Hyperchaotic image encryption using phase-truncated fractional Fourier transform and DNA-level operation

Abstract

Abstract A novel asymmetric image encryption method is developed by integrating with hyper-chaotic system (HCS), deoxyribonucleic acid (DNA) level operation, Arnold transform (ART) and phase-truncated fractional Fourier transform (ptFrFT). In this method, all the initial values and/or control parameters of HCS, DNA, Arnold transform and ptFrFT are generated from a plaintext image by utilizing the SHA-256 hash algorithm, which are also taken as security keys for one-time pad. In this case, the plaintext is scrambled by ART and then encoded into a noise-like interim image using ptFrFT with two random phase masks as private keys obtained by HCS. Afterwards, the interim image is converted into the final ciphertext using DNA-level diffusion and scrambling. All these operations yield large enough key space and high sensitivity to the keys. Only if all the correct keys are employed, the useful information can be achieved. Some numerical results are demonstrated that the proposal has good security and strong robustness to different attacks.