Steganography using dynamic codes

• US 6,353,672 B1
• Filed: 03/08/2000
• Issued: 03/05/2002
• 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): Johns, Andrew W.
• Application Number:
  US09/520,926
• Time in Patent Office: 727 Days
• Field of Search: 382/100, 382/232, 704/200.1, 381/73.1, 380/201, 380/203, 380/210, 380/236, 380/252, 380/42, 380/43, 380/287, 380/54
• US Class Current: 382/100
• 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 input content signal—representing audio or video—is steganographically encoded to hide plural-bit auxiliary data therein. The encoding operation changes over time, e.g., by using different “key” data for successive portions of the content signal. In some embodiments, the key data used in one portion of the signal is a function of auxiliary data decoded from a preceding portion. Consequently, to successfully decode the auxiliary data, the decoder must have successfully decoded a previous portion. In essence, decoding instructions are sent “on the fly” in such embodiments. In some embodiments, the auxiliary data is changed in temporally adjoining portions of the content signal—e.g., in successive frames of video or blocks of audio. In other embodiments, the key is changed less frequently, e.g., on a daily basis. External events may also trigger changing of the key data.

Claims

1. A method of processing a digital signal comprised of plural successive portions, said portions representing human-perceptible audio or image information, comprising:

steganographically encoding first plural-bit auxiliary data in a first of said portions;

steganographically encoding second, different plural-bit auxiliary data in a second of said portions;

wherein at least one message bit in the first plural-bit data is encoded in a plurality of instances, and for each instance, the message bit is encoded in a groups of samples in the digital signal such that for each instance, the message bit is encoded differently according to a key.

2. The method of claim 1 in which said portions are frames of video.

3. The method of claim 1 in which said portions are blocks of audio.

4. The method of claim 1 that includes steganographically encoding the second auxiliary data in a portion immediately following said first portion.

5. The method of claim 1 in which the second of said portions is encoded, at least in part, with information dependent on the first of said portions.

6. The method of claim 1 in which the second plural-bit auxiliary data is a function, at least in part, of the first plural-bit auxiliary data.

7. The method of claim 1 in which the first auxiliary data is a function of first key data, and the second auxiliary data is a function of second key data different than the first.

8. The method of claim 7 in which the second key data is a function of the first auxiliary data.

9. The method of claim 8 in which the second key data is a function of the first key data.

10. A method of steganographically encoding auxiliary data within a signal comprised of plural successive portions, said portions representing human-perceptible audio or image information, characterized in that:

the encoding proceeds with reference to key data;

the key data used for a first portion is different than key data used for a second portion; and

the key data used in the second portion is dependent on auxiliary data conveyed in the first portion.

11. A method of steganographically decoding auxiliary data from a signal comprised of plural successive portions, said portions representing human-perceptible audio or image information, the steganographically decoding requiring use of reference data in order to discern the auxiliary data from the signal, characterized in that the reference data changes on the fly, depending on auxiliary data decoded from a preceding portion.

12. The method of claim 11 in which said portions comprise frames of video.

13. The method of claim 11 in which said portions comprise blocks of audio.

14. The method of claim 11 in which said portions are non time-contiguous.

15. The method of claim 14 wherein signal decoded today makes use of reference data from a signal provided yesterday.

16. The method of claim 11 in which the reference data changes in response to a predetermined triggering event.

17. The method of claim 16 in which said triggering event is a passage of a predetermined period of time.

18. The method of claim 11 wherein the reference data includes at least one steganographically encoded message symbol that is decoded from a first set of samples in the signal and the message symbol is used to interpret at least one steganographically encoded message symbol decoded from a second set of samples in the signal.

19. The method of claim 11 wherein the reference data includes at least one message symbol that is used to interpret at least one message symbol decoded from a second set of samples in the signal;

and

at least one steganographically decoded message symbol is used to make decisions about binary values in a steganographic message decoded from the signal.

20. The method of claim 19 wherein a set of steganographically decoded message symbols are used to make decisions about binary values in a steganographic message decoded from the signal.

21. In a method of steganographic decoding, an improvement comprising steganographically decoding data from a first portion of the encoded information that provides information necessary to steganographically decode a following portion of the encoded information.

22. In a method of steganographic encoding of content data with auxiliary data, an improvement comprising steganographically encoding data within a first portion of the content data that provides information necessary to steganographically decode a following portion of the content data.

23. The method of claim 22 in which the encoding proceeds with reference to data related to human perception attributes of the content data.

24. The method of claim 22 in which the auxiliary data includes copy control data.

25. The method of claim 24 that further includes:

decoding auxiliary data from a version of the encoded content data; and

controlling a record capability of an associated apparatus in accordance with at least a portion of the decoded auxiliary data.

26. The method of claim 25 that includes decoding at least a portion of the auxiliary data from the encoded content data by performing plural statistical analyses on the encoded content data;

the plural statistical analyses producing statistical characteristic measurements that are interpreted as message symbols based on a mapping between message symbols and the statistical characteristic measurements.

27. The method of claim 22 that further includes:

compressing the encoded content data;

decompressing the compressed content data;

the aforesaid compressing and decompressing being lossy, wherein the decompressed content data is not identical to the encoded content data; and

decoding the auxiliary data from the decompressed content data notwithstanding the losses associated with said lossy compressing/decompressing operations.

28. The method of claim 22 in which the encoding comprises performing binary addition operations between elements of the content data and corresponding elements of an overlay signal.

29. The method of claim 22 in which the encoding occurs with a representation of the content data in a temporal or spatial domain, for audio and video, respectively, rather than in a transformed, frequency domain.

30. The method of claim 22 in which at least some of said auxiliary data serves as an index or pointer to remote data stored at a remote location, said remote data relating to said content.

31. The method of claim 22 in which said encoding includes increasing the values of at least some content data samples, and decreasing the values of other content data samples.

32. The method of claim 22 which includes encoding a calibration signal in the encoded content data together with said auxiliary data, said calibration signal having known properties facilitating identification thereof by a recipient of the encoded content data, said encoded calibration signal being substantially imperceptible to a human listener of the encoded audio or viewer of the encoded video.

33. The method of claim 32 in which the calibration signal has a known spectral attribute.

34. A computer program stored on a tangible physical medium, including instructions for causing a computer programmed thereby to perform the method of claim 22.

35. The method of claim 22 wherein the data encoded in the first portion includes a message used to control decoding of a message in the following portion.

36. The method of claim 22 wherein the data encoded in the first portion includes a message used to produce data for interpreting signal characteristics as encoded binary message symbols.