Proximity-based access control for implantable medical devices

We propose a proximity-based access control scheme for implantable medical devices (IMDs). Our scheme is based on ultrasonic distance-bounding and enables an implanted medical device to grant access to its resources only to those devices that are in its close proximity. We demonstrate the feasibility of our approach through tests in an emulated patient environment. We show that, although implanted, IMDs can successfully verify the proximity of other devices with high accuracy. We propose a set of protocols that support our scheme, analyze their security in detail and discuss possible extensions. We make new observations about the security of implementations of ultrasonic distance-bounding protocols. Finally, we discuss the integration of our scheme with existing IMD devices and with their existing security measures.