Acta Metallurgica Sinica(English letters) ›› 2015, Vol. 22 ›› Issue (5): 1-9.doi: 10.1016/S1005-8885(15)60673-2

• Wireless •     Next Articles

New image encryption combining fractional DCT via polynomial interpolation with dependent scrambling and diffusion


  1. 1. School of Mechatronic Engineering, Nanchang University, Nanchang 330031, China 2. School of Information Engineering, Nanchang University, Nanchang 330031, China
  • Received:2014-12-08 Revised:2015-06-06 Online:2015-10-30 Published:2015-10-30
  • Supported by:

    This work was supported by the National Natural Science Foundation of China (61262084, 61462061) and the Natural Science Foundation of Jiangxi Province (20122BAB201029).


Based on the fractional discrete cosine transform (DCT) via polynomial interpolation (PI-FrDCT) and the dependent scrambling and diffusion (DSD), an image encryption algorithm is proposed. Under certain conditions, the introduction of PI-FrDCT reduces computational complexity compared with fractional DCT (FrDCT). By using a sigmoid function, the encrypted results are limited within a range from 0 to 255. The real-valued output of PI-FrDCT is beneficial to the storage, display and transmission of the cipher-text. During the stage of confusion and diffusion, the values of all PI-FrDCT coefficients change simultaneously as their locations are replaced. DSD enhances the scrambling and diffusion level of encrypted images and provides nonlinearity to the encryption system. Simulation results demonstrate that the proposed encryption algorithm is feasible, effective and secure.

Key words: image encryption|fractional discrete cosine transform (DCT)|polynomial interpolation|image scrambling|image diffusion|preservation of reality