Method for human-assisted random key generation and application for digital watermark system

• US 5,822,432 A
• Filed: 01/17/1996
• Issued: 10/13/1998
• Est. Priority Date: 01/17/1996
• Status: Expired due to Term

• Current Assignee: Wistaria Trading Inc.
• Original Assignee: The Dice Company
• Inventors: Moskowitz, Scott A., Cooperman, Marc
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/587,944
• Time in Patent Office: 1,000 Days
• Field of Search: 380/28, 380/54, 380/46, 382/232, 382/238, 395/615
• US Class Current: 380/28
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/0071 using multiple or alternating watermarks
• CPC Class Codes: G06T 1/0085 Time domain based watermarking, e.g. watermarks spread over several images
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain
• CPC Class Codes: G06T 2201/0083 whereby only watermarked image required at decoder, e.g. source-based, blind, oblivious
• 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: H04L 2209/608 Watermarking
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

A method for the human-assisted generation and application of pseudo-random keys for the purpose of encoding and decoding digital watermarks to and from a digitized data stream. A pseudo-random key and key application "envelope" are generated and stored using guideline parameters input by a human engineer interacting with a graphical representation of the digitized data stream. Key "envelope" information is permanently associated with the pseudo-random binary string comprising the key. Key and "envelope" information are then applied in a digital watermark system to the encoding and decoding of digital watermarks. The invention includes improvements to the methods of encoding and decoding digital watermarks. Improvements are: separation of the encoder from the decoder, increased information capacity relative to spread spectrum methods, destruction of content resulting from attempts to erase watermarks, detection of presence of watermarks without ability to access watermark information, multi-channel watermark capability, use of various classes of keys for watermark access control, support for alternative encoding, decoding, or other component algorithms, use of digital notary to authenticate and time stamp watermark certificates.

Claims

1. A method for using a computer system to generate a key for digital watermarking, the method comprising the steps of:

identifying a digital sample stream in which a digital watermark is to be encoded;

selecting a random or pseudo-random sequence for use in encoding the digital watermark within the digital sample stream;

receiving human interactive input information describing application of the random or pseudo-random sequence to the digital sample stream; and

generating a key associating the random or pseudo-random sequence with the human interactive input information.

2. The method of claim 1, wherein said step of identifying a digital sample stream comprises selecting a digital sample stream from a list provided by the computer system.

3. The method of claim 2, wherein the computer system includes a display device, said method further comprising the step of displaying a graphical representation of the digital sample stream on the display device, the graphical representation including at least one of:

a time axis and a signal frequency axis;

a time axis and a signal amplitude axis; and

a vertical axis and a horizontal axis.

4. The method of claim 3, wherein the human interactive input information includes at least one of:

one or more time delimiters;

one or more frequency delimiters;

a signal encoding level; and

one or more area delimiters.

5. The method of claim 4, further comprising the step of updating the graphical representation to reflect receipt of human interactive input information.

6. The method of claim 5, wherein the random or pseudo-random sequence comprises a binary sequence of 1s and 0s.

7. The method of claim 6, wherein the computer system further includes a database, the method further comprising the step of storing the generated key as a record in the database.

8. The method of claim 7, further comprising the step of encrypting the record containing the generated key using a passphrase.

9. The method of claim 6, wherein the computer system further includes a keyboard, said step of selecting a random or pseudo-random sequence comprising the substeps of:

(a) collecting a series of random bits derived from keyboard latency intervals in random typing;

(b) processing the series of random bits through a secure one-way hash function;

(c) using the results of the secure one-way hash function to seed a block encryption cipher loop;

(d) cycling through the block encryption cipher loop, extracting the least significant bit of each result of the secure one-way hash function after each cycle; and

(e) concatenating the extracted bits to form the random or pseudo-random sequence.

10. The method of claim 1, wherein the method is implemented using an encoder and a decoder comprising separate software applications or hardware devices.

11. The method of claim 10, wherein the digital watermark comprises a multi-channel watermark, said step of generating a key comprising generating a public watermark key providing the decoder with access to only a watermark channel corresponding to the public watermark key.

12. The method of claim 11, wherein the decoder can access only a limited number of watermark channels of the multi-channel watermark corresponding to public watermark keys made available to the decoder.

13. The method of claim 1, wherein the public watermark key enables the decoder to detect the presence of a valid watermark but not to access information in the watermark.

14. The method of claim 10, further comprising the step of placing a separate signal which does not interfere with the watermark into the digital sample stream, wherein the separate signal indicates at least one of:

watermark synchronization information for locating the digital watermark in the digital sample stream; and

presence of a valid watermark in the digital sample stream.

15. The method of claim 1, wherein the human interactive input information includes a list of time delimiters describing temporal segments of the digital sample stream.

16. The method of claim 1, wherein the human interactive input information includes a list of frequency delimiters describing frequency bands to be included in watermark computations.

17. The method of claim 1, wherein the human interactive input information includes a list of area delimiters.

18. The method of claim 1, wherein the human interactive input information includes a signal encoding level.

19. The method of claim 1, wherein the human interactive input information includes a sample window size for watermark computations.

20. The method of claim 1, wherein the human interactive input information includes encoding channel utilization information.

21. The method of claim 20, wherein the encoding channel utilization information includes mono, stereo or other sample channels to be watermarked.

22. The method of claim 1, wherein human interactive input information includes at least one of:

a list of time delimiters describing segments of the digital sample stream;

a list of frequency delimiters describing frequency bands to be included in watermark computations;

a signal encoding level;

a sample window size for watermark computations; and

encoding channel utilization information.

23. The method of claim 22, wherein the human interactive input information describes limits on where in the digital sample stream, at what encoding level, and in which frequency bands in the digital sample stream the random or pseudo-random sequence is to be applied for the purpose of encoding the digital watermark into the digital sample stream, the human interactive input information comprising at least one of:

a list of time delimiters;

a list of frequency delimiters;

a list of area delimiters; and

a signal encoding level.

24. The method of claim 23, wherein the digital sample stream corresponds to at least one of:

an audio recording;

a video recording; and

an image.

25. The method of claim 1, further comprising the step of encoding multiple copies of a digital watermark into a single digital sample stream.

26. The method of claim 25, further comprising the step of interleaving watermark information from each digital watermark in a time domain.

27. The method of claim 25, further comprising the step of selectively placing watermark information from each digital watermark into specific frequency bands of the digital sample stream or interleaving watermark information from each digital watermark in a frequency domain.

28. The method of claim 23, wherein time delimiters are preselected, prior to user modification or selection, based upon measured properties of a segment of the digital sample stream, the time delimiters being determined based upon mathematical calculations of at least one of the following signal properties:

autocorrelation;

root mean squared energy;

mean squared difference in samples;

distortion; and

spectral energy characteristics.

29. The method of claim 23, wherein frequency delimiters are preselected, prior to user modification or selection, based upon measured properties of a segment of the digital sample stream, the frequency delimiters being determined based upon mathematical calculations of at least one of the following signal properties:

autocorrelation;

root mean squared energy;

mean squared difference in samples;

distortion; and

spectral energy characteristics.

30. The method of claim 23, wherein signal encoding levels at specific temporal locations in a segment of the digital sample stream are preselected, prior to user modification or selection, based upon measured properties of signals contained in the segment, the signal encoding levels being determined based upon mathematical calculations of one or more of the following signal properties:

autocorrelation;

root mean squared energy;

mean squared difference in samples;

distortion; and

spectral energy characteristics.

33. The method of claim 1, further comprising the step of encoding multiple digital watermarks into a single digital sample stream, wherein each digital watermark is encoded with a separate key.

34. The method of claim 33, further comprising the step of interleaving watermark information from each digital watermark in a time domain.

35. The method of claim 33, further comprising the step of selectively placing watermark information from each digital watermark into specific frequency bands of the digital sample stream or interleaving watermark information from each digital watermark in a frequency domain.

36. The method of claim 1, further comprising the step of associating a list of component function references with the generated key, the list of component function references dictating component functions to be applied in encoding and decoding the digital watermark.

31. A method of using digital watermarks to convey information for a content metering service, the method comprising the steps of:

identifying a digital sample stream corresponding to content in which a digital watermark is to be encoded wherein the digital watermark contains at least one of a title identification, a unit measure, a unit price, a percentage transfer threshold at which liability is incurred to a purchaser, a percent of content transferred, an authorized purchaser identification, a seller account identification, a payment means identification, a digitally-signed information from a sender indicating a percent of content transferred, and digitally-signed information from a receiver indicating a percent of content received;

selecting a random or pseudo-random sequence for use in encoding the digital watermark within the digital sample stream;

receiving human interactive input information describing application of the random or pseudo-random sequence to the digital sample stream; and

generating a key associating the random or pseudo-random sequence with the human interactive input information.

32. A method of encoding digital watermarks which contain information pertaining to distribution restrictions and a location of an addressable directory containing related content, the method comprising the steps of:

identifying a digital sample stream in which the digital watermarks are to be encoded wherein the digital watermarks contain at least one of a geographical constraint on distribution, a logical constraint on distribution, a Universal Resource Locator, a telephone number, an Internet Protocol address, an Internet domain name, an E-mail address, and a file name;

selecting a random or pseudo-random sequence for use in encoding the digital watermarks within the digital sample stream;

receiving human interactive input information describing application of the random or pseudo-random sequence to the digital sample stream; and

generating a key associating the random or pseudo-random sequence with the human interactive input information.