Asymmetric hybrid encryption scheme based on modified equal modulus decomposition in hybrid multi-resolution wavelet domain

We analyze and present an attack scheme of the asymmetric optical cryptosystem proposed recently based on coherent superposition and equal modulus decomposition [Opt. Lett.40, 475 (2015)OPLEDP0146-959210.1364/OL.40.000475]. We prove that the attacker can recover the original image with the ciphertext and public keys through the amplitude-phase retrieval algorithm by using two constraints. One constraint of the amplitude-phase retrieval algorithm is the public key and the other is obtained through the analysis of the cryptosystem. The simulation results demonstrate the feasibility of the attack method.

A novel asymmetric cryptosystem based on coherent superposition, which is free from silhouette problem, is proposed. Being different from the phase-truncated Fourier transform-based cryptosystem, the encryption process uses equal modulus decomposition (EMD) to create an effective trapdoor one-way function. As a result, the proposed method achieves high robustness against the special attack based on iterative Fourier transform. Simulation results are presented to prove the validity of the proposed system.

The equal modulus decomposition (EMD) is a novel asymmetric cryptosystem based on coherent superposition which was proposed to resist the specific attack. In a subsequent work, the scheme was shown to be vulnerable to specific attack. In this paper, we counter the vulnerability through an encoding technique which uses multiple diffraction intensity pattern recordings as the input to the EMD setup in the gyrator domain. This allows suppression of the random phase mask in the EMD path. As a result, the proposed scheme achieves resistance to specific attack. The simulation results and the security analysis demonstrate that EMD based on multiple intensity pattern recording is an effective optical asymmetric cryptosystem suitable for securing data and images.

An asymmetric scheme based on equal modulus decomposition (EMD) and singular value decomposition (SVD) encrypted using Fresnel and gyrator transform is proposed to enhance the security of the system and to make it free from silhouette problem. In this technique, it uses triple masking technique where double masking is done through random phase mask (diffusers) and the third masking is done through EMD using $$\theta$$ . After the triple masking the distorted obtained image is decomposed into segments (U, S, V) using SVD and each decomposed encrypted segment is transmitted through different channels and kept at different locations. The extra degree of freedom (keys) provided by triple making technique increases the key space hereby enhances the optical encryption security that makes it difficult for an attacker to find the exact key to recover an original image. It also makes it highly resistant to many conventional and iterative attacks. The robustness of the asymmetric proposed cryptosystem has been examined by simulating on MATLAB 8.3.0 (R2014a). The experimental results are provided to highlight the effectiveness, robustness and suitability of the proposed cryptosystem and to prove the feasibility and validity of the proposal.

Multiple-image encryption based on chaotic phase mask and equal modulus decomposition in quaternion gyrator domain

An optical Hash function construction based on equal modulus decomposition for authentication verification

Optical asymmetric single-channel cryptosystem based on QZ synthesis for color images

In this paper, a hybrid iris biometric protection scheme using 4D hyperchaotic system by means of coherent superposition and modified equal modulus decomposition in hybrid multi-resolution wavelet domain is proposed. The 4D hyperchaotic framework is employed for producing the permutation keystream for pixel swap-over mechanism. The hybrid multi-resolution is produced by means of Kronecker product of Walsh transform and fractional Fourier transform of different orders. Fractional orders of the hybrid multiresolution wavelet along with the parameters and initial conditions of the 4D hyperchaotic framework, later fill in as additional keys, thus enhancing the key space of the proposed mechanism. The proposed scheme has nonlinear characteristics and has high robustness against brute-force attack attributable to its enormous key-space. Numerical simulations have been carried out on grayscale images to prove the authenticity and efficacy of the proposed cryptosystem. The functioning of the proposed cryptosystem is investigated against various attacks including special attack. Outcomes display that the proposed iris template protection scheme not only has higher robustness against noise attack but is also unassailable to the iterative transform-based attacks.

Cheng et al. proposed an asymmetric image encryption scheme which is based on adaptively synchronised chaotic cellular neural network and unified chaotic systems in [Communication in Nonlinear Science and Numerical Simulation 18(10) 2825–2837 2013]. The cryptosystem was asymmetric in nature and the synchronization error converged quickly to zero. Numerical simulations for performance evaluation included synchronization effectiveness, cryptosystem robustness and statistical analyses like key space, key sensitivity and NPCR/UACI analyses, all with effective results. But, this paper demonstrates the cryptanalysis of Cheng et al. cryptosystem by exploiting inherent deficiencies of encryption algorithm like low robustness and poor plain-image sensitivity. It is done by mounting the proposed cryptographic CPA or KPA attack which leads to successful retrieval of original plaintext image. The simulated cryptanalysis shows that Cheng et al. cryptosystem is not suitable for practical utility in image security applications.

a watermarking scheme for Grayscale image isproposed based on a family of the chaotic maps and discretecosine transform. Jacobian Elliptic mapis employed to encrypt ofwatermarked logo. Piecewise nonlinear chaotic map is also usedto determine the location of DCT coefficients for the watermarkembedding. The purpose of this algorithm is to improve theshortcoming of watermarking such as small key space and lowsecurity. Therefore the size of key space for initial conditions andcontrol parameters is computed about and this keyspace is large enough to resist the attacks. Toevaluate therobustness and effectiveness of proposed method, several attacksare applied to the

Devil׳s vortex Fresnel lens phase masks on an asymmetric cryptosystem based on phase-truncation in gyrator wavelet transform domain

Multivariate Quadratic public key schemes have been suggested back in 1985 by Matsumoto and Imai as an alternative for the RSA scheme. Since then, several other schemes have been proposed, for example Hidden Field Equations, Unbalanced Oil and Vinegar schemes, and Stepwise Triangular Schemes. All these schemes have a rather large key space for a secure choice of parameters. Surprisingly, the question of equivalent keys has not been discussed in the open literature until recently. In this article, we show that for all basic classes mentioned above, it is possible to reduce the private | and hence the public | key space by several orders of magnitude. For the Matsumoto-Imai scheme, we are even able to show that the reductions we found are the only ones possible, i.e., that these reductions are tight. While the theorems developed in this article are of independent interest themselves as they broaden our understanding of Multivariate Quadratic public key systems, we see applications of our results both in cryptanalysis and in memory e‐cient implementations of MQ-schemes.

A new image cipher in time and frequency domains

ℳultivariate uadratic public key schemes have been suggested as early as 1985 by Matsumoto and Imai as an alternative for the RSA scheme. Since then, several schemes have been proposed, for example hidden field equations, unbalanced oil and vinegar schemes, and stepwise triangular schemes. All these schemes have a rather large key space for a secure choice of parameters. Surprisingly, the question of equivalent keys has not been discussed in the open literature until recently. In this article, we show that for all basic classes mentioned above, it is possible to reduce the private – and hence the public – key space by several orders of magnitude, i.e. the size of the set of possible private and hence public keys can be reduced. For the Matsumoto–Imai scheme, we are even able to show that the reductions we found are the only ones possible, i.e. that these reductions are tight. While the theorems developed in this article are of independent interest themselves as they broaden our understanding of ℳultivariate uadratic public key systems, we see applications of our results both in cryptanalysis and in memory efficient implementations of -schemes.

A novel color image encryption scheme is developed to enhance the security of encryption without increasing the complexity. Firstly, the plain color image is decomposed into three grayscale plain images, which are converted into the frequency domain coefficient matrices (FDCM) with discrete cosine transform (DCT) operation. After that, a two-dimensional (2D) coupled chaotic system is developed and used to generate one group of embedded matrices and another group of encryption matrices, respectively. The embedded matrices are integrated with the FDCM to fulfill the frequency domain encryption, and then the inverse DCT processing is implemented to recover the spatial domain signal. Eventually, under the function of the encryption matrices and the proposed diagonal scrambling algorithm, the final color ciphertext is obtained. The experimental results show that the proposed method can not only ensure efficient encryption but also satisfy various sizes of image encryption. Besides, it has better performance than other similar techniques in statistical feature analysis, such as key space, key sensitivity, anti-differential attack, information entropy, noise attack, etc.