Abstract: This invention relates to a method of securing magnetically encoded data from altering, forging, or counterfeiting. The invention pertains to magnetic storage media such as magnetic tape, magnetic striped cards, and other documents or objects which contain magnetic media. This invention utilized the inherent variations in the timing of magnetically encoded data in combination with the random effect of the magnetic media. Data is protected by reading the original encoded data just after encoding and storing this initial timing data stream. It is authenticated by a comparison of the timing data stream of any subsequent reading of this encoded data to the original timing data stream. Acceptance criterion depends on the magnetic media and applications chosen.