Abstract:
A communication system including a device, an access point (AP) communicating with the device, and a mobile terminal communicating with the device and the AP, and a method in which the device and the AP share a device key that is a private key used in wireless local area network (WLAN) communication, are provided. A one-directional function operation module is provided in each component constituting the communication system, thereby enabling one-directional function operation. Data to be transmitted and received is applied to one-directional function operation in one-directional function operation module, such that the data can be securely transmitted or received.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit under 35 U.S.C. §119(a) of a Korean Patent Application No. 2005-34007, filed on Apr. 25, 2005, the entire content of which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a method and system for configuring security information in a wireless local area network (WLAN). More particularly, the present invention relates to a method and system for configuring security information between a device and an access point (AP) that constitute a WLAN.  
         [0004]     2. Description of the Related Art  
         [0005]     In the present times, wired LAN communication used for Internet access in offices, schools, etc is being substituted by wireless communication such as 802.11 WLAN communication, Bluetooth communication, or infrared communication. The WLAN is called as Wi-Fi because the wireless network is conveniently available, like a HiFi audio system. The WLAN permits access to high-speed Internet with a PDA or a notebook computer within a certain distance around an access point (AP). The use of the WLAN does not require a telephone wire or a private cable because it uses a wireless resource but needs a PDA or notebook computer with a WLAN card. Initially, the WLAN had coverage of up to 10 m. In the 21 st  century, the coverage has significantly widened to about 50 to 200 m. The WLAN enables massive multimedia information to be transferred at a rate of 4 to 11 Mbps.  
         [0006]     As a need for high-speed wireless Internet increases, the WLAN becomes the choice infrastructure for high-speed wireless public networks. The WLAN is spotlighted because it can overcome the low transmission rate of mobile communication systems and guarantee secure communication for a WLAN user by using advanced security technology. In the WLAN, security technology as well as an improved wireless transmission rate are especially required.  
         [0007]     Devices constituting the WLAN communicate with external networks or other devices using wireless resources. Generally, the wireless resources are easily exposed to attack from others compared to wired resources. Thus, there is a need for a technique for performing secure communication between a device and an AP.  
       SUMMARY OF THE INVENTION  
       [0008]     Certain embodiments of the present invention address the above-described problem. Accordingly, it is an object of the present invention to provide a technique of sharing a device key to facilitate secure communication between a device and an access point (AP).  
         [0009]     Another object of the present invention is to provide a technique of securely discarding a device key that is shared between a device and an AP constituting a wireless local area network (WLAN).  
         [0010]     The above exemplary objects of the present invention may be realized by providing a communication system, which may comprise a device, an access point (AP) communicating with the device, and a mobile terminal communicating with the device and the AP, and a method in which a mobile terminal shares a private key with the AP, where a private key configuration request message is transmitted to the AP. A private key configuration request message may comprise network information of the mobile terminal. A private key configuration response message is received from the AP, the private key configuration response message comprising network information of the AP, the private key corresponding to the AP network information is generated, and a private key configuration information message comprising the generated private key is transmitted.  
         [0011]     In accordance with an exemplary embodiment of the present invention, there are provided a communication system, which may comprise a device, an access point (AP) communicating with the device, and a mobile terminal communicating with the device and the AP, and a method in which a mobile terminal shares a device key with the device, where a device key configuration request message is transmitted to the device. A device key configuration response message is received from the device, the device key configuration response message including network information of the device. The device key is generated based on a stored private key, a count, and the received network information of the device, and a device key configuration information message including the generated device key is transmitted.  
         [0012]     In accordance with yet another exemplary embodiment of the present invention, there are provided a communication system, which may comprise a device, an access point (AP) communicating with the device, and a mobile terminal communicating with the device and the AP, and a method in which a device shares a device key with the AP, where a WPA configuration request message is sent, the WPA configuration request message including a randomly generated random  1 , with a MAC address of the device and a count that are used to generate the device key. An authentication WPA configuration request message is received, the authentication WPA configuration request message including a first one-directional function operation value obtained by applying the random  1  to one-directional function operation, and a randomly generated random  2 . When a value obtained by applying the random  1  to the one-directional function operation is equal to the first one-directional function operation value, an authentication WPA configuration response message is sent, the authentication WPA configuration response message including a second one-directional function operation value obtained by applying the received random  2  to the one-directional function operation.  
         [0013]     In accordance with yet another exemplary embodiment of the present invention, there are provided a communication system, which may comprise a device, an access point (AP) communicating with the device, and a mobile terminal communicating with the device and the AP, and a method in which a mobile terminal instructs the device to discard a stored device key, where a device key discard request message is sent, the device key discard request message including a randomly generated random a and network information of the AP. An authentication device key discard request message is received, the authentication device key discard request message including an a-th one-directional function operation value obtained by applying the random a and a pre-stored device key to one-directional operation, a randomly generated random b, and network information of the device. The device key is generated using a stored private key and the received network information of the device, and an authentication device key discard response message is sent when a value obtained by applying the generated device key and the random a to the one-directional operation is equal to the a-th one-directional function operation value, the authentication device key discard response message including a b-th one-directional function operation value obtained by applying the received random b to the one-directional function operation.  
         [0014]     In accordance with yet another exemplary embodiment of the present invention, there are provided a communication system, which may comprise a device, an access point (AP) communicating with the device, and a mobile terminal communicating with the device and the AP, and a method in which a mobile terminal instructs the AP to discard a stored device key, where a WPA discard request message is sent, the WPA discard request message including a randomly generated random c and network information of the AP. An authentication WPA discard request message is received, the authentication WPA discard request message including a c-th one-directional function operation value obtained by applying the random c and a pre-stored device key to one-directional operation, and a randomly generated random d. When a value obtained by applying the pre-stored device key and the receiving random c to the one-directional operation is equal to the c-th one-directional function operation value, an authentication WPA discard response message is sent, the authentication WPA discard response message including a d-th one-directional function operation value obtained by applying the received random d to the one-directional function operation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The above aspects and features of the present invention will be more apparent by describing certain embodiments of the present invention with reference to the accompanying drawings, in which like reference numerals will be understood to refer to like parts, components and structures, where:  
         [0016]      FIG. 1  illustrates a wireless local area network (WLAN) including a mobile terminal, a device, and an access point (AP) according to an exemplary embodiment of the present invention;  
         [0017]      FIG. 2  illustrates a process in which a mobile terminal and an AP share a private key therebetween according to an exemplary embodiment of the present invention;  
         [0018]      FIG. 3  illustrates a process in which a device and an AP share a device key therebetween according to an exemplary embodiment of the present invention; and  
         [0019]      FIG. 4  illustrates a process in which a device and an AP discard stored information according to an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0020]     Certain exemplary embodiments of the present invention will be described in detail with reference to the annexed drawings. In the drawings, as noted above, the same elements are denoted by the same reference numerals throughout the drawings. In the following description, detailed descriptions of known functions and configurations incorporated herein have been omitted for conciseness and clarity.  
         [0021]      FIG. 1  shows components constituting a wireless local area network (WLAN) according to an exemplary embodiment of the present invention. The WLAN includes a device  102 , an access point (AP)  104 , and a mobile terminal (relaying terminal)  100 . The WLAN generally includes at least one device and at least one AP. For convenience of illustration,  FIG. 1  shows only one device  102  and one AP  104 . The characteristic of each device forming the WLAN will be explained hereinafter.  
         [0022]     The mobile terminal  100  is portable, like a mobile phone or a personal digital assistant (PDA) phone, and provides a user interface (UI). The mobile terminal  100  includes an infrared communication module for enabling infrared communication, and a one-directional function algorithm module for generating keys.  
         [0023]     The device  102  performs wireless communication with the AP  104  over a wireless channel and infrared communication with the mobile terminal  100  over an infrared channel. Even though the infrared channel is one of wireless channels, the infrared channel and the wireless channel are used herein as distinct mediums. The device  102  includes an infrared communication module for enabling infrared communication and a one-directional function algorithm module for generating keys.  
         [0024]     The AP  104  includes an infrared communication module for enabling infrared communication with the mobile terminal  100 . The AP  104  and the device  102  sharing a private key therebetween will be described with reference to  FIGS. 2 and 3 .  
         [0025]      FIG. 2  shows a process in which an AP  104  and a mobile terminal  100  share a private key therebetween according to an exemplary embodiment of the present invention.  
         [0026]     The mobile terminal  100  has an AP mode in which the mobile terminal  100  communicates with the AP  104  and a device mode in which the mobile terminal  100  communicates with the device  102 . The mobile terminal  100  is switched to the AP mode to share a private key with the AP  104 . The mobile terminal  100  initializes stored parameter values prior to communicating with the AP  104 . The AP  104  initializes a count and a service set identifier (SSID). The SSID is a unique identifier of 32 bytes that constitutes a header of a packet that is transferred over the WLAN. If a plurality of APs constitute the WLAN, each AP has a unique SSID. The device  102  wirelessly communicates with the AP  104  that is specified by the SSID.  
         [0027]     The mobile terminal  100  sends a private key configuration request message (MKconfig_request message) with mobile terminal information to the AP  104  over the infrared channel (S 200 ). The private key configuration request message is a message for requesting to initiate a private key configuration mode in which a private key is configured. The mobile terminal  100  transmits and receives necessary messages and information to and from with the AP  104  over the infrared channel. The mobile terminal information contained in the private key configuration request message includes network information of the mobile terminal  100 .  
         [0028]     In response to receiving the private key configuration request message, the AP  104  checks whether a private key for the mobile terminal  100  is stored. In addition, the AP  104  searches for an SSID that is network information of the AP.  
         [0029]     The AP  104  transmits a private key configuration response message (MKconfig_response message) including the SSID to the mobile terminal  100  over the infrared channel (S 202 ). The private key configuration response message indicates that the AP  104  can receive a new private key. In response to receiving the private key configuration response message, the mobile terminal  100  determines whether the same SSID as the received SSID is stored. If the same SSID as the received SSID is stored, the mobile terminal  100  generates and stores a new private key. In this case, the mobile terminal  100  stores the private key associated with the stored SSID.  
         [0030]     If the same SSID as the received SSID is not stored, the mobile terminal  100  assigns a memory area to store the received SSID in the memory and generates and stores a random private key. In response to receiving the private key configuration response message, the mobile terminal  100  increments a count by one. If the same SSID as the received SSID is not stored, the mobile terminal  100  does not have a stored private key associated with the SSID.  
         [0031]     The mobile terminal  100  transmits a private key configuration information message (MKconfig_info message) to the AP  104  over the infrared channel (S 204 ). The private key configuration information message includes an old private key and the newly generated (or the randomly generated) private key count. If there is no old private key, that is if the same SSID as the received SSID is not stored, the mobile terminal  100  represents information about the old private key as null.  
         [0032]     In response to receiving the private key configuration information message, the AP  104  determines whether the received old private key is the same as a stored private key. If the received old private key is the same as the stored private key, the AP  104  transmits a private key configuration complete message (MKconfig_complete message) to the mobile terminal  100  over the infrared channel (S 206 ). The AP  104  updates a table with the information contained in the private key configuration message. The mobile terminal  100  then notifies the user that private key share is terminated. That is, the mobile terminal  100  notifies the user that the private key share is terminated, through for example a display unit, a sound outputting unit, or a vibration unit.  
         [0033]     If the received old private key is not the same as the stored private key, the AP  104  sends a private key configuration failure message (MKconfig_failure message) to the mobile terminal  100  (S 206 ).  
         [0034]     When the received count is equal to or smaller than the stored count, the AP  104  recognizes that a third party is involved in the private key share between the mobile terminal  100  and the AP  104 . Only if the received count is greater than the stored count, the AP  104  sends the private key configuration complete message.  
         [0035]     While the mobile terminal is shown in  FIG. 2  as generating the private key, the AP may generates the private key according to setting of the user. That is, the AP may generate the private key using its own network information when receiving the private key configuration request message.  
         [0036]     By performing the above-described exemplary processes, the mobile terminal  100  and the AP  104  share the new private key. The mobile terminal  100  is switched to the device mode in response to a request from the user. While the mobile terminal  100  and the AP  104  communicate with each other over the infrared channel, the present invention is not limited to an infrared channel. That is, the mobile terminal  100  and the AP  104  may communicate with each other over other local area communication channel.  
         [0037]      FIG. 3  shows a process in which the device  102  and the AP  104  share a private key therebetween according to an exemplary embodiment of the present invention. A process in which the device  102  and the AP  104  share a private key therebetween according to an exemplary embodiment of the present invention will be now described in detail with reference to  FIG. 3 .  
         [0038]     The mobile terminal  100  transmits a device key configuration request message (DK config_request message) to the device  102  over the infrared channel (S 300 ). For convenience of illustration, a private key shared between the device and the AP is called a device key. The device key configuration request message is for requesting to transmit configuration information. After transmitting the device key configuration request message, the mobile terminal  100  increments its own count by one.  
         [0039]     The device  102  transmits a device key configuration response message (DKconfig_response message) to the mobile terminal  100  over the infrared channel (S 302 ). The device configuration response message includes a MAC address of the device. In response to receiving the device configuration response message, the mobile terminal  100  configures the device key using a stored private key, the received MAC address, and the count. When the mobile terminal  100  does not receive the device configuration response message within a set period of time, the mobile terminal  100  notifies the user that an error has occurred.  
         [0040]     The mobile terminal  100  transmits a device configuration information message (DKconfig_info message) to the device  102  over the infrared channel (S 304 ). The device configuration information message includes the device key generated in S 302 , and the SSID and the count stored in the mobile terminal  100 . In response to receiving the device configuration information message, the device  102  determines whether the same SSID as the received SSID is stored in its own memory. If the same SSID as the received SSID is stored in the memory, the device  102  updates the memory with the received information. If the same SSID as the received SSID is not stored, the device  102  assigns a memory area to store the received information in the memory, and stores the received information into the assigned memory.  
         [0041]     The device  102  then sends a device key configuration complete message (DKconfig_complete message) to the mobile terminal  100  over the infrared channel (S 306 ). On the other hand, when an error occurs in the above-described process, the device  102  sends a device key configuration failure message (DKconfig_failure message) to the mobile terminal  100  over the infrared channel (S 306 ). The device key configuration failure message includes information about causes of the error.  
         [0042]     After transmitting the device key configuration complete message, the device  102  establishes a wireless channel to wirelessly communicate with the AP  104  (S 308 ).  
         [0043]     The device  102  transmits a WPA configuration request message (WPAconfig_request message) to the AP  104  (S 310 ). The WPA configuration request message includes a random  1  obtained from a device key corresponding to the same SSID as the SSID of the current channel, the MAC address, and the count. The random  1  is a value that is randomly generated by the device  102 .  
         [0044]     In response to receiving the WPA configuration request message, the AP  104  proceeds to a subsequent process only if the received count is greater than the stored count. That is, if the received count is not greater than the stored count, the AP  104  regards the WPA configuration request message as a retransmission message. The AP  104  generates a device key using the received MAC address and the count. The AP  104  applies the generated device key and the received random 1  to a one-directional function to calculate a first one-directional function operation value. The AP  104  further generates random  2 . The random  2  is a value that is randomly generated by the AP  104 .  
         [0045]     The AP  104  transmits an authentication WPA configuration request message (AuthWPAconfig_request message) to the device  102  (S 312 ). The authentication WPA configuration request message includes the first one-directional function operation value and the random  2 . If the stored count is equal to or greater than the received count as described above, the AP  104  transmits a WPA configuration failure message (WPAconfig_failure message) to the device  102  (S 312 ).  
         [0046]     In response to receiving the authentication WPA configuration request message, the device  102  determines whether the value obtained by applying the device key and the random 1  to the one-directional function is equal to the first one-directional function operation value. If the value is not equal to the first one-directional function operation value, the device  102  sends an authentication WPA configuration failure message (AuthWPAconfig_failure message) to the AP  104  (S 312 ). If the value is equal to the first one-directional function operation value, the device  102  applies the device key and the random  2  to the one-directional function to calculate a second one-directional function operation value.  
         [0047]     The device  102  then sends an authentication WPA configuration response message (AuthWPAconfig_response message) to the AP  104 . The authentication WPA configuration response message includes the second one-directional function operation value.  
         [0048]     In response to receiving the authentication WPA configuration response message, the AP  104  determines whether the value obtained by applying the stored device key and the random  2  to the one-directional function is equal to the second received one-directional function operation value. If the value is not equal to the second one-directional function operation value, the AP  104  sends a WPA configuration failure message (WPAconfig_failure message) to the device  102  (S 316 ). If the value is equal to the second one-directional function operation value, the AP  104  writes device information to a registration device table. That is, the AP  104  stores the MAC address and the device key of the device  102  in the registration device table. The AP  104  updates and stores the count.  
         [0049]     The AP  104  sends a WPA configuration complete message (WPAconfig_complete message) to the device  102  (S 316 ). The above-described processes allow the device  102  and the AP  104  to authenticate each other. The device  102  performs a re-association process to terminate and extend the session (S 318 ).  
         [0050]      FIG. 4  shows a process in which the device  102  and the AP  104  discard an authenticated device key according to an exemplary embodiment of the present invention.  
         [0051]     The device  102  stores a device key and the mobile terminal  100  stores a private key. The AP  104  stores the device key and the private key. The private key is shared between the device  102  and the mobile terminal  100  and is not distinct between devices. Thus, the step S 200  is performed once on one mobile terminal and one AP.  
         [0052]     The mobile terminal  100  sends a device key discard request message (DKrev_request message) to the device  102  (S 400 ). The device key discard request message includes a SSID and a random a. The random a is a value that is randomly generated by the mobile terminal  100 .  
         [0053]     In response to receiving the device key discard request message, the device  102  searches for a device key corresponding to the SSID. The device  102  applies to the searched device key and the received random a to a one-directional function to calculate an a-th one-directional function operation value.  
         [0054]     The device  102  sends an authentication device key discard request message (AuthDKrev_request message) to the mobile terminal  100  (S 402 ). The authentication device key discard request message includes a MAC address and a random b of the device  102 , a count, and an a-th one-directional function operation value. If there is no same SSID, the device  102  sends a device key failure message (DK_failure message) to the mobile terminal  100  (S 402 ).  
         [0055]     In response to receiving the authentication device key discard request message, the mobile terminal  100  generates the device key using the private key, the MAC address, and the count. The mobile terminal  100  determines whether a value obtained by applying the generated device key and the stored random a to the one-directional function is equal to the a-th received one-directional function operation value. If the value is not equal to the a-th received one-directional function operation value, the mobile terminal  100  sends an authentication device key discard failure message (AuthDKrev_failure message) to the device  102  (S 404 ). If the value is equal to the a-th received one-directional function operation value, the mobile terminal  100  applies the device key and the random b to the one-directional function to generate a b-th one-directional function operation value.  
         [0056]     The mobile terminal  100  sends an authentication device key discard response message (AuthDKrev_response message) to the device  102  (S 404 ). The authentication device key discard response message includes the b-th one-directional function operation value. In response to receiving the authentication device key discard response message, the device  102  determines whether a value obtained by applying the stored device key and random b to the one-directional function is equal to the b-th received one-directional function operation value.  
         [0057]     If the value is not equal to the b-th received one-directional function operation value, the device  102  sends a device key discard failure message (DKrev_failure message) to the mobile terminal  100  (S 406 ). If the value is equal to the b-th received one-directional function operation value, the device  102  sends a device key discard complete message (DKrev_complete message) to the mobile terminal  100  (S 406 ) and discards the stored information. When the mobile terminal  100  receives the device key discard complete message, the mobile terminal  100  recognizes that the device  102  discards the stored information. The mobile terminal  100  may write to a stored discard table a fact that the device  102  discards the stored information.  
         [0058]     A process in which the information stored in the AP  104  is discarded will be now described.  
         [0059]     The mobile terminal  100  sends a WPA discard request message (WPArev_request message) to the AP  104  (S 408 ). The WPA discard request message is for requesting to discard the device  102  information stored in the AP  104 . The WPA discard request message includes a random c, and a MAC address of the device  102 . The random c is a value that is randomly generated by the mobile terminal  100 .  
         [0060]     In response to receiving the WPA discard request message, the AP  104  searches for a MAC address corresponding to an SSID. If there is no corresponding MAC address, the AP  104  sends a WPA discard failure (WPArev_failure) message (S 410 ). If there is the MAC address, the AP  104  obtains a device key corresponding to the MAC address. The AP  104  calculates a c-th one-directional function operation value by applying a stored device key and the received random c to one-directional function operation. In addition, the AP  104  generates a random d.  
         [0061]     The AP  104  sends an authentication WPA discard request message (AuthWPArev_request message) to the mobile terminal  100  (S 410 ). The authentication WPA discard request message includes the random d and the c-th one-directional function operation value.  
         [0062]     In response to receiving the authentication WPA discard request message, the mobile terminal  100  determines whether a value obtained by applying the stored device key and the random c to one-directional function is equal to the received c-th one-directional function operation value. If the value is not equal to the received c-th one-directional function operation value, the mobile terminal  100  sends an authentication WPA discard failure message (AuthWPArev_failure message) to the AP  104  (S 412 ). If the value is equal to the received c-th one-directional function operation value, the mobile terminal  100  generates a d-th one-directional function operation value that is a value obtained by applying the device key and the random d to one-directional function.  
         [0063]     The mobile terminal  100  sends an authentication WPA discard response message (AuthWPArev_response message) to the AP  104  (S 412 ). The authentication WPA discard response message includes a d-th one-directional function operation value. In response to receiving the authentication WPA discard response message, the AP  104  determines whether a value obtained by applying the stored device key and the random d to one-directional function is equal to the d-th received one-directional function operation value.  
         [0064]     If the value is not equal to the d-th received one-directional function operation value, the AP  104  sends a WPA discard failure message (WPArev_failure message) to the mobile terminal  100  (S 414 ). If the value is equal to the d-th received one-directional function operation value, the AP  104  transmits a WPA discard complete message (WPArev_complete message) to the mobile terminal  100  and discards the stored device related information (S 414 ). That is, the AP  104  discards the device MAC address and the device key stored in the registration device table. When the mobile terminal  100  receives the WPA discard complete message, the mobile terminal  100  recognizes that the AP  104  discards the stored information.  
         [0065]     As described above, security of data against attack from a third party may be improved by sharing authentication information between the device and the AP using mobile terminal. That is, a more secure transmission and reception of data may be achieved by sharing the private key and the device key using a one-directional function generating module included in the mobile terminal and the AP.  
         [0066]     While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and equivalents thereof.