With recent advances in wireless sensor networks and embedded computing technologies, miniaturized pervasive health monitoring devices have become practically feasible. In addition to providing continuous monitoring and analysis of physiological parameters, the recently proposed Wireless Body Area Networks (WBAN) incorporates context aware sensing for increased sensitivity and specificity. A number of tiny wireless sensors, strategically placed on the human body, create a WBAN that can monitor various vital signs, providing real-time feedback to the user and medical personnel. The wireless body area networks promise to revolutionize health monitoring. Since the sensors collect personal medical data, security and privacy are important components in this kind of networks. It is a challenge to implement traditional security infrastructures in these types of lightweight networks, since they are by design limited in both computational and communication resources. A key enabling technology...