Research On The Algorithm Of Multiple-image Encryption Based On The Improved VOI

Optical encryption has been developed quickly as a new mean of encryption in recent years.And multiple-image encryption has became the research hot instead of single-image encryption.Several multiple-image encryption methods have been investigated and discussed includingPhase Extraction, Computing Holography, Phase Recovery Algorithm and Wave DivisionMultiplexing method.However, these multiple image encryption methods would due to crosstalk because of verticalsuperpose of multiple images. Analyse the theory of multiple images encrypted longitudinallyprocess and discuss it’s effectiveness. By comparing it’s effectiveness with multiple imagesencrypted transversely process’s effect, the MATLAB simulation confirmed that multiple imagesencrypted transversely has higher effect and it can improve the quality of multiple-image encryptionsystem.This paper proposes an algorithm for multiple-image encryption based on the improved VirtualOptical Imaging (VOI). The improved algorithm enhances the security of system and avoid thecrosstalk by integrating several images into one as an encrypting object and increasing key space.The improvement of VOI system focuses on three issues. First, it encrypts the phase information,which can improve the performance of decryption effect of the system. Second, it combines randomphase plate with a random amplitude board at the position of the random phase plate to increase thedimension of the key space and the ability to against the attacks. Finally, it adds a random phaseplate before the image place, which enhances the security of the system.It uses the PSNR (Peak Signal to Noise Ratio) to evaluate the performance of the proposedalgorithm and MATLAB simulation to prove the validity, robustness and security of this algorithm.It turns out that the proposed algorithm for multiple-image encryption based on the improvedVirtual Optical Imaging is feasible. Compared with the traditional VOI-based encryption method,the simulations show that the proposed method demonstrates a good performance in terms offeasibility, robustness and security.