Abstract:
A WCDMA 3G voice communication protection method and a terminal using the method are provided. The method is performed by a terminal operating in conjunction with an S-USIM for voice communication protection. When a calling terminal connects a voice communication channel to a called terminal, secure voice communication is prepared for by collecting information about relevant voice communication. At the calling terminal, synchronous data is set by exchanging the voice communication information with the called terminal, and a secure synchronization procedure is performed based on the set synchronous data. At each of S-USIMs that operate in conjunction with the calling and called terminals, a session key for secure voice communication is generated based on the synchronous data. Secure communication is performed by encrypting and transmitting voice-coded data to be transmitted based on the session key, and decrypting and reproducing received voice-coded data based on the session key.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2011-0125106, filed on Nov. 28, 2011, which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to a Wideband Code Division Multiple Access 3 rd  Generation (WCDMA 3G) voice communication protection method and a terminal using the method. More particularly, the present invention relates to a WCDMA 3G voice communication protection method and a terminal using the method, which use a secure mobile communication terminal composed of a Secure-Universal Subscriber Identity Module (hereinafter referred to as a “S-USIM”) for voice communication protection and a secure 3G terminal as each of calling and called terminals in a WCDMA 3G mobile communication network, thus providing end-to-end protection for voice communication. 
     2. Description of the Related Art 
     Recently, owing to the advantages of easily accessing networks and enabling communication to be possible in a mobile environment, a communication environment has been reorganized from a conventional wired communication network-centered environment into a wireless mobile communication network-centered environment. 
     In particular, with the improvement of sound quality and the popularization of smart phones due to the development of recent technologies, the number of users who use WCDMA 3G mobile communication has rapidly increased. 
     Generally, it is known that WCDMA 3G mobile communication makes it difficult for a third party to access communication data in a wireless channel due to the characteristics of Code Division Multiple Access (CDMA) communication schemes. However, when information about a mobile communication terminal is known, it is possible for a third party to access communication data in a wireless channel. In particular, in an interval except for a wireless channel, the data of a voice encoder is transmitted in the form of plain text, thus causing the problem of being vulnerable to access of communication data by a third party. Due thereto, in order to protect voice communication that is performed over a WCDMA 3G mobile communication network, end-to-end security for voice communication data between a calling terminal and a called terminal is currently required. 
     In WCDMA 3G mobile communication, subscriber information is stored in a universal subscriber identity module (hereinafter also referred to as a “USIM”). That is, since subscribers are identified based on the USIM, each user detachably installs a USIM containing information about the subscriber, thus enabling a mobile communication terminal to be easily replaced and used. 
     However, in this situation, when an encryption function or a key management function is directly installed in a mobile communication terminal, a problem arises in that it is difficult to manage such functions because a mismatch may occur between the subscriber and the key stored in the mobile communication terminal. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a voice communication protection method and a terminal using the method, which use a secure mobile communication terminal composed of an S-USIM and a secure 3G terminal as each of calling and called terminals in a WCDMA 3G mobile communication network, thus performing end-to-end protection for voice communication. 
     In accordance with an aspect of the present invention to accomplish the above object, there is provided a Wideband Code Division Multiple Access 3rd Generation (WCDMA 3G) voice communication protection method, the method being performed by a terminal operating in conjunction with a Secure-Universal Subscriber Identity Module (S-USIM) for voice communication protection and configured to protect WCDMA 3G voice communication, including when a calling terminal connects a voice communication channel to a called terminal, preparing for secure voice communication by collecting information about relevant voice communication; at the calling terminal, setting synchronous data by exchanging the voice communication information with the called terminal, and performing a secure synchronization procedure based on the set synchronous data; at each of S-USIMs that operate in conjunction with the calling and called terminals, generating a session key for secure voice communication based on the synchronous data; and performing secure communication by encrypting and transmitting voice-coded data to be transmitted based on the session key, and decrypting and reproducing received voice-coded data based on the session key. 
     Preferably, the preparing for the secure voice communication may be configured to prepare for the secure voice communication by collecting voice communication information that includes USIM information corresponding to the S-USIM operating in conjunction with the calling terminal and terminal information corresponding to the calling terminal. 
     Preferably, the performing the secure synchronization procedure may be configured to establish timing synchronization for secure communication based on the synchronous data, thus performing the secure synchronization procedure. 
     Preferably, the generating the session key may include searching for a user key corresponding to the synchronous data; and generating the session key based on the user key and the synchronous data. 
     Preferably, the terminal operating in conjunction with the S-USIM may correspond to a secure 3G terminal. 
     In accordance with another aspect of the present invention to accomplish the above object, there is provided a terminal using a Wideband Code Division Multiple Access 3rd Generation (WCDMA 3G) voice communication protection method, including a Radio Frequency (RF) communication unit for allowing the terminal to transmit or receive synchronous data and voice data to or from another party terminal via RF communication; an audio processing unit for converting a voice corresponding to a user of the terminal into voice-coded data or converting voice-coded data corresponding to the other party terminal into a voice; an encryption/decryption processing unit for encrypting voice-coded data to be transmitted based on a session key generated by a relevant Secure-Universal Subscriber Identity Module (S-USIM), and decrypting received voice-coded data based on the session key; and a control unit for performing a secure synchronization procedure with the other party terminal using voice communication information, and performing secure communication by transmitting encrypted data and reproducing decrypted data. 
     Preferably, the control unit may allow the terminal to set synchronous data by exchanging the voice communication information with the other party terminal, and performs the secure synchronization procedure based on the set synchronous data. 
     Preferably, the session key may correspond to a session key for secure voice communication, which is generated by the S-USIM based on the synchronous data set using the secure synchronization procedure. 
     Preferably, the control unit may perform the secure synchronization procedure by establishing timing synchronization for secure communication based on the synchronous data. 
     Preferably, the terminal may further include an interworking unit for allowing the terminal to operate in conjunction with the S-USIM corresponding to a security token. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram schematically showing an environment in which a terminal using a WCDMA 3G voice communication protection method is located according to an embodiment of the present invention. 
         FIG. 2  is a block diagram showing the construction of the secure 3G terminal unit of the terminal using the WCDMA 3G voice communication protection method according to an embodiment of the present invention. 
         FIG. 3  is a block diagram showing the construction of the S-USIM unit of the terminal using the WCDMA 3G voice communication protection method according to an embodiment of the present invention. 
         FIG. 4  is a flowchart showing a WCDMA 3G voice communication protection method according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail below with reference to the accompanying drawings. In the following description, redundant descriptions and detailed descriptions of known functions and elements that may unnecessarily make the gist of the present invention obscure will be omitted. Embodiments of the present invention are provided to fully describe the present invention to those having ordinary knowledge in the art to which the present invention pertains. Accordingly, in the drawings, the shapes and sizes of elements may be exaggerated for the sake of a clearer description. 
     Hereinafter, a WCDMA 3G voice communication protection method and a terminal using the method according to embodiments of the present invention will be described in detail with reference to the attached drawings. 
       FIG. 1  is a diagram schematically showing an environment in which a terminal using a WCDMA 3G voice communication protection method is located according to an embodiment of the present invention. 
     Referring to  FIG. 1 , each of a calling terminal  100  and a called terminal  200  corresponds to the terminal using the WCDMA 3G voice communication protection method according to an embodiment of the present invention. In this case, the calling terminal  100  and the called terminal  200  are connected to each other over a WCDMA 3G mobile communication network and then perform an end-to-end protection procedure for voice communication. 
     The terminal using the WCDMA 3G voice communication protection method includes a terminal unit  110  and a Secure-Universal Subscriber Identity Module (S-USIM) unit  120  for voice communication protection. 
     The terminal unit  110  corresponds to a secure 3G terminal. 
     The S-USIM unit  120  corresponds to a security token (hardware security module). 
     The terminal using the WCDMA 3G voice communication protection method corresponds to a secure mobile communication terminal. The secure mobile communication terminal is characterized in that the S-USIM unit  120  takes charge of an encryption function and a key management function and the secure 3G terminal  110  takes charge of the operation of the S-USIM unit  120  and the support of a secure operation. 
     Next, the construction of the terminal using the WCDMA 3G voice communication protection method will be described in detail below with reference to  FIGS. 2 and 3 . 
       FIG. 2  is a block diagram showing the construction of the terminal unit of the terminal using the WCDMA 3G voice communication protection method according to an embodiment of the present invention, and  FIG. 3  is a block diagram showing the construction of the S-USIM unit of the terminal using the WCDMA 3G voice communication protection method according to an embodiment of the present invention. 
     First, the secure 3G terminal using the WCDMA 3G voice communication protection method according to an embodiment of the present invention will be described based on the calling terminal  100 . 
     Referring to  FIG. 2 , the terminal unit  110  includes a Radio Frequency (RF) communication unit  111 , an input unit  112 , an audio processing unit  113 , a control unit  114 , a display unit  115 , an encryption/decryption processing unit  116 , and an interworking unit  117 . 
     The RF communication unit  111  performs RF communication with the called terminal  200 . 
     The input unit  112  inputs a voice from a relevant user. 
     The audio processing unit  113  converts the voice corresponding to the user into voice-coded data or converts voice-coded data corresponding to the secure 3G terminal  200 , which is the called terminal, into a voice. 
     The control unit  114  sets its own S-USIM information, that is, S-USIM information received from its own S-USIM unit  120 , to synchronous data. Here, the synchronous data includes terminal information such as a time value for a nonce, an S-USIM Identification (ID) required to search for a user key, a phone number, etc. 
     The control unit  114  performs a secure synchronization procedure based on the set synchronous data. In detail, the control unit  114  exchanges the synchronous data for the synchronous data of the called party-side secure mobile communication terminal  200 , and establishes timing synchronization for secure communication based on the exchanged synchronous data. 
     Further, the control unit  114  transmits the voice-coded data converted by the audio processing unit  113  to the called terminal  200  via the RF communication unit  111 . Furthermore, the control unit  114  transfers the voice-coded data received via the RF communication unit  111  to the audio processing unit  113 . 
     The display unit  115  may display a voice communication protection procedure, which is currently being performed by the terminal unit  110 , to the user. The display unit of the present invention is not limited to such a display unit  115 . 
     The encryption/decryption processing unit  116  requests the encryption of voice-coded data to the S-USIM unit  120  or requests the decryption of encrypted voice-coded data to the S-USIM unit  120 . Further, the encryption/decryption processing unit  116  transmits the encrypted voice-coded data to the called terminal  200  or transfers the decrypted voice-coded data to the audio processing unit  113 , under the control of the control unit  114 . 
     The interworking unit  117  allows the terminal unit  110  to operate in conjunction with the S-USIM unit  120  in the secure mobile communication terminal  100 . 
     Referring to  FIG. 3 , the S-USIM unit  120  includes a subscriber authentication unit  121 , an S-USIM control unit  122 , a key management unit  123 , and a generation unit  124 . 
     The subscriber authentication unit  121  performs a procedure for authenticating the user of the secure mobile communication terminal, that is, the subscriber. 
     The S-USIM control unit  122  receives a request for S-USIM information from the relevant terminal unit and transmits S-USIM information corresponding to the request to the terminal unit. 
     Further, the S-USIM control unit  122  encrypts voice-coded data based on a session key that is generated by the generation unit  124  in response to an encryption request made by the relevant terminal unit, or decrypts encrypted voice-coded data based on a session key that is generated by the generation unit  124  in response to a description request. 
     The key management unit  123  searches for a user key corresponding to the received synchronous data. 
     The generation unit  124  generates a session key on the basis of the user key and the synchronous data. 
     Next, the WCDMA 3G voice communication protection method will be described in detail with reference to  FIG. 4 . 
       FIG. 4  is a flowchart showing a WCDMA 3G voice communication protection method according to an embodiment of the present invention. 
     Referring to  FIG. 4 , the WCDMA 3G voice communication protection method according to an embodiment of the present invention is applied to each of a calling terminal  100  and a called terminal  200 . In this case, the calling terminal  100  corresponds to a calling party-side secure mobile communication terminal, and includes a terminal unit  110  and an S-USIM unit  120 . Further, the called terminal  200  corresponds to a called party-side secure mobile communication terminal, and includes a terminal unit  210  and an S-USIM unit  220 . 
     Hereinafter, the calling terminal  100  and the called terminal  200  will be collectively referred to as “secure mobile communication terminals  100  and  200 ”. 
     The calling terminal unit  110  requests a call to the called terminal unit  210 , and the called terminal unit  210  accepts the request of the calling terminal unit  110 . Then, a voice call is connected between the calling terminal  100  and the called terminal  200  at step S 410 . 
     For example, the calling terminal unit  110  converts a voice input from a relevant user into voice-coded data, transmits the voice-coded data to the called party-side secure 3G terminal, converts voice-coded data received from the called terminal unit  210  into a voice, and reproduces the voice. 
     After the voice call has been connected, each of the terminal units  110  and  210  of the secure mobile communication terminals initiates a secure voice communication preparation procedure of preparing for secure voice communication by collecting voice communication information, for example, its own S-USIM information and terminal information of the secure 3G terminal, at steps S 421  and S 422 . 
     Each of the terminal units  110  and  210  of the secure mobile communication terminals sets terminal information, such as a time value of the secure 3G terminal, among the voice communication information, to synchronous data at steps S 431  and S 432 . 
     Each of the terminal units  110  and  210  of the secure mobile communication terminals requests S-USIM information to a corresponding S-USIM unit  120  or  220  at steps S 441  and S 442 . Each of the S-USIM units  120  and  220  transfers corresponding S-USIM information to a corresponding terminal unit  110  or  210  at steps S 443  and S 444 . Each of the terminal units  110  and  210  of the secure mobile communication terminals sets the S-USIM information received from each S-USIM unit  120  or  220  to synchronous data. 
     The synchronous data set by the terminal unit  110  or  210  of each secure mobile communication terminal includes terminal information such as a time value for a nonce, an S-USIM ID required to search for a user key, a phone number, etc. 
     After each of the terminal units  110  and  210  of the secure mobile communication terminals has set the synchronous data, it performs a secure synchronization procedure based on the synchronous data at step S 451  and S 452 . 
     In detail, the calling terminal unit  110  and the called terminal unit  210  exchange synchronous data collected after steps S 431  and S 432  (the secure voice communication preparation procedure) with each other, and establish timing synchronization for secure communication on the basis of the exchanged synchronous data. 
     The calling terminal unit  110  replaces the voice-coded data obtained by converting the voice input from its user with synchronous data and synchronous establishment data for establishing timing synchronization, and transfers the results of the replacement to the called terminal unit  210 . The called terminal unit  210  replaces the voice-coded data obtained by converting the voice input from its user with the synchronous data and synchronous establishment data for establishing timing synchronization, and transfers the results of the replacement to the called terminal unit  110 . 
     After steps S 451  and S 452  (the secure synchronization procedure) have been terminated, each of the terminal units  110  and  210  of the secure mobile communication terminals provides its own station (home station) synchronous data and foreign station synchronous data to a corresponding S-USIM unit  120  or  220 , and requests the generation of a session key for voice communication from the corresponding S-USIM unit  120  or  220  at steps S 461  and S 462 . 
     Each of the S-USIM units  120  and  220  of the secure mobile communication terminals searches for a user key corresponding to the received synchronous data, and generates a session key for secure voice communication based on the found user key and the synchronous data at steps S 463  and S 464 . 
     Each of the terminal units  110  and  210  of the secure mobile communication terminals requests encryption to the corresponding S-USIM unit  120  or  220  by transferring the voice-coded data to the corresponding S-USIM unit at steps S 471  and S 472 . 
     Each of the S-USIM units  120  and  220  of the secure mobile communication terminals encrypts the voice-coded data based on the session key in response to the encryption request at step S 471  or S 472 , and transfers the encrypted voice-coded data to a corresponding terminal unit  110  or  210  at steps S 473  and S 474 . 
     Each of the terminal units  110  and  210  of the secure mobile communication terminals transfers the encrypted voice-coded data to the secure mobile communication, terminal of the other party at step S 480 . 
     Each of the terminal units  110  and  210  of the secure mobile communication terminals requests decryption by transferring the encrypted voice-coded data, which has been received from the secure mobile communication terminal of the other party, to a relevant S-USIM unit  120  or  220  at steps S 481  and S 482 . 
     Each of the S-USIM units  120  and  220  of the secure mobile communication terminals decrypts the encrypted voice-coded data on the basis of the session key in response to the decryption request made at step S 481  or S 482 , and transfers the results of the decryption to the corresponding terminal unit  110  or  210  at steps S 483  and S 484 . 
     Each of the terminal units  110  and  210  of the secure mobile communication terminals reproduces the received decryption results, that is, voice-coded data, at steps S 491  and S 492 . 
     During the secure communication procedure ranging from steps S 471  and S 472  to steps S 491  and S 492 , a procedure in which the terminal unit of the secure mobile communication terminal requests encryption by transferring voice-coded data to the S-USIM unit and in which the S-USIM unit encrypts the voice-coded data and transfers the encrypted voice-coded data to the terminal unit may be replaced with a procedure in which the terminal unit of the secure 3G terminal requests a random number to the S-USIM unit and in which the S-USIM unit generates the random number and provides it to the terminal unit and the terminal unit encrypts the voice-coded data using the received random number. 
     Further, during the secure communication procedure, a procedure in which the terminal unit of the secure 3G terminal requests decryption by transferring encrypted voice-coded data to the S-USIM unit and in which the S-USIM unit decrypts the encrypted voice-coded data and transfers voice-coded data to the terminal unit may be replaced with a procedure in which the terminal unit of the secure 3G terminal requests a random number to the S-USIM unit and in which the S-USIM unit generates the random number and provides it to the terminal unit and the terminal unit decrypts the encrypted voice-coded data using the received random number. 
     As described above, the preferred embodiments of the present invention have been disclosed in the drawings and the present specification. In this case, although specific terms have been used, they are merely intended to describe the present invention and are not intended to limit the meanings of the terms or the scope of the present invention disclosed in the accompanying claims. Accordingly, those skilled in the art will appreciate that various modifications and other equivalent embodiments are possible from the above descriptions. Therefore, the scope of the present invention should be defined by the technical spirit of the invention as disclosed in the accompanying claims. 
     According to embodiments of the present invention, there are advantages in that voice-coded data transmitted over a WCDMA 3G mobile communication network is encrypted and transmitted by a secure mobile communication terminal, so that a voice communication method of providing cryptographic end-to-end security against illegal access by a third party in the WCDMA 3G mobile communication network can be provided, and an S-USIM takes charge of an encryption function and a key management function and is used as a security token, thus improving the entire security and management efficiency.