Multiuser optical information authentication using photon counting in spiral phase transform domain

In the present time, the substantial advances in communication technology have prompted many challenges including secure transmission of sensitive information. Optical techniques have also been studied extensively for information security and validation. In this paper, we present a new optical information authentication techniques using photon counting in spiral phase transform (SPT) domain. SPT is used for the optical propagation. For SPT, a modified spiral phase function is utilized which defines the order of the transform. In the encryption process, an asymmetric approach is used, in which, first the input image is combined with the random phase mask and Fresnel propagated with a distance, d to get the intermediated image. Further, the polar decomposition (PD) is applied to the intermediate image which will give a rotational matrix and two symmetric matrices. The symmetric matrices can be used for authenticating the original information and serve as the private keys. The final encrypted image is obtained by performing the SPT of a particular order on the rotational matrix after PD. The encrypted image is made sparse by randomly retaining few pixels using photon counting approach. For authentication, the nonlinear correlation approach is studied, which offer better correlation peaks with fewer sparse-based complex samples. The numerical simulation results have been presented in support of the validity and effectiveness of the proposed technique. The proposed method deals with the optical encryption, authentication and also overcomes the limitations of data storage issue.