Abstract: The essence of the invention is a socalled "data bit variable spacer generator", block 79, which contributes to the generation of a control output "c" from a combinatory logic circuit group 78. The logic level of "c" determines whether a clear data bit from the parity flip flop FF6 is to be sent out or a random bit from block RMG. The `variable data bit generator` is controlled by a number of parallel bit outputs from registers SH1 and SH2 which hold an encryption key after being conditioned by other logic inputs derived from key parity flip flops (FF1 and FF2) and clear data bit levels from block 81. Registers SH1 and SH2 shift and recirculate when the `c` output is high. Similar principles are used when data are decrypted. The circuit is suitable for integration with other functions on a single substrate chip.

Abstract: A self-contained purse-like electronic fund transfer device mainly for use in personal payment transactions, designed to be in the permanent possession of the user and featuring electromagnetic power injection from, and data transfer coupling with, a data terminal. A reader unit has a displaceable concave portion and the handheld personal payment device a convex portion in which the active flux carrying conductors are embedded in such a manner that relatively large angular shifts between the two parts do not interfere with the efficiency of the coupling or the speed of the transaction.

Abstract: A proximity data transfer system for transferring data in digital form between a portable data carrying component and a data sensor component. The data carrying component includes a data store and circuitry for producing magnetic field disturbances of a form related to the data stored therein. The data sensor component includes circuitry capable of sensing the field disturbances, interpreting these disturbances as binary information and inserting the information in a register.