Wireless communication system, wireless communication apparatus, and method of exchanging cryptography key between wireless communication apparatuses

A wireless communication system includes first and second communication apparatuses transmitting/receiving encrypted communication data by radio. The first includes: a first encrypting/decrypting unit encrypting communication data and decrypting encrypted communication data; a first interface unit electrically connectable with a portable nonvolatile memory (NVRAM), to which the NVRAM can be physically removably inserted; and a first cryptography key processing unit generating a temporary cryptography key used for encrypting/decrypting the communication data and a master cryptography key for generating the temporary cryptography key. The second communication apparatus includes: a second encrypting/decrypting unit encrypting the communication data and decrypting the encrypted communication data; a second interface unit electrically connectable with the NVRAM, to which the NVRAM storing the master cryptography key is physically removably inserted; and a second cryptography key processing unit generating the temporary cryptography key based on the master cryptography key read from the NVRAM connected with the second interface unit.