| 摘要 |
PROBLEM TO BE SOLVED: To allow an encryption communication to be performed in real time in a carrier detection type network. SOLUTION: In the encryption communication system, all communication apparatuses taking part in the encrypted communication share a key for encrypting packet communication between the communication apparatuses in an in-car LAN comprising a CAN bus 5 and a communication apparatus. All of communication apparatus taking part in the encrypted communication sense a packet flowing in the CAN bus 5. Based on this, each encryption block 22 possessed by each identical communication apparatus, synchronizes to change the key for encrypting/decoding. The communication apparatuses taking part in the encryption communication also hold the packet to be transmitted in plain text and encrypt, with the current key, only the packet that will be first transmitted among packets to be transmitted. COPYRIGHT: (C)2004,JPO
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