Method and apparatus for fingerprinting and authenticating magnetic media

• US 5,428,683 A
• Filed: 04/04/1994
• Issued: 06/27/1995
• Est. Priority Date: 04/09/1993
• Status: Expired due to Term

• Current Assignee: Washington University In St Louis
• Original Assignee: Washington University In St Louis
• Inventors: Engel, George L., Indeck, Ronald S., Muller, Marcel W., Hege, Alan L.
• Primary Examiner(s): Cain, David C.
• Application Number:
  US08/222,693
• Time in Patent Office: 449 Days
• Field of Search: 380/3, 380/4, 380/23, 380/25
• US Class Current: 713/176
• CPC Class Codes: G06F 21/101 by binding digital rights to specific entities
• CPC Class Codes: G06F 21/16 Program or content traceability, e.g. by watermarking
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories
• CPC Class Codes: G06F 2211/007 Encryption, En-/decode, En-/decipher, En-/decypher, Scramble, (De-)compress
• CPC Class Codes: G06K 1/125 by magnetic means
• CPC Class Codes: G06K 19/086 with markings consisting of randomly placed or oriented elements, the randomness of the elements being useable for generating a unique identifying signature of the record carrier, e.g. randomly placed magnetic fibers or magnetic particles in the body of a credit card
• CPC Class Codes: G06K 19/12 the marking being sensed by magnetic means
• CPC Class Codes: G06K 7/015 Aligning or centering of the sensing device with respect to the record carrier
• CPC Class Codes: G06Q 20/347 Passive cards
• CPC Class Codes: G07D 7/04 Testing magnetic properties of the materials thereof, e.g. by detection of magnetic imprint G07D7/01 takes precedence
• CPC Class Codes: G07F 7/08 by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• CPC Class Codes: G07F 7/0813 Specific details related to card security
• CPC Class Codes: G07F 7/086 by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10
• CPC Class Codes: G07F 7/125 Offline card verification
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/00094 involving measures which result in a restriction to authorised record carriers
• CPC Class Codes: G11B 20/00123 the record carrier being identified by recognising some of its unique characteristics, e.g. a unique defect pattern serving as a physical signature of the record carrier
• CPC Class Codes: G11B 21/106 on disks
• CPC Class Codes: G11B 23/284 on the record carrier
• CPC Class Codes: G11B 5/59611 Detection or processing of peak/envelop signals
• CPC Class Codes: G11B 5/59633 : Servo formatting G11B5/59627, G11B5/59677, G11B5/59683, G11B5/59688 take precedence
• CPC Class Codes: Y04S 40/20 : Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

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.

Claims

1. A device for authenticating an object having a fingerprint recorded, said object having a magnetic medium portion, said recorded fingerprint comprising a signal corresponding to a first read of a remanent noise in said magnetic medium portion, means for determining said fingerprint by a second read of said remanent noise in said magnetic medium portion, and means for comparing said recorded fingerprint with said determined fingerprint including means for compensating for differences between said first read and said second read to determine whether said fingerprints match, thereby authenticating said object.

2. The device of claim 1 wherein said compensating means includes means for compensating for differences between a speed at which each of said first read and said second read is performed.

3. The device of claim 2 wherein said speed compensation means includes means for adjusting a sampling rate at which said second read is performed.

4. The device of claim 3 wherein said adjusting means includes means for measuring the speed of said second read and comparing it with the speed of said first read.

5. The device of claim 2 wherein said speed compensation means includes means for oversampling said remanent noise during at least said second read.

6. The device of claim 5 wherein said speed compensation means includes means for adjusting a rate of said oversampling.

7. The device of claim 2 wherein each of said recorded and determined fingerprints comprises a digital sample of said remanent noise, and wherein said speed compensation means includes means for creating for said second read a digital sample approximately 100 times larger than the digital sample of said first read.

8. A method for authenticating an object, said object including at least in part a magnetic medium portion having a fingerprint, said fingerprint comprising a remanent noise for said magnetic medium portion previously determined by a first read thereof, said method comprising the steps of:

determining a remanent noise directly from said magnetic medium portion by a second read thereof,

comparing said determined remanent noise with said previously determined remanent noise, and

compensating for differences between said first read and said second read to determine whether said fingerprints match, thereby authenticating said object.

9. The method of claim 8 wherein the step of compensating further includes the step of compensating for differences between a speed at which each of said first read and said second read is performed.

10. The method of claim 9 wherein the step of speed compensating further includes the step of adjusting a sampling rate at which said second read is performed.

11. The method of claim 10 wherein the step of adjusting includes the steps of measuring the speed of said second read and comparing it with the speed of said first read.

12. The method of claim 9 wherein the step of speed compensating further includes the step of oversampling said remanent noise during at least said second read.

13. The method of claim 12 wherein the step of speed compensating further includes the step of adjusting a rate of oversampling.

14. The method of claim 9 wherein each of said previously determined remanent noise and said determined remanent noise comprises a digital sample of said remanent noise, and wherein the step of speed compensating further comprises the step of creating for said second read a digital sample approximately 100 times larger than the digital sample of said first read.

15. An object having its fingerprint recorded for the later verification of its identity, said object having a magnetic medium portion, said fingerprint comprising a remanent noise for said magnetic medium portion determined by a first read of said magnetic medium portion, and a speed of said read being recorded in association with said fingerprint for later use in compensating for differences between a speed of a subsequent read and the speed of said first read.

16. The object of claim 15 further comprising a plurality of spaced timing marks on said magnetic medium portion so that a speed of said magnetic medium portion may be determined during a read.

17. A security card with a fingerprint for limiting access to a controlled access environment, said security card having a magnetic medium portion, said fingerprint comprising a remanent noise for said magnetic medium portion, said security card being validated to permit access only upon a match of a subsequent determination of said fingerprint with a previously determined fingerprint.

18. The security card of claim 17 further comprising a data bit recorded on said magnetic medium portion, a value of said data bit corresponding to a placement of said fingerprint on said magnetic medium portion.

19. The security card of claim 18 wherein said fingerprint is randomly located on said magnetic medium portion.

20. An object having its fingerprint recorded for the later verification of its identity, said object having a magnetic medium portion, said fingerprint comprising a remanent noise for said magnetic medium portion, and at least one data bit recorded on said magnetic medium portion, a value of said data bit corresponding to a location of said fingerprint.

21. The object of claim 20 wherein said fingerprint is recorded on said magnetic medium portion, said data bit thereby pointing to a location on said magnetic medium portion.

22. The object of claim 21 wherein said fingerprint is randomly located on said magnetic medium portion.