EFFICIENT PACKET ENCRYPTION METHOD

PROBLEM TO BE SOLVED: To provide an efficient packet encryption key in which the computation time for encryption/decryption is decreased and even when a packet is lost or the like, it can be recovered. SOLUTION: This method comprises a step for generating an S-vector, a step for setting a sequence number, a step for setting a first variable, a step for setting a second variable, a step for setting a byte sequence number, a step for calculating a third variable from the second variable and the byte sequence number, a step for incrementing the byte sequence number, a step for calculating a fourth variable by adding the first variable to the value within the S-vector by the third variable, a step for locating an encryption byte and also a step for taking the exclusive ORing to generate the byte based on the third variable and the value within the S-vector by the fourth variable. COPYRIGHT: (C)2003,JPO