Asymmetric multi-image cryptosystem based on phase–amplitude approach, QR decomposition and Fourier transform

In this paper, we propose a multi-image encryption scheme using QR decomposition (QRD) and chaotic phase mask (CPM) in the Fourier transform domain. We apply both phase truncation and amplitude truncation operations to design the scheme in such a way that each image has its own secret key and cannot be recovered using the secret key of other images. The QRD used in the scheme provides asymmetry, which makes the cryptosystem robust against well-known attacks, such as known-plaintext and chosen-plaintext attacks. The CPM used in the Fourier domain enlarges the key space, thus protecting it from brute force attack. The presented scheme is ideal for n multiple images ( n being a natural number), which makes the algorithm quite fascinating. Simulation performed by MATLAB R2022a evaluates the mean squared error, key sensitivity and mesh plot results, which demonstrate the credibility of the cryptosystem.