| 摘要 |
A decryption device, comprising a substrate, a plurality of encrypted information symbols located within a rectangular array of further symbols carried by the substrate, wherein the array is arranged in a predetermined number of rows by a further predetermined number of columns. A pair of registration marks are carried by the substrate and located on opposite sides of a predetermined one of the rows. An overlay is adapted for covering the rectangular array, and includes a first pair of apertures arranged to uncover the pair of registration marks, and a plurality of further apertures arranged to uncover the plurality of encrypted information symbols responsive to the first pair of apertures uncovering the pair of registration marks.
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