Color Image Encryption Algorithm Research Articles

A fast color image encryption algorithm based on hyper-chaotic systems

This paper presents a new way of image encryption scheme, which consists of two processes; key stream generation process and one-round diffusion process. The first part is a pseudo-random key stream generator based on hyper-chaotic systems. The initial conditions for both hyper-chaotic systems are derived using a 256-bit-long external secret key by applying some algebraic transformations to the key. The original key stream is related to the plain-image which increases the level of security and key sensitivity of the proposed algorithm. The second process employs the image data in order to modify the pixel gray-level values and crack the strong correlations between adjacent pixels of an image simultaneously. In this process, the states which are combinations of two hyper-chaotic systems are selected according to image data itself and are used to encrypt the image. This feature will significantly increase plaintext sensitivity. Moreover, in order to reach higher security and higher complexity, the proposed method employs the image size in key stream generation process. It is demonstrated that the number of pixel change rate (NPCR) and the unified average changing intensity (UACI) can satisfy security and performance requirements (NPCR \(>\)99.80 %, UACI \(>\)33.56 %) in one round of diffusion. The experimental results reveal that the new image encryption algorithm has the advantages of large key space, high security, high sensitivity, and high speed. Also, the distribution of gray-level values of the encrypted image has a semi-random behavior.

Single-channel color image encryption algorithm based on fractional Hartley transform and vector operation

A single-channel color image encryption algorithm is proposed by combining fractional Hartley transform (FRHT) with vector operation. The original color image is decomposed into RGB components and the G and B components are encrypted into two phase-only masks ? G and ? B with vector operation, respectively. The R, ? G and ? B are transformed by FRHT and vector operation twice to obtain amplitude, random phase and decryption phase key. The new amplitude combined with the random phase is transformed by FRHT once more and then the result is scrambled by the chaotic scrambling to strengthen the security of the algorithm. The private phase key is dependent on the original image, which makes the proposed encryption algorithm more secure than the linear color image encryption algorithm based on the double random phase encoding in FRHT. Simulation results demonstrate the security and effectiveness of the proposed algorithm.

AN IMPROVED COLOR IMAGE ENCRYPTION ALGORITHM WITH PIXEL PERMUTATION AND BIT SUBSTITUTION

Today the transmission of multimedia data including image and video is growing in telecommunications. Security is one of the main issues in transferring such sensitive informat ion. Powerful image encryption algorithm is the sol ution for this problem. This paper is an implementation of a color image encrypt ion algorithm based on Rubik’s cube technique. The Rubik’s cube technique is used for pixel permutation and a bit substitutio n method based on DNA sequences are used to change the value of each pixel on the image. Then the time-stamp is appended with enc rypted image, which can be used to identify the rep lay attack. For evaluating the performance of the algorithm a series of tests are performed. These tests include information entr opy analysis, correlation analysis, analysis of NPCR and UACI values etc.

Cryptanalysis of a color image encryption algorithm based on chaos

A novel image encryption algorithm based on logistic map is proposed recently. In this paper, a chosen plaintext attack on this algorithm is presented and some other flaws of the algorithm are pointed out. Theoretical analysis and experimental simulation indicate that the plain image can be recovered exactly from the cipher image without secret key. Therefore, this algorithm is not secure enough for practical applications. An improvement is proposed to enhance the security of the original algorithm. Simulation results and theoretical analysis show that the improved scheme has expected cryptographic properties and is more secure than the original algorithm.

Color image encryption algorithm based on cutting spectrum and 2D Arnold transform

To reduce the heavy transmission burden of multichannel color image encryption algorithms,a single-channel color image encryption algorithm based on cutting spectrum and 2D Arnold transform was presented.In the proposed algorithm,the R,G,B components of the original color image were extracted,and their spectra were obtained separately by the Fractional Fourier Transform(FrFT) of different orders,followed by cutting their spectra to construct a new spectrum,then the combined spectrum was scrambled by the 2D Arnold transform to confuse and diffuse the spectrum information well enough.The encrypted image was a gray image,thus the transmission burden was reduced apparently while the main information of the original color image was kept.The simulation results and performance analyses verify the validity and the security of the encryption algorithm.

New color image encryption algorithm based on compound chaos mapping and hyperchaotic cellular neural network

We propose an image encryption/decryption algorithm based on chaotic control parameter and hyperchaotic system with the composite permutation-diffusion structure. Compound chaos mapping is used to generate control parameters in the permutation stage. The high correlation between pixels is shuffled. In the diffusion stage, compound chaos mapping of different initial condition and control parameter generates the diffusion parameters, which are applied to hyperchaotic cellular neural networks. The diffusion key stream is obtained by this process and implements the pixels’ diffusion. Compared with the existing methods, both simulation and statistical analysis of our proposed algorithm show that the algorithm has a good performance against attacks and meets the corresponding security level.

Optical color image hiding scheme based on chaotic mapping and Hartley transform

We present a color image encryption algorithm by using chaotic mapping and Hartley transform. The three components of color image are scrambled by Baker mapping. The coordinates composed of the scrambled monochrome components are converted from Cartesian coordinates to spherical coordinates. The data of azimuth angle is normalized and regarded as the key. The data of radii and zenith angle are encoded under the help of optical Hartley transform with scrambled key. An electro-optical encryption structure is designed. The final encrypted image is constituted by two selected color components of output in real number domain.

Color image security system using chaos-based cyclic shift and multiple-order discrete fractional cosine transform

In this paper, a color image encryption algorithm is designed by use of chaos-based cyclic shift and multiple-order discrete fractional cosine transform (MODFrCT). The RGB components of the color image are vertically combined and then simultaneously scrambled by chaos-based cyclic shift to make these three components affect each other. The scrambled RGB components are separately transformed with the MODFrCT, whose orders are determined by the Chirikov standard chaotic map. Based on chaotic inherent properties, the corresponding keys are highly sensitive. At the same time, the transmission of the cipher image is very fast since the DFrCT is a reality preserving transform. Simulation results proved the validity of the proposed algorithm.

Color image encryption based on the affine transform and gyrator transform

A color image encryption algorithm is designed by using the affine transform in the gyrator transform domains. The RGB components of the color image are converted into the real part and the imaginary part of a complex function by employing the affine transform. Subsequently the complex function is encoded and transformed in gyrator domain. The gyrator transform is performed twice to enhance the security of this encryption algorithm. The parameters in the affine transform and the gyrator transform are regarded as the key in the encryption algorithm. Some numerical simulations are made to test the validity and capability of the proposed color encryption algorithm.

Single-Channel Color Image Encryption Using the Reality-Preserving Fractional Discrete Cosine Transform in YCbCr Space

A novel single-channel color image encryption algorithm is proposed, which utilizes the reality-preserving fractional discrete cosine transform in YCbCr space. The color image to be encrypted is decomposed into Y, Cb, and Cr components, which are then separately transformed by Discrete Cosine Transform (DCT). The resulting three spectra sequences, obtained by zig-zag scanning the spectra matrices, are truncated and the lower frequency coefficients of the three components are scrambled up into a single matrix of the same size with the original color image. Then the obtained single matrix is encrypted by the fractional discrete cosine transform, which is a kind of encryption with secrecy of pixel value and pixel position simultaneously. The encrypted image is convenient for display, transmission and storage, thanks to the reality-preserving property of the fractional discrete cosine transform. Additionally, the proposed algorithm enlarges the key space by employing the generating sequence as an extra key in addition to the fractional orders. Simulation results and security analysis demonstrate the proposed algorithm is feasible, effective and secure. The robustness to noise attack is also guaranteed to some extent.

Color Image Encryption Algorithm Combining Compressive Sensing with Arnold Transform

A new color image encryption algorithm combining compressive sensing with Arnold transform is proposed, which can encrypt the color image into a gray image. Considering the dimensional reduction and random projection of compressive sensing, we utilize compressive sensing to encrypt and compress the three color components of color image simultaneously. The three encrypted and compressed color components’ dimensions are smaller than the original image, thus they can be grouped into a gray image, and then the gray image is scrambled by Arnold transform to enhance the security. The proposed algorithm can also be applied in the multiple-image encryption. The experimental results show the validity and the reliability of the proposed algorithm.

Color image security system based on discrete Hartley transform in gyrator transform domain

A novel color image encryption algorithm based on Arnold- and discrete Hartley transform in gyrator transform domain is proposed. In this method, a color image is segregated into red, green, and blue channels. Each channel is permutated by first Arnold transform operation and the spatial distribution of pixel value is changed by first discrete cosine transform at image plane. The resulting image is encoded by discrete Hartley transform. The encoded information is again permutated by second Arnold transform and the spatial distribution of pixel value is changed by second discrete cosine transform at frequency plane, and finally gyrator transform is executed. The period and iterative number of Arnold transform, and transformation angles of gyrator transform in each channel are main keys, which increase the security of the proposed system. The proposed method can be well protected under chosen- and known plaintext attacks. Numerical simulations are conducted to illustrate the security, validity, and feasibility of the proposed method.

Breaking a novel colour image encryption algorithm based on chaos

Recently, a colour image encryption algorithm based on chaos was proposed by cascading two position permutation operations and one substitution operation, which are all determined by some pseudo-random number sequences generated by iterating the Logistic map. This paper evaluates the security level of the encryption algorithm and finds that the position permutation-only part and the substitution part can be separately broken with only $\lceil (\log_2(3MN))/8 \rceil$ and 2 chosen plain-images, respectively, where $MN$ is the size of the plain-image. Concise theoretical analyses are provided to support the chosen-plaintext attack, which are verified by experimental results also.

A symmetric color image encryption algorithm using the intrinsic features of bit distributions

In recent years, a variety of chaos-based image encryption algorithms have been proposed. Most of them employ the confusion-diffusion architecture and operate at the pixel level. In this paper, we analyze the intrinsic features of the bit distributions, the high correlation among bit planes and other issues related to the bit information of an image. Due to the superior characteristics of bit-level operations and the intrinsic bit features of the image, an expand-and-shrink strategy is employed to shuffle the image with reconstructed permuting plane. Simulations have been carried out and the results demonstrate the superior security and high efficiency of the proposed scheme.

Novel color image encryption algorithm based on the reality preserving fractional Mellin transform

A nonlinear color image encryption algorithm based on reality preserving fractional Mellin transform (RPFrMT) is proposed. So far as image encryption is concerned, RPFrMT has two fascinating advantages: (1) the real-valued output of the transform ensures that the ciphertext is real which is convenient for display, transmission and storage; (2) as a nonlinear transform, RPFrMT gets rid of the potential insecurity which exists in the conventional linear encryption schemes. The original color image is first transformed from RGB color space to R′G′B′ color space by rotating the color cube. The three components of the output are then transformed by RPFrMT of different fractional orders. To further enhance the security of the encryption system, the result of the former step is scrambled by three dimensional scrambling. Numerical simulations demonstrate that the proposed algorithm is feasible, secure, sensitive to keys and robust to noise attack and occlusion. The proposed color image encryption can also be applied to encrypt three gray images by transforming the gray images into three color components of a specially constructed color image.

A fast color image encryption algorithm based on coupled two-dimensional piecewise chaotic map

In recent years, a variety of chaos-based image cryptosystems have been proposed. Owing to the exceptionally desirable properties of mixing and sensitivity to initial conditions and parameters of chaotic maps, chaos-based encryption has suggested a new and efficient way to deal with the intractable problem of fast and highly secure image encryption. This paper proposes a novel chaos-based image encryption algorithm to encrypt color images by using a Coupled Two-dimensional Piecewise Nonlinear Chaotic Map, called CTPNCM, and a masking process. Distinct characteristics of the algorithm are high security, high sensitivity, and high speed that can be applied in encryption of color images. In order to generate the initial conditions and parameters of the CTPNCM, 256-bit long external secret key is used. Computer simulations confirm that the new algorithm has high security and is very fast for practical image encryption. It is demonstrated that the number of pixel change rate (NPCR), the unified average changing intensity (UACI), and entropy can satisfy security and performance requirements (NPCR>0.99672, UACI>0.334904, Entropy>7.99921). Experimental results reveal the fact that the proposed algorithm yields better security performance in comparison to the results obtained from other algorithms.

A novel colour image encryption algorithm based on chaos

In this paper, a novel colour image encryption algorithm based on chaos has been proposed. We use chaotic system to encrypt the R, G, B components of a colour image at the same time and make these three components affect each other. So the correlations between R, G, B components can be reduced and the security of algorithm is increased. Simulation results show that the proposed algorithm can encrypt colour image effectively and resist various typical attacks.

A novel color image encryption algorithm based on DNA sequence operation and hyper-chaotic system

A new color image encryption algorithm based on DNA (Deoxyribonucleic acid) sequence addition operation is presented. Firstly, three DNA sequence matrices are obtained by encoding the original color image which can be converted into three matrices R, G and B. Secondly, we use the chaotic sequences generated by Chen's hyper-chaotic maps to scramble the locations of elements from three DNA sequence matrices, and then divide three DNA sequence matrices into some equal blocks respectively. Thirdly, we add these blocks by using DNA sequence addition operation and Chen's hyper-chaotic maps. At last, by decoding the DNA sequence matrices and recombining the three channels R, G and B, we get the encrypted color image. The simulation results and security analysis show that our algorithm not only has good encryption effect, but also has the ability of resisting exhaustive attack, statistical attack and differential attack.

Novel single-channel color image encryption algorithm based on chaos and fractional Fourier transform

A new color image encryption algorithm based on fractional Fourier transform (FrFT) and chaos is proposed. The colors of the original color image are converted to HSI (hue-saturation-intensity), and the S component is transformed by the random-phase encoding based on FrFT to obtain a new random phase. The I component is transformed by double random-phase encoding based on FrFT using the H component and the new random phase as two phase plates. Then chaos scrambling technology is used to encrypt the image, which makes the resulting image nonlinear and disorder both in spatial domain and frequency domain. Additionally, the ciphertext is not a color image but a combination of a gray image and a phase matrix, so the ciphertext has camouflage property to some extent. The results of numerical simulations demonstrate the effectiveness and the security of this algorithm.

Color image encryption by using Arnold transform and color-blend operation in discrete cosine transform domains

A color image encryption algorithm is designed by use of Arnold transform and discrete cosine transform (DCT). The RGB components of the color image are scrambled by Arnold transform at the aspect of pixel sequence. The scrambled RGB components are exchanged and mixed randomly under the control of a matrix defined by random angle. DCT is employed for changing the pixel values of color image. In this encryption scheme the operations mentioned above are performed twice continuously. The parameters of Arnold transform and the random angle serve as the key of the color image encryption method. Some numerical simulations are made to test the validity and capability of the color encryption algorithm.