Trust management and reputation systems in mobile participatory sensing applications: A survey

Participatory sensing is an emerging paradigm in which citizens everywhere voluntarily use their computational devices to capture and share sensed data from their surrounding environments in order to monitor and analyze some phenomenon (e.g., weather, road traffic, pollution, etc.). Interest in participatory sensing systems has risen since a large mobile sensor network can now be opportunistically constructed with much less cost and effort than it was the case a decade ago. However, relying on citizens who share their contributions raises many challenges. Participants can disrupt the system by contributing corrupted, fabricated, or erroneous data. Consequently, monitoring the participants' behavior in order to estimate their honesty is an essential requirement. This enables to evaluate the veracity and accuracy of participants' contributions and therefore, to build robust and reliable participatory sensing systems. Recently, several trust and reputation systems have been proposed to trace participants' behavior in these systems. This survey presents a study and analysis of existing trust systems in participatory sensing applications. First, we study the nature of participatory sensing applications by surveying existing systems and outlining their common features. We then analyze the main vulnerabilities and attacks that can be launched in these systems. Furthermore, we discuss the concept of trust and we introduce a classification of existing trust systems. The two main classes of trust assessment methods for participatory sensing (i.e. Trusted Platform Module and reputation) are discussed. In addition, we analyze the merits as well as the limitations of each of them. We then derive a comparative study of several existing trust systems for participatory sensing. From this study, we identify many trust problems that have not been solved and many attacks have not been addressed yet in the literature. Finally, we list future research directions regarding trust management in participatory sensing systems.