificates D and K of terminal A (20) and wireless terminal B (40) are acquired and held in advance. Therefore, at the time of switching the wireless communication path caused by the movement of the wireless terminal, the base station 5 and each wireless terminal use the held certificate and the base station or wireless terminal that is the destination of data transmission / reception. It is possible to determine whether or not the authentication has been completed, and it is not necessary to exchange a new certificate. For this reason, it is possible to perform an efficient authentication process at the time of switching the wireless communication path.

  Each wireless terminal also acquires information (multi-hop handover parameter) indicating a communication state when acquiring the certificate B including the RSA signature of the base station 5. This multi-hop handover parameter includes, for example, the number of wireless terminals (hops) that become relay stations from the base station 5 to the wireless terminal A (20) and the wireless terminal B (40), and the communication quality at the time of data reception. It consists of level (QoS) and the like.

  Each wireless terminal determines whether or not to switch the wireless communication path that is transmitting and receiving data by comparing information indicating the communication state. In addition, the multihop handover parameter is obtained by updating the number of hops by a wireless terminal (for example, wireless terminal A (20)) serving as a relay station and adding the wireless terminal A (20) as a relay station (number of hops). Including the own wireless terminal), generating a multi-hop handover parameter in the own wireless terminal, and the wireless terminal (for example, the wireless terminal B (40)) secures confidentiality with the base station 5. When performing, it is transmitted together with the certificate B of the base station 5.

(Authentication process 1 when switching wireless communication path of wireless terminal)
Next, an authentication process at the time of switching will be described with reference to FIG. 5, FIG. 6 (a), and FIG. When the wireless terminal B (40) moves and transmits / receives data to / from the base station 5 through the wireless terminal A (20) via the wireless communication path that is secured, the base station 5 The certificate K used for authentication of B (40) is acquired and held, and the wireless terminal B acquires the certificate B used for authentication of the base station 5 and holds it together with the common key J for terminal B. Further, when the terminal B (40) acquires the certificate B used for authentication of the base station 5 from the wireless terminal A (20), the information indicating the communication state of the wireless terminal A (20) (for multi-hop handover) Parameter) is also acquired (S501).

  The wireless terminal B (40) moves to another device (the base station 5 or the like) along with movement or the like when transmitting / receiving data on the wireless communication path via the wireless terminal A (20) that has established confidentiality. When receiving broadcast information (control information for establishing communication, etc.) broadcast from a base station other than the base station (S502), it is possible to directly transmit / receive data to / from the base station based on the received broadcast information Grasp (S503).

  When the base station that can transmit and receive data is the base station 5 (S504), the wireless terminal B (40) requests a parameter for multihop handover in the base station 5 from the base station 5. Or by receiving the broadcast information, it is possible to grasp that the communication destination capable of wireless communication is the base station 5, and therefore, the multi-hop handover parameter based on the number of hops and the communication quality May be generated by the wireless terminal B (40). Thereby, the radio terminal B (40) acquires the multi-hop handover parameter in the base station 5 (S505). On the other hand, when it is confirmed that the information is not broadcast information from the authenticated base station 5 (S504), the authentication process is executed again for the base station, and the base station certificate and shared common key, and for multi-hop handover are used. A parameter is acquired (S506).

  The wireless terminal B (40) compares the multihop handover parameter acquired from the wireless terminal A (20) with the certificate B of the base station 5 in advance with the multihop handover parameter acquired from the base station 5 ( S510). At this time, as a method of performing the comparison, for example, priorities are set for items (number of wireless terminals (number of hops), communication quality (QoS)) included in the parameters for multi-hop handover, and the communication quality is first compared, When they are the same or nearly the same, a method is used in which the number of wireless terminals (hops) that are relay stations is compared.

  In addition to the comparison result by the multi-hop handover parameter, the wireless terminal (in this case, the wireless terminal A (20)) serving as the relay station obtains the certificate of the base station that the wireless terminal has a wireless communication path (this In this case, since the base station certificate B) is also acquired, it is confirmed whether or not a new authentication process needs to be performed when switching to a wireless communication path including a wireless terminal serving as a relay station ( S511) and can be used to determine whether or not to switch the wireless communication path. Therefore, it can also be determined whether or not the wireless terminal B (40) performs a mutual authentication process by generating and transmitting a certificate used for authentication for different base stations.

  As a result of the comparison (S510) and the confirmation (S511), the wireless terminal B (40) transmits / receives data directly to / from the base station 5 by transmitting / receiving data to / from the base station 5 via the wireless terminal A (20). It is determined whether it is better to perform transmission / reception (S512). If it is determined that it is better to directly transmit / receive data to / from the base station 5, the wireless terminal B (40) confirms that it has obtained the certificate B used for authentication of the base station 5. (Corresponding to Yes in S513), the base station 5 is directly requested to switch the wireless communication path for transmitting and receiving data. The base station 5 that has received the request for switching the wireless communication path from the wireless terminal B (40) holds the certificate K used for authentication of the wireless terminal B (40). The wireless terminal B (40) is notified that the wireless communication path can be switched. Receiving this notification, the wireless terminal B (40) switches data transmission / reception with the base station 5 to a new wireless communication path (S515). Thereby, the wireless terminal B (40) and the base station 5 can reduce the processing load at the time of switching the wireless communication path of the wireless terminal B (40).

  Thereafter, the base station 5 and the wireless terminal B (40) perform transmission / reception of data encrypted using the terminal B common key J that has already been shared (S516). As a result, it is possible to switch data transmission / reception to a new wireless communication path while maintaining confidentiality in which the communication contents to be secured in advance are not intercepted.

(Authentication process 2 when switching the wireless communication path of the wireless terminal)
Next, authentication processing at the time of switching will be described with reference to FIGS. 5, 6B, and 7. When the wireless terminal B (40) moves and transmits / receives data to / from the base station 5 through the wireless terminal A (20) via the wireless communication path that is secured, the base station 5 The certificate K used for authentication of B (40) is acquired and held, and the wireless terminal B acquires the certificate B used for authentication of the base station 5 and holds it together with the common key J for terminal B. In addition, when the terminal B (40) acquires the certificate B used for authentication of the base station 5 from the wireless terminal A (20) during the process of ensuring the confidentiality, the communication state of the wireless terminal A (20) (Information for multi-hop handover) is also acquired (S501).

  When the wireless terminal B (40) transmits / receives data on the wireless communication path via the wireless terminal A (20) that has established confidentiality, the wireless terminal B (40) transmits another device (wireless terminal C (60) or other terminal). Etc.) is received from the communication information (control information for establishing communication, etc.) (S502). From this received notification information, the wireless terminal B (40) grasps that the wireless terminal C (60) has reached a range where data can be transmitted and received (S503). The wireless terminal C (60) has the same components as the wireless terminal A (20) and the wireless terminal B (40).

  The wireless terminal B (40) confirms that the mutual authentication between the wireless terminal C (60) and the wireless terminal has not yet been performed by confirming the certificate held in advance (corresponding to No in S507). The same process as the process from S1 to S5 in the process of ensuring the above-described secrecy is performed, and the common key L is shared. At the same time, a certificate B used for authentication of the base station 5 is acquired from the wireless terminal C (60) together with the multi-hop handover parameters in the wireless terminal C (S509).

  The wireless terminal B (40) compares the multi-hop handover parameter acquired from the wireless terminal C (60) with the previously stored multi-hop handover parameter of the wireless terminal A (20) (S510).

  Further, the wireless terminal B (40) transmits the wireless communication path to the base station 5 from the certificate B used for authentication of the base station 5 acquired together with the wireless terminal C (60). It confirms that it has (S511). Then, it is determined that data should be transmitted / received to / from the base station 5 via the wireless terminal C (60) (S512).

  The wireless terminal B (40) confirms the certificate B used for authentication of the base station 5 (corresponding to Yes in S513), and wireless communication for transmitting / receiving data to / from the base station 5 through a new wireless communication path. The base station 5 is requested to switch the route. The base station 5 that has received the wireless channel switching request from the wireless terminal B (40) holds the certificate K used for authentication of the terminal B (40), confirms that it has already been authenticated, The wireless terminal B (40) is notified that the communication path can be switched. Receiving this notification, the wireless terminal B (40) switches data transmission / reception with the base station 5 to a new wireless communication path (S515). Thereby, the wireless terminal B (40) and the base station 5 can reduce the processing load at the time of switching the wireless communication path of the wireless terminal B (40).

  Thereafter, the base station 5 and the wireless terminal B (40) perform transmission / reception of data encrypted using the terminal B common key J that has already been shared (S516). As a result, it is possible to switch data transmission / reception to a new wireless communication path while maintaining confidentiality in which the communication contents to be secured in advance are not intercepted.

(Authentication process 3 when switching the wireless communication path of the wireless terminal)
Next, authentication processing at the time of switching will be described with reference to FIGS. 5, 6 (c), and 7. When the wireless terminal B (40) moves and transmits / receives data directly to / from the base station 5 through a wireless communication path that is secured, the base station 5 is used for authentication of the wireless terminal B (40). The certificate K is obtained and held, and the wireless terminal B obtains the certificate B used for authentication of the base station 5 and holds it together with the common key J for the terminal B. Further, when the terminal B (40) obtains the certificate B used for authentication of the base station 5 during the process of ensuring the secrecy, information indicating the communication state of the base station 5 (parameter for multi-hop handover) ) Is also acquired (S501).

  When the wireless terminal B (40) transmits / receives data on the wireless communication path in which confidentiality is established, the wireless terminal B (40) is transmitted from another device (wireless terminal D (80) or other terminals). ) Receive broadcast information (such as control information for establishing communication) is received (S502). Based on the received notification information, it can be understood that data transmission / reception with the wireless terminal D (80) is possible (corresponding to No in S503). The wireless terminal D (80) has the same components as the wireless terminal A (20) and the wireless terminal B (40).

  The wireless terminal B (40) confirms that the mutual authentication between the wireless terminal D (80) and the wireless terminal has not been performed by confirming the certificate held in advance (S507), and the above-described confidentiality is confirmed. In the S process to be secured, the same process as the process from S1 to S5 is performed, the common key M is shared, and, from the wireless terminal C (60), together with the multihop handover parameters in the wireless terminal D, the base station 5 is acquired (S509).

  The radio terminal B (40) compares the multi-hop handover parameter acquired from the radio terminal D (80) with the multi-hop handover parameter of the base station 5 held in advance (S510).

  Further, the wireless terminal B (40) transmits the wireless communication path to the base station 5 from the certificate B used for authentication of the base station 5 acquired together with the wireless terminal D (80). It confirms that it has (S511). Then, it is determined that it is better to transmit / receive data to / from the base station 5 via the wireless terminal D (80) (corresponding to Yes in S512).

  The wireless terminal B (40) confirms the certificate B used for authentication of the base station 5 (corresponding to Yes in S513), and wireless communication for transmitting / receiving data to / from the base station 5 through a new wireless communication path. The base station 5 is requested to switch the route. The base station 5 that has received the wireless channel switching request from the wireless terminal B (40) holds the certificate K used for authentication of the terminal B (40), confirms that it has already been authenticated, The wireless terminal B (40) is notified that the communication path can be switched. Receiving this notification, the wireless terminal B (40) switches data transmission / reception with the base station 5 to a new wireless communication path (S515). Thereby, the wireless terminal B (40) and the base station 5 can reduce the processing load at the time of switching the wireless communication path of the wireless terminal B (40).

  The base station 5 and the wireless terminal B (40) perform transmission / reception of data encrypted using the terminal B common key J that has already been shared (S516). As a result, it is possible to switch data transmission / reception to a new wireless communication path while maintaining confidentiality in which the communication contents to be secured in advance are not intercepted.

(Authentication process 4 when switching the wireless communication path of the wireless terminal)
Further, the wireless terminal B (40), after the inter-terminal authentication with the other wireless terminal, from the acquired base station certificate, the wireless terminal B (40) communicates with the base station 5 with which the other wireless terminal is currently communicating. If it is determined that the wireless communication path is switched (S512), the process from S1 to S16 described above is executed to newly secure confidentiality (S514). .

  In addition, this invention is not limited only to said each embodiment, A various deformation | transformation or change is possible in the range which does not deviate from the meaning of invention.

1 is a system configuration diagram showing a wireless communication system according to a first embodiment of the present invention. It is a block diagram which shows the principal part structure of an example of a radio | wireless communications system. It is a sequence diagram which shows the process which establishes the secrecy in a radio | wireless communications system. It is the schematic which shows the state which shared the common key between the base station and several radio | wireless terminals. It is a block diagram which shows the principal part structure of an example of the radio | wireless communications system which concerns on the 2nd Embodiment of this invention. It is the schematic which shows the change of the communication connection state between a base station and several radio | wireless terminals. It is a flowchart figure which shows the process which judges the switching of a wireless communication path, ensuring the secrecy in the radio | wireless terminal of a radio | wireless communications system.

Explanation of symbols

1: authentication server, 5: base station,
15: first encryption unit, 17: first decryption unit,
13: First memory, 20: Wireless terminal,
21: First certificate generation unit, 23: Control unit,
27: second memory, 29: second encryption unit,
31: Second decryption unit, 35: Second certificate generation unit,
37: first common key generation unit, 39: control unit,
43: third memory 45: third encryption unit,
47: third decryption unit, 51: second common key generation unit,
53: Third common key generation unit, 55: Control unit,
57: first communication state information generation unit, 59: second communication state information generation unit,
61: Third communication state information generation unit.

Claims (5)

In the wireless communication method in which the first wireless communication device transmits and receives data to and from the third wireless communication device via the second wireless communication device.
A second wireless communication device acquiring a first encryption key corresponding to the decryption key transmitted from the first wireless communication device having a decryption key;
Generating a first common key for encrypting and decrypting data transmitted and received between the first wireless communication device and the second wireless communication device;
The second wireless communication apparatus encrypting and transmitting the first common key using the acquired first encryption key;
The first wireless communication apparatus receiving the encrypted first common key, decrypting with the decryption key, and obtaining the first common key;
Sharing a second common key for encrypting and decrypting data transmitted and received between the second wireless communication device and the third wireless communication device;
The third wireless communication device acquiring the first encryption key from the second wireless communication device;
Generating a third common key for encrypting and decrypting data transmitted and received between the third wireless communication device and the first wireless communication device;
The third wireless communication device encrypts the third common key using the first encryption key, and the encrypted third common key is transmitted through the second wireless communication device. Transmitting to the first wireless communication device;
The first wireless communication apparatus receiving the encrypted third common key, decrypting with the decryption key, and obtaining the third common key;
One of the first wireless communication device and the third wireless communication device encrypts data using the third common key, and the first wireless communication is performed via the second wireless communication device. Transmitting to the other of the device and the third wireless communication device;
A wireless communication method comprising:   The wireless communication method according to claim 1, wherein the third common key is different from the second common key. The first wireless communication device further includes a step of transmitting a certificate used for authentication of the first wireless communication device together with the first encryption key to the second wireless communication device;
In the step of acquiring the first encryption key by the second wireless communication device, a certificate used for authentication of the first wireless communication device is acquired together with the first encryption key;
The second wireless communication device further includes a step of transmitting the acquired certificate used for authentication of the first wireless communication device together with the first encryption key to the third wireless communication device. ,
In the step of acquiring the first encryption key from the second wireless communication device by the third wireless communication device, a certificate used for authentication of the first wireless communication device together with the first encryption key Holding a certificate used for authentication of the acquired first wireless communication device,
In the step of the third wireless communication device transmitting the encrypted third common key to the first wireless communication device via the second wireless communication device, together with the third common key A certificate used for authentication of the third wireless communication device is encrypted with the first encryption key and transmitted to the first wireless communication device;
In the step of obtaining the third common key, the first wireless communication device receives the encrypted third common key and a certificate used for authentication of the third wireless communication device, and Decrypting with the decryption key and holding the decrypted certificate used for authentication of the third wireless communication device,
When the third wireless communication device transmits / receives data to / from the first wireless communication device directly or via the fourth wireless communication device, the held first wireless communication A certificate used for authentication of the first wireless communication device using a certificate used for device authentication, and the first wireless communication device used for authentication of the held third wireless communication device A step of performing an authentication process using the certificate,
The wireless communication method according to claim 1 or 2. The third wireless communication device is
Information indicating the communication state of the first wireless communication device transmitted from the first wireless communication device and / or of the fourth wireless communication device transmitted from the fourth wireless communication device Obtaining information indicating a communication state;
Obtaining information indicating a communication state of the second wireless communication device transmitted from the second wireless communication device;
Information indicating a communication state of the first wireless communication device and / or information indicating a communication state of the fourth wireless communication device and information indicating a communication state of the second wireless communication device And determining whether to transmit / receive data to / from the first wireless communication device directly or via the fourth wireless communication device,
When the third wireless communication device determines in the determination to transmit / receive data to / from the first wireless communication device directly or via the fourth wireless communication device, A third wireless communication apparatus executes authentication processing of the first wireless communication apparatus using a certificate used for authentication of the held first wireless communication apparatus, and the first wireless communication apparatus Executes authentication processing using a certificate used for authentication of the held third wireless communication device,
The wireless communication method according to claim 3. In the wireless communication system in which the first wireless communication device transmits and receives data to and from the third wireless communication device via the second wireless communication device.
The first wireless communication device
A decryption key storage unit that stores a decryption key; and a first transmission unit that transmits a first encryption key corresponding to the decryption key to the second wireless communication device side;
The second wireless communication device is:
A first common key generation unit for generating a first common key for encrypting and decrypting data transmitted and received between the first wireless communication device and the second wireless communication device; A first encryption unit that encrypts the first common key using the first encryption key acquired from the first wireless communication device, and the first encryption unit that is encrypted A second transmitter for transmitting the first common key,
The first wireless communication device further includes:
Receiving the encrypted first common key, and decrypting with the decryption key; and obtaining the first common key based on the decryption by the decryption unit A common key acquisition unit,
The second wireless communication device and the third wireless communication device are for encrypting and decrypting data transmitted and received between the second wireless communication device and the third wireless communication device. Means for sharing the second common key are provided,
The third wireless communication device is:
A third common key generation unit for generating a third common key for encrypting and decrypting data transmitted and received to and from the first wireless communication device; and a first common key from the base station An encryption key is obtained, the third common key is encrypted using the first encryption key, and the encrypted third common key is transmitted through the second wireless communication apparatus to the first A second transmitter for transmitting to the wireless communication device of
The first wireless communication device further includes:
A third common key acquisition unit that receives the encrypted third common key, decrypts it with the decryption key, and obtains the third common key based on the decryption; Configured,
One of the first wireless communication device and the third wireless communication device encrypts data using the third common key, and the first wireless communication is performed via the second wireless communication device. A wireless communication system, wherein the wireless communication system transmits to the other of the apparatus and the third wireless communication apparatus.

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