Method for constructing inner codes for anti-collusion forensic code for watermarking digital content

摘要

A method and apparatus are described including generating a unique code for each of a plurality of users using a plurality of symbols, generating a plurality of codes representing the plurality of symbols, substituting the plurality of codes into the unique code for each of the plurality of users, permuting the code resulting from the substitution to produce a codeword for each of the plurality of users and embedding the codeword into digital content. The second generating act further includes generating a string of first symbols followed by second symbols, wherein the first symbols are all ones and the second symbols are all negative ones, wherein a number of first symbols is equal to a number of the second symbols, and wherein if a length of the first symbols followed by the second symbols is less than a length of the code, then the first symbols followed by the second symbols are repeated until the code length is filled.

主权项

1. A method, said method comprising:
generating a unique code for each of a plurality of users using a plurality of symbols; generating a plurality of inner codes representing said plurality of symbols, wherein said second generating act further comprises generating a string of first symbols followed by second symbols, and further wherein said first symbols are all ones and said second symbols are all negative ones, wherein there is an equal quantity of said first symbols and said second symbols in each generated inner code, and further wherein if a length of said first symbols followed by said second symbols is less than a predetermined length of each of said plurality of inner codes, then said first symbols followed by said second symbols are repeated until said code length is filled, wherein said plurality of inner codes representing said plurality of symbols is an exponential orthogonal code; substituting said plurality of inner codes into said unique code for each of said plurality of users; permuting said code resulting from said substitution to produce a codeword for each of said plurality of users; and embedding said codeword into digital content.