Abstract:

There are two problems in the existing reversible data hiding schemes for encrypted domain. The frist one is that the reversibility which implies exact data extraction and perfect image recovery cannot be ensured. The other is that some schemes are not processed in the really encrypted domain. This paper proposes a real reversible data hiding algorithm in encrypted image. In this algorithm, two neighbor pixels are divided into a group and encrypted by the additive homomorphism algorithm with the same encryption key. And then the difference between two pixels in each group is calculated to generate the difference histogram. Through difference histogram shifting, the data hider can embed data. To further improve the embedding capacity, multi-level difference histogram shifting can be used. In general, this algorithm solves both of the two existing problems to realize data hiding in the really encrypted domain and exact reversibility. Experiment results demonstrate that the proposed algorithm can ensure the privacy security of image, and its embedding capacity is higher. After extracting data completely, it can recover the original image reversibly.

Key words: encrypted image, reversible data hiding, additive homomorphism, difference histogram shifting