Importance

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Abstract

A data processing system is provided which protects the secrecy of confidial data transmitted between a transmitting terminal and key, such as a credit card, which is used to authorize a dialogue between a data processing machine and an operator. A light pen is provided which is personal to each operator and which includes means for formulating the confidential data in a predetermined code and transmitting the coded information by means of an information carrying light wave. The light pen includes a keyboard which may be in the form of cursors movable along a longitudinal graduated scale which sets the coded data in accordance with the position of the cursors. To this end, the light pen houses an encoder, the output of which is fed to a shift register. The output of the shift register is modulated and fed to an optical-electrical transducer system which is screened to prevent unauthorized detection. The credit card receives the coded information through its own electrical transducer. The information is demodulated, and fed to a register, the output of which is compared to information stored in a memory contained in an integrated circuit chip which forms part of the card. A control responsive to the output of the comparator authorizes the dialogue to take place.

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First Claim