Method and device for guaranteeing the integrity and authenticity of a set of data.

In order to guarantee the integrity and the authenticity of the data transmitted into a control center and one or more receiver units, each receiver unit includes a decoder (IRD) and a security unit (SC) and also a means of communication (NET, REC) with the control center. The method consists of calculating a check information (Hx) representative of the result of a so-called mono-directional and collision-free function, carried out on all or only a part of the data transmitted and to transmit the result to the control center for verification. The center may inform the decoder on the authenticity of the data along the return paths or the main path.