A novel hybrid compressive encryption cryptosystem based on block quarter compression via DCT and fractional Fourier transform with chaos

The proposed compression encryption scheme comprises two-fold techniques including BQC-DCT and encryption. For the first phase, the image is split among four equal portions. The DCT is then implemented to each section separately thereafter these four blocks are merged to one, the process greatly reduces the computational time elapsed in compression. In the Encryption Phase, the chaotic sequence is generated from the logistic map, its initial values and angle parameters of FrFT are serving as the private keys. This novel hybrid combination may accomplish better execution in comparison with the other methods, because of PSNR which suggests that the Fourier Transform is better in image encryption as compare to many progressive methods. The proposed scheme with two transforms applied has tremendous dominance in the various performance assessments such as security performance assessment, statistical assessment, and reconstruction performance assessment. Simulation results indicate that the technique will minimize computational time and improve reconstruction with enhanced security for both medium and large-size images. © 2021, Bharati Vidyapeeth's Institute of Computer Applications and Management.