Patent ID: 6651149
Filing Date: 2003-11-18
Classification: G06F,G06Q

Abstract:
A data storage medium comprising:a first memory area that is read-only and stores first certification data that is unique to the data storage medium; a second memory area that stores data and second certification data supplied from the outside; an identity circuit which determines whether or not the first and second certification data are identical with each other, the identity circuit including a generator which generates binary data and inverted binary data from the first certification data, and an adder which adds the inverted binary data of the first certification data to binary data corresponding to the second certification data; and a switch circuit which provides the data stored in the second memory area to the outside only when the identity circuit determines that the first and second certification data are identical with each other, the switch circuit including a circuit which connects the second memory area to an output terminal only when a sum provided by the adder includes all 1s.