Research On Interference-based Multiple-image Encryption In The Fractional Fourier Domain

With the rapid development of modern communication technology,the image transmission security is becoming more and more important.Optical image encryption techniques can offer fast inherent computing and parallelism,and present a good potential for information protection by providing more key degree of freedom,such as amplitude,phase and wavelength.So it has played an important role in optical information processing.Recently,researchers have kept an eye on interference-based optical encryption for its simple principle,computation and operation.Many interference-based encryption algorithms have been proposed in past eight years,but most of them are dealing with one or two images.So there is some trouble in dealing with highly correlated images.To solve this problem,some interference-based multiple-image encryption algorithms are proposed in this paper.A briref introduction is given as follows:First of all,interference-based encryption in the discrete multiple-parameter fractional Fourier domain is proposed to enlarge the key space and enhance the system security,because the key space of the tradition interference-based encryption is so small.Secondly,a technique for multiple-image encryption based on discrete cosine transform and interference-based encryption in the fractional Fourier domain is proposed.After being modulated and compressed by discrete cosine transform,the images are multiplexed into a complex signal.The complex signal is performed by interference-based encryption in the fractional Fourier domain to obtain the encrypted images.This algorithm used the discrete cosine transform to reduce the transmission burden and improve the security of the encryption algorithm as well.An improved multiple-image encryption scheme is proposed by using discrete multiple-parameter fractional Fourier transform and scrambling technology which enlarges the key space of the system,improves system's efficiency,and further provides a much higher security level.Thirdly,a new method of multiple-image encryption is presented by utilizing phase retrieval and interference-based encryption in the discrete multiple-parameter fractional Fourier domain.This algorithm also has the high system security level.Finally,the silhouette problem is removed completely by adding the third encrypted mask which is a random mask.Numerical simulation experiments have been carried out to verify the reliability security,reliability of the proposed methods and analysis the sensitivity of key.These algorithms have less computation,simplified operation and great prospects of application.