A method for authenticating at least one document having a predetermined format and carrying at least one security pattern of appearance that varies as a function of an angle of observation, the method comprising the steps of: capturing at least one image of the document; determining a camera angle by comparing geometric characteristics detected in the document and stored predetermined geometric characteristics; deducing an expected appearance for the security pattern; comparing the expected appearance with an appearance detected in the image of the document; and declaring the document authentic when the expected appearance matches the detected appearance.