The growth of the applications and services market for mobile devices is currently slowed down by the lack of a flexible and reliable security infrastructure. The development and adoption of a new generation of mobile applications depends on the end user's ability to finely manage system security and control application's behavior. The virtual execution environment for mobile software and services should support the security needs of users and applications. This paper proposes an extension to the security architecture of the java virtual machine for mobile systems, to support fine-grained policy specification and run-time enforcement. Access control decisions are based on system state, application and system history data, as well as request specific parameters. The prototype implementation is running on desktops, as emulator, and on mobile devices, proving the high level of flexibility and security, with excellent performance provided by the extended architecture.

The vision of Ubiquitous Computing [22] creates the world in which information is omnipresent, migrating seamlessly through the environment to be accessible whenever and wherever needed. Such a vision poses substantial challenges to information security and privacy protection.Unlike in traditional, static, execution environments, information in the Ubiquitous world is exposed, throughout its lifetime, to constantly varying security and privacy threats caused by the inherent dynamicity and unpredictability of the new computing environment and its mobility. Existing data protection mechanisms, built for non- or predictably slowly-changing environments, are unable to strike the balance in the information availability vs. security and privacy threat trade-off in the Ubiquitous world thus hindering the feasibility of the overall vision.In this paper, we present our initial work on a novel paradigm for information security and privacy protection in the ubiquitous world. We model security and privacy threats through sets of contextual attributes and mitigate the projected risks through proactive and reactive data format transformations, subsetting and forced migrations while trying to maximize information availability. We also try to make the approach flexible, scalable and infrastructure independent, as required by the very vision of the Ubiquitous Computing.

Numerous systems have been designed which use virtualization to subdivide the ample resources of a modern computer. Some require specialized hardware, or cannot support commodity operating systems. Some target 100% binary compatibility at the expense of performance. Others sacrifice security or functionality for speed. Few offer resource isolation or performance guarantees; most provide only best-effort provisioning, risking denial of service.This paper presents Xen, an x86 virtual machine monitor which allows multiple commodity operating systems to share conventional hardware in a safe and resource managed fashion, but without sacrificing either performance or functionality. This is achieved by providing an idealized virtual machine abstraction to which operating systems such as Linux, BSD and Windows XP, can be ported with minimal effort.Our design is targeted at hosting up to 100 virtual machine instances simultaneously on a modern server. The virtualization approach taken by Xen is extremely efficient: we allow operating systems such as Linux and Windows XP to be hosted simultaneously for a negligible performance overhead --- at most a few percent compared with the unvirtualized case. We considerably outperform competing commercial and freely available solutions in a range of microbenchmarks and system-wide tests.