Image encryption using block based transformation with fractional Fourier transform

In order to transmit image data in open network, a novel image encryption algorithm based on fractional Fourier transform and block-based transformation is proposed in this paper. The image encryption process includes two steps: the original image was divided into blocks, which were rearranged into a transformed image using a transformation algorithm, and then the transformed image was encrypted using the fractional Fourier transform (FRFT) algorithm. The security of the proposed algorithm depends on the transformation algorithm, sensitivity to the randomness of phase mask and the orders of FRFT. Theoretical analysis and experimental results demonstrate that the algorithm is favorable.