Future Internet_**2010**, \(2\), 190-211; doi:10.3390/fi2030190  
_future internet_  
**ISSN 1999-5903**  
www.mdpi.com/journal/futureinternet  
_Article_  
**Applications and Security of Next-Generation, User-Centric Wireless Systems**  
**[PERSON] \({}^{1}\), [PERSON] \({}^{2}\) and [PERSON] \({}^{3,\star}\)**  
\({}^{1}\) Department of Computer Science, Rutgers University, Piscataway, NJ, 08854, USA;  
E-Mail: [EMAIL_ADDRESS]  
\({}^{2}\) Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA, 24061, USA;  
E-Mail: [EMAIL_ADDRESS]  
\({}^{3}\) Department of Computer Science, Virginia Tech, Blacksburg, VA, 24061, USA  
\({}^{\star}\) Author to whom correspondence should be addressed; E-Mail: [EMAIL_ADDRESS]. _Received: 6 March 2010; in revised form: 3 June 2010 / Accepted: 16 July 2010 / Published: 28 July 2010_  
**Abstract:** Pervasive wireless systems have significantly improved end-users' quality of life. As manufacturing costs decrease, communications bandwidth increases, and contextual information is made more readily available, the role of next generation wireless systems in facilitating users' daily activities will grow. Unique security and privacy issues exist in these wireless, context-aware, often decentralized systems. For example, the pervasive nature of such systems allows adversaries to launch stealthy attacks against them. In this review paper, we survey several emergent personal wireless systems and their applications. These systems include mobile social networks, active implantable medical devices, and consumer products. We explore each system's usage of contextual information and provide insight into its security vulnerabilities. Where possible, we describe existing solutions for defending against these vulnerabilities. Finally, we point out promising future research directions for improving these systems' robustness and security. **Keywords:** wireless; pervasive; security; location based; context-aware; implantable medical devicesIntroduction  
The number of wireless devices for personal use (including mobile phones, wireless keyboards, and wireless networks) has increased dramatically in recent years. This change is in part due to decreased manufacturing costs and increased ease of deployment. Researchers are working on applying wireless technologies to emergent, user-centric applications (e.g. mobile social networking). These researchers believe that continued widespread adoption of wireless technologies will further improve end-users' quality of life. We categorize wireless systems into three classes based on their communication and organizational infrastructure (or lack thereof). These categories are _centralized_, _decentralized_, and _hybrid_ systems. In centralized wireless systems (e.g. wireless LANs), a base station or system administrator is responsible for managing the participating devices, including assigning security credentials and system resources to them. On the other hand, decentralized systems (e.g. peer-to-peer devices) lack pre-existing infrastructure and must organize themselves spontaneously. We further categorize wireless systems as either _contextual_ or _traditional_ (e.g. non-contextual). Context-aware systems monitor their environment for changes and adapt to these changes. Context-aware systems can provide a more robust end-user experience, for example, by enabling the delivery of contextually relevant media and advertisements to end-users. In this paper, we focus on the security and contextual aspects of pervasive, personal, often decentralized wireless systems. Decentralization creates technical challenges in the security and privacy of wireless systems due to a lack of trusted authorities therein. The personal nature of such systems dictates that successful attacks upon them may reveal highly sensitive information; this is especially the case for context-aware systems. Finally, the pervasive aspect of these systems gives attackers an ample number of devices to strike upon and to hide behind.