Dynamical Investigation of a Flexible Symmetry-Breaking Cyclic Chaotic Oscillator for Biomedical Image Encryption.

Today, telediagnosis and telesurgery in the e-healthcare domain use medical images that are sensitive to external disturbances and manipulations leading to huge differences in the final result. To keep safe such images, cryptography is among the best methods and especially when it integrates chaotic systems due to their sensitivity to initial seeds. So, a chaos-based cryptosystem using DNA confusion and diffusion is proposed and applied to biomedical images in this work. It also includes hash functions that compress an indeterminate size of data into fixed size of data. The security and the reliability of the information system are ensured with the combination of two hash functions. The execution time is then considerable, and the integrity of the encrypted image is guaranteed. Encoding/decoding rules and operations are selected using the result of the numerical integration of the logistic map. At the level of diffusion, seven functions are employed reinforcing the security level of our cryptosystem. The construction of the DNA (deoxyribonucleic acid) key is done through the iteration of the new cyclic chaotic system having initial states derived using the keys obtained from the combination of hash functions and external key, thus building a PRNS (pseudorandom number sequence). The entire dynamics of the new system in both symmetric and asymmetric cases is then performed, exhibiting relevant behaviors such as the coexistence of up to eight attractors, intermittency, parallel branches of bifurcations, and metastable chaos very rare in literature, to name a few. PSpice is used to verify the numerical results. Based on confusion and diffusion, the new encryption/decryption algorithm is effective in both processes. The experimental results show that the cryptosystem is able to withstand brute force, exhaustive, statistical, differential, and robustness attacks. Also, the comparison of the algorithm with good ones from the literature shows that it is among the best proposed up to date. [ABSTRACT FROM AUTHOR]