Abstract: When traditional data interpolation methods are applied to data hiding in encrypted images, they will reduce security of the data hiding system. To address this problem, we exploit random weight strategy to design a random interpolation method for encrypted images. The proposed method firstly generates the initial interpolated image, which is twice the size of the encrypted image. For the pixels in the odd rows and the odd columns of the interpolated image, the proposed method fills them with the corresponding pixels of the encrypted image. For the rest pixels of the interpolated image, the proposed method generates random values by pseudo-random function and calculates the interpolated results in terms of their detailed locations. Experimental results show that the histograms of interpolated encrypted images calculated by our random interpolation are approximately uniformly distributed. Comparison results demonstrate that our random interpolation outperforms three popular existing interpolation methods.

Key words: random interpolation, data hiding, encrypted image, reversible information hiding, histogram