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AssigneeEcole Polytechnique Federale De Lausanne (Epfl)
InventorIsaac Amidror
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This invention discloses new methods, security devices and apparatuses for authenticating documents and valuable articles which may be applied to any support, including transparent synthetic materials and traditional opaque materials such as paper. The invention relates to moire intensity profiles which occur in the superposition of specially designed random structures. By using specially designed random basic screen and random master screen, where at least the basic screen is comprised in the document, a moire intensity profile of a chosen shape becomes visible in their superposition, thereby allowing the authentication of the document. An important advantage of the present invention is that it can be incorporated into the standard document printing process, so that it offers high security at the same cost as standard state of the art document production. Another major advantage of the present invention is in its intrinsically incorporated encryption system due to the arbitrary choice of the random number sequences for the generation of the specially designed random dot screens that are used in this invention.
A method for authenticating documents by using at least one moire intensity profile, the method comprising the steps of:
An apparatus for authentication of documents making use of at least one moire intensity profile, the apparatus comprising:
A method for authenticating documents by using at least one moire intensity profile, the method comprising the steps of:
A security device for authentication of documents comprising at least one basic screen with at least one basic screen dot shape, that is located on the document, where the document authentication is done by superposing a master screen with a master screen dot shape and a basic screen, thereby producing a moire intensity profile and permitting the comparison of said moire intensity profile with a reference moire intensity profile and the acceptance or the rejection of the document depending on the result of the comparison, and where the basic screens are random basic screens and the master screen is a random master screen.
A security document protected by a security device, said security device comprising at least one basic screen with at least one basic screen dot shape, that is located on the document, where the document authentication is done by superposing a master screen with a master screen dot shape and a basic screen, thereby producing a moire intensity profile and permitting the comparison of said moire intensity profile with a reference moire intensity profile and the acceptance or the rejection of the document depending on the result of the comparison, and where the basic screens are random basic screens and the master screen is a random master screen.
Dependencies are inferred from the claim text.