A method for converting a key exchange protocol in a duplex channel into a key exchange protocol in a half-duplex channel is provided to facilitate conversion without increase of a network load by generating a new session key for a half-duplex channel without the change of contents of a transmission message of the key exchange protocol in the duplex channel. A method for converting a key exchange protocol in a duplex channel into a key exchange protocol in a half-duplex channel includes the steps of: converting a round message in the duplex channel into a round message in the half-duplex channel(S21); and applying a Pseudo random function to a session key of the round message in the duplex channel and a session identifier of the round message in the half-duplex channel and generating a session key for the round message in the half-duplex channel for a session corresponding to the identifier(S23).
展开▼
