Multimedia Digital Fingerprinting Codes

In that thesis we consider the problem of data protection. The subject matter of that thesis is the different techniques of digital fingerprinting. In the first part, we give an explicit formulation of discrete version of the problem and provide an overview of known construction such as IPP codes, Collusion secure digital fingerprinting codes and the recent concept – almost IPP codes. We continue to investigate the latter concept. In particular, we prove that for the binary case almost t-IPP codes don't exist. Also, we introduce a new concept in theory of almost IPP codes that relaxes the tracing procedure, namely, the net of suspicious user. We investigate the upper and lower bounds on the size of such nets and explain how known constructions can be used to avoid ambiguous situations behind law-court and to achieve the desired level security. The second part of the thesis is devoted to the multimedia (continuous) version of digital fingerprinting. In that thesis we show how this problem can be reduced to the problem of special noiseless multiple-access channels and improve the known results. In particular, we show that there exist a class of codes of exponential size in length that allow to trace all the users from guilty coalition. Also, we describe an algorithm of tracing which works in polynomial time in length of the code.