Sequential Encryption for Multiple Implantable Medical Devices

Wireless communication became an essential tool for modern Implantable Medical Devices (IMDs) for information exchange. In spite of the many advantages wireless technology has, it puts the patients health in serious danger if no proper security mechanism is deployed. We aim to secure these devices while taking into consideration the limitations these small devices suffer from. IMDs have resources that are relatively simple and sometimes require surgery to be altered. Consequently, common security mechanisms cannot be simply implemented in fear of consuming all the resources dedicated to healthcare needs. A certain balance between security and efficiency must be sought in each IMD architecture. In this work, we propose a sequential and secure encrypted communication scheme for patients with multiple IMDs. We present a model that delivers the information generated by all IMDs in one packet to the final receiver. This information will be encrypted sequentially going from one IMD to the next. This scheme eliminates the need for single IMD authentications with the receiver. Instead of each IMD communicating independently with the same receiver, each device will send its information to a different IMD in a single communication action. Performing this way, the scheme would exploit the inherent properties of the entropy of the physiological signals to randomize the exchanged messages. The scheme succeeded in NIST tests with high rates around 95%. This relieves the IMDs from the need for the encryption in addition to a recovery rate of 100% for the proposed architecture. At the end, the final message will be attack- resistant with length <; 1Kb in short handling time in order of 100 ms.