Abstract: Embodiments herein relate to systems for tracking and maintaining the integrity of patient device data over extended periods of time. In a first aspect, a medical device system is included having an implantable device that can include a control circuit, a communication circuit, and one or more sensors. The system can also include an external device including a control circuit and a communication circuit. The external device can be configured to receive patient data from the implantable device and execute a hashing operation on units of received patient device data and one or more previous digest packets to create new digest packets. The external device can be configured to store the new digest packets and forward digest packets onto another device of the medical device system when requested to allow patient data to be authenticated. Other embodiments are also included herein.