APPARATUS AND METHOD FOR EMBEDDING AND EXTRACTING INFORMATION IN ANALOG SIGNALS USING REPLICA MODULATION

• US 20020097873A1
• Filed: 06/29/1998
• Published: 07/25/2002
• Est. Priority Date: 05/19/1997
• Status: Active Grant

• Current Assignee: Verance Corporation
• Original Assignee: Verance Corporation
• Inventors: PETROVIC, RADE
• Granted Patent: US 6,427,012 B1
• Time in Patent Office: Days
• US Class Current: 380/238
• CPC Class Codes: G06F 21/60 Protecting data
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: H04H 20/31 using in-band signals, e.g. subsonic or cue signal

Abstract

Apparatus and methods are provided for embedding or encoding auxiliary signals into an analog host or cover signal. A replica of the cover signal or a portion of the cover signal in a particular domain (time, frequency or space) is generated according to a stego key specifying modification values to specified parameters of the cover signal. The replica signal is then modified by an auxiliary signal corresponding to the information to be embedded, and inserted back into the cover signal. Embedded auxiliary signals are extracted by generating replicas of received signals and correlating the replicas with the received signals.

Claims

1. A method for embedding an auxiliary signal in an analog cover signal, comprising the steps of:

generating a replica signal from said cover signal;

modifying said replica signal as a function of said auxiliary signal; and

inserting the modified replica signal back into said analog cover signal.

2. A method according to claim 1, wherein the step of generating comprises the step of modifying at least a portion of said cover signal in a predetermined domain according to a stego key.

3. A method according to claim 2, wherein said predetermined domain is the frequency domain.

4. A method according to claim 2, wherein said predetermined domain is the time domain.

5. A method according to claim 2, wherein said predetermined domain is the spatial domain.

6. A method according to claim 2, wherein said replica signal is obtained by shifting the frequency of said at least one portion of said cover signal by a predefined amount specified by said stego key.

7. A method according to claim 2, wherein said replica signal is obtained by shifting the phase of said at least one portion of said cover signal by a predefined amount specified by said stego key.

8. A method according to claim 2, wherein said replica signal is obtained by shifting the amplitude of said at least one portion of said cover signal by a predefined amount specified by said stego key.

9. A method according to claim 2, wherein said replica signal is obtaining by shifting a predetermined combination of the frequency, phase, and/or amplitude of said at least one portion of said cover signal by predefined amounts specified by said stego key.

10. A method according to claim 1, wherein the step of modifying comprises the step of multiplying said replica signal with said auxiliary signal.

11. A method for extracting an embedded auxiliary signal from an analog stego signal, comprising the steps of:

generating a replica signal from said stego signal;

modifying said stego signal as a function of said replica signal; and

extracting said information symbol by filtering said modified stego signal.

12. A method according to claim 11, wherein the step of generating comprises the step of modifying at least a portion of said stego signal in a predetermined domain according to a stego key.

13. A method according to claim 12, wherein said predetermined domain is the frequency domain.

14. A method according to claim 12, wherein said predetermined domain is the time domain.

15. A method according to claim 12, wherein said predetermined domain is the spatial domain.

16. A method according to claim 12, wherein said replica signal is obtained by shifting the frequency of said at least one portion of said stego signal by a predefined amount specified by said stego key.

17. A method according to claim 12, wherein said replica signal is obtained by shifting the phase of said at least one portion of said stego signal by a predefined amount specified by said stego key.

18. A method according to claim 12, wherein said replica signal is obtained by shifting the amplitude of said at least one portion of said stego signal by a predefined amount specified by said stego key.

19. A method according to claim 12, wherein said replica signal is obtained by shifting a predetermined combination of the frequency, phase and/or amplitude of said at least one portion of said stego signal by a predefined amount specified by said stego key.

20. A method according to claim 11, wherein the step of modifying comprises the step of multiplying said replica signal with said stego signal.

21. Apparatus for embedding and extracting auxiliary signals in an analog cover signal, comprising:

means for generating a replica signal from said cover signal;

means for modifying said replica signal as a function of said auxiliary signal;

means inserting the modified replica signal back into said analog cover signal to produce a stego signal;

means for receiving said stego signal;

means for generating a replica signal from said stego signal;

means for modifying said received stego signal as a function of said replica signal of said received stego signal; and

means for extracting said auxiliary signal by filtering said modified received stego signal.

22. Apparatus according to claim 21, wherein said means for generating a replica signal comprises means for modifying at least a portion of said cover signal in a predetermined domain according to a stego key.

23. Apparatus according to claim 22, wherein said predetermined domain is the frequency domain.

24. Apparatus according to claim 22, wherein said predetermined domain is the time domain.

25. Apparatus according to claim 22, wherein said predetermined domain is the spatial domain.

26. Apparatus according to claim 22, wherein said replica signal is obtained by shifting the frequency of said at least one portion of said cover signal by a predefined amount specified by said stego key.

27. Apparatus according to claim 22, wherein said replica signal is obtained by shifting the phase of said at least one portion of said cover signal by a predefined amount specified by said stego key.

28. Apparatus according to claim 22, wherein said replica signal is obtained by shifting the amplitude of said at least one portion of said cover signal by a predefined amount specified by said stego key.

29. Apparatus according to claim 22, wherein said replica signal is obtaining by shifting a predetermined combination of the frequency, phase, and/or amplitude of said at least one portion of said cover signal by predefined amounts specified by said stego key.

30. Apparatus according to claim 21, wherein said means for modifying said replica signal comprises means for multiplying said replica signal with said auxiliary signal.