Quantum Image Encryption Using a Self-Adaptive Hash Function-Controlled Chaotic Map (SAHF-CCM)

Abstract

Recently, quantum image encryption algorithms are attracting more and more attention, due to the upcoming quantum threat problem to the current cryptographic encryption algorithms with the rapid progress toward the quantum computer production. The aim of this paper is to introduce a self-adaptive encryption scheme to protect quantum image efficiently with minimal storage requirements. The methodology is to use two rounds of encryption with two different pseudorandom number sequences which are obtained from a new designed pseudorandom number generator (PRNG). This PRNG consists of two parts. The first part is based on iterating a recently proposed chaotic-based parallel keyed hash function which is used as a controller for a second part. The second part is a multiplication of Tent and Chebyshev chaotic maps (TCM). This combination of hash function and chaotic maps provides high randomness and a dramatical increase in the control parameters and initial values number which achieves extremely large key space and so makes the scheme stronger against brute force attacks. The seed or initial value of PRNG depends on the input image itself which makes the scheme self-adaptive and so it is stronger against chosen plaintext attacks and known-plaintext attacks. In the first round of encryption, the value of each pixel qubits of the input image is changed to a new value by XORing it with the corresponding qubits of the first pseudorandom sequence using CNOT and Toffoli quantum gates then shifting to the next qubit with the Swap quantum gate. In this round, the pixel value is changed. In the second round, diffusion of the changed pixel value is extended to each pixel in the input image using the second pseudorandom sequence and Toffoli quantum gates. The time complexity of the proposed scheme is less than many recently published quantum image encryption schemes. The scheme security analysis is discussed, and the experimental results proved that the scheme is robust, secure and efficient.