A home health care system can be used to monitor the elderly people or patients with chronic diseases. Information assurance, privacy, reliability and other requirements of home health care systems are complex. We show how keys can be securely established between the different components within the home health care system. We demonstrate that Genetic Design Methodology (GDM) can efficiently model the requirements of the complex home health care system and the key establishment protocols. We show that when new requirements are added to the system, the proposed model can successfully track if the existing key establishment protocol assumptions are still valid in themodified system. An implementation of the protocols is executed on mica2 motes and examined in detail. The time elapsed, complexity of the code and memory requirements are analysed. We show that a key establishment protocol based on RSA has advantages over a key establishment protocol based on ECC for this application.