Optical encryption using phase-shifting interferometry in a joint transform correlator

Abstract

We propose an optical encryption technique where the encrypted field and the decrypting key are obtained by three-step phase-shifting interferometry and registered as digital Fresnel holograms in a joint transform correlator architecture. Decryption can be achieved by digital or optical means. The technique allows the complete process to be achieved at high speed and data to be transfered via digital communication channels. Experimental implementation is performed in a system based on a programmable liquid-crystal TV display working in pure phase mode to represent the input data and to introduce the required phase shifts. A CCD is used to register the output data.

Optical multiple-image encryption based on fully phase encoding and interference

“…The SLM , PZT and CCD are controlled by a computer. [1,30]. It should be pointed out that in the path of the reference wave the PZT is used to change the phase of the reference wave.…”

Vulnerability to chosen-plaintext attack of optoelectronic information encryption with phase-shifting interferometry

“…Then the complex amplitude distribution of the reference beam at the exit of the interferometer can be expressed by $$U_{R}false(x,y;\alpha false)=\text{exp}false(i\alpha false)·FR{T}_{\lambda ,z}false\{\text{exp}false[i{\varphi }_{2}false(x\prime ,y\prime false)false]false\},$$ where FRT λ, d {·} denotes the Fresnel diffraction with the illumination wavelength of λ and the distance of z. α is the relative phase changes introduced by the retarder plates on the reference beam. Let U O ( x, y ) = A O exp [iϕ O ( x, y )], U R ( x , y , α) = A R exp { i [ ϕ R ( x, y ) + α]}, then the intensity pattern recorded by the CCD camera is given by $$Ifalse(x,y;\alpha false)=false|U_{O}false(x,yfalse)+U_{R}false(x,y;\alpha false){|}^2={false[A_{O}false(x,yfalse)false]}^2+{false[A_{R}false(x,yfalse)false]}^2+2A_{O}false(x,yfalse)A_{R}false(x,yfalse)\times \text{cos}false[{\varphi }_{O}false(x,yfalse)-{\varphi }_{R}false(x,yfalse)-\alpha false].$$ In this way, the phase ϕ E ( x , y ) and the amplitude A E ( x, y ) of the ciphertext can be recorded with the interferograms as follows: 22,23 $${\varphi }_{E}false(x,yfalse)=\text{arctan}true[\frac{Ifalse(x,y;-3\pi /2false)-Ifalse(x,y;-\pi /2false)}{Ifalse(x,y;0false)-Ifalse(x,y;-\pi false)}true],$$ $$A_{E}false(x,yfalse)=\frac{1}{4}\frac{Ifalse(x,y;0false)-Ifalse(x,y;-\pi false)}{\text{cos}false[{\varphi }_{O}false(x,yfalse)-{\varphi }_{R}false(x,yfalse)}$$…”

“…Much effort has been made on the construction of high-security-level and feasible cryptosystems based on the PSI technique, 19–22 owing to the following advantages: 1. The complex-value ciphertext is recorded with a group of intensity-only interferograms, which facilitate the storage and transmission; 2.…”

A Multi-User Encryption and Authentication System Based on Joint Transform Correlation

“…Subsequently, JTC systems have been thoroughly studied and elaborate structures have been proposed [2,3]. Further, Mela and Lemmi introduced an optical encryption technique using three-step phase-shifting interferometry based on JTC in the Fresnel domain [4]. The technique allows a high-speed encryption-decryption process for binary data and is able to operate in a robust and extremely simple optoelectronic system.…”