Technological advances in recent years have led to the development of a new generation of computer and telecoms networks, presenting major challenges and opening up attractive areas of research: Wireless Sensor Networks (WSNs). However, when it comes to battery and mobility management, there has been no such progress. Node energy constraints, low bandwidth, network mobility, packet loss and security are just some of the issues facing WSNs. In the latter, there is a need for secure routing protocols that meet the new needs of applications and at the same time take into account the limitations of this type of network.In this thesis, we focused on the problem of security in wireless sensor networks.