| 摘要 |
A method and apparatus are disclosed for determining the remanent noise in a magnetic medium by, for example, 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 stored on the same magnetic medium, in a database, or both to thereby "fingerprint" the magnetic medium. This "fingerprint" may then be later used to verify and authenticate the magnetic medium as being an original. The magnetic medium may be of a type adapted to record information magnetically or, even more broadly, any magnetic surface or substance that can be sensed through its magnetic field. In such manner, any magnetic medium, or any object having an associated magnetic medium, may be "fingerprinted" including credit cards, computer program diskettes, magneto-optic discs, videotapes, cassette tapes, bank checks, stock certificates, etc. A different or additional portion of the magnetic medium can be selected each time the medium is authenticated. In this manner, different fingerprint data can be used for each authentication procedure for added security, and to avoid the ramifications of possible counterfeiting, on-line interception, electronic eavesdropping, or sharing of access data by unscrupulous users. |
