The purpose of wireless sensor networks is to transmit physical quantities from the sensor node to the base station. This requires collaboration between the various devices for proper operation. In this work, we propose a model to evaluate the credibility of information exchanged in a wireless sensor network. Indeed, the credibility evaluation of the data is done at the level of the sensor node and at the cluster head. This model has been realized in respect of the topology of the LEACH routing protocol. We also propose an improvement for LEACH routing protocol and the detection of Dead Node, based on residual energy and on the calculation of the credibility index CIN for each sensor node.