Patent ID: 6438666
Filing Date: 2002-08-20
Classification: G06F

Abstract:
An apparatus for controlling access to confidential data comprising:a non-volatile memory for storing data; and a logic circuit for controlling access to the data contained in the non-volatile memory, the logic circuit selectively accessing the non-volatile memory to determine whether at least a portion of the data contained in the non-volatile memory comprises confidential data by analyzing a property inherent in the accessed data, wherein the non-volatile memory does not contain any flag bits used for the determination of whether confidential data is present, wherein the logic circuit is responsive to a predefined input to erase the non-volatile memory in stages, wherein in a first stage, the logic circuit writes a first intermediate value to a first location of the non-volatile memory, in a second stage, the logic circuit writes a second intermediate value to a second location of the non-volatile memory, and, in a third stage, the logic circuit writes a final value to the first and second locations of the non-volatile memory, wherein the property comprises a count of data blocks having a predetermined characteristic, and wherein the first intermediate value is selected such that, if erasing of the non-volatile memory is terminated before the completion of the first stage, the counted number of data blocks in the non-volatile memory will indicate that confidential data is present.