Content authentication and recovery using digital watermarks
First Claim
Patent Images
1. A method for hiding auxiliary data in a media signal, the method comprising:
- compressing a first media signal to generate a compressed first media signal from which a counterpart to the first media signal can later be decompressed; and
embedding the compressed first media signal into a second media signal, the second media signal representing a content object;
wherein the first media signal also represents a content object, and said two content objects are perceptually similar.
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Abstract
The disclosure describes methods for using digital watermarking to authenticate digital media signals, such as images, audio and video signals. It also describes techniques for using embedded watermarks to repair altered parts of a media signal when alteration is detected. Alteration is detected using hashes, digital watermarks, and a combination of hashes and digital watermarks.
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Citations
44 Claims
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1. A method for hiding auxiliary data in a media signal, the method comprising:
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compressing a first media signal to generate a compressed first media signal from which a counterpart to the first media signal can later be decompressed; and embedding the compressed first media signal into a second media signal, the second media signal representing a content object; wherein the first media signal also represents a content object, and said two content objects are perceptually similar. - View Dependent Claims (3)
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2. A method for hiding auxiliary data in a media signal, the method comprising:
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compressing a first media signal; and embedding the compressed first media signal into a second media signaL the second media sisuial representing a content obiect; wherein the first media signal also represents a content object, and said two content objects are perceptually similar; and wherein the compressed first media signal comprises plural samples, and said embedding includes associating a symbol with a sorting order, determining a sorting order of a block of samples, and modulating the sorting order of the block of samples as necessary to make the sorting order match the sorting order associated with a symbol to be embedded.
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4. A method of processing a host signal, comprising:
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decoding an auxiliary signal imperceptibly embedded into said host signal; decompressing said decoded auxiliary signal to yield a content object; and using the decompressed auxiliary signal to authenticate the host signal; wherein the host signal represents a first content object, and the auxiliary signal represents at least a portion of a content object that is perceptually similar to said first content object. - View Dependent Claims (6, 7, 8, 38, 44)
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5. A method of processing a host signal, comprising:
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decoding an auxiliary signal imperceptibly embedded into said host signal; and using the auxiliary signal to authenticate the host signal; wherein the host signal represents a first content object, and the auxiliary signal represents at least a portion of a content object that is perceptually similar to said first content object; and wherein the compressed auxiliary signal comprises plural symbols and the host signal comprises plural blocks of samples, and wherein the decoding includes using a sorting order decoder to analyze sorting orders of selected blocks of samples, and to determine symbols corresponding to the sorting orders.
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9. A method of watermarking media content comprising:
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selecting non-overlapping blocks A, B and C of the media content; losslessly compressing blocks B and C of the content to form compressed content; watermark embedding the compressed content into block B of the media content to form a new block B′
;creating a hash of block A and B′
;watermark embedding the hash into block C to create a new block C′
; andcombining blocks A, B′ and
C′
to form watermarked media content. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method for encoding a reversible watermark in a media signal comprising:
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embedding a watermark message signal into a reference media signal to create a watermarked reference signal, where the watermark message signal includes information about a watermark embedder function used to embed the watermark message signal into the reference signal; subtracting the reference signal from the watermarked reference signal to form a difference signal; and adding the difference signal to a host media signal to embed the watermark message signal in the host signal; wherein adding the difference signal is reversible by decoding the information about the watermark embedder function from the host media signal, using the information about the watermark embedder function to re-compute the difference signal, and subtracting the difference signal from the host media signal to restore the host signal. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. A method for authenticating a watermarked media signal that has been watermarked using a watermark embedding function on an un-watermarked version of the media signal, comprising:
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decoding a watermark message from the watermarked media signal, wherein the watermark message includes a hash of the un-watermarked media signal and watermark embedding information used by the watermark embedding function to create the watermarked media signal; transforming the watermark embedding information and hash into a watermark difference signal using the watermark embedding function; subtracting the watermark difference signal from the watermarked media signal to restore the un-watermarked media signal; computing a new hash of the restored, un-watermarked media signal; and comparing the new hash with the hash decoded from the watermarked media signal to determine the authenticity of the watermarked media signal. - View Dependent Claims (24, 25, 26)
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27. A method for encoding a reversible watermark in a media signal comprising:
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creating a watermark difference signal carrying information about a watermark embedder function used to embed the watermark message signal into the difference signal; and adding the difference signal to a host media signal to embed the watermark message signal in the host signal; wherein adding the difference signal is reversible by decoding the information about the watermark embedder function from the host media signal, using the information about the watermark embedder function to re-compute the difference signal, and subtracting the difference signal from the host media signal to restore the host signal. - View Dependent Claims (28)
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29. A method of hiding auxiliary data in a media signal, the method comprising:
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dividing the media signal into blocks; partitioning the media signal into two regions; for a plurality of the blocks, compressing the media signal from a first region of a block and embedding redundant instances of the compressed media signal of the block into a second region of two or more blocks. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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37. A method of authenticating a media signal using hidden embedded data in the media signal, the method comprising:
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dividing the media signal into blocks; partitioning the blocks into regions; for a plurality of blocks, extracting hidden compressed bit streams of a first region of other blocks from a second region in the blocks; for a plurality of blocks, evaluating whether a block is altered by comparing the extracted compressed bit streams for a block with the media signal in the first region of the block; and when an altered block is detected by the comparison, using a fragile hash to identify location of altered data, and using an extracted compressed bit stream to replace the altered data.
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39. A method comprising:
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receiving a first set of data representing a first content object; generating a second set of data representing a second content object that is perceptually similar to the first content object; and digitally watermarking the second set of data into the first set of data. - View Dependent Claims (40, 41, 42)
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43. A signal processing method that includes receiving a first set of data representing a first content object, processing the first set of data to yield a second set of data, and digitally watermarking the second set of data in the first set of data, characterized in that the second set of data represents a content object that is perceptually similar to said first content object.
Specification