Hindawi Publishing Corporation International Journal of Distributed Sensor Networks Volume 2013, Article ID 842608, 11 pages http://dx.doi.org/10.1155/2013/842608 Research Article A Hybrid Security Mechanism for Intra-WBAN and Inter-WBAN Communications Sarah Irum, 1 Aftab Ali, 1 Farrukh Aslam Khan, 1,2 and Haider Abbas 2,3 1 National University of Computer and Emerging Sciences, Islamabad 44000, Pakistan 2 King Saud University, Riyadh 11653, Saudi Arabia 3 National University of Sciences & Technology, Islamabad 44000, Pakistan Correspondence should be addressed to Farrukh Aslam Khan; fakhan@ksu.edu.sa Received 27 January 2013; Revised 25 May 2013; Accepted 10 June 2013 Academic Editor: Muhammad Khurram Khan Copyright © 2013 Sarah Irum et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. he emerging wireless body area networks (WBANs) have a great potential for the growth and development of future ubiquitous healthcare systems. However, due to the use of unreliable wireless media, WBANs are exposed to a variety of attacks. he prevention of these attacks depends upon the cryptographic techniques. he strength of cryptography is based on the keys used for encryption and decryption in the communication process. Security is still an alarming challenge for WBANs and needs attention of the research community. he proposed work introduces a hybrid key management scheme for both intra-WBAN and inter-WBAN communications. he proposed technique is based on preloaded keys as well as keys automatically generated from biometrics of the human body. he biometric-based calculations are of linear time complexity to cater the strict resource constraints and security requirements of WBANs. he proposed security mechanism provides an eicient solution for the security of both intra- WBAN and inter-WBAN communications. he results of the proposed technique are compared with an existing key management technique known as BARI+. he results show signiicant improvement over the results produced by BARI+ in terms of storage, communication, energy overhead, and security. 1. Introduction Wireless body area network (WBAN) is a special type of network in which sensors are deployed on the human body. he sensors collect physiological values from the body and transmit the collected records to the concerned medical server. he applications of WBANs include health monitoring of patients in a hospital and monitoring of soldiers in a battleield. he WBAN monitoring system is used to monitor a person’s vital signs remotely. he system also receives feedback for maintaining a good health status of the subject so that proper action can be taken to rectify the abnormalities [1, 2]. he introduction of WBANs to E-Health monitoring system has revolutionized the ield of health monitoring and resulted in better quality of life [3]. Since we deal with the personal information of a person, the security and privacy becomes an essential part of this communication. In case of medical applications, the security threats may lead a patient to a dangerous condition, and sometimes to the death of the patient [4]. WBAN communication can be classiied into intra-WBAN communication and inter- WBAN communication. Intra-WBAN communication refers to the on-body sensors communication while inter-WBAN communication refers to the communication between two diferent WBANs. WBAN communication faces security issues as biomedical sensors implanted on the human body for mobile healthcare monitoring communicate with external networks, which increases the security risk. Since biomedical sensor nodes are allowed to monitor and transmit potentially sensitive medical data, the security and privacy becomes a major concern in WBANs. WBANs consist of lightweight sensors, which are limited both in terms of computational and communication resources; therefore, the security models and protocols used for wireless sensor networks (WSNs) cannot be applied to WBANs in exactly the same manner for diferent resource-constrained applications and scenarios [5, 6]. he existing key management techniques for WBANs are either plug-and-play or based on preloading. he work proposed in this paper consists of a hybrid technique; that is, it supports both plug-and-play capability as well as some