A lensless optical security system based on double random-phase encoding in the Fresnel domain is proposed. This technique can encrypt a primary image to random noise by use of two statistically independent random-phase masks in the input and transform planes, respectively. In this system the positions of the significant planes and the operation wavelength, as well as the phase codes, are used as keys to encrypt and recover the primary image. Therefore higher security is achieved. The sensitivity of the decrypted image to shifting along the propagation direction and to the wavelength are also investigated.

Double random-phase encoding in the Fresnel domain

Over the years extensive studies have been carried out to apply coherent optics methods in real-time communications and image transmission. This is especially true when a large amount of information needs to be processed, e.g., in high-resolution imaging. The recent progress in data-processing networks and communication systems has considerably increased the capacity of information exchange. However, the transmitted data can be intercepted by nonauthorized people. This explains why considerable effort is being devoted at the current time to data encryption and secure transmission. In addition, only a small part of the overall information is really useful for many applications. Consequently, applications can tolerate information compression that requires important processing when the transmission bit rate is taken into account. To enable efficient and secure information exchange, it is often necessary to reduce the amount of transmitted information. In this context, much work has been undertaken using the principle of coherent optics filtering for selecting relevant information and encrypting it. Compression and encryption operations are often carried out separately, although they are strongly related and can influence each other. Optical processing methodologies, based on filtering, are described that are applicable to transmission and/or data storage. Finally, the advantages and limitations of a set of optical compression and encryption methods are discussed.

https://hal.archives-ouvertes.fr/docs/00/51/69/80/PDF/20.pdf

Optical image compression and encryption methods

A number of methods have recently been proposed in the literature for the encryption of two-dimensional information by use of optical systems based on the fractional Fourier transform. Typically, these methods require random phase screen keys for decrypting the data, which must be stored at the receiver and must be carefully aligned with the received encrypted data. A new technique based on a random shifting, or jigsaw, algorithm is proposed. This method does not require the use of phase keys. The image is encrypted by juxtaposition of sections of the image in fractional Fourier domains. The new method has been compared with existing methods and shows comparable or superior robustness to blind decryption. Optical implementation is discussed, and the sensitivity of the various encryption keys to blind decryption is examined.

/pdf/optical-image-encryption-by-random-shifting-in-fractional-7mdzyi0wkp.pdf

Optical image encryption by random shifting in fractional Fourier domains

Fractional Fourier transform as a signal processing tool: An overview of recent developments

A novel image encryption algorithm in streaming mode is proposed which exhaustively employs an entire set of DNA complementary rules alongwith one dimensional chaotic maps. The proposed algorithm is highly efficient due to encrypting the subset of digital image which contains 92.125 % of information. DNA addition operation is carried out on this MSB part. The core idea of the proposed scheme is to scramble the whole image by means of piecewise linear chaotic map (PWLCM) followed by decomposition of image into most significant bits (MSB) and least significant bits (LSB). The logistic sequence is XORed with the decoded MSB and LSB parts separately and finally these two parts are combined to get the ciphered image. The parameters for PWLCM, logistic map and selection of different DNA rules for encoding and decoding of both parts of an image are derived from 128-bit MD5 hash of the plain image. Simulated experimental results in terms of quantitative and qualitative ways prove the encryption quality. Efficiency and robustness against different noises make the proposed cipher a good candidate for real time applications.

An efficient and noise resistive selective image encryption scheme for gray images based on chaotic maps and DNA complementary rules

We propose a new image encryption algorithm based on a generalized fractional Fourier transform, to which we refer as a multifractional Fourier transform. We encrypt the input image simply by performing the multifractional Fourier transform with two keys. Numerical simulation results are given to verify the algorithm, and an optical implementation setup is also suggested.

Optical image encryption based on multifractional Fourier transforms

We first show that the bandlimited signals associated with linear canonical transform (LCT) form a reproducing kernel Hilbert space. An orthogonal basis for the class of bandlimited signals associated with LCT is then proposed by use of the reproducing kernel, with respect to which the coordinates of signal are actually values taken by the signal at certain instants of time. Finally, a nonuniform sampling theorem for bandlimited signals associated with LCT is presented.

On Bandlimited Signals Associated With Linear Canonical Transform

In this paper, a quantum color image encryption scheme based on coupled hyper-chaotic Lorenz system with three impulse injections is proposed. Firstly, in order to enhance the complexity of trajectory, three impulse signals values are injected into coupled hyper-chaotic Lorenz system during iterations. Then, six sequences generated from this system are used to encrypt red, green and blue components of the quantum color original image by XOR operations and right cyclic shift operations. Six initial values and three impulse signals values are used as keys, which could reduce the burden of keys transmission and make the cryptosystem own a key space large enough to resist exhaustive attack, even the attack from a quantum computer. Numerical simulations demonstrate that the proposed encryption scheme has a good feasibility and effectiveness for protecting quantum color images and is more secure in comparison with other encryption algorithms.

A quantum color image encryption scheme based on coupled hyper-chaotic Lorenz system with three impulse injections

Methods of image encryption based on fractional Fourier transform have an incipient flaw in security We show that the schemes have the deficiency that one group of encryption keys has many groups of keys to decrypt the encrypted image correctly for several reasons In some schemes, many factors result in the deficiencies, such as the encryption scheme based on multiple-parameter fractional Fourier transform [Opt Lett33, 581 (2008)] A modified method is proposed to avoid all the deficiencies Security and reliability are greatly improved without increasing the complexity of the encryption process

Qiwen Ran

Papers

Optical image encryption based on multifractional Fourier transforms

On Bandlimited Signals Associated With Linear Canonical Transform

A quantum color image encryption scheme based on coupled hyper-chaotic Lorenz system with three impulse injections

Deficiencies of the cryptography based on multiple-parameter fractional Fourier transform

QRCI: A new quantum representation model of color digital images