A system for verifying the authenticity of data contained in a magnetic medium using the remanent noise characteristics of the magnetic medium. In one embodiment, the invention includes a sensing unit configured to generate a signal indicative of the sensed magnetic field and an amplifier. The amplifier...http://www.google.com/patents/US7377433?utm_source=gb-gplus-sharePatent US7377433 - Method and apparatus for authenticating a magnetic fingerprint signal using compressive amplification
