Optical asymmetric JTC cryptosystem based on multiplication-division operation and RSA algorithm

Abstract

The joint transform correlator (JTC) cryptosystem is a simple and practical optical cryptosystem. However, the anti-attack capability of JTC cryptosystem is still needed to be improved because of its linearity, and the identical key mask in both encryption and decryption also brings inconvenience and security risks in the key distribution and management. Aiming at overcoming these drawbacks, a novel optical asymmetric JTC cryptosystem is proposed in this paper. To design optical asymmetric JTC cryptosystem, a simple but effective trapdoor one-way function based on the image multiplication and division (IMD) operation is created for the first time to author’s knowledge. To improve the distribution and management of key mask in JTC cryptosystem, RSA algorithm is utilized to protect the structural parameters and geometric size of the structured spiral phase mask (SSPM), so the security of JTC cryptosystem can be enhanced simultaneously. The merits of our proposed optical asymmetric JTC cryptosystem, whose keys include a RPM public key, the RSA public key, the IMD private key and the RSA private key, are as follows: (1) the IMD operation is low in complexity and easy to be carried out with the aid of a time-varying noise image after the denoised joint power spectrum is obtained; (2) the keys in our proposal conform more closely to the basic agreement of asymmetric cryptosystem that have great advantages in the key distribution and management. Both simulation analysis and initial experimental results verified the correctness and feasibility of our proposal, which is provided with not only simplicity in configuration but also reliable security performance.