Paper 2007/041

Symmetric Tardos fingerprinting codes for arbitrary alphabet sizes

B. Skoric, S. Katzenbeisser, and M. U. Celik


Fingerprinting provides a means of tracing unauthorized redistribution of digital data by individually marking each authorized copy with a personalized serial number. In order to prevent a group of users from collectively escaping identification, collusion-secure fingerprinting codes have been proposed. In this paper, we introduce a new construction of a collusion-secure fingerprinting code which is similar to a recent construction by Tardos but achieves shorter code lengths and allows for codes over arbitrary alphabets. For binary alphabets, $n$ users and a false accusation probability of $\eta$, a code length of $m\approx \pi^2 c_0^2\ln(n/\eta)$ is provably sufficient to withstand collusion attacks of at most $c_0$ colluders. This improves Tardos' construction by a factor of $10$. Furthermore, invoking the Central Limit Theorem we show that even a code length of $m\approx \half\pi^2 c_0^2\ln(n/\eta)$ is sufficient in most cases. For $q$-ary alphabets, assuming the restricted digit model, the code size can be further reduced. Numerical results show that a reduction of 35\% is achievable for $q=3$ and 80\% for~$q=10$.

Available format(s)
Publication info
Published elsewhere. Modified version has been submitted to Designs, Codes and Cryptography
collusion-resistant watermarking
Contact author(s)
boris skoric @ philips com
2007-02-14: received
Short URL
Creative Commons Attribution


      author = {B.  Skoric and S.  Katzenbeisser and M. U.  Celik},
      title = {Symmetric Tardos fingerprinting codes for arbitrary alphabet sizes},
      howpublished = {Cryptology ePrint Archive, Paper 2007/041},
      year = {2007},
      note = {\url{}},
      url = {}
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