Method for making copy protected optical discs

• US 6,646,967 B1
• Filed: 08/12/1997
• Issued: 11/11/2003
• Est. Priority Date: 08/12/1997
• Status: Expired due to Fees

• Current Assignee: Denon Digital LLC (Americ Disc, Inc.)
• Original Assignee: Denon Digital LLC (Americ Disc, Inc.)
• Inventors: Garcia, Ben
• Primary Examiner(s): HINDI, NABIL Z
• Application Number:
  US08/909,545
• Time in Patent Office: 2,282 Days
• Field of Search: 369/275.1, 369/275.3, 369/275.4, 369/292, 369/272, 369/59, 369/60, 369/48, 369/47, 369/58, 369/54, 369/53.21, 369/32, 380/3, 380/4
• US Class Current: 369/53.21
• 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 20/00173 wherein the origin of the content is checked, e.g. determining whether the content has originally been retrieved from a legal disc copy or another trusted source
• CPC Class Codes: G11B 20/00927 wherein said defects or errors are generated on purpose, e.g. intended scratches
• CPC Class Codes: G11B 7/00736 Auxiliary data, e.g. lead-in, lead-out, Power Calibration Area [PCA], Burst Cutting Area [BCA], control information sector headers or adresses in prepits G11B7/00745; address data in track wobble G11B7/24082
• CPC Class Codes: G11B 7/261 Preparing a master, e.g. exposing photoresist, electroforming

Abstract

A machine-non-readable defect is formed on a CD-ROM by re-modulation of a master cutting laser beam recorder. Re-modulation in specific program areas creates non-readable marks which interfere with any attempt to image-copy the CD-ROM. The non-machine-readable marks can be followed by valid data which may be used as keys to verify the authenticity of the CD-ROM. The machine-non-readable defect is invisible to the human eye to thwart detection and subsequent reverse engineering attempts.

Claims

1. A method for protecting against unauthorized copying of information on an optical medium comprising the steps of:

a) placing at least one mark at each of at least one corresponding predetermined location on an optical medium, which at least one location is within a continuous spiral track of said optical medium, which mark is incapable of being reproduced except by a mass reproduction recorder, and which mark, when read by a device adapted to read data contained in said continuous spiral track is incapable of being read, and, thereby prevents writing a copy of said mark on an optically recordable medium;

b) adding an executable code module to said optical medium, said executable code module adapted to verify said at least one mark, and allow access to data and programs on said optical medium after said verification of said at least one mark.

2. The method defined by claim 1 wherein said executable code module verifies said at least one mark by determining whether a location of said at least one mark on said optical medium is at said corresponding predetermined location.

3. The method defined by claim 1 wherein said executable code module verifies said at least one mark by determining whether a location of said at least one mark on said optical medium is at said corresponding predetermined location, and comparing a key value associated with said mark with a correct key value.

4. The method defined by claim 1 further comprising the steps of:

a) determining whether an optical medium being read has said at least one mark at said at least one corresponding predetermined location;

b) allowing access to information on said optical medium being read only if each of said at least one marks is determined to be at each of said at least one corresponding predetermined locations.

5. The method defined by claim 1 wherein said predetermined location is a predetermined physical location.

6. The method defined by claim 1 wherein said predetermined location is contained in a path table on said optical recordable medium.

7. The method defined by claim 1 wherein said at least one mark is created by switching modulation of a laser beam recorder used in a mass optical disc manufacturing setting.

8. The method defined by claim 1 wherein said executable code module verifies said at least one mark by maintaining a value identifying a particular location on said optical medium at which said at least one mark should be and comparing said value with a location value obtained from reading an optical medium being verified.

9. The method defined by claim 1 wherein said executable code module verifies said at least one mark by maintaining a name of a container file which holds said mark on said optical medium and then resolving the container file name in a path or file allocation table on an optical medium being verified.

10. The method defined by claim 3 wherein a buffer zone exists on said optical medium between said mark and said key value.

11. The method defined by claim 3 wherein said mark is stored in one sector of said optical medium and said key value is stored in a second sector of optical medium.

12. The method defined by claim 10 wherein said mark is stored in one sector of said optical medium and said key value is stored in a second sector of said optical medium, and said buffer zone is at least 150 sectors disposed between said one sector and said second sector.

13. The method defined by claim 7 wherein said modulation is obtained by an oscillator operating at a frequency between 720 kHz and 196 kHz.

14. The method defined by claim 7 wherein said modulation is obtained by an oscillator operating at one of 0 Hz and a constant DC level greater than 0 Hz.

15. A method for protecting against unauthorized copying of information on an optical medium comprising the steps of:

a) placing at least one mark at each of at least one corresponding predetermined location on an optical medium, which at least one location is within a continuous spiral track of said optical medium, which mark is incapable of being reproduced except by a mass reproduction recorder, and which mark, when read by a device adapted to read data contained in said continuous spiral track is incapable of being read, and, thereby prevents reading and of data following said mark and subsequent writing of said unread data on an optically recordable medium;

b) adding an executable code module to said optical medium, said executable code module adapted to verify correctness of data following said mark contained on said optical medium.

16. The method defined by claim 15 wherein a buffer zone of a predetermined size is disposed between said data to be verified and said mark.

17. The method defined by claim 16 wherein said mark is stored in one sector of said optical medium and said data to be verified is stored in a second sector of said optical medium, and said buffer zone is at least 150 sectors disposed between said one sector and said second sector.