Authentication-based optical cryptosystem with noise-free information retrieval

It is widely recognized that the main challenges facing the optical cryptosystem are the speckle noise and the linearity-induced security leak. In this paper, we report, for the first time to our best knowledge, a novel approach to cope with these two problems. The original information is firstly transformed into a series of images by aid of an image-character map (ICM), where the one to one relationship between the 26 characters and 26 images is predefined Then, these images are encrypted in the diffractive-imaging-based encryption (DIBE) scheme and the multiple ciphertexts corresponding to them finally merge into a synthetic ciphertext (SC) via space multiplexing. For decryption, the recovered images are unrecognizable but can be authenticated by nonlinear correlation. The authenticated images are converted back to characters with the help of the ICM, and thus the primary information can be exactly retrieved. Numerical results are presented to demonstrate the practicality of the proposed security system.