Abstract
The multitude of applications and security configurations of mobile devices requires automated approaches for effective user privacy protection. Current permission managers, the core mechanism for privacy protection in smartphones, have shown to be ineffective by failing to account for privacy's contextual dependency and personal preferences within context. In this paper we focus on the relation between privacy decisions (e.g. grant or deny a permission request) and their surrounding context, through an analysis of a real world dataset obtained in campaigns with 93 users. We leverage such findings and the collected data to develop methods for automated, personalized and context-aware privacy protection, so as to predict users' preferences with respect to permission requests. Our analysis reveals that while contextual features have some relevance in privacy decisions, the increase in prediction performance of using such features is minimal, since two features alone are capable of capturing a relevant effect of context changes, namely the category of the requesting application and the requested permission. Our methods for prediction of privacy preferences achieved an F1 score of 0.88, while reducing the number of privacy violations by 28% when compared to the standard Android permission manager.

Abstract

Abstract
Signal interference and packet collisions are typically viewed as negative factors that hinder wireless communication networks. When security is the primary concern, signal interference may actually be very helpful. Starting with a stochastic network model, we are able to show that packet collisions caused by jamming nodes can indeed be used effectively to attain new levels of secrecy in multiterminal wireless environments. To this effect, we propose a practical jamming protocol that uses the well-known request-to-send/clear-to-send (RTS/CTS) handshake of the IEEE 802.11 standard as a signaling scheme. Various jammer selection strategies are investigated depending on the position of source, destination, and jamming nodes. The goal is to cause asmuch interference as possible to eavesdroppers that are located in unknown positions, while limiting the interference observed by the legitimate receiver. To evaluate the performance of each strategy, we introduce and compute a measure for the secure throughput. Our results show that jamming can increase the levels of secrecy significantly albeit at a substantial cost in terms of energy efficiency.

Abstract
Inspired by recent results on information-theoretic security, we consider the transmission of confidential messages over wireless networks, in which the legitimate communication partners are aided by friendly jammers. We characterize the security level of a confined region in a quasi-static fading environment by computing the probability of secrecy outage in connection with two new measures of physical-layer security: the jamming coverage and the jamming efficiency. Our analysis for various jamming strategies based on different levels of channel state information provides insight into the design of optimal jamming configurations and shows that a single jammer is not sufficient to maximize both figures of merit simultaneously. Moreover, a single jammer requires full channel state information to provide security gains in the vicinity of the legitimate receiver.

Abstract
We consider the problem of securing routing information in Mobile Ad-hoc Networks (MANETs). Focusing on the Optimized Link State Routing protocol, we devise a feedback reputation mechanism which assesses the integrity of routing control traffic by correlating local routing data with feedback messages sent by the receivers of control traffic. Based on this assessment, misbehaving nodes are shown to be reliably detected and can be adequately punished in terms of their ability to communicate through the network. To the best of our knowledge, this is the first practical implementation of a reputation mechanism in a standardized proactive routing protocol for MANETs.

Abstract
The increasing requirement for ubiquitous access of the users, enable the seamless support of different networks, with different technologies, and also with different types, such as moving networks and ad-hoc networks. This paper describes the Ad-hoc network integration architecture being developed inside the IST project Daidalos II. The main purpose of this architecture is to seamlessly support the movement of nodes between ad-hoc and infrastructure networks, maintaining in the ad-hoc networks all the features being supported in the infrastructure, such as, efficient routing for unicast and multicast flows, distributed QoS mechanisms' security, and seamless mobility, including multihoming support.