Abstract:
A method by authorizing the access of a client by performing an anonymous Diffie-Hellman exchange that can produce authentication material (secret key) between the client and the server, and binding the key to the service-oriented state information asserted by the client. The secret key can be used in the future to prove the ownership of resources as outlined in the state information. This method enables resource ownership-dependent service authorization without requiring initial identity authentication.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit from U.S. Provisional Application No. 60/566,069, filed on Apr. 29, 2004 in the United States Patent and Trademark Office, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to an extensible authentication protocol (EAP). More particularly, the present invention relates to a method of performing an authentication between an authentication server and a client.  
         [0004]     2. Description of the Related Art  
         [0005]     The present invention suggests a communication system that does not require user authentication as in a wireless local area network (WLAN). The WLAN and problems occurring in the communication system requiring no user authentication are explained to facilitate the understanding of the present invention. The WLAN is called Wi-Fi in that it is conveniently used like a hi-fi audio. Personal digital assistants (PDAs) or notebook computers positioned within a predetermined distance from a point at which access points (APs) are installed can use ultrahigh speed Internet. Unlike a wired LAN, the WLAN uses a radio frequency and thus does not need telephone lines or private lines. However, the PDAs or the notebook computers must contain wireless LAN cards.  
         [0006]     A transmission rate of the WLAN is 4 Mbps to 11 Mbps and thus can receive and transmit mass multimedia information. In addition, the usage rate of the WLAN is inexpensive compared to its usage time, and the WLAN is outstanding in terms of mobility and security. Therefore, the WLAN is very useful for temporally installing a network in department stores, hospitals, museums, exhibitions, seminars, construction sites, or the like.  
         [0007]      FIG. 1  shows an AP and a plurality of clients (nodes) constituting a conventional WLAN. Operations performed by devices constituting the conventional WLAN will now be described with reference to  FIG. 1 .  
         [0008]     An AP  100  is linked to a plurality of clients  110 ,  112 ,  114 , and  116 . The AP  100  transmits data received from the plurality of clients  110 ,  112 ,  114 , and  116  to an external server or receives data solicited by the plurality of clients  110 ,  112 ,  114 , and  116  from the external server. The AP  100  transmits the data received from the external server to the plurality of clients  110 ,  112 ,  114 , and  116 .  
         [0009]     The plurality of clients  110 ,  112 ,  114 , and  116  transmit data to or receive data from the external server using the AP  100 .  
         [0010]     It is supposed that the clients  110 ,  112 ,  114 , and  116  try to access the AP  100 . In general, the AP  100  may access the plurality of clients  110 ,  112 ,  114 , and  116  only within a set radio resource. Thus, in a case where a solicitation for a radio resource exceeding the set radio resource is made, the AP  100  allows some of the plurality of clients  110 ,  112 ,  114 , and  116  making a solicitation for an access to access the AP  100  according to a predetermined protocol.  
         [0011]     In general, the AP  100  gives priority to a client that has first tried to access to the AP  100  and allows the client to access according to the priority.  
         [0012]     The client provides the AP with its state information requested from the AP to the AP. (For example, the state information can be the IP address of the client.) Meanwhile, a third client can collect state information of a current client, the third client is able to access the AP instead of the current client. (Following the same example, the third client can attempt to steal the IP address assigned to the victim client. This would be a service theft.)  
         [0013]     In this regard, various solutions have been suggested to prevent the third client from accessing the AP using the state information of the current client.  
         [0014]     In general, the WLAN performs an authentication process to a client using an extensible authentication protocol (EAP). For this purpose, the WLAN includes an authentication server in addition to a client and an AP.  
         [0015]     According to the conventional EAP, the authentication server authenticates a client using a user password. Also, the client must be authenticated prior to an access to a network.  
       SUMMARY OF THE INVENTION  
       [0016]     Accordingly, the present general inventive concept has been made to solve the above-mentioned and/or problems, and an aspect of the present general inventive concept is to provide an extensible authentication protocol (EAP) by which an authentication server can authenticate a client without using a user password.  
         [0017]     According to an aspect of the present invention, there is provided a method of authenticating a client, including: soliciting state information of the client soliciting an access; and generating authentication information using the received state information according to a Diffie-Hellman algorithm. Note that Diffie-Hellman is algorithm is used for anonymous authentication. It is not used for verification of authenticated identities.  
         [0018]     According to another aspect of the present invention, there is provided an authentication system including: a client transmitting state information; and an authentication information generator soliciting the client trying to an access to transmit the state information and generating authentication information from the received state information according to a Diffie-Hellman algorithm. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     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:  
         [0020]      FIG. 1  illustrates an AP and a plurality of clients constituting a conventional WLAN;  
         [0021]      FIG. 2  illustrates a client authentication system including a client, an AP, an access router (AR), and a home agent (HA) according to an embodiment of the present invention; and  
         [0022]      FIG. 3  illustrates a process of authenticating a client using a HA according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     Certain embodiments of the present invention will be described in greater detail with reference to the accompanying drawings.  
         [0024]     In the following description, same drawing reference numerals are used for the same elements even in different drawings. The matters defined in the description such as a detailed construction and elements are nothing but the ones provided to assist in a comprehensive understanding of the invention. Thus, it is apparent that the present invention can be carried out without those defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.  
         [0025]     The present invention suggests a method for a home agent to generate an encryption key by use of state information of a client and to authenticate the client using the generated encryption key.  
         [0026]      FIG. 2  depicts a client authentication system including a client  210 , an access point (AP)  212 , an access router (AR)  214 , and a home agent (HA)  216  according to an embodiment of the present invention. Operations performed by the client authentication system and the devices constituting the client authentication system will now be described with reference to  FIG. 2 .  
         [0027]     In operation S 200 , the client  210  trying to access a network sets a layer  2  with the AP  212 . If the client  210  accesses the AP  212  to try to access the network, the AP  212  sets the layer  2  with the client  210 . In other words, the AP  212  transmits and receives an MAC frames to and from the client  210 .  
         [0028]     In operation S 202 , the client  210  which has set the MAC address sets up a layer  3  connection with the AR  214 . In specific, the client  210  and the AR  214  establish the layer  3  by transceiving information required for the establishment of the layer  3 . Also, if the client  210  links to the AR  214 , the client  210  is assigned a care of address (CoA) that is a temporal address from the AR  214 . The CoA is an address through which the client  210  can be reached while roaming to external networks.  
         [0029]     In operation S 204 , the client  210  obtains information as to the HA  216  from the AR  214 . Note that the client  210  obtains information relating to a relevant agent from the AR  214  in case of other systems, excluding the WLAN, that do not require the user authentication.  
         [0030]     In operation S 206 , the HA  216  performs an authentication process to the client  210 . In specific, the HA  216  performs the authentication process to the client  210  which has solicited an access, using state information of the client  210 . In this particular implementation of the invention, the state information includes the mapping between the home address and CoA of the client  210 .  
         [0031]     In operation S 208 , the HA  216  performs a binding process to the client  210 . If the layer  3  is changed, the HA  216  registers the changed CoA in the external network following the same procedure.  
         [0032]     As described above, the HA  216  performs the authentication process to the client  210  using the anonymous Diffie-Hellman and bind that authentication to the state information of the client  210 . The state information includes a home and care-of addresses assigned to the client  210 .  
         [0033]      FIG. 3  is a view illustrating a process of authenticating the client  210  using the HA  216  according to an embodiment of the present invention. The process of authenticating the client  210  using the HA  216  will now be described with reference to  FIG. 3 .  
         [0034]     In operation S 300 , the client  210  tries to access the HA  216 . The client  210  tries to access the home network to transmit data to or receive data from the external network.  
         [0035]     In operation S 302 , the HA  216  solicits the client  210 , which has solicited an access thereto, to transmit the state information. As described above, the state information may include an address assigned to the client  210  for the access to the home network.  
         [0036]     In operation S 304 , the client  210  transmits its state information thereof to the HA  216 .  
         [0037]     In operation S 306 , the HA  216  generates an encryption key using the received state information and stores the generated encryption key in a memory. According to an embodiment of the present invention, the HA  216  generates the encryption key from the received state information according to Diffie-Hellman algorithm. The HA  216  stores the received state information and the encryption key generated from the state information at the same time. Table I shows an example of information stored in the memory of the HA  216 .  
                       TABLE 1                       Device   State information   Encryption key                   Device 1   a   A       Device 2   b   B       .   .   .       .   .   .       .   .   .       Device n   c   C                  
 
         [0038]     In Table 1, the HA  216  generates the encryption key A from the received state information a according to the Diffie-Hellman algorithm, generates the encryption key B from the received state information b, and generates the encryption key C from the received state information c. In the prior art, the authentication information is generated using a user password. However, in the present invention, the authentication information (encryption key) is generated using the anonymous Diffie-Hellman exchange with the client  210 . Therefore, since a user password is not required to be input, a user does not need to manipulate an additional key for authentication. In short, transmission and reception of the state information according to an embodiment of the present invention are performed without manipulating the additional key by the user.  
         [0039]     The HA  216  performs such an authentication process to generate the authentication information for the client  210 .  
         [0040]     In operation S 308 , the client  210  transmits the state information to the HA  216  to access the home network.  
         [0041]     In operation S 310 , the HA  216  generates the authentication information using the state information received in operation S 308  and determines whether the generated authentication information is equal to one of authentication information that are generated and stored prior to the generated authentication information.  
         [0042]     If the HA  216  determines in operation S 310  that the generated authentication information is equal to one of the stored authentication information, the HA  216  allows the access of the client  210  to the home network. If the HA  216  determines in operation S 310  that the generated authentication information is not equal to one of the stored authentication information, the HA  216  does not allow the access of the client  210  to the external network.  
         [0043]     Alternatively, the HA  216  may provide the generated authentication information to the client  210  after operation S 306 . The client  210 , like the HA  216 , stores its state information and the authentication information generated from the state information. The client  210 , which intends to access the HA  216 , transmits a message containing its state information and the authentication information to the HA  216  in operation S 308 .  
         [0044]     Upon receiving the message containing the state information and the authentication information, the HA  216  determines whether the received state information is stored in the memory. If the state information is not stored in the memory according to the determination, the HA  216  does not allow the access of the client  210  that solicits the access. Conversely, if the state information is stored in the memory, the HA  216  determines whether the received authentication information equals the stored authentication information, and allows the access of the client  210  that solicits the access when the two information equal to each other. Note that the HA  216  allows the access only when the authentication information equal with respect to the same state information.  
         [0045]     Accordingly, an authentication is performed with respect to the client  210  soliciting an access without manipulating an additional user key.  
         [0046]     As described above, in a method and a system for client authentication according to an embodiment of the present invention, a HA can authenticate a client using state information without a user password.  
         [0047]     The foregoing embodiment and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. Also, the description of the embodiments of the present invention is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.