Multiple-image optical encryption: an improved encoding approach

Abstract

An improved encoding approach to multiple-image optical encryption based on a cascaded phase retrieval algorithm (CPRA) is proposed. The system consists of several stages of a standard 4-f correlator, in which the keys are not only the phase mask pairs produced by CPRA but also the phase distribution of the output plane of the front stage. The security and the capacity of the system are also discussed. Results indicate that the system can resist known-plaintext attack to some extent, and the encrypted capacity is considerably enhanced. Computer simulations have proved the validity of the proposed idea. The system can be implemented using a pure optical architecture.

Encriptación de información mediante procesamiento óptico

“…Asimismo, se han generado procedimientos que permiten el manejo seguro de varios datos y el aumento de la seguridad del sistema de encriptación, por ejemplo, con técnicas que tienen como objetivo engañar a posibles intrusos introduciendo un procedimiento de ocultamiento (Barrera-Ramírez, et al, 2007), mediante la modificación del tamaño de una pupila (Barrera-Ramírez, et al, 2008), usando versiones escaladas de una máscara aleatoria de fase (Barrera-Ramírez, et al, 2009a), empleando llaves complejas (Barrera-Ramírez, et al, 2009b) y encriptación de datos complejos (Barrera & Torroba, 2009c). Otros incluyen el multiplexado con dos difusores y un conjunto de pupilas como llave de seguridad (Singh, et al, 2008), dos patrones de speckle elongados y superpuestos (Singh, et al, 2009), un algoritmo de recuperación de fase en cascada (Yong- Liang, et al, 2009) y dos estaciones de seguridad independientes (Alfalou & Mansour, 2009).…”

A review of single and multiple optical image encryption techniques

“…While designing a technique that is robust to noise is necessary, the number of images to be encoded at the same time is another quality criterion for multiple image encoding. In 2009, when MGSA-based encryption was proposed by Hwang et al [50], a different technique based on 4-f and a cascaded phase retrieval algorithm (CPRA) was also developed [54]. With this proposed structure, cross-talk noise is eliminated while encrypted image capacity is increased.…”

“…As can be seen from the figure, if the wrong key is used in the first stage of decryption, no images are accessible. With the system developed based on CPRA and 4-f, the image encryption capacity has been increased even more than previous studies [50][51][52][53] without cross-talk-induced noise [54]. The problem with the 4-f based multi-image encoding method is that users are dependent on each other at the receiver side due to its hierarchical structure.…”

Sistema Óptico de Encriptación de Doble Máscara de Fase bajo Arquitectura 4f

“…Desde otra perspectiva, se pueden utilizar un conjunto de estaciones del sistema de encriptación 4f para propósitos de multiplexado seguro de datos (Yong-Liang et al, 2009). Para lograr la recuperación de la información que esta encriptada, es necesario implementar un algoritmo de recuperación de fase tipo cascada.…”