Secure Random Phase Key Exchange Schemes for Image Cryptography

Abstract

We propose novel random phase key exchange schemes for image cryptography, which are complex sinusoidal waveform versions of the Diffie–Hellman (DH) key exchange algorithm. We demonstrate that the proposed schemes can be particularly helpful to establish a shared secret key in Fourier optics-based image cryptosystems since the problem of symmetric secret key establishment is one of the fundamental difficulties in Fourier optics-based image cryptography. We also propose a ring-type key exchange system in which multiple users can securely share a secret key, which is an extension of the key exchange scheme for two users. The schemes are verified by numerical simulations.