Abstract: A method for determining, onboard a first mobile entity, a level of trust for a second mobile entity in communication with the first mobile entity, and a communication system implementing the method are described. The method includes determining), by the first mobile entity, direct trust data, calculating an initial reputation indicator based on the direct trust data, including a belief value, a disbelief value, an uncertainty value, and a base trust rate, calculating a confidence level based on the belief value, the base trust rate, and the uncertainty value, and determining an updated reputation indicator based on the initial reputation indicator and the confidence level. The base trust rate is indicative of the trust level for data transmitted from an unknown mobile entity not in contact with the first mobile entity. The updated reputation indicator indicates a level of trust of the first mobile entity in the second mobile entity.