An apparatus comprises a medical device configured for implantation into a living organism. The medical device comprises processing circuitry, a memory and interface circuitry configured for communication with a monitoring device. The medical device is configured to receive a request for access from the monitoring device, to measure a physiological value of the living organism, to perform a pairing protocol with the monitoring device, the pairing protocol comprising a secure channel set-up phase followed by an authentication phase, and to permit access by the monitoring device responsive to a successful pairing in accordance with the pairing protocol, the successful pairing being based at least in part on a determination that a physiological value supplied by the monitoring device substantially matches the measured physiological value. The medical device performs the secure channel set-up phase before sending the measured physiological value to the monitoring device.
