Patent ID: 8068784

Claim:
A communication system, comprising: a first communication apparatus including first short-range communication means for transmitting an inquiry signal to a short-range external communication apparatus via electromagnetic waves and waiting for a response to the inquiry signal; first long-range communication means for communicating via electromagnetic waves in a range wider than a communication area of the first short-range communication means; first switching means for switching to the first short-range communication means or the first long-range communication means; and asymmetric key generating means for generating an encryption key and a decryption key corresponding to the encryption key, the encryption key and the decryption key being asymmetric to each other, and a second communication apparatus including second short-range communication means for receiving the inquiry signal from a short-range external communication apparatus and transmitting a response signal in response to the inquiry signal; second long-range communication means for communicating via electromagnetic waves in a range wider than a communication area of the second short-range communication means; second switching means for switching to the second short-range communication means or the second long-range communication means; session key generating means for generating a random number and using the random number to generate a session key; and encrypting means for encrypting the session key, wherein the second communication apparatus uses the encryption key transmitted from the first communication apparatus to encrypt the session key into an encrypted session key and transmits the encrypted session key to the first communication apparatus, and the first communication apparatus uses the decryption key to decrypt the encrypted session key into the session key and transmits to the second communication apparatus a communication switching request signal to request a switching from a short-range communication by the first and second short-range communication means to a long-range communication, with the session key, by the first and second long-range communication means of the first and second communication apparatuses.