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Recently, it has been noticed that wireless and mobile technology networks have evolved enormously paving the way for a new paradigm known as ubiquitous computing. Examples of ubiquitous applications include the Internet of Things (IOTs), smart cities, location-based mobile applications and context-aware systems. A ubiquitous network can be seen as a telecommunications network that connects a collection of things, objects or devices to allow communication and data exchange between systems, software applications, and users. Besides, ubiquitous environments include software agents, services, and applications, which are expected to seamlessly interact and exchange user sensitive information with each other. In addition, devices are embedded in physical objects and can collect sensitive information without human intervention (Denko, Sun et al. 2011).
The use of wireless technology is increasing rapidly, not only in the more developed countries, but also in developing countries, which have poor telecommunications infrastructures. Accordingly, a wide range of short range mobile services is being developed and the prospective developments are even more promising. Whereas in the past a customer had to be physically present at a certain time and at a certain place to meet with his or her friends, now he or she can do much of the social part from behind his or her computer or smart phone through the use of social mobile applications. Integration of several wireless technologies, i.e., short range or proximity area networks (PANs), wireless local area networks (WLANs) and 4G/5G mobile telecommunication networks and wireless wide area networks (WWN), lead to meshed wireless networks (MWNs), which enable even better ways to meet users’ needs anywhere and everywhere (Malladi and Agrawal 2002, Choi, Crowgey et al. 2006).
Ubiquitous applications represent another opportunity for the mobile industry and the financial institutions, since they bring convenience, flexibility and simplicity for the consumers (Daskapan, Berg et al. 2010). Despite the expected benefits behind these new developments, privacy and trust issues represent important challenges for the success and widespread adoption of these services (Ali-Eldin 2011, DasGupta and Chaki 2015). Trustworthiness of the service providers that collect information and offer their services represent a specific concern for such services (Linck, Pousttchi et al. 2006). Although there are many alternatives for modelling trust (Zimmermann 1994, Blaze, Feigenbaum et al. 1999, Agency 2001, Adams and Lloyd 2002), many security and privacy proposals lack a good understanding of the notion of trust and the use of an appropriate trust model (Karnouskos, Hondroudaki et al. 2004). Especially autonomous privacy and security control puts more pressure on traditional trust approaches, since in such environments trustworthiness of the service provider (SP) by the user should be evaluated autonomously and dynamically. Given also the limited local resources and limited connectivity of wireless devices, a tailored trust model is needed (Wang and Kranakis 2003).