Abstract: A magnetic logic device can comprise a generally planar first substrate for an electrical circuit and a plurality of generally planar second substrates for a magnetic circuit, formed in a stacked arrangement over the first substrate. Each said second substrate can have formed thereon a magnetic circuit and each magnetic circuit can have a plurality of logic elements, a data writing element and a data reading element. The data writing element of each magnetic circuit can correspond in planar positioning to a respective magneto-electrical writing element of the first substrate and the data reading element of each magnetic circuit can correspond in planar positioning to a respective magneto-electrical reading element of the first substrate.

Abstract: A digital signature is obtained by digitising a set of data points obtained by scanning a coherent beam over a paper, cardboard or other article, and measuring the scatter. A thumbnail digital signature is also determined by digitising an amplitude spectrum of a Fourier transform of the set of data points. A database of digital signatures and their thumbnails can thus be built up. The authenticity of an article can later be verified by re-scanning the article to determine its digital signature and thumbnail, and then searching the database for a match. Searching is done on the basis of the Fourier transform thumbnail to improve search speed. Speed is improved, since, in a pseudo-random bit sequence, any bit shift only affects the phase spectrum, and not the amplitude spectrum of a Fourier transform represented in polar coordinates.

Abstract: A method and apparatus for determining a class signature from an article made of paper or cardboard in order to identify a generic type of class to which the article belongs. An optical beam illuminates the article and a detector arrangement collects data points from light scattered from many different parts of the article as the article is scanned by the beam. The class signature derives from intrinsic properties imparted to the paper/cardboard during manufacture by, it is believed, the screen used during dewatering of paper pulp. Detection of the class signature allows the manufacturer or the particular paper making machine that made the paper to be identified.

Abstract: A method and apparatus for determining a digital signature from an article made of paper, cardboard, plastic or many other material types. A coherent source directs a beam to illuminate the article and a detector arrangement collects data points from light scattered from many different parts of the article to collect a large number of independent data points, typically 500 or more. By collecting a large number of independent signal contributions specific to many different parts of the article, a digital signature can be computed that is unique to the area of the article that has been scanned. This measurement can be repeated whenever required to test authenticity of the article. Using this method, it has been discovered that it is essentially pointless to go to the effort and expense of making specially prepared tokens, since unique characteristics are measurable in a straightforward manner from a wide variety of every day articles.

Abstract: A method and apparatus for determining a digital signature from an article made of paper, cardboard, plastic or many other material types. A coherent light source directs a beam to illuminate the article and a detector arrangement collects data points from light scattered from many different parts of the article to collect a large number of independent data points, typically 500 or more. By collecting a large number of independent signal contributions specific to many different parts of the article, a digital signature can be computed that is unique to the area of the article that has been scanned. This measurement can be repeated whenever required to test authenticity of the article. Using this method, it has been discovered that it is essentially pointless to go to the effort and expense of making specially prepared tokens, since unique characteristics are measurable a in a straightforward manner from a wide variety of every day articles.

Abstract: An apparatus may be provided for determining a signature from an article in a reading volume of the apparatus. The apparatus can comprise a source operable to generate a coherent beam and a beam directing member operable to direct the coherent beam into the reading volume. The apparatus may also comprise a detector arrangement for collecting signals created by scatter of the coherent beam within the reading volume, wherein different ones of the signals relate to scatter from different parts of the reading volume, the detector arrangement having a numerical aperture greater than a predetermined minimum and a processor operable to determine a signature for an article in the reading volume from the collected signals. Use of such apparatus can be repeated whenever required to test authenticity of the article.

Abstract: A security device (100) comprises at least one magnetic element (102). The magnetic element (102) is responsive to an applied magnetic field to provide a characteristic response. The characteristic response can be used to identify a particular security device (100) when interrogated by a security system, thereby aiding in prevention of copying of the security device (100).