Fully phase image encryption using double random-structured phase masks in gyrator domain

Abstract

We propose a method for fully phase image encryption based on double random-structured phase mask encoding in the gyrator transform (GT) domain. The security of the system is strengthened by parameters used in the construction of a structured phase mask (SPM) based on a devil's vortex Fresnel lens (DVFL). The input image is recovered using the correct parameters of the SPMs, transform orders of the GT, and conjugate of the random phase masks. The use of a DVFL-based SPM enhances security by increasing the key space for encryption, and also overcomes the problem of axis alignment associated with an optical setup. The proposed scheme can also be implemented optically. The computed values of mean squared error between the retrieved and the original image show the efficacy of the proposed scheme. We have also investigated the scheme's sensitivity to the encryption parameters, and robustness against occlusion and multiplicative Gaussian noise attacks.

Optical Image Encryption Using Devil’s Vortex Toroidal Lens in the Fresnel Transform Domain

“…We have randomly selected 10,000 pairs of adjacent pixels (horizontal, vertical, or diagonal) for computation of CC from the input and the encrypted images separately. Then, the CC of each pair is calculated by the following relation [25]:…”

“…In an attempt to strengthen security, the DRPE was further extended to several other transform domains such as the fractional Fourier [9,10], Fresnel [11][12][13][14][15][16][17][18][19][20][21][22][23], gyrator [24,25], and fractional Mellin [26,27]. However, majority of these techniques use random phase keys making them vulnerable to a variety of plaintext and ciphertext attacks.…”

Optical asymmetric image encryption using gyrator wavelet transform

“…Here, an input image is encrypted by two fractional orders and a series of scaling factors. Recently, optical gyrator transform system has been introduced for encrypting secret image [15,16]. However, due to inherent linearity such cryptosystems are not highly secure [17,18].…”

Optical interference-based image encryption using circular harmonic expansion and spherical illumination in gyrator transform domain

“…To alleviate the strict optical alignment, some DRPE systems based on configuration of joint transform correlator (JTC) [10,11] or joint fractional Fourier transform correlator (JFTC) [12,13] have been proposed. On the other hand, some modified schemes use structured instead of random phase mask to overcome the problem of axis alignment, and to enlarge the key space with some structure parameters [14,15]. These structured phase masks (SPM), generally, have a rotationally symmetric distribution and are made from a spiral phase plate [14] or a devil's vortex Fresnel lens (DVFL) [15].…”

“…On the other hand, some modified schemes use structured instead of random phase mask to overcome the problem of axis alignment, and to enlarge the key space with some structure parameters [14,15]. These structured phase masks (SPM), generally, have a rotationally symmetric distribution and are made from a spiral phase plate [14] or a devil's vortex Fresnel lens (DVFL) [15].…”