Optical image encryption algorithm based on hyper-chaos and public-key cryptography

• Published in: Optics and laser technology 2020-07, Vol.127, p.106171, Article 106171
• Main Authors: Liu, Yujia, Jiang, Zhaoguo, Xu, Xiping, Zhang, Fuqi, Xu, Jiahong
• Format: Article
• Language: English
• Subjects: Algorithms; Asymmetric cryptosystem; Asymmetry; Chaos theory; Complexity; Cryptography; Digital imaging; Encryption; Fresnel diffraction; Fresnel propagation; Hyper-chaotic system; Image encryption; Image transmission; Information optics; Masks; Noise intensity; Parameters
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2020.106171

•Using hyper-chaotic sequences to construct phase masks of optical encryption system.•Optimize the distribution and management of phase mask keys.•Improve the sensitivity of the FDT-DRPE system to the first Fresnel diffraction.•Improve RSA encryption method, reduce the amount of calculation and time complexity.•The process of encryption and decryption can be implemented optically or digitally. Aiming at the problem of secure transmission and distribution of complex keys in image encryption system based on optical transformation, an innovative optical image encryption algorithm is proposed based on hyper-chaos and public key cryptography. Firstly, two hyper-chaotic random phase masks are constructed by using the four-wing and Chen 4D hyper-chaotic system. Then, with the hyper-chaotic phase masks, the original image is encrypted by double random phase encoding in the Fresnel domain. Finally, the public key cryptosystem is used to allocate and manage the initial values, system parameters and Fresnel diffraction system parameters of the hyper-chaotic system to achieve asymmetric encryption of images. In the process of decryption, the receiver obtains hyper-chaotic random phase masks by decrypting the private keys in the public key cryptosystem, and decrypts the encrypted image by optical or digital means. The experimental results show that the proposed algorithm has a high key sensitivity, uniform and flat statistical distribution characteristics, and can resist the noise attacks with intensity coefficient of 0.1. The asymmetric image encryption and decryption time only needs 0.0245 s and 0.072 s, respectively. Through the fusion of hyper-chaos and public key cryptosystem, the key space is increased, the key volume is reduced, the computational complexity is reduced, and the algorithm operation efficiency is improved.