Method and apparatus for fingerprinting and authenticating magnetic media

A method and apparatus is disclosed for determining the remanent noise in a magnetic medium by DC saturation of a region thereof and measurement of the remaining DC magnetization. A conventional magnetic recording transducer may be used to determine the remanent noise. Upon determination, the remanent noise may then be digitized and recorded on the same magnetic medium to thereby "fingerprint" the magnetic medium. This "fingerprint" may then be later used to verify and authenticate the magnetic medium as being an original. In such manner, any magnetic medium, or any object having an associated magnetic medium, may be "fingerprinted" including credit cards, computer programs, compact discs, videotapes, cassette tapes, etc.