Body Area Networks are the networks of wireless medical sensors, deployed on a person for enabling pervasive, individualized real time health management. As BAN deals with personal health data, securing them especially their communication over the wireless link is very crucial if there is adequate security feature for the patient in the body area sensor network then the adversaries can change the actual data which will lead to wrong diagnostics and treatment of the patient in order to provide a personalized health care system. The Body Area Network along with the group key is established for the security concern where they will provide a separate key to each of the sensors that are of deployed in the patient body when this key matches with that of the health care server system the key establishment of the network