DATA ENCRYPTING METHOD, DATA DECRYPTING METHOD, LAN CONTROL DEVICE INCLUDING ILLEGAL ACCESS PREVENTION FUNCTION, AND INFORMATION PROCESSING APPARATUS

摘要

PROBLEM TO BE SOLVED: To exchange data only with a specified party, to keep secrecy of data to be exchanged, and to prevent illegal access. SOLUTION: A transmission encryption section 11 transmits data of one packet after setting an encrypted authentication code to an IP header option part each time the data are to be transmitted. A reception decryption section 12 acquires the authentication code contained in the received data and determines whether to permit reception of data based on a result of decrypting the authentication code. When no authentication code is set and when the authentication code can not be normally decrypted, connection is refused or cut off. The data themselves are also encrypted to keep secrecy of data to be transmitted. Thus, secrecy of data to be exchanged between a terminal device 1 and a server 2 can be kept, further, illegal access to the server 2 can be prevented, and secrecy of data of the server 2 can be kept. COPYRIGHT: (C)2007,JPO&INPIT