Method and apparatus for watermarking digital bitstreams

• US 6,330,672 B1
• Filed: 06/30/1998
• Issued: 12/11/2001
• Est. Priority Date: 12/03/1997
• Status: Expired due to Term

• Current Assignee: Hanger Solutions, LLC (IP Investments Group LLC)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Shur, David Hilton
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): KABAKOFF, STEPHEN ERIC
• Application Number:
  US09/108,135
• Publication Number:
  US 20010049788A1
• Time in Patent Office: 1,260 Days
• Field of Search: 713/176, 380/54, 380/202, 705/51, 705/57, 705/58, 382/251, 382/100
• US Class Current: 713/176
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/0035 Output size adaptive watermarking
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0053 Embedding of the watermark in the coding stream, possibly without decoding; Embedding of the watermark in the compressed domain
• CPC Class Codes: G06T 2201/0083 whereby only watermarked image required at decoder, e.g. source-based, blind, oblivious
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: H04N 1/32128 attached to the image data, e.g. file header, transmitted message header, information on the same page or in the same computer file as the image for information embedded in the image H04N1/32144
• CPC Class Codes: H04N 1/32149 Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/32154 Transform domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32187 with selective or adaptive application of the additional information, e.g. in selected frequency coefficients
• CPC Class Codes: H04N 1/32272 Encryption or ciphering
• CPC Class Codes: H04N 1/32277 Compression
• CPC Class Codes: H04N 1/32299 using more than one embedding method
• CPC Class Codes: H04N 1/32304 Embedding different sets of additional information
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/19 using optimisation based on Lagrange multipliers
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/467 characterised by the embedded information being invisible, e.g. watermarking
• CPC Class Codes: H04N 19/48 using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data motion estimation in a transform domain H04N19/547; processing of decoded motion vectors H04N19/513
• CPC Class Codes: H04N 19/90 : using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
• 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 21/8358 : 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 2201/3233 : of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/3239 : using a plurality of different authentication information
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/3281 : Encryption; Ciphering

Abstract

A signal is encoded, for example, perceptually and, during or after the perceptual coding process, a digital watermark is inserted into a quantized digital information signal resulting from the perceptual coding process in such a manner that its insertion is imperceptible to one later listening to, displaying or otherwise utilizing the information signal. Moreover, the digital watermark may be inserted in accordance with a key indicative of the location of the mark in the digitally encoded signal. The key may be protected with a trusted entity and distributed in such a manner as to be not detectable by a pirate. Consequently, the key may be utilized at watermarking apparatus that can be located anywhere in the distribution channel of a copyright protected work. The key may be embedded in a secure microprocessor of validating apparatus at a point of distribution or even at a point of sale. In this manner, when or after a digital bitstream is fixed in a medium of expression or broadcast, the watermark can be applied at the time of fixing in a copy, thus validating an original legitimate copy. For example, a compact disc recording may be validated at the point of sale as an authorized copy through watermarking (validating) apparatus according to the present invention or, at the time of broadcast over radio frequencies or distribution via the Internet, information may be watermarked. In this manner, even though a work may be pirated, further information may be included or otherwise indicated by the watermark to assist in, not only recognizing a pirated work and the original from which the pirate copy was produced, but the identity of the pirate who later makes an unauthorized copy of the original.

Claims

1. Apparatus for inserting a digital watermark into protected information comprises

a transformation function of a perceptual coder for coding an information signal representative of the protected information,

a watermark location selector responsive to the perceptual coder for selecting a location for inserting a digital watermark, said watermark location selector including a logical gate responsive to a random number generator, said random number generator, responsive to a seed and a selection of a watermark overhead, for outputting a binary sequence,

a digital watermark generator for generating a digital watermark sequence responsive to a plurality of predetermined watermark parameters and

a quantizer of the perceptual coder responsive to the digital watermark generator and the watermark location selector for inserting a digital watermark at selected locations within an output bitstream, said output bitstream including the perceptually coded information signal.

2. Apparatus as recited in claim 1 wherein said transformation function comprises a modified discrete cosine transform for transforming from the time domain to the frequency domain and outputting spectral coefficients for comparison with a perceptual threshold, a coefficient being below the threshold identifying that coefficient as a candidate location for a portion of a digital watermark.

3. Apparatus as recited in claim 1 wherein said transformation function comprises a discrete cosine transform for transforming from the time domain to the frequency domain and outputting spectral coefficients for comparison with a perceptual threshold, a coefficient being below the threshold identifying that coefficient as a candidate location for a portion of a digital watermark.

4. Apparatus as recited in claim 1 wherein said transformation function comprises an N point fast Fourier transform for transforming from the time domain to the frequency domain and outputting spectral coefficients for comparison with a perceptual threshold, a coefficient being below the threshold identifying that coefficient as a candidate location for a portion of a digital watermark.

5. Apparatus as recited in claim 1 wherein said logical gate of said watermark location selector comprises a logical AND gate, said logical AND gate being responsive to said binary sequence output of said random number generator and said watermarking sequence output of said watermark generator.

6. Apparatus as recited in claim 1 wherein said digital watermark generator comprises an input comprising said plurality of predetermined watermarking parameters including play authorization data.

7. Apparatus as recited in claim 6 wherein said plurality of watermarking parameters comprises one of data representing an identity of a recipient of said protected information and data representing an identity of a perceptual coding transformation algorithm.

8. Apparatus as recited in claim 6 wherein said plurality of watermarking parameters comprises one of data representing an identity of a contractual arrangement and data representing an identity of the date of said contractual relationship.

9. Apparatus as recited in claim 8 wherein said contractual arrangement comprises a lease and said plurality of watermarking parameters further comprises data indicative of an expiration date of said lease representing a date after which access to said protected information is to be denied.

10. Apparatus as recited in claim 6 wherein said plurality of watermarking parameters is encrypted prior to insertion.

11. Apparatus as recited in claim 1 wherein said digital watermark generator comprises means for encrypting a plurality of watermarking parameters with a key K related to said seed.

12. Apparatus as recited in claim 1 wherein said digital watermark generator comprises means for encrypting a plurality of watermarking parameters with a key K unrelated to said seed.

13. Apparatus as recited in claim 1 wherein said protected information comprises video data and said quantization has a step size selected according to the magnitude of errors that will not be visible.

14. A method for inserting a digital watermark into protected information comprising the steps of

perceptually encoding an information signal representative of the protected information,

selecting, responsive to the perceptual coding step, a location for inserting a digital watermark including the step of generating a binary sequence using a random number generator responsive to selecting a seed and a watermark overhead and providing said binary sequence to a logical gate,

generating a digital watermark sequence responsive to a plurality of watermark parameters for input to said logical gate, and

during perceptual coding, quantizing the information signal to insert the generated digital watermark at selected locations within an output bitstream, said output bitstream including the perceptually coded information signal.

15. A method as recited in claim 14 wherein said perceptual coding comprises a transformation function of a modified discrete cosine transform for transforming from the time domain to the frequency domain and outputting spectral coefficients for comparison with a perceptual threshold, a coefficient being below the threshold identifying that coefficient as a candidate location for a portion of a digital watermark.

16. A method as recited in claim 14 wherein said perceptual coding comprises a transformation function of a discrete cosine transform for transforming from the time domain to the frequency domain and outputting spectral coefficients for comparison with a perceptual threshold, a coefficient being below the threshold identifying that coefficient as a candidate location for a portion of a digital watermark.

17. A method as recited in claim 14 wherein said perceptual coding comprises a transformation function of an N point fast Fourier transform for transforming from the time domain to the frequency domain and outputting spectral coefficients for comparison with a perceptual threshold, a coefficient being below the threshold identifying that coefficient as a candidate location for a portion of a digital watermark.

18. A method as recited in claim 14 wherein said step of selecting a watermark location comprises generating a random number binary sequence and logical ANDing an output of said random number generator and a candidate watermarking sequence.

19. A method as recited in claim 18 wherein said step of generating a random number is responsive to inputting a seed and selecting a watermarking overhead.

20. A method as recited in claim 14 wherein said step of generating a digital watermark comprises an input comprising said plurality of watermarking parameters including play authorization data.

21. A method as recited in claim 20 wherein said plurality of watermarking parameters comprises one of data representing an identity of a recipient of said protected information and data representing an identity of a perceptual coding transformation algorithm.

22. A method as recited in claim 20 wherein said plurality of watermarking parameters comprises one of data representing an identity of a contractual arrangement and data representing an identity of the date of said contractual relationship.

23. A method as recited in claim 22 wherein said contractual arrangement comprises a lease and said plurality of watermarking parameters further comprises data indicative of an expiration date of said lease representing a date after which access to said protected information is to be denied.

24. A method as recited in claim 20 wherein said plurality of watermarking parameters is encrypted prior to insertion.

25. A method as recited in claim 19 wherein said digital watermark generating step comprises encrypting a plurality of watermarking parameters with a key K related to said seed.

26. A method as recited in claim 19 wherein said step of generating a digital watermark comprises encrypting a plurality of watermarking parameters with a key K unrelated to said seed.

27. A method as recited in claim 14 wherein said protected information comprises video data and said quantization step has a step size selected according to the magnitude of errors that will not be visible.

28. Apparatus for inserting a hidden data stream into a perceptually encoded media stream comprising

an N point transform for outputting N coefficients and

a quantizer for selecting a scale factor, quantizing the input N coefficients and inserting the hidden data stream in indexed locations of the perceptually encoded media stream responsive to said N point transform, said indexed locations being determined responsive to selection of a seed and a watermark overhead for input to a random number generator for generating a binary sequence.

29. Decoder apparatus for detecting a watermark for authorizing play, said watermark being generated responsive to an input comprising a plurality of watermarking parameters including play authorization data and being located responsive to selection of a key and a watermark overhead comprising

a key receiver for receiving a key relating to said location of a watermark,

a watermark detector responsive to the key receiver for locating the watermark and for analyzing if the watermark contains play authorization data and

a presentation circuit for presenting a decoded information signal responsive to the watermark detector when said play authorization data of said watermark authorizes play.

30. Decoder apparatus for detecting a digital watermark in an information signal, the digital watermark being generated responsive to an input comprising a plurality of watermarking parameters including play authorization data and being located responsive to selection of a key and a watermark overhead and including the name of a customer and the date and location of a transaction, and for outputting the watermark for tracing an unlicensed copy of the information signal to a pirate, the unlicensed copy including said watermark.

31. A method for inserting a digital watermark into protected information comprising the steps of

perceptually encoding an information signal representative of the protected information,

selecting, responsive to the perceptual coding step, a location for inserting a digital watermark,

generating a digital watermark including a plurality of watermark parameters, and

during perceptual coding, manipulating perceptual coding coefficients to insert the generated digital watermark at selected locations within an output bitstream, the output bitstream including the perceptually coded information signal, said selection of locations for the generated watermark being responsive to a comparison of said perceptual coding coefficients with a calculated perceptual threshold and includes the steps of selecting a watermark overhead and a seed for input to a random number generator.

32. A method for inserting a digital watermark into protected information as recited in claim 31 wherein said protected information comprises audio information.

33. A method for inserting a digital watermark into protected information characterized by the steps of

determining a candidate digital watermark sequence,

selecting a digital watermark overhead for controlling generation of a binary output sequence for logical combination with said candidate digital watermark sequence and

locating, responsive to said logical combination and said selected digital watermark overheads, a digital watermarking sequence generated responsive to a plurality of watermark parameters into said protected information data signal.

34. A method as recited in claim 33 wherein said step of selecting a digital watermark overhead provides an input to a random number generator whose output is provided to a logical gate for logical combination with said candidate digital watermark sequence.

35. A method as recited in claim 34 wherein said output of said random number generator is further determined by the selection of a seed as a further input.

36. A method as recited in claim 34 wherein said digital watermark overhead is selected as one of a percent or a probability of a binary output of the random number generator being equal to one.