Method and a device for guaranteeing the integrity and authenticity of data transmitted between a management center and one or several receiver units, wherein each receiver unit comprises a decoder (IRD) and a security unit (SC) and means for communicating (NET, REC) with the management center. The method consists in calculating a check information (Hx) representative of the result of a unidirectional and collision-free function, performed on all or part of the transmitted data and in transmitting the result to the management center for verification. The center will be able to inform the decoder concerning the authenticity of the data through return channels or through the main channel.