A method of automatically authenticating a secure document including at least one label-forming portion, the method being characterized in that it comprises the following steps: a) printing an authentic label provided with optically-variable elements including at least a first zone of optically-variable elements of a first type presenting reflection properties that are different from the surface of the label for a light source in the visible light frequency range oriented in predetermined manner relative to said surface, said optically-variable elements of the first type comprising holographic patterns of foil removal constituted by foil graphics elements in a transparent strip or by transparent graphics elements in a holographic foil strip; b) photographing said authentic label at least under first lighting conditions in the visible light frequency range in order to create at least one first reference image; c) calculating a reference digital fingerprint of the label from said at least one first reference image and storing said reference digital fingerprint; d) photographing a label that is to be verified of a secure document of authenticity that is to be verified under conditions similar to the conditions in which the authentic label was photographed, shooting from the same angle and in succession at least in first lighting conditions in the visible light frequency range and in second lighting conditions essentially different from the first lighting conditions and in the same visible light frequency range, in order to create at least first and second verification images, using a camera having at least a communications unit, a memory unit, and a calculation unit; e) verifying the optically-variable nature of said elements from said at least first and second verification images and calculating a verification digital fingerprint of the label for verification from at least one of said first and second verification images; and f) comparing the verification digital fingerprint and the corresponding reference digital fingerprint, calculating the distance between these two digital fingerprints, and comparing said distance with a predetermined threshold in order to authenticate the label for verification of the secure document that is to be authenticated only if said distance is less than or equal to said threshold. a) printing an authentic label provided with optically-variable elements including at least a first zone of optically-variable elements of a first type presenting reflection properties that are different from the surface of the label for a light source in the visible light frequency range oriented in predetermined manner relative to said surface, said optically-variable elements of the first type comprising holographic patterns of foil removal constituted by foil graphics elements in a transparent strip or by transparent graphics elements in a holographic foil strip; b) photographing said authentic label at least under first lighting conditions in the visible light frequency range in order to create at least one first reference image; c) calculating a reference digital fingerprint of the label from said at least one first reference image and storing said reference digital fingerprint; d) photographing a label that is to be verified of a secure document of authenticity that is to be verified under conditions similar to the conditions in which the authentic label was photographed, shooting from the same angle and in succession at least in first lighting conditions in the visible light frequency range and in second lighting conditions essentially different from the first lighting conditions and in the same visible light frequency range, in order to create at least first and second verification images, using a camera having at least a communications unit, a memory unit, and a calculation unit; e) verifying the optically-variable nature of said elements from said at least first and second verification images and calculating a verification digital fingerprint of the label for verification from at least one of said first and second verification images; and f) comparing the verification digital fingerprint and the corresponding reference digital fingerprint, calculating the distance between these two digital fingerprints, and comparing said distance with a predetermined threshold in order to authenticate the label for verification of the secure document that is to be authenticated only if said distance is less than or equal to said threshold.