A novel interpretation of content authentication

This work deals with practical and theoretical issues raised by the information-theoretical framework for authentication with distortion constraints proposed by Martinian et al. The optimal schemes proposed by these authors rely on random codes which bear close resemblance to the dirty-paper random codes which show up in data hiding problems. On the one hand, this would suggest to implement practical authentication methods employing lattice codes, but these are too easy to tamper with within authentication scenarios. Lattice codes must be randomized in order to hide their structure. One particular multimedia authentication method based on randomizing the scalar lattice was recently proposed by Fei et al. We reexamine here this method under the light of the aforementioned information-theoretical study, and we extend it to general lattices thus providing a more general performance analysis for lattice-based authentication. We also propose improvements to Fei et al.’s method based on the analysis by Martinian et al., and we discuss some weaknesses of these methods and their solutions.