A medical device with limited computational capability includes medical hardware, a first register to store a static, substantially unique identifier of the medical device, a second register to store a static encryption key, an interface to receive and transmit data over a short-range communication link, and processing hardware. The processing hardware is configured to apply the static encryption key to the identifier of the medical device to generate an encrypted identifier, transmit the encrypted identifier of to another device via the interface, receive an encrypted identifier of the other device, decrypt the encrypted identifier of the other device using the static encryption key to determine an identifier of the other device, generate a dynamic encryption key using the identifier of the medical device and the identifier of the other device, and apply the dynamic encryption key to medical data transmitted between the medical device and the other device.