A mobile communication terminal used in wideband code division multiple access (WCDMA) 3G mobile communication includes: a communication terminal unit configured to receive a short text message from a user and transmit encrypted data generated by encrypting the short text message; and a secure-universal subscriber identity module (S-USIM) unit configured to generate a session key for encrypting the short text message, when receiving a request to encrypt the short text message from a communication terminal unit.