Single-channel Color Image Encryption Research Articles

Optical single-channel color image encryption based on chaotic palmprint phase masks

Optical single-channel color image encryption based on chaotic palmprint phase masks

Optical single-channel color image encryption based on chaotic fingerprint phase mask anddiffractive imaging.

An optical single-channel color image encryption scheme based on chaotic fingerprint phase mask and diffractive imaging is proposed. In this proposed encryption scheme, the fingerprint used to generate therandom phase masks is served as a secret key directly. Additionally, the random phase masks generated by the fingerprint, chaotic Lozi map, and secure hash algorithm (SHA-256) are used only as interim variables. With the help of the chaotic fingerprint phase masks placed at different diffraction distances, the color image that is encoded into a grayscale pattern by the phase-truncation technique is encrypted into a noise-like diffraction pattern. For decryption, the color image can be retrieved from the noise-like diffraction pattern by using an iterative phase retrieval algorithm, fingerprint, and phase keys generated from the encryption process. Since the fingerprint key shared by the sender and authorized receiver is strongly linked with the user and does not need to be transmitted over the open network, the security of this proposed encryption scheme can be greatly improved. Additionally, the parameters of the chaotic Lozi map and Fresnel diffraction distances can also provide additional security to the proposed encryption scheme. Furthermore, compared with the encryption schemes based on digital holography, the implementation of this proposed encryption scheme is relatively simple. The numerical simulations and analysis verify the feasibility, security, and robustness of this proposed encryption scheme.

Real single-channel color image encryption method based on computational ghost imaging

A real single-channel color image encryption method based on computational ghost imaging is proposed. Compared with the currently proposed color single-channel encryption scheme, the method does not decompose the color image into three gray-scale images or encode it into a grayscale image for encryption. Instead, the color speckle patterns are used as the key to directly encrypt. The ciphertext is a grayscale image and thus has camouflage properties to a certain extent. Furthermore, the optical encryption setup is easy to be implemented and the key is generated by a chaotic system, which not only guarantees security but also reduces the volume of key transmission. The feasibility and high security of this method are supported by both computer simulations and optical experiments.

Optical single-channel color image cryptosystem based on vector decomposition and three-dimensional chaotic maps.

We propose an optical single-channel color image cryptosystem based on vector decomposition and three-dimensional (3D) chaotic maps. In the proposed cryptosystem, the color image is first decomposed into R, G, and B channels, and then the three channels are individually scrambled by a generalized Arnold transform. Subsequently, the scrambled channels are phase encoded and then synthesized into one vector. The synthesized vector is used as the input image of the double random phase encoding (DRPE) in the gyrator domain. The introduction of the vector decomposition enables the cryptosystem to realize single-channel color image encryption, and the first phase mask of DRPE acts as the main secret key when the input image is a non-negative amplitude-only map. In addition, the phase masks of DRPE are generated by a 3D logistic map, which can facilitate the update, management, and transmission of the phase keys. Numerical simulation results demonstrate that the proposed cryptosystem is robust against various attacks and outperforms the other relevant cryptosystems. Furthermore, the proposed cryptosystem can be directly extended to encrypt multiple color images.

基于柱面衍射和彩色空间转换的单通道彩色图像加密

基于柱面衍射和彩色空间转换的单通道彩色图像加密

An asymmetric single-channel color image encryption based on Hartley transform and gyrator transform

A novel asymmetric single-channel color image encryption using Hartley transform and gyrator transform is proposed. A color image is segregated into R, G, and B channels and then each channel is independently Hartley transformed. The three transformed channels are multiplied and then phase- and amplitude truncated to obtain first encrypted image and first decryption key. The encoded image is modulated with a conjugate of random phase mask. The modulated image is gyrator transformed and then phase- and amplitude truncated to get second encrypted image and second decryption key. The asymmetric (decryption) keys, random phase mask, and transformation angle of gyrator transform serve as main keys. The optoelectronic encryption and decryption systems are suggested. Numerical simulation results have been demonstrated to verify the performance and security of the proposed security system.

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.

Single-channel color image encryption using phase retrieve algorithm in fractional Fourier domain

A single-channel color image encryption is proposed based on a phase retrieve algorithm and a two-coupled logistic map. Firstly, a gray scale image is constituted with three channels of the color image, and then permuted by a sequence of chaotic pairs generated by the two-coupled logistic map. Secondly, the permutation image is decomposed into three new components, where each component is encoded into a phase-only function in the fractional Fourier domain with a phase retrieve algorithm that is proposed based on the iterative fractional Fourier transform. Finally, an interim image is formed by the combination of these phase-only functions and encrypted into the final gray scale ciphertext with stationary white noise distribution by using chaotic diffusion, which has camouflage property to some extent. In the process of encryption and decryption, chaotic permutation and diffusion makes the resultant image nonlinear and disorder both in spatial domain and frequency domain, and the proposed phase iterative algorithm has faster convergent speed. Additionally, the encryption scheme enlarges the key space of the cryptosystem. Simulation results and security analysis verify the feasibility and effectiveness of this method.

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.

Single-channel color image encryption based on iterative fractional Fourier transform and chaos

A single-channel color image encryption is proposed based on iterative fractional Fourier transform and two-coupled logistic map. Firstly, a gray scale image is constituted with three channels of the color image, and permuted by a sequence of chaotic pairs which is generated by two-coupled logistic map. Firstly, the permutation image is decomposed into three components again. Secondly, the first two components are encrypted into a single one based on iterative fractional Fourier transform. Similarly, the interim image and third component are encrypted into the final gray scale ciphertext with stationary white noise distribution, which has camouflage property to some extent. In the process of encryption and description, chaotic permutation makes the resulting image nonlinear and disorder both in spatial domain and frequency domain, and the proposed iterative fractional Fourier transform algorithm has faster convergent speed. Additionally, the encryption scheme enlarges the key space of the cryptosystem. Simulation results and security analysis verify the feasibility and effectiveness of this method.

Single-channel color image encryption using a modified Gerchberg–Saxton algorithm and mutual encoding in the Fresnel domain

A single-channel color image encryption is proposed based on the modified Gerchberg-Saxton algorithm (MGSA) and mutual encoding in the Fresnel domain. Similar to the double random phase encoding (DRPE), this encryption scheme also employs a pair of phase-only functions (POFs) as encryption keys. But the two POFs are generated by the use of the MGSA rather than a random function generator. In the encryption process, only one color component is needed to be encrypted when these POFs are mutually served as the second encryption keys. As a result, a more compact and simple color encryption system based on one-time-pad, enabling only one gray cipheretext to be recorded and transmitted when holographic recording is used, is obtained. Moreover, the optical setup is lensless, thus easy to be implemented and the system parameters and wavelength can be served as additional keys to further enhance the security of the system. The feasibility and effectiveness of the proposed method are demonstrated by numerical results.

Single-channel color image encryption based on asymmetric cryptosystem

A single-channel color image encryption is proposed based on asymmetric cryptosystem. The color components respectively multiplied with three random phase encryption keys are first combined into one gray image using convolution for further encoding into a real-value gray ciphertext with the asymmetric cryptosystem. Then four decryption keys, which are different from encryption keys and generated in the encryption process, can be used for image decryption. As a result, a more compact and robust system, permitting a real-value gray ciphertext to be transmitted, has been obtained. The feasibility and effectiveness of the proposed method are demonstrated by numerical results.

Color image encryption based on joint fractional Fourier transform correlator

In this paper, an optical color image encryption/decryption technology based on joint fractional Fourier transform correlator and double random phase encoding (DRPE) is developed. In this method, the joint fractional power spectrum of the image to be encrypted and the key codes is recorded as the encrypted data. Different from the case with classical DRPE, the same key code was used both in the encryption and decryption. The security of the system is enhanced because of the fractional order as a new added key. This method takes full advantage of the parallel processing features of the optical system, and could optically realize single-channel color image encryption. The experimental results indicate that the new method is feasible.

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.

基于联合分数变换相关器和相位恢复算法的全相位彩色图像加密

A novel fully phase color image encryption/decryption scheme based on joint fractional Fourier transform correlator (JFRTC) and phase retrieval algorithm (PRA) is proposed. The security of the system is enhanced by the fractional order as a new added key. This method takes full advantage of the parallel processing features of the optical system and could optically realize single-channel color image encryption. The system and operation procedures are simplified. The simulation results of a color image indicate that the new method provides efficient solutions with a strong sense of security.

Color image encryption using double random phase encoding

A new encryption technique is proposed to encrypt color images using existing optical encryption systems for gray-scale images. The color images are converted to their indexed image formats before they are encoded. At the decryption end, the color images are recovered by converting the decrypted indexed images back to their RGB formats. The proposed single-channel color image encryption method is more compact and robust than the multichannels methods. Since color information is added to the shape information, better verification performance can be achieved in optical security systems. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 318–323, 1999.