COMMUNICATION SYSTEM AND CONTROL DEVICE

Provided is a communication system including: a first device configured to transmit encrypted information that is encrypted by using a first encryption key; and a second device configured to execute a predetermined process based on the encrypted information obtained from the first device, and a second encryption key that is common to the first encryption key. The first device includes a first change section configured to change the first encryption key in the case where a first condition is satisfied. The second device includes a second change section configured to change the second encryption key in the case where a second condition is satisfied, the second condition being common to the first condition.