Patent ID: 8472629

Claim:
A communication system including a master device and a plurality of slave devices, wherein the master device comprises: a generation unit that generates a session key; a unit that receives public keys from the plurality of slave devices, encrypts the session key using the public key of each slave device and transmits the encrypted session keys to the plurality of slave devices; a first reception unit that receives decryption completion notifications, for notifying completion of decryption of the encrypted session key by the slave device, from the plurality of slave devices; a communication parameters transmission unit that encrypts communication parameters using the session key and transmits the encrypted communication parameters to the plurality of slave devices, based on the reception of the decryption completion notifications by the first reception unit; a second reception unit that receives acquirement notifications, for notifying acquisition of the communication parameters by the slave device, from the plurality of slave devices; and a switching unit that switches to setting the communication parameters after the acquirement notifications have been received from all of the plurality of slave devices by the second reception unit, and each slave device comprises: a decryption unit that transmits the public key to the master device, receives the session key encrypted using the public key, and decrypts the session key; a notification unit that transmits the decryption completion notification to the master device in a case where decryption of the session key is completed by the decryption unit; a communication parameters decryption unit that receives the communication parameters encrypted using the session key from the master device and decrypts the communication parameters using the decrypted session key; and a second notification unit that transmits the acquirement notification to the master device in a case where the decryption of the communication parameters completes.