Method and system for digital watermarking

• US 5,905,800 A
• Filed: 03/25/1998
• Issued: 05/18/1999
• Est. Priority Date: 01/17/1996
• Status: Expired due to Term

• Current Assignee: Wistaria Trading Inc.
• Original Assignee: The Dice Company
• Inventors: Moskowitz, Scott A., Cooperman, Marc
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US09/047,448
• Time in Patent Office: 419 Days
• Field of Search: 380/4, 380/28, 380/30, 380/54, 380/44, 340/825, 340/34
• US Class Current: 380/28
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• CPC Class Codes: G06T 1/0085 Time domain based watermarking, e.g. watermarks spread over several images
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0083 whereby only watermarked image required at decoder, e.g. source-based, blind, oblivious
• 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: H04L 2209/608 Watermarking
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

A method for applying a digital watermark to a content signal is disclosed. In accordance with such a method, a watermarking key is identified. The watermarking key includes a binary sequence and information describing application of that binary sequence to the content signal. The digital watermark is then encoded within the content signal at one or more locations determined by the watermarking key.

Claims

1. A method for applying a digital watermark to a content signal, comprising the steps of:

identifying a watermarking key comprising a binary sequence and information describing application of the binary sequence to the content signal;

encoding the digital watermark within the content signal at one or more locations determined by the watermarking key; and

generating a key pair associated with the watermarking key.

2. The method of claim 1, wherein the key pair includes a public key and a private key.

3. The method of claim 2, wherein the public key enables authentication of the encoded digital watermark.

4. The method of claim 3, wherein the public key does not enable decoding of the encoded digital watermark.

5. The method of claim 2, further comprising the step of adding a digital signature to the content signal, wherein the public key enables authentication of the digital signature.

6. The method of claim 5, wherein the public key does not enable decoding of the encoded digital watermark.

7. The method of claim 2, wherein the digital watermark comprises a multichannel watermark having a plurality of channels, and the public key enables decoding of less than all the channels of the multi-channel watermark.

8. The method of claim 1, further comprising the step of repeating said identifying and encoding steps for each of a plurality of digital watermarks.

9. The method of claim 8, further comprising the step of generating a public key associated with one of the plurality of digital watermarks.

10. The method of claim 9, wherein the public key enables authentication of the associated digital watermark.

11. The method of claim 9, wherein the public key enables decoding of the associated digital watermark.

12. The method of claim 1, wherein said step of encoding the digital watermark further comprises applying the digital watermark to the content signal to interfere with subsequent processing of the content signal.

13. The method of claim 12, wherein the subsequent processing comprises copying of the content signal.

14. The method of claim 12, wherein the subsequent processing comprises transfer of a file containing the content signal.

15. The method of claim 12, wherein the subsequent processing comprises playback of the content signal.

16. The method of claim 12, wherein said step of encoding the digital watermark further comprises applying the digital watermark to the content signal to interfere with subsequent processing of the content signal unless the digital watermark is first decoded.

17. The method of claim 12, wherein said step of encoding the digital watermark further comprises applying the digital watermark to the content signal to interfere with subsequent processing of the content signal unless the digital watermark is first authenticated.

18. The method of claim 1, further comprising the step of applying watermark synchronization information to the content signal, wherein the watermark synchronization information indicates a location of the encoded digital watermark within the content signal.

19. A digital watermarking system for encoding and decoding a digital watermark within a content signal, comprising a digital watermark encoder and a digital watermark decoder, wherein said digital watermark encoder and said digital watermark decoder are configured to respectively encode and decode a digital watermark using (1) a watermarking key comprising a binary sequence and information describing application of the binary sequence to the content signal and (2) a key pair associated with the watermarking key.

20. The digital watermarking system of claim 19, wherein said digital watermark encoder and said digital watermark decoder comprise separate software applications.

21. The digital watermarking system of claim 19, wherein said digital watermark encoder and said digital watermark decoder comprise separate hardware devices.

22. A method for applying a digital watermark to a content signal, comprising the steps of:

identifying a watermarking key comprising a binary sequence and information describing application of the binary sequence to the content signal, wherein the application of the binary sequence to the content signal is based on characteristics of the content signal; and

encoding the digital watermark within the content signal at one or more locations determined by the watermarking key.

23. The method of claim 22, further comprising the step of generating a key pair associated with the watermarking key, the key pain including a public key and a private key.