A method for applying encryption in communication between terminals includes determining a security key to be used when the terminal transmits and receives data to/from another terminal, determining information for updating the security key; transmitting a signal including information related to the security key and the information for updating the security key, to the another terminal, and encrypting data to be transmitted to the another terminal or decrypting data received from the another terminal, by using the security key. A security key is configured during communication between terminals, and is updated without separate communication between the terminals. Encryption and decryption are performed during transmission and reception of data. Therefore, security can be secured at relatively low complexity during the transmission and reception of data between the terminals. Other embodiments including a terminal are also disclosed.