To provide a communication method and a communication device capable of improving the flexibility of a key exchange system in encryption communication of a wireless communications system simply and at a low cost.

The communication method encrypts and communicates data between a first communication device and a second communication device. The first communication device comprises a storage step for storing a plurality of kinds of parameter information used for calculating a key for encryption, a determination step for determining one of the parameter information as the one in use for communication when the communication is performed with the second communication device, a transmitting step for transmitting the determined parameter information to the second communication device, and a calculation step in which the first communication device and the second communication device calculate the key based on the determined parameter information.

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