The invention relates to a method for authenticating an illustration, comprising—encoding a message in the form of a two-dimensional barcode comprising blocks, each block coding a fragment of said message and comprising a set of coding sub-blocks, each sub-block comprising a set of binary elements. It is essentially characterised in that the encoding comprises prior steps consisting in:—defining or identifying a set of noteworthy points in the illustration,—calculating a set of attributes depending on certain at least of the noteworthy points,—selecting, among the calculated attributes, at least one attribute allowing a digital fingerprint to be defined—optionally compressing said digital fingerprint,—optionally signing said digital fingerprint by means of a cryptographic signature, and—recording in the message one among:—a set of at least one attribute,—the digital fingerprint,—the compressed digital fingerprint, and—the signed and optionally compressed digital fingerprint.