COVID-19  has a profound effect on modern human life, and it is unclear what its future will be. Till now, 8417100 people were infected and 451661 people died. For many years, contact tracking has been the main way to prevent the spread of infectious diseases, especially the isolation of infected people. For example, The eradication of smallpox was achieved not by universal immunization, but by exhaustive contact tracing to find all infected persons. Contact tracing is the process of identification of persons who may have come into contact with an infected person and subsequent collection of further information about these contacts. The significant growth of positioning technologies, mobile computing, and wireless networks has led us to a new era of contact tracing, so-called digital contact tracing technology. The most important challenge facing people is the lack of privacy-preserving of these systems. on the one hand side in a centralized approach, the main problem with digital contact tracing regards the type of information which can be collected from each person and the way related data is treated by companies and institutions. On the other hand, public health responsible people need as much as possible accurate and complete data.