A method for authenticating a transmission between a first and a second circuit transiting through at least one third circuit, wherein: data are transmitted from the first to the third circuit, and from the third to the second circuit; a first signature of the data is calculated by the first circuit; at least a second signature of the data is calculated by the third circuit; at least one first portion of the first signature is transmitted by the first circuit to the third one; and the second signature is transmitted by the third circuit to the second one, a portion of this signature being distorted in case of a failure of authentication of the first portion of the first signature by the third circuit.