Audio steganography

• US 6,330,335 B1
• Filed: 01/13/2000
• Issued: 12/11/2001
• Est. Priority Date: 11/18/1993
• Status: Expired due to Term

• Current Assignee: Digimarc Corporation
• Original Assignee: Digimarc Corporation
• Inventors: Rhoads, Geoffrey B.
• Primary Examiner(s): Hayes, Gail
• Assistant Examiner(s): Darrow, Justin T.
• Application Number:
  US09/482,752
• Time in Patent Office: 698 Days
• Field of Search: 380/34, 380/36, 380/46, 380/252, 380/253, 380/254, 713/176, 713/190, 700/94, 455/2, 455/100
• US Class Current: 380/252
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06Q 20/1235 with control of digital rights management [DRM]
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/40145 Biometric identity checks
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 1/0057 Compression invariant watermarking
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G07C 9/253 visually
• CPC Class Codes: G07D 7/0032 using holograms
• CPC Class Codes: G07D 7/004 using digital security elements, e.g. information coded on a magnetic thread or strip
• CPC Class Codes: G07F 17/16 for devices exhibiting advertisements, announcements, pictures or the like
• CPC Class Codes: G07F 17/26 for printing, stamping, franking, typing or teleprinting apparatus ticket printing or the like apparatus G07F17/42
• CPC Class Codes: G07F 7/08 by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• CPC Class Codes: G07F 7/086 by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G07F 7/1016 Devices or methods for securing the PIN and other transaction-data, e.g. by encryption arrangements for secret communication, see H04L9/00
• CPC Class Codes: G07F 7/12 Card verification
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G11B 20/00007 Time or data compression or expansion audio compression based on psychoacoustics G10L19/00; data processing for reproducing audio data at different playback speeds G10L21/04; video compression H04N19/00; data compression per se H03M7/30
• 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 20/00094 : involving measures which result in a restriction to authorised record carriers
• CPC Class Codes: G11B 20/00115 : wherein the record carrier stores a unique medium identifier
• CPC Class Codes: G11B 20/00166 : involving measures which result in a restriction to authorised contents recorded on or reproduced from a record carrier, e.g. music or software
• CPC Class Codes: G11B 20/00181 : using a content identifier, e.g. an international standard recording code [ISRC] or a digital object identifier [DOI]
• CPC Class Codes: G11B 20/0021 : involving encryption or decryption of contents recorded on or reproduced from a record carrier
• 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: G11B 20/00891 : embedded in audio data
• CPC Class Codes: G11B 20/10037 : A/D conversion, D/A conversion, sampling, slicing and digital quantisation or adjusting parameters thereof
• CPC Class Codes: G11B 20/10527 : Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2020/00014 : the compressed signal being an audio signal
• CPC Class Codes: G11B 2020/10546 : specifically adapted for audio data
• CPC Class Codes: G11B 2020/10555 : wherein the frequency, the amplitude, or other characteristics of the audio signal is taken into account
• CPC Class Codes: H04B 1/665 : using psychoacoustic properties of the ear, e.g. masking effect
• CPC Class Codes: H04N 1/00005 : relating to image data
• CPC Class Codes: H04N 1/00037 : Detecting, i.e. determining the occurrence of a predetermined state H04N1/00031 takes precedence
• CPC Class Codes: H04N 1/00079 : remotely
• CPC Class Codes: H04N 1/32144 : embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 1/32149 : Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/32203 : Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 : involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• CPC Class Codes: H04N 1/32251 : in multilevel data, e.g. greyscale or continuous tone data
• CPC Class Codes: H04N 1/32288 : Multiple embedding, e.g. cocktail embedding, or redundant embedding, e.g. repeating the additional information at a plurality of locations in the image
• CPC Class Codes: H04N 2005/91321 : the copy protection signal being a copy protection control signal, e.g. a record inhibit signal
• CPC Class Codes: H04N 2005/91335 : the copy protection signal being a watermark
• CPC Class Codes: H04N 2005/91342 : the copy protection signal being an authentication signal
• CPC Class Codes: H04N 2005/9135 : by superimposing the spectrally spread copy protection signal onto the video signal
• CPC Class Codes: H04N 2201/3205 : of identification information, e.g. name or ID code H04N2201/3209 takes precedence
• CPC Class Codes: H04N 2201/3207 : of an address
• CPC Class Codes: H04N 2201/3226 : of identification information or the like, e.g. ID code, index, title, part of an image, reduced-size image
• CPC Class Codes: H04N 2201/3233 : of authentication information, e.g. digital signature, watermark
• CPC Class Codes: H04N 2201/327 : which are undetectable to the naked eye, e.g. embedded codes
• CPC Class Codes: H04N 2201/3271 : Printing or stamping
• CPC Class Codes: H04N 2201/328 : Processing of the additional information
• CPC Class Codes: H04N 5/89 : using holographic recording H04N5/91 takes precedence
• CPC Class Codes: H04N 5/90 : on discs or drums
• CPC Class Codes: H04N 5/913 : for scrambling ; for copy protection
• CPC Class Codes: H04N 9/8042 : involving data reduction
• CPC Class Codes: H04N 9/8047 : using transform coding
• CPC Class Codes: H04N 9/8205 : involving the multiplexing of an additional signal and the colour video signal
• CPC Class Codes: Y10S 283/901 : Concealed data

Abstract

An identification code signal is hidden in a carrier signal (such as an electronic data signal or a physical medium) in a manner that permits the identification signal later to be discerned. The carrier signal can thereby be identified, or some machine responsive action can thereby be taken. The technique can be applied in video imagery embodiments to control associated video equipment, e.g. to serve as a copy control signal.

Claims

1. A method of processing input audio data to steganographically encode a multi-bit code therein, thereby producing output audio data, characterized by:

defining a global scaling parameter;

algorithmically determining, from the input audio data, a first parameter for each of a first plurality of portions of the audio data, said first parameter relating to the relative capability of said portion to conceal encoding thereof;

encoding at least a portion of the code through each of a second plurality of portions of the audio data to produce the output audio data, said second plurality being a subset of the first plurality, the code in each of said second plurality of portions being encoded in accordance with both the first parameter corresponding to said each portion, and said global scaling parameter;

wherein the relative strength of the code through different portions of the output audio changes both in accordance with characteristics of the input audio, and globally in accordance with a global scale factor.

2. The method of claim 1 which includes computing a second parameter for each of said first plurality of portions, and computing the first parameter from the second parameter by a non-linear function.

3. The method of claim 1 in which each first parameter is related to a corresponding second parameter by a square root relationship.

4. The method of claim 1 in which the defining includes displaying a graphical user interface, said interface including a feature permitting a user to assign a value to the global scaling parameter, wherein the relative strength of the code through different portions of the output audio changes in accordance with characteristics of the input audio, and globally in accordance with a global scale factor set by the user through the user interface.

5. The method of claim 1 which includes processing audio data in real time to steganographically encode the code therein.

6. The method of claim 1 in which the encoding includes processing in accordance with pseudo-random noise data.

7. The method of claim 1 in which the encoding includes encoding the input audio in a sampled time domain, without a transformation to a frequency domain.

8. The method of claim 1 in which the second plurality of portions includes all of the first plurality of portions.

9. The method of claim 1 in which the second plurality of portions does not include all of the first plurality of portions.

10. The method of claim 9 wherein there are certain portions of the output audio that have no part of the code encoded therein.

11. The method of claim 1 in which the encoding includes processing in accordance with a non-pseudo random first signal.

12. The method of claim 1 in which each of said portions comprises a single audio sample value.

13. The method of claim 1 in which each of said portions comprises a plurality of audio sample values.

14. A machine readable storage medium having output audio produced in accordance with the process of claim 1 stored therein.

15. A method of steganographically embedding multi-bit auxiliary data into an input audio signal that is thereafter compressed to yield a compressed signal, said embedding being both locally adapted based on audio contents and globally adjustable, and thereafter discerning the multi-bit auxiliary data from a non-identical counterpart to said audio signal obtained by decompressing the compressed signal, the method comprising encoding and decoding processes characterized in that:

(A) the encoding process includes;

(1) providing an input audio signal comprising a plurality of sample values;

(2) providing a control by which a user can set the relative value of a global scaling parameter, said parameter determining a relative strength at which the multi-bit auxiliary data will be embedded into the audio signal;

(3) for each of a plurality of portions of the audio data, algorithmically determining a first parameter corresponding thereto, said first parameter relating to the relative capability of said portion to conceal encoding thereof by the auxiliary data;

(4) for each of a plurality of samples in said audio, transforming the value thereof in accordance with;

(a) a first parameter corresponding thereto,

(b) the global scaling parameter, and

(c) at least some of said multi-bit auxiliary data, wherein first encoded audio data is produced having the auxiliary data embedded therein, said embedding being both globally scaled, and locally adapted based on audio contents; and

(6) compressing the first encoded audio data; and

(B) the decoding process includes;

(1) decompressing the compressed first encoded audio data to produce second encoded audio data, said second encoded audio data being non-identical to the first encoded audio data due to said compression/decompression process;

(2) discerning the multi-bit auxiliary data from the second encoded audio data without reference to the input audio signal.

16. The method of claim 15 in which the discerning includes processing a plurality of portions of said second encoded audio signal to determine the auxiliary multi-bit data encoded therein, wherein greater or lesser confidence in the auxiliary multi-bit data discerned from said second encoded audio signal can be obtained by processing more or less portions, respectively.

17. The method of claim 16 which includes performing said processing by a hardware decoding circuit.

18. The method of claim 17 which includes disabling recording capability of an apparatus based on said discerned auxiliary multi-bit data.

19. The method of claim 17 which includes incrementing a program specific billing meter based on said discerned auxiliary multi-bit data.

20. The method of claim 15 which includes:

after (A)(6), storing said compressed, first encoded audio data on an optically encoded storage disk; and

prior to (B)(1), reading said compressed, first encoded audio data from said optically encoded storage disk.

21. The method of claim 15 which includes converting the second encoded audio data to analog form, and thereafter discerning the multi-bit auxiliary data therefrom.

22. The method of claim 21 which includes digitizing the analog form of the second encoded audio data to produce a digitized signal, and discerning the multi-bit auxiliary data from said digitized signal.

23. The method of claim 15 in which all of said acts occur in the sampled time domain, rather than some occurring in a transformed, frequency domain.

24. The method of claim 15 in which said providing a control includes displaying a graphical user interface, said interface including a feature permitting the user to assign a value to the global scaling parameter, wherein the relative strength of the multi-bit auxiliary data through different portions of the second encoded audio data changes locally in accordance with characteristics of the audio data, and globally in accordance with the global scale factor set by the user through the user interface.

25. The method of claim 15 in which (A)(4) additionally includes processing the value of said plurality of samples in accordance with samples of a pseudo-random noise signal.

26. The method of claim 15 in which each of said portions comprises a single audio sample.

27. The method of claim 15 in which each of said portions comprises a plurality of audio samples.

28. The method of claim 15 in which the encoding process includes encoding a single bit of said multi-bit code in each portion of said audio data.

29. A method useful for restricting use of audio signals comprising:

providing an input audio signal;

providing a multi-bit data signal with which the input audio signal is to be steganographically encoded, said multi-bit data signal including a usage control signal;

establishing a global scaling parameter for use with said input audio signal, said global parameter determining a relative strength at which the multi-bit data signal will be steganographically encoded therein;

processing the input audio signal in accordance with said multi-bit data signal and said global scaling parameter, wherein an encoded audio signal is produced having the multi-bit data signal encoded therein, said encoding being manifested as slight changes to sample values in said audio signal when said signal is represented in the sampled time domain;

compressing the encoded audio signal with a lossy compression process;

storing the compressed encoded audio signal on a storage medium;

reading the compressed encoded audio signal from said storage medium using an audio device that includes an audio playback feature;

decompressing said read compressed encoded audio signal, yielding a corrupted audio signal, said corruption being due to lossiness of the compression/decompression process;

applying said corrupted audio signal to hardware decoder circuitry within said audio device;

said hardware decoder circuitry recovering said multi-bit data signal from the corrupted audio signal over the course of a portions thereof, said plurality of portions enhancing a signal-to-noise ratio of said encoded multi-bit data signal, allowing reliable recovery thereof despite steganographic encoding of said multi-bit data signal, and corruption of said audio signal by said compression/decompression lossiness; and

limiting use of said audio device in accordance with the usage control signal included in said multi-bit data signal.

30. The method of claim 29 which includes:

algorithmically determining a plurality of scaling parameters based on characteristics of said input audio signal, each scaling parameter corresponding to a portion of said input audio signal when represented in a particular domain, wherein said scaling parameters are adaptively related to audio contents; and

processing the input audio signal in accordance with (1) said multi-bit data signal, (2) said global scaling parameter, and (3) said plurality of scaling parameters, wherein an encoded audio signal is produced having the multi-bit data signal encoded therein.

31. The method of claim 29 in which, for each of a plurality of samples of said encoded audio signal when said signal is represented in a sampled time domain, the value of each sample is a function of both first and second bits of said multi-bit data signal, wherein there is a many bit-to-one sample mapping between bits of said multi-bit data signal and samples of said audio.

32. The method of claim 29 in which said processing includes performing a binary addition operation between a representation of said input audio signal, and an auxiliary signal embodying the multi-bit data signal.

33. A method useful for restricting use of audio signals comprising:

providing an input audio signal;

providing a multi-bit data signal with which the input audio signal is to be steganographically encoded, said multi-bit data signal including a usage control signal;

establishing a global scaling parameter for use with said input audio signal, said global scaling parameter determining a relative strength at which the multi-bit data signal will be steganographically encoded therein;

processing the input audio signal in accordance with said multi-bit data signal and said global scaling parameter, wherein an encoded audio signal is produced having the multi-bit data signal encoded therein, said encoding being manifested as slight changes to sample values in said audio signal when said signal is represented in the sampled time domain;

compressing the encoded audio signal with a lossy compression process;

storing the compressed encoded audio signal on a storage medium;

reading the compressed encoded audio signal from said storage medium using an audio device;

decompressing said read compressed encoded audio signal, yielding a corrupted audio signal, said corruption being due to lossiness of the compression/decompression process;

applying said corrupted audio signal to a processor within said audio device;

said processor recovering said multi-bit data signal from the corrupted audio signal notwithstanding corruption of said audio signal by said compression/decompression lossiness; and

limiting use of said audio device in accordance with the usage control signal included in said multi-bit data signal.

34. The method of claim 33 which includes:

algorithmically determining a plurality of scaling parameters based on characteristics of said input audio signal, each scaling parameter corresponding to a portion of said input audio signal when represented in a particular domain, wherein said scaling parameters are adaptively related to audio contents; and

processing the input audio signal in accordance with (1) said multi-bit data signal, (2) said global scaling parameter, and (3) said plurality of scaling parameters, wherein an encoded audio signal is produced having the multi-bit data signal encoded therein.

35. The method of claim 33 in which, for each of a plurality of samples in said encoded audio signal when said signal is represented in a sampled time domain, the value of each sample is a function of both first and second bits of said multi-bit data signal, wherein there is a many bit-to-one sample between bits of said multi-bit data signal and samples of said audio.

36. The method of claim 33 in which said processing includes performing a binary addition operation between a representation of said input audio signal, and an auxiliary signal embodying the multi-bit data signal.