An electrically assisted vehicle comprising: an electric motor; a device that is configured to send motor control-related data to be used in controlling rotation of the electric motor; and a control circuit that is configured to control the electric motor based on the motor control-related data, wherein, the control circuit and the device are capable of communicating with each other, the control circuit and the device both retaining a same data generation rule; the control circuit is configured to send first data to the device; the device is configured to receive first reception data from the control circuit, is configured to generate second data at least including a portion of the first reception data, is configured to generate third data from the second data by using the data generation rule, and is configured to send the third data to the control circuit; and the control circuit is configured to receive second reception data from the device, is configured to generate fourth data at least from the first data by using the data generation rule, is configured to compare a portion of the second reception data and the fourth data, and if a result of comparison indicates a match, is configured to permit control of the electric motor that is based on the motor control-related data, wherein, the first reception data received by the device includes the first data; the device is configured to generate the third data from the second data by using the data generation rule, the second data including the first data; the second reception data received by the control circuit includes the third data; and the control circuit is configured to generate the fourth data at least from the first data by using the data generation rule, and is configured to compare the third data against the fourth data, wherein the third data includes the motor control-related data. an electric motor; a device that is configured to send motor control-related data to be used in controlling rotation of the electric motor; and a control circuit that is configured to control the electric motor based on the motor control-related data, wherein, the control circuit and the device are capable of communicating with each other, the control circuit and the device both retaining a same data generation rule; the control circuit is configured to send first data to the device; the device is configured to receive first reception data from the control circuit, is configured to generate second data at least including a portion of the first reception data, is configured to generate third data from the second data by using the data generation rule, and is configured to send the third data to the control circuit; and the control circuit is configured to receive second reception data from the device, is configured to generate fourth data at least from the first data by using the data generation rule, is configured to compare a portion of the second reception data and the fourth data, and if a result of comparison indicates a match, is configured to permit control of the electric motor that is based on the motor control-related data, wherein, the first reception data received by the device includes the first data; the device is configured to generate the third data from the second data by using the data generation rule, the second data including the first data; the second reception data received by the control circuit includes the third data; and the control circuit is configured to generate the fourth data at least from the first data by using the data generation rule, and is configured to compare the third data against the fourth data, wherein the third data includes the motor control-related data.