Method for fingerprinting multimedia content

• US 20070180537A1
• Filed: 01/06/2006
• Published: 08/02/2007
• Est. Priority Date: 01/07/2005
• Status: Active Grant

• Current Assignee: University of Maryland
• Original Assignee: University of Maryland
• Inventors: Wu, Min, He, Shan
• Granted Patent: US 7,814,564 B2
• Time in Patent Office: Days
• US Class Current: 726/32
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G06F 21/16 Program or content traceability, e.g. by watermarking
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 2201/0063 in relation to collusion attacks, e.g. collusion attack resistant
• CPC Class Codes: G06T 2201/0065 Extraction of an embedded watermark; Reliable detection

Abstract

To identify participants in collusion directed to altering a digital fingerprint embedded in multimedia content, an ECC based fingerprinting technique establishes a code symbol for each of a plurality of segments of digital data forming the multimedia content. The code symbols are concatenated to form a fingerprint signal, which is subdivided into a plurality of subsegments for each segment in the digital data. The subsegments are permuted and embedded into the digital data. When a suspicious copy of the multimedia content is discovered, the permuted fingerprint signal is extracted from the content and inversely permuted to form a test fingerprint. The identity of one of the colluders is determined by correlation with characteristics of the codeword originally assigned to the user. The determination of identity may be enhanced by the addition of group data embedded as an additional fingerprint in the digital data. Joint consideration of coding and embedding provide benefits over previous fingerprinting techniques.

Claims

1. A method for identifying a participant in production of an unauthorized version of multimedia content through a digital fingerprint embedded in digital data thereof, the method comprising:

assigning to each of a plurality of authorized users of the digital data a corresponding codeword, said codeword including a plurality of symbols selected from a predetermined alphabet of symbols;

dividing the digital data into a plurality of host data segments equal in number to said plurality of symbols;

encoding a fingerprint signal as a concatenation of digital code sequences corresponding to each of said plurality of symbols, said fingerprint signal including a plurality of fingerprint segments equal in number to said plurality of host data segments, each of said fingerprint segments containing a corresponding one of said code sequences;

segmenting each of said fingerprint segments into a plurality of subsegments;

permuting said subsegments of said fingerprint signal;

embedding said permuted fingerprint signal into the digital data;

extracting a test fingerprint signal from a copy of the digital data;

segmenting said test fingerprint signal into said plurality of subsegments;

permuting said subsegments of said test fingerprint signal inversely with respect to said permutation of said subsegments of said fingerprint signal; and

identifying the participant as one of said authorized users assigned a codeword determined from said inversely permuted test fingerprint signal.

2. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 1, where said participant identifying step includes the steps of:

correlating said inversely permuted test fingerprint signal with each of a plurality of said fingerprint signals, each of said fingerprint signals encoded from said codeword assigned to a corresponding one of said plurality of authorized users; and

identifying said participant as said authorized user assigned to said codeword corresponding to one of said fingerprint signals being correlated to said inversely permuted fingerprint signal by greater than a predetermined threshold.

3. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 1, where said participant identifying step includes the steps of:

correlating each of said fingerprint segments of said inversely permuted test fingerprint signal with a code sequence corresponding to each symbol of said alphabet of symbols;

identifying a symbol in said each fingerprint segment of said inversely permuted test fingerprint signal as that corresponding to said code sequence being correlated to said fingerprint segment by greater than a predetermined threshold;

concatenating each symbol identified in said symbol identifying step to form a codeword; and

identifying said participant as said authorized user assigned to said codeword formed in said symbol concatenating step.

4. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 1, where said codeword assigning step includes the step of:

selecting said codeword assigned to said authorized user from one of a plurality of groups of said codewords, each codeword in a corresponding one of said groups, when encoded into said concatenation of digital code sequences, being orthogonal to said concatenation of digital code sequences corresponding to remaining ones of said codewords in said corresponding one of said groups.

5. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 4 further including the steps of:

establishing a group codeword for each of said groups;

encoding a group fingerprint signal as a concatenation of digital code sequences corresponding to each of a plurality of symbols in a corresponding one of said group codewords;

embedding said group fingerprint signal into said digital data;

extracting a test group fingerprint signal from said copy of the digital data;

identifying a group corresponding to said participant as one of said plurality of groups determined from said test group fingerprint signal.

6. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 5, where said group identifying step includes the step of:

correlating said test group fingerprint signal with each of a plurality of said group fingerprint signals, each of said group fingerprint signals encoded from each of said group codewords; and

identifying said group as that corresponding to one of said group fingerprint signals being correlated to said test group fingerprint signal by greater than a predetermined threshold.

7. A method for identifying a participant in production of an unauthorized version of multimedia content through a digital fingerprint embedded in digital data thereof, the method comprising:

forming a plurality of user codewords, each of said user codewords corresponding to a concatenation of a plurality of coding sequences;

grouping said user codewords into a plurality of groups such that said concatenation of coding sequences corresponding to each of said user codewords in a corresponding one of said groups is orthogonal to said concatenation of coding sequences corresponding to remaining ones of said user codewords in said one of said groups;

assigning each of said user codewords in a corresponding one of said groups to a corresponding authorized user of the digital data such that at least one characteristic of said user is common to other users assigned a user codeword from said corresponding one of said groups;

dividing the digital data into a plurality of host data segments equal in number to said plurality of coding sequences;

encoding a fingerprint signal as said concatenation of code sequences corresponding to each of said user codewords, said fingerprint signal including a plurality of fingerprint segments equal in number to said plurality of host data segments, each of said fingerprint segments containing a corresponding one of said code sequences;

segmenting each of said fingerprint segments into a plurality of subsegments;

permuting said subsegments of said fingerprint signal;

embedding said permuted fingerprint signal into the digital data;

extracting a test fingerprint signal from a copy of the digital data;

segmenting said test fingerprint signal into said plurality of subsegments;

permuting said subsegments of said test fingerprint signal inversely with respect to said permutation of said subsegments of said fingerprint signal; and

identifying the participant as one of said authorized users assigned a user codeword determined from said inversely permuted test fingerprint signal.

8. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 7 further including the steps of:

forming a group codeword for each of said plurality of groups, said group codeword including a plurality of symbols;

encoding a group fingerprint signal as a concatenation of digital code sequences corresponding to each of said plurality of symbols in a corresponding one of said group codewords;

embedding said group fingerprint signal into said digital data;

extracting a test group fingerprint signal from said copy of the digital data;

identifying a group corresponding to said participant as one of said plurality of groups determined from said test group fingerprint signal.

9. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 8, where said group identifying step includes the step of:

correlating said test group fingerprint signal with each of a plurality of said group fingerprint signals respectively encoded from each of said group codewords; and

identifying said group as that corresponding to one of said group fingerprint signals being correlated to said test group fingerprint signal by greater than a predetermined threshold.

10. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 9, where said participant identifying step includes the steps of:

correlating each of said fingerprint segments of said inversely permuted test fingerprint signal with a code sequence corresponding to each symbol of said alphabet of symbols;

identifying a symbol in said each fingerprint segment of said inversely permuted test fingerprint signal corresponding to said code sequence that is correlated to said fingerprint segment by greater than a predetermined threshold;

concatenating each symbol identified in said symbol identifying step to form a codeword; and

identifying said participant as said authorized user assigned to a user codeword corresponding to said codeword formed in said symbol concatenating step.

11. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 10, where said participant identifying step includes the step of searching for said codeword formed in said symbol concatenating step in only said group of user codewords identified in said group identifying step.

12. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 8, where said group codeword forming step includes the step of setting each of said symbols forming said group codeword to be identical to one another.

13. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 8, where said group codeword forming step includes the step of forming said group codeword to be, when encoded as a concatenation of digital code sequences, orthogonal to said concatenation of digital code sequences corresponding to remaining ones of said group codewords.

14. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 13, where said group codeword forming step includes the step of forming said group codeword to be, when encoded as said concatenation of said digital code sequences, orthogonal to said concatenation of code sequences corresponding to each of said codewords in said group.

15. A method for identifying a participant in production of an unauthorized version of multimedia content through a digital fingerprint embedded in digital data thereof, the method comprising:

assigning to each of a plurality of authorized users of the digital data a corresponding codeword, said codeword including a plurality of symbols selected from a predetermined alphabet of symbols;

encoding each symbol in said alphabet of symbols as a corresponding digital code sequence;

segmenting each digital code sequence for each of said symbols of said alphabet into a plurality of subsequences;

segmenting the digital data into a plurality of host data segments equal in number to said plurality of symbols forming said codeword, each of said host data segments designated with a corresponding symbol of said codeword;

segmenting each of said host data segments into a plurality of subsegments, each of said subsegments designated with a portion of said symbol designated to said corresponding host data segment;

forming a sub-segmented codeword from said symbol portions designated to each of said plurality of subsegments, said sub-segmented codeword being ordered identically to an order of said symbol portions of said designated subsegments;

permuting said sub-segmented codeword;

embedding a corresponding one of said subsequences respectively into a corresponding copy of each of said plurality of subsegments to produce a plurality of embedded subsegments equal in number to a number of symbols in said alphabet multiplied by a number of subsegments in said plurality of subsegments;

concatenating said embedded subsegments in accordance with said permuted sub-segmented codeword to form a data signal;

extracting a test fingerprint signal from said data signal, said test fingerprint signal including a plurality of subsegments equal in number to a number of subsegments in said sub-segmented codeword;

permuting said subsegments of said test fingerprint signal inversely with respect to said permutation of said subsegments of said sub-segmented codeword; and

identifying the participant as one of said authorized users assigned a codeword determined from said inversely permuted test fingerprint signal.

16. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 15, where said collusion participant identifying step includes the steps of:

correlating said inversely permuted test fingerprint signal with each of a plurality of said fingerprint signals, each of said fingerprint signals encoded from said codeword assigned to a corresponding one of said plurality of authorized users; and

identifying said participant as said authorized user assigned to said codeword corresponding to one of said fingerprint signals being correlated to said inversely permuted fingerprint signal by greater than a predetermined threshold.

17. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 15, where said collusion participant identifying step includes the steps of:

forming in said inversely permuted test fingerprint signal a plurality of fingerprint segments equal in number to said plurality of host data segments;

correlating each of said fingerprint segments of said inversely permuted test fingerprint signal with a code sequence corresponding to each symbol of said alphabet of symbols;

identifying a symbol in said each fingerprint segment of said inversely permuted test fingerprint signal as that corresponding to said code sequence being correlated to said fingerprint segment by greater than a predetermined threshold;

concatenating each symbol identified in said symbol identifying step to form a codeword; and

identifying said participant as said authorized user assigned to said codeword formed in said symbol concatenating step.

18. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 15, further including the step of multicasting said plurality of subsegments prior to said subsegment concatenation step.

19. The method for identifying a participant in production of an unauthorized version of multimedia content as recited in claim 18, further including the step of providing to a distribution channel said data signal subsequent to said subsegments multicasting step and prior to said test fingerprint signal extracting step.