Reversible watermarking with subliminal channel

Abstract

With some difficulty in making more redundant capacity, only a symmetrically encrypted hash code is embedded in some reversible watermarking schemes, which makes it possible that a dishonest verifier fabricates legal contents. This paper shows that for reversible watermarking, by exploiting a subliminal channel, only a capacity of several more bytes than the length of a hash code is needed to embed a longer public-key signature. Only 4 bytes more suffices in the research. To exemplify the idea, the paper gives a variant of the R-S watermarking scheme. The variant adopts the broad-band subliminal channel in RSA-PSS signature scheme. The analysis and experiments show that with the aid of the channel it is easier to implement the reversibility, localize the tampering, and so forth. © 2008 Springer Berlin Heidelberg.