| 摘要 |
PCT No. PCT/DE80/00129 Sec. 371 Date May 8, 1981 Sec. 102(e) Date Apr. 29, 1981 PCT Filed Sep. 8, 1980 PCT Pub. No. WO81/00776 PCT Pub. Date Mar. 19, 1981.A method of securing data recorded on a data support and a device for performing the method are disclosed. In addition to the basic information contained in the data recorded on the data support, for generating an additional security code, selected individual properties of the recorded data are used which differ from each other as regards their physical and/or chemical properties. In one embodiment, individual characters imprinted on the data support are used which differ from each other with respect to contrast or half-tone density in a manner unperceivable to human sight, but easily detectable by a detector or an automatic reading apparatus. Authenticity of the data support or data is determined by a security code contained in the specific physical or chemical properties of the selected individual characters. The method prevents from duplication or falsifying of data supports.
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