Abstract
The development of quantum computers and quantum algorithms conveys a challenging scenario for several cryptographic protocols due to the mathematical scaffolding upon which those protocols have been built. Quantum walks constitute a universal quantum computational model which is widely used in various fields, including quantum algorithms and cryptography. Quantum walks can be utilized as a powerful tool for the development of modern chaos-based cryptographic applications due to their nonlinear dynamical behavior and high sensitivity to initial conditions. In this paper, we propose new encryption mechanism for privacy preserving Internet of Things-based healthcare systems in order to protect the patients' privacy. The encryption/decryption processes are based on controlled alternate quantum walks. The proposed cryptosystem approach is composed of two phases: substitution and permutation, both based on independently computed quantum walks. Simulation results and numerical analysis of our data provide enough evidence to reasonably conjecture that our image encryption protocol is robust and efficient for protecting patients' privacy protection.