1. Method for acceptance of a candidate fibrous medium made of paper, cardboard or non-woven as an authentic fibrous medium, comprising the following steps: generation of at least one authentic digital signature from a structural characteristic extracted from a reference zone of an authentic fibrous medium, said digital signature representing the fibrous structure of the reference zone, and recording said digital signature on a digital data medium; generation of a candidate digital signature from a structural characteristic extracted from a reference zone of a candidate fibrous medium, said digital signature representing the fibrous structure of said reference zone comparison of the candidate digital signature with at least one of the previously recorded authentic digital signatures, in order to issue a positive or negative decision about acceptance of the candidate fibrous medium, characterised in that: the structural characteristic of the candidate fibrous medium and the structural characteristic(s) of the authentic fibrous medium(a) are obtained scanning a volume of the medium, the comparison is intended to use a statistical method to determine a similarity index between the candidate digital signature and the authentic digital signature, and to compare this similarity index with a given acceptance threshold, the acceptance threshold being chosen so as to enable issuing a positive acceptance decision if the candidate digital signature does not exactly correspond to the authentic digital signature with which it is compared.