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Performance and code length optimization of joint decoding tardos fingerprinting

: Berchtold, Waldemar; Schäfer, Marcel


Association for Computing Machinery -ACM-, Special Interest Group on Multimedia -SIGMM-:
MM&Sec 2012, 14th ACM Workshop on Multimedia and Security. Proceedings : September 6-7, 2012, Coventry, UK
New York: ACM, 2012
ISBN: 978-1-4503-1417-6
Workshop on Multimedia and Security (MM&Sec) <14, 2012, Coventry>
Conference Paper
Fraunhofer SIT ()
collusion attack; collusion secure fingerprinting; joint decoder; watermarking

To trace back copyright infringements, digital transaction watermarking today is a widely accepted method. Here, copies of a single work are individualized by embedding userspecific watermark messages. However, transaction watermarking is vulnerable to collusion attacks, where multiple individualized copies of one work are compared and/or combined to attack the integrity or availability of the embedded watermark message. To resist such attacks one may apply so called fingerprinting codes. These are mathematical codes that achieve collusion resistance by i.e. enforcing a higher payload. But due to the payload limitations of many multimedia files, e.g. short audio files or images, reducing the code length of fingerprinting codes is of immense importance. The reduction of only few bits may ma ke the difference whether a fingerprint message can be embedded to ensure collusion security or not. In this work we propose a combined tracing algorithm of Skoric et al [13] and Meerwald and Furon [9] based on the fingerprint generation process of [4]. To combine these algorithms, [13] and [9] have been modified according to this manner. For the same error rates as in [9], we achieve both a significant reduction in the code length as well as an improvement of the decoding performance. Additionally, our joint decoding tracing strategy also works for collusion sizes larger than 8.