Importance

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Abstract

A method of using a card which has a substrate with at least one magnetic track thereon, the method involving dividing the track into a plurality of spaced blocks with a start sentinel being magnetically recorded at the start of each block. A user's critical data is recorded in at least some of the blocks, this critical data including a portion of the user's personal identification number. The method further includes enhancing the security of a cash card by recording in variable locations on the cash card the last date when the user has had a transaction with a terminal, recording in scrambled locations on the card balance information plus security information and storing in a terminal a set of descrambling tables. The user introduces the card into the terminal and enters the user's personal identification number associated with the card. The terminal reads and stores the information recorded on the card and performs a calculation utilizing the personal identification number to locate in the stored information the aforementioned last date. If the last date is earlier than a predetermined date, the central office is accessed for data to be used in continuing the transaction. If the last date is more recent, a calculation is performed using the last date and personal identification number to select one of the descrambling tables, which is then used to locate particular portions of the stored information.

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First Claim