| 摘要 |
A credit card (10) has a layer (28) of high coercivity magnetic material which is of a sufficiently high magnetic coercivity that once its dipoles are polarized, they are unable to be returned to a randomized distribution. The card is embossed with a man-readable code (30) and is electromagnetically recorded with a man-nonreadable code. Particularly, the electromagnetically recorded code includes an account code (42, 44), a visual comparison algorithm code (50), a visual comparison code (52), an electronic comparison code (54), a card identification number (56), and a personal identification number (58). A reader (60) reads the account code and produces a man-readable display (102) of the electromagnetically coded account number. To verify that he has compared the display with the account number on a receipt, the merchant marks the symbols on the receipt which correspond to the highlighted symbols of the display. From the visual comparison code, the reader determines a preselected subset of the man-readable to be highlighted. Further, the reader operates on the electronic comparison code with a preselected mathematical algorithm and compares the algorithm answer with a preselected portion of the account number. As a further verification, the reader operates on the card identification number with another preselected algorithm and compares the algorithm answer with the visual comparison code. Optionally, the reader may have a keyboard (130) on which the cardholder can enter a personal identification number which the reader compares with the electronically encoded personal identification number.
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