Steganographic method and device

• US 7,568,100 B1
• Filed: 07/23/1997
• Issued: 07/28/2009
• Est. Priority Date: 06/07/1995
• Status: Expired due to Fees

• Current Assignee: Wistaria Trading Inc.
• Original Assignee: Wistaria Trading Inc.
• Inventors: Moskowitz, Scott A., Cooperman, Marc
• Primary Examiner(s): Smithers, Matthew
• Assistant Examiner(s): CALLAHAN, PAUL E
• Application Number:
  US08/999,766
• Time in Patent Office: 4,388 Days
• Field of Search: 380/53, 380/54, 380/205, 380/207, 380/208, 380/46, 713/176, 705/57, 726/32
• US Class Current: 713/176
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: G06T 2201/0064 for copy protection or copy management, e.g. CGMS, copy only once, one-time copy
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G11B 20/00891 embedded in audio data
• CPC Class Codes: H04L 2209/04 Masking or blinding
• CPC Class Codes: H04L 2209/08 Randomization, e.g. dummy operations or using noise
• CPC Class Codes: H04L 2209/605 Copy protection
• CPC Class Codes: H04L 2209/608 Watermarking
• CPC Class Codes: H04L 9/0643 Hash functions, e.g. MD5, SHA, HMAC or f9 MAC
• CPC Class Codes: H04L 9/0656 Pseudorandom key sequence combined element-for-element with data sequence, e.g. one-time-pad [OTP] or Vernam's cipher
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3263 involving certificates, e.g. public key certificate [PKC] or attribute certificate [AC]; Public key infrastructure [PKI] arrangements network architectures or network communication protocols for supporting authentication of entities using certificates in a packet data network H04L63/0823
• CPC Class Codes: H04N 1/32149 Methods relating to embedding, encoding, decoding, detection or retrieval operations
• CPC Class Codes: H04N 1/3216 using Fourier transforms
• 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 1/32245 Random or pseudorandom selection of pixels
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• 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 21/2541 Rights Management protecting software against unauthorised usage in a vending or licensing environment G06F21/10; security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08
• CPC Class Codes: H04N 21/4348 : Demultiplexing of additional data and video streams
• CPC Class Codes: H04N 21/835 : Generation of protective data, e.g. certificates protecting software against unauthorised usage in a vending or licensing environment G06F21/10
• CPC Class Codes: H04N 21/8352 : involving content or source identification data, e.g. Unique Material Identifier [UMID]
• 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 2201/3205 : of identification information, e.g. name or ID code H04N2201/3209 takes precedence
• 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 2201/3281 : Encryption; Ciphering
• CPC Class Codes: H04N 7/1675 : Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58

Abstract

An apparatus and method for encoding and decoding additional information into a stream of digitized samples in an integral manner. The information is encoded using special keys. The information is contained in the samples, not prepended or appended to the sample stream. The method makes it extremely difficult to find the information in the samples if the proper keys are not possessed by the decoder. The method does not cause a significant degradation to the sample stream. The method is used to establish ownership of copyrighted digital multimedia content and provide a disincentive to piracy of such material.

Claims

1. A method for steganographically protecting a digital signal comprising the step of:

a) providing a carrier signal that has been encoded with independent information;

b) using a stega-cipher to steganographically decode independent information including a digital watermark from the carrier signal;

c) generating a first derivative encoded signal representing the original carrier signal combined with the encoded independent information, including the digital watermark, wherein the first derivative encoded signal is an arbitrarily close approximation of the original carrier signal; and

d) modifying the first derivative encoded signal to produce a second derivative encoded signal, wherein the second derivative encoded signal differs from the original carrier signal by a greater degree than the first derivative encoded signal differs from the original carrier signal, as measured by an arbitrary signal metric.

2. A method for steganographically protecting a digital signal comprising the step of:

a) providing a carrier signal;

b) using a stega-cipher to steganographically encode independent information including a digital watermark into the carrier signal;

c) selecting a mask set, said mask set including one or more random or pseudo-random series of bits, referred to as masks;

d) selecting a random or pseudo-random start of message delimiter; and

e) selecting independent information to be encoded.

3. The method according to claim 2, wherein the carrier signal includes a stream of digital samples.

4. The method according to claim 2, wherein the carrier signal includes a continuous analog waveform.

5. The method according to claim 2, wherein the digital watermark, includes at least one selected from the group consisting of:

rights ownership identification, authorship identification of the encoded carrier signal, ownership identification of a unique copy of the encoded carrier signal, and a serialization code uniquely identifying a copy of the encoded carrier signal.

6. The method according to claim 2, further comprising the step of:

using a map table to define where watermark information is to be encoded into the carrier signal based on the random or pseudo-random masks, wherein the map table is defined such that any index of the map table enables encoding of information.

7. The method according to claim 2, further comprising the step of:

f) generating a message bit stream to be encoded such that the stream includes;

1) the random or pseudo-random start of message delimiter;

2) a number of message bytes to follow the message; and

3) the independent information.

8. The method according to claim 7, wherein the independent information contains, at least one selected from the group consisting of:

a hash value computed on the start of message delimiter, and a digital signature of the start of message delimiter.

9. The method according to claim 7, further comprising the step of:

g) separating an input sample stream into smaller discrete sample windows comprising segments of the input sample stream.

10. The method according to claim 9, further comprising of the step of:

h) using positions within the sample windows and a position within the input stream to index random or pseudo-random masks and compute a mapping function to determine encoding positions and encode digital watermark information into the sample windows.

11. The method according to claim 10, further comprising the step of:

i) computing a spectral transform of the sample windows prior to digital watermark data encoding.

12. The method according to claim 11, further comprising the step of:

j) computing an inverse spectral transform of the encoded spectral transform data after digital watermark data encoding.

13. The method according to claim 2, further comprising the step of:

adding unique data to each individual watermark, rendering it distinct from any other watermark in the same sample stream.

14. The method according to claim 13, further comprising the step of:

pre-processing sample windows in the sample stream to be watermarked.

15. The method according to claim 14, further comprising the step of:

determining which sample windows will contain the individual digital watermark to be encoded.

16. The method according to claim 15, further comprising the step of:

calculating a size of the independent information comprising the digital watermark plus a size of an added hash value to determine a number of sample windows required to contain a complete watermark.

17. The method according to claim 16, further comprising the step of:

computing a secure one way hash function of the carrier signal data in said sample windows, wherein said hash function is insensitive to changes introduced into the carrier signal for the purpose of carrying digital watermark information.

18. The method according to claim 17, further comprising the step of:

concatenating the hash value with the independent information, creating an expanded, unique digital watermark.

19. The method according to claim 2, wherein the step of steganographically encoding independent information into the carrier signal causes an imperceptible change in the carrier signal.

20. A method for steganographically protecting a digital signal comprising the steps of:

a) providing a carrier signal that has been encoded with independent information;

b) using a stega-cipher to steganographically decode independent information including a digital watermark from the carrier signal;

c) selecting a mask set, said mask set including one or more random or pseudo-random series of bits, referred to as masks;

d) selecting a random or pseudo-random start of message delimiter; and

e) selecting an input sample stream to be decoded.

21. The method according to claim 20, wherein the carrier signal includes a stream of digital samples.

22. The method according to claim 20, wherein the carrier signal includes a continuous analog waveform.

23. The method according to claim 20, wherein the digital watermark includes at least one selected from the group consisting of:

rights ownership identification, authorship identification of the encoded carrier signal, ownership identification of a unique copy of the encoded carrier signal, and a serialization code uniquely identifying a copy of the encoded carrier signal.

24. The method according to claim 20, further comprising the step of:

decoding a single message bit from a single sample by reading a single bit of the single sample as the message bit.

25. The method according to claim 20, further comprising the step of:

decoding a single message bit from a single sample by mapping the single sample in the range of sample values which indicate a particular message bit value.

26. The method according to claim 20, further comprising the step of:

decoding a single message bit from a single spectral value by mapping the single spectral value into a range of sample values which indicate a particular message bit value.

27. The method according to claim 20, further comprising the step of:

f) separating the input sample stream into smaller discrete sample windows comprising segments of the input sample stream.

28. The method according to claim 27, further comprising the step of:

g) using positions within one of the sample windows and a position within the input stream to index random or pseudo-random masks and compute a mapping function to determine decoding positions and to decode digital watermark information from the sample window.

29. The method according to claim 28, further comprising the step of:

h) computing a spectral transform of the sample window prior to digital watermark data decoding.

30. The method according to claim 28, further comprising the step of:

h) validating at least one selected from the group consisting of;

(1) a hash value computed on the start of message delimiter, and

(2) a digital signature of the start of message delimiter,

wherein the step h) of validating occurs after the start of message delimiter and the encoded information of said hash value or said digital signature have been decoded and the validation consists of computing an appropriate result using the start of message delimiter, comparing it to a value in the decoded data, and verifying any signature.

31. The method according to claim 20, further comprising the step of:

obtaining a unique hash value contained in the independent information comprising part of the digital watermark.

32. The method according to claim 31, further comprising the additional step of:

re-processing sample windows in the sample stream which contained the decoded watermark.

33. The method according to claim 32, further comprising the step of:

computing a secure one way hash function of the carrier signal data in said sample windows, wherein said hash function is insensitive to changes introduced into the carrier signal for the purpose of carrying digital watermark information.

34. The method according to claim 33, further comprising the step of:

comparing the computed hash value to the value contained in the watermark.

35. The method according to claim 20, wherein the step of steganographically decoding independent information into the carrier signal causes an imperceptible change in the carrier signal.