Methods and systems for fingerprinting digital data

• US 20040071314A1
• Filed: 09/29/2003
• Published: 04/15/2004
• Est. Priority Date: 10/28/1999
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Yacov Yacobi
• Inventors: Yacobi, Yacov
• Granted Patent: US 7,177,442 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G06T 2201/0063 in relation to collusion attacks, e.g. collusion attack resistant
• CPC Class Codes: H04N 1/32101 Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
• CPC Class Codes: H04N 2201/3235 Checking or certification of the authentication information, e.g. by comparison with data stored independently
• CPC Class Codes: H04N 2201/3236 Details of authentication information generation

Abstract

Methods and systems for fingerprinting digital data are described. In the described embodiment, Direct Sequence Spread Spectrum (DSSS) technology is utilized. Unique fingerprinting words are defined where each includes at least one spread sequence. In one embodiment, a fingerprinting word comprises a plurality symbols, called “Γ symbols.” Each Γ symbol is composed of 2c-1 blocks, where c represents the number of colluders that are desired to be protected against. Each block contains d spread sequence chips. The fingerprinting words are assigned to a plurality of entities to which protected objects embedded with the fingerprinting words are to be distributed. To ascertain the identity of an entity that has altered its unique fingerprinting word, the relative weight of each block is computed in accordance with a defined function and blocks whose weights satisfy a predetermined relationship are “clipped” to a so-called working range. Each Γ-symbol of the altered fingerprinting word is then processed to produce a set of one or more colors that might be the subject of a collusion. Each Γ-symbol in the fingerprinting word for each entity is then evaluated against a corresponding produced set and the entity having the most overall Γ-symbol coincidences is incriminated.

Claims

1. One or more protected digital objects embodied on one or more computer-readable media, individual digital objects being embedded with at least one fingerprinting word produced in accordance with a method comprising:

defining a plurality of fingerprinting words, each fingerprinting word being unique and containing at least one spread sequence; and

assigning individual fingerprinting words to individual respective entities, the fingerprinting words serving to identify an entity to which it is assigned;

said fingerprinting words being structured to permit a collusion analysis to ascertain identities of potential colluders who change an associated fingerprinting word.

2. The one or more protected digital objects of claim 1, wherein each fingerprinting word contains a plurality of spread sequences.

3. The one or more protected digital objects of claim 1, wherein the defining of the plurality of the fingerprinting words comprises selecting a length for the fingerprinting words, the length being a function of a number of colluders that are desired to be defended against and an error rate ε

.

4. The one or more protected digital objects of claim 1, wherein each fingerprinting word contains a plurality of Γ

-symbols, each Γ

-symbol containing 2c-1 spread sequences, where c is the number of colluders that are desired to be defended against.

5. The one or more protected digital objects of claim 1, wherein at least one digital object comprises a document.

6. The one or more protected digital objects of claim 1, wherein at least one digital object comprises a video object.

7. The one or more protected digital objects of claim 1, wherein at least one digital object comprises a music object.

8. One or more protected digital objects embodied on one or more computer-readable media and produced in accordance with a method comprising:

defining a plurality of fingerprinting words, each fingerprinting word being unique and containing at least one spread sequence, wherein each fingerprinting word contains a plurality of Γ

-symbols, each Γ

-symbol containing 2c-1 spread sequences, where c is the number of colluders that are desired to be defended against, said fingerprinting words being structured to permit a collusion analysis to ascertain identities of potential colluders who change an associated fingerprinting word;

assigning individual fingerprinting words to individual respective entities who constitute potential colluders, the fingerprinting words serving to identify an entity to which it is assigned; and

embedding at least one fingerprinting word in at least one digital object.

9. The one or more protected digital objects of claim 8, wherein at least one digital object comprises a document.

10. The one or more protected digital objects of claim 8, wherein at least one digital object comprises a music object.

11. The one or more protected digital objects of claim 8, wherein at least one digital object comprises a video object.

12. A Γ

-code data structure configured for use in an embedding process for protecting digital data, the Γ

-code data structure comprising;

a memory;

a plurality of spread sequences in the memory, the spread sequences being arranged in blocks that are combinable to define fingerprinting words that are assignable to individual entities to which protected objects are to be distributed; and

said fingerprinting words being structured to permit a collusion analysis to ascertain identities of potential colluders who change an associated fingerprinting word.

13. The Γ

-code data structure of claim 12, wherein the blocks are combinable to define individual Γ

-symbols, each Γ

-symbol comprising 2c-1 blocks, where c is the number of colluders that are desired to be defended against.

14. One or more protected objects comprising:

digital data embodied on one or more computer-readable media; and

a fingerprinting word embedded in the digital data, the fingerprinting word containing at least one spread sequence, the fingerprinting word being associated with an entity to which the object is to be, or has been distributed;

said fingerprinting word being structured to permit a collusion analysis to ascertain one or more identities of potential colluders who change the fingerprinting word.

15. The one or more protected objects of claim 14, wherein the fingerprinting word contains a plurality of Γ

-symbols, each Γ

-symbol containing at least one spread sequence.

16. The one or more protected objects of claim 15, wherein each Γ

-symbol contains a plurality of spread sequences.

17. The one or more protected objects of claim 16, wherein each fingerprinting word contains the same number of Γ

-symbols.

18. The one or more protected objects of claim 16, wherein each Γ

-symbol contains 2c-1 spread sequences, where c is the number of colluders that are desired to be defended against.

19. The one or more protected objects of claim 14, wherein at least one object comprises a document.

20. The one or more protected objects of claim 14, wherein at least one object comprises a music object.

21. The one or more protected objects of claim 14, wherein at least one object comprises a video object.

22. One or more computing devices embodying the one or more protected objects of claim 14.