INFORMATION-CIPHERING METHOD AND DATA COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To transfer data by mode of not ciphering a header field in a physical layer by dividing into function layers in which data transferring systems are different at each layer of different data frame structure. SOLUTION: A not ciphered sub-block (plain text in) is ciphered from a network side and transferred to a mobile station(MS) side as a ciphered block (ciphered text). A block counter (BLCNT) is set to be an initial value by a set line signal (clear) at the time of starting a data frame of each adaptive layer and generates a data count (count (b)). A ciphering algorithm A8 calculates an output bit string (block 1) for each block from a prescribed ciphering key Kc and the count (b). A network side obtains a text by bit-adding a block 1 to the plain text.