CIPHER COMMUNICATION METHOD AND APPARATUS FOR THE SAME

A cipher communication method for an encryption apparatus an includes: receiving a second encryption key while performing a cipher communication using a first encryption key; storing encryption key input information on the first and second encryption keys in a static region; copying the stored encryption key input information into a dynamic region; selecting any one of the first and second encryption keys based on the copied encryption key input information and current time information; generating encryption key position information and encryption key selection information on the selected encryption key; and transmitting a cipher text and the encryption key selection information to another encryption apparatus connected to the encryption apparatus through a network such that the another encryption apparatus acquires an encryption key to decrypt the cipher text.