# US 4,785,361 A · Method and apparatus for frustrating the unauthorized copying of recorded data

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- Number: US 4,785,361 A
- Document ID: US4785361A
- Status: Granted
- Kind: A
- Application number: 06/943,389
- Filed: 1986-12-16
- Granted: 1988-11-15
- Earliest claimed: 1982-11-08
- Assignees: Vault Corporation
- Inventors: W. Krag Brotby
- Web page: https://patentgrep.com/patent/US4785361A

## CPC

- G11B 20/00659: {involving a control step which is implemented as an executable file stored on the record carrier}
- G06F 21/80: in storage media based on magnetic or optical technology, e.g. disks with sectors (preventing unauthorised reproduction or copying of disc-type recordable media G11B20/00)
- 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)}
- 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}
- G11B 20/00586: {said format change concerning the physical format of the recording medium}
- G11B 20/00695: {said measures preventing that data are read from the recording medium}
- G11B 20/00927: {wherein said defects or errors are generated on purpose, e.g. intended scratches}
- G06F 2211/007: Encryption, En-/decode, En-/decipher, En-/decypher, Scramble, (De-)compress
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

Authorized disks made in accordance with the invention are physically distinguishable from the blank disks which would be used for making unauthorized copies. A security check procedure is included in the initializing routine that is recorded on the authorized disk and that is executed prior to the reading out of any of the protected data. The security check procedure involves a test to determine whether the disk on which it has been recorded has or does not have the physical fingerprint that is the hallmark of an authorized disk. If the fingerprint is absent, the security check procedure prevents the protected material from being read out. Thus, unauthorized copies are useless because the protected data cannot be read out of them.

## Claims

### Claim 1

A method for frustrating the unauthorized copying of protected data that has been recorded in an authorized medium that includes an initializing routine that is executed before any of the protected data is read out of the authorized medium, said method comprising the steps of:
(a) establishing a File X;
(b) initially storing in File X a particular number N.sub.o ;
(c) providing an incrementing apparatus that is present only when an authorized medium is used, for generating a series of increments and for successively incrementing the number in File X each time the medium is read, said incrementing apparatus not being present when an unauthorized medium is used and being rendered inoperative when an authorized medium has been tempered with;
(d) establishing a File Y as part of the initializing routine;
(e) initially storing in File Y the number N.sub.o used in step (b);
(f) incrementing the number in File Y successively each time the medium is read, in accordance with the same series of increments that was generated in step (c);
(g) testing to determine whether the number in File X equals the number in File Y;
(h) preventing read-out of the protected data when the number in File X does not equal the number in File Y.

### Claim 2

Apparatus for frustrating the unauthorized copying of protected data that has been recorded therein along with an initializing routine that is executed before the protected data can be read out, said initializing routine including instructions for generating a first series of increments and for successively incrementing a first number stored in said initializing routine each time said apparatus is used, said apparatus comprising:
a medium; and,
incrementing means associated with said medium for generating a second series of increments identical to said first series of increments and for successively incrementing a second number equal to said first number and stored in a particular file in said medium each time said medium is read, whereby an unauthorized copy, which lacks said incrementing means, can be recognized by said initializing routine in time to prevent read-out of the protected data by any inequality between successive increments of said first number and corresponding successive increments of said second number.