A method for providing security for a commercial article that envisages reuse of an antitheft protection device fixed to said commercial article being a packaged or unpackaged physical object (10,32; 80), the device (12,42; 70) having: - at least one active or passive component that is capable of transmitting electromagnetic waves to the outside of the device or of receiving electromagnetic waves from the outside, and that is intented to partly carry out an antitheft function in cooperation with an antitheft complementary system, - at least one transponder that has a unique and non modifiable identifier (TID), - means for fixing and locking the device to the physical object or to the packaging thereof in a locked position so that a user cannot separate the device from the physical object without an external tool, said locking means comprising a locking mechanism, - at least one unique identifier that is an optically readable code (QR1) distinct from a commercial article code (EAN, EPC, etc.) assigned to the physical object, as a commercial article, said at least one optically readable code being protected from the outside by a transparent protection interface , said at least one optically readable code being adapted to represent a URL address for a site or for a web page. the method comprising: - the association of said at least one optically readable code of the device with the identifier TID, the commercial article code (EAN, EPC, etc.) and an URL address assigned to the physical object to which the device is intented to be fixed, - the dissociation of said at least one optically readable code and the identifier TID borne by the device with the commercial article code (EAN, EPC, etc.) said URL address assigned to the physical object to which the device has been fixed and locked when a commercial transaction has been carried out on said physical object and said device has been separated from the latter. - at least one active or passive component that is capable of transmitting electromagnetic waves to the outside of the device or of receiving electromagnetic waves from the outside, and that is intented to partly carry out an antitheft function in cooperation with an antitheft complementary system, - at least one transponder that has a unique and non modifiable identifier (TID), - means for fixing and locking the device to the physical object or to the packaging thereof in a locked position so that a user cannot separate the device from the physical object without an external tool, said locking means comprising a locking mechanism, - at least one unique identifier that is an optically readable code (QR1) distinct from a commercial article code (EAN, EPC, etc.) assigned to the physical object, as a commercial article, said at least one optically readable code being protected from the outside by a transparent protection interface , said at least one optically readable code being adapted to represent a URL address for a site or for a web page. - the association of said at least one optically readable code of the device with the identifier TID, the commercial article code (EAN, EPC, etc.) and an URL address assigned to the physical object to which the device is intented to be fixed, - the dissociation of said at least one optically readable code and the identifier TID borne by the device with the commercial article code (EAN, EPC, etc.) said URL address assigned to the physical object to which the device has been fixed and locked when a commercial transaction has been carried out on said physical object and said device has been separated from the latter. <EOS>