Maryam Tavakoli - Imam Reza international university, Islamic Azad University, Mashhad Branch Mashhad, Iran
Hasan Shakeri - Imam Reza international university, Islamic Azad University, Mashhad Branch Mashhad, Iran

Communication in open communities and distributed systems has a dynamic nature and is shaped without a central institution. Therefore, using the traditional strategies of security like authentication and access control have faces challenges; and a new approach has been developed called soft security. The trust management systems can be considered the demonstrative examples of soft security-based systems. However, even a trust management system is vulnerable against attacks and malevolent behaviors.In this article, the three attacks namely Newcomer attack, On-off attack, unfair rating, and the collusion of malevolent agents which are among the most important attacks on a trust management system have been explained; and the given strategies in the previous tasks were represented. Then our trust management model is offered in which some security strategies to enhance the resistance of the system against these three attacks were applied. The results of the evaluation tests on the proposed model demonstrate the growing accuracy in trust estimation facing these attacks in comparison with the present models.

trust management system, attacks, security strategies, resistance trust model