Asymmetric multiple-image interference cryptosystem using discrete cosine transform and conditional decomposition

In this study, we propose an asymmetric multiple-image encryption technique based on optical interference that utilizes the discrete cosine transform (DCT) and conditional decomposition. First, the DCT spectrum of each original image is cropped by a low-pass filter and spatially multiplexed into a synthetized spectral signal with the same size as the original image. The synthetized spectral signal is then transformed by the DCT to the spatial domain. After undergoing pixel-scrambling, the synthetized signal is encrypted into three phase-only masks (POMs) based on the interference in the discrete multiple-parameter fractional Fourier transform domain and conditional decomposition. One of the POMs is a plaintext-independent cyphertext and the other two are plaintext-dependent private keys. The silhouette of the original image cannot be identified using only one or two of the POMs, all POMs are required. Finally, we demonstrate the performance of our technique through simulations.