Method and apparatus for use of a watermark and a unique time dependent reference for the purpose of copy protection

• US 6,865,675 B1
• Filed: 03/25/1999
• Issued: 03/08/2005
• Est. Priority Date: 07/14/1998
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Epstein, Michael
• Primary Examiner(s): Sheikh, Ayaz
• Assistant Examiner(s): MOORTHY, ARAVIND K
• Application Number:
  US09/276,437
• Time in Patent Office: 2,175 Days
• Field of Search: 713/176, 713/158, 713/178, 713/165, 713/166, 713/200, 382/100, 382/232, 705/51, 705/57, 725/104, 380/201, 380/203, 380/241, 380/242
• US Class Current: 713/176
• CPC Class Codes: G06F 21/1063 Personalisation
• CPC Class Codes: G06F 21/16 Program or content traceability, e.g. by watermarking
• CPC Class Codes: G06T 1/0021 Image watermarking
• 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 20/00884 involving a watermark, i.e. a barely perceptible transformation of the original data which can nevertheless be recognised by an algorithm
• CPC Class Codes: H04N 2005/91328 the copy protection signal being a copy management signal, e.g. a copy generation management signal [CGMS]
• CPC Class Codes: H04N 2005/91335 the copy protection signal being a watermark
• CPC Class Codes: H04N 21/235 Processing of additional data, e.g. scrambling of additional data or processing content descriptors
• CPC Class Codes: H04N 21/23892 involving embedding information at multiplex stream level, e.g. embedding a watermark at packet level
• CPC Class Codes: H04N 21/4325 by playing back content from the storage medium reproduction of recorded television signals H04N5/76; reproduction of recorded television signals H04N9/79
• CPC Class Codes: H04N 21/435 Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
• CPC Class Codes: H04N 21/4508 Management of client data or end-user data
• CPC Class Codes: H04N 21/8355 involving usage data, e.g. number of copies or viewings allowed
• CPC Class Codes: H04N 21/8358 involving watermark protecting executable software by watermarking G06F21/16; image watermarking in general G06T1/0021; watermarks inserted in still images for transmission purposes H04N1/32144; inserting watermarks during video coding H04N19/467
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

A copyright protection system for protecting content wherein a time dependent ticket is calculated at a source device by combining a checkpoint with a ticket. The checkpoint is transmitted from a display device to the source device prior to the source device transmitting watermarked content to the display device. The checkpoint is also stored at the display device. Thereafter, the source device transmits, to the display device, watermarked content, the ticket, and the time dependent ticket. At the display device, the stored checkpoint is compared to a current count of a local clock that was utilized for producing the checkpoint. If the stored checkpoint is within a window of time of the local clock, then the stored checkpoint is combined with the ticket in the same way that the checkpoint is combined with the ticket at the source device. A result of the combination is compared to the time dependent ticket and if the result equals the time dependent ticket, then the watermark and ticket may be compared in the usual way to determine the copy protection status of the copy protected content.

Claims

1. A method of protecting content transmitted as a stream of data, the method comprising the steps of:

determining a checkpoint at a receiving device;

calculating, at a source device, a time dependent ticket utilizing the checkpoint, wherein a watermark, a ticket, and the checkpoint together indicate a copy protection status of the content;

transmitting said stream of data, said watermark, said ticket, and said time dependent ticket to said receiving device; and

comparing said time dependent ticket to a stored checkpoint at said receiving device.

2. The method of claim 1, wherein said step of calculating said time dependent ticket comprises the steps of:

combining said checkpoint with said ticket; and

calculating a one-way operation on said combined checkpoint and ticket.

3. The method of claim 2, further comprising the step of selecting said one-way function to be a hashing function.

4. The method of claim 1, further comprising the step of comparing, at said receiving device, said ticket and said watermark to determine the copy protection status of the content if said time dependent ticket compares to said stored checkpoint.

5. The method of claim 1, wherein said checkpoint is a checkpoint from a receiver counter.

6. The method of claim 5, wherein said receiver counter is randomized.

7. The method of claim 5, wherein the step of comparing said time dependent ticket further comprises the step of comparing said stored checkpoint to a current count from said receiver counter.

8. The method of claim 1, wherein said step of calculating said time dependent ticket further comprises the step of signing said time dependent ticket with a private key of said source device, and wherein said step of comparing said time dependent ticket further comprises the step of verifying the signature using a public key of said source device.

9. A copy protection system for protecting content wherein a ticket and a watermark indicates a copy protection status of said content, the system comprising:

a source device configured to calculate a time dependent ticket using a checkpoint and a one-way function, and to provide a data stream containing said content, said ticket, a watermark, and said time dependent ticket; and

a display device configured to produce said checkpoint, configured to receive said data stream, and configured to compare said time dependent ticket to said checkpoint using said ticket and said one-way function.

10. The system of claim 9, wherein said one-way function is a hashing function.

11. The system of claim 9, wherein said source device is further configured to calculate said time dependent ticket by combining said checkpoint with said ticket, and then calculating a one-way operation on said combined checkpoint and ticket.

12. The system of claim 9, wherein said display device is further configured to compare said ticket to said watermark and to display said content if said time dependent ticket compares to said checkpoint.

13. The system of claim 9, wherein said display device comprises a counter and wherein said checkpoint is a checkpoint from said counter.

14. The system of claim 13, wherein said display device is further configured to randomize said counter.

15. The system of claim 13, wherein said display device is further configured to compare said checkpoint to a current count from said counter prior to displaying said content.

16. The system of claim 9, wherein said source device is further configured to sign said time dependent ticket with a private key of said source device and to send said signed time dependent ticket to said display device, and wherein said display device is further configured to verify the signed time dependent ticket using a public key of said source device.

17. A source device for protecting content wherein a ticket and a watermark indicate a copy protection status of the content, said source device comprising:

a reader device configured to read watermarked content from a physical medium and configured to read a physical mark from said physical medium; and

a processor configured to receive a checkpoint, configured to calculate said ticket using said physical mark and a one-way function, configured to calculate a time dependent ticket using said ticket, said checkpoint, and said one-way function, and configured to provide to a receiver a data stream containing said watermarked content, said ticket, and said time dependent ticket.

18. The system of claim 17, wherein said one-way function is a hashing function.

19. A display device for receiving data from a source device, said data containing watermarked content, a time dependent ticket and a ticket, wherein said ticket and watermark together indicate a copy protection status of the content, and wherein said time dependent ticket is formed from said ticket and a checkpoint, said display device comprising:

a counter for generating said checkpoint and a current time reference;

means for storing said checkpoint and for providing said checkpoint to said source device prior to reception of said data; and

a processor, wherein if said stored checkpoint is contained within a time window determined by said current time reference, said processor is configured to;

receive said time dependent ticket and said data,

combine said ticket with said stored checkpoint to produce a first result,

perform a one-way function on said first result to produce a second result, and

compare said second result to said time dependent ticket, wherein said display device is further configured to display said data if said second results compares to said time dependent ticket.

20. The system of claim 19, wherein said one-way function is a hashing function.