Patent ID: 7197643

Claim:
A key exchange proxy network system performing, as proxy, a key exchange processing to be performed between a first terminal unit and a second terminal unit for encryption communication therebetween, said key exchange proxy network system comprising: a first service control unit accessed by the first terminal unit, and a first key exchange proxy unit performing the key exchange processing as proxy for the first terminal unit; wherein the first service control unit comprises: a first message reception section receiving a message from the first terminal unit, or the second terminal unit, or the first key exchange proxy unit; a first protocol control section which retains a first data for deciding whether the message received by the first message reception section is a key exchange message or a message including a key, decides whether the reception message is the key exchange message or the message including the key based on said first data, determines the first key exchange proxy unit as transfer destination when the reception message is the key exchange message received from either the first terminal unit or the second terminal unit, determines the second terminal unit as transfer destination when the reception message is the key exchange message received from the first key exchange proxy unit, and determines the first terminal unit as transfer destination when the reception message is the message including the key; and a first message transmission section transmitting the message received by the first message reception section to the transfer destination determined by the first protocol control section, and the first key exchange proxy unit comprises: a second message reception section receiving the message from the first service control unit; a second protocol control section which exchanges the key exchange message with the second terminal unit, and determines the key, when the message received by the second message reception section is the key exchange message; and a second message transmission section transmitting the key determined by the second protocol control section to the first service control unit as message including the key.