Enhanced security is provided in a system comprising a medical device and a monitoring device. The medical device is configured for implantation into a living organism, and comprises processing circuitry and an interface for communicating with the monitoring device. Access to the medical device by the monitoring device is controlled based on measurement of one or more physiological values of the living organism by at least one of the two devices. In an illustrative embodiment, the medical device and the monitoring device are configured to include respective physiological value sensors for measuring respective dynamic physiological values of the living organism. The medical device is further configured to determine if the dynamic physiological values are sufficiently similar to one another and to grant or deny the monitoring device access to the medical device based on the determination.
