This article proposes a novel approach of improvising the cryptographic features of substitution-boxes (S-Box) based on the Choquet Fuzzy Integral (CFI) and DNA techniques. First, we propose a strong structure for the construction of four S-Boxes using CFI. The key for generating the CFI based (FZ) S-Boxes consists of two parts, namely, an external secret key and a secret image. Each of these FZ S-boxes is then encoded using DNA techniques, with dynamic rules selection which is dictated by a secret control code. The resultant four S-boxes are designated as DNAFZ S-Boxes. To apply for image encryption, the plain image is, at first 8-bit binary-coded, shuffled by an M-sequence, and down-sampled into four sub-images. Subsequently, the pixel values of each sub-image are replaced with the corresponding values of one of the four DNAFZ S-Boxes. Next, each DNAFZ encoded sub-image is diffused with a different DNA encoded chaotic sequence from Chen’s hyper-chaotic map. Finally, the four DNAFZ/Chaotic encoded sub-images are combined to build the final encrypted image. The proposed DNAFZ S-boxes shows excellent statistical properties under majority logic criterions such as correlation, homogeneity, energy, entropy, and contrast. Moreover, numerical simulation is used to examine the efficacy of encrypted images against different attacks. In particular, the values of the pixel correlation coefficient are found to be quite small either horizontally, vertically, or diagonally (between 7.8597e-04 and 0.00527, between 8.7856e-04 and 0.00452, and between 0.00241 and 0.00021, respectively). In addition, the information entropy of the encrypted image is found to be within the range of (7.9965:7.9989) which is very near to the ideal value of 8. As for the UACI and the NPCR, they are in the ranges between 33.46 and 33.32 and between 99.58 and 99.62, respectively. These values are also very close to the optimum ones. The results are compared to those of other encryption algorithms and proved that the proposed encryption method delivers better results than other conventional ones including LSS chaotic map, Arnold transforms, Dynamic Henon map, Hybrid chaotic map optimized substitution, and cubic S-Box.

Image encryption and steganography techniques are receiving a lot of interest and investigations due to their high importance in multimedia communication systems. A novel highly efficient image encryption and steganography technique are presented in this paper. For the first time, the proposed technique uses hybrid DNA encoding and Choquet’s Fuzzy Integral sequences. At first, a confused version of the image, using a simple chaotic map, is encoded using DNA’s bases. Four coded images are generated using the four DNA bases, namely AT, CG, GC, and TA. Parallel to that, a Choquet’s fuzzy Integral sequence is generated and DNA encoded similarly to obtain four pseudo-random sequences. Secondly, the resulting four fuzzy/DNA sequences are used to diffuse the four DNA encoded images using the complementary DNA XOR rule, according to certain control code. Finally, the wavelet fusion algorithm is then used to fuse the resulting four fuzzy-DNA encoded images, to get the encrypted image. For added security, a new steganography approach is used. In particular, the encrypted image is divided into four sub-images, each of which is hidden in a different carrier image selected from a known group of carrier images according to a given key. The simulation results and security analysis confirmed the efficiency of the proposed image encryption algorithm as well as the steganography approach used for enhanced security. Ten different images with a size of 256 ×256 are used to test the proposed method. The results show that the proposed algorithm has a higher key sensitivity. The pixel correlation coefficient values are very small (between 5.3220e-04 and 0.0011 horizontally, between 8.7670e-04 and 0.0022 vertically and between 0.0002 and 0.0045 diagonally). Furthermore, the measured information entropy of the encrypted images is between 7.9970 and 7.9979 which are very close to the ideal value of 8. Additionally, the measured unified average changing intensity and number of pixels change rate values take the values between 33.46 and 33.39 and between 99.61 and 99.64, respectively, which are again closed to the ideal values. The steganography test shows that the hidden encrypted images are almost invisible at high values of SNR and are characterized by good NCC values under different types of attacks. The performance of the new proposed algorithm is proved to overcomes many other previously published image encryption techniques.

Free Space Optics (FSO) has emerged as a viable solution to meet the growing demand for high bandwidth, secure data transmission, and high speed. However, the FSO system is highly susceptible to environmental factors, with precipitation in particular having a significant impact on FSO links. Optical loss, phase fluctuation, and multipath fading of the received optical power are all caused by these external factors. From this perspective, to improve the system’s performance in such conditions, a novel image encryption technique based on the Choquet Fuzzy Integral (CFI) in conjunction with the integer wavelet transform is proposed. The security of the proposed method is demonstrated via analysis security on the one, and its efficacy in terms of transmission performance of an encrypted image over an FSO channel exposed to rainy weather conditions is analyzed on the other. Authentic meteorological data from two distinct cities are considered to demonstrate the model’s real-world applicability: Alexandria, Egypt, in Africa, and Jeddah, Kingdom of Saudi Arabia (KSA), in Asia. To evaluate the system’s performance, a variety of metrics such as FSO range, Signal-to-Noise Ratio (SNR), Peak Signal-to-Noise Ratio (PSNR), and the Structural Similarity Index Method (SSIM) are used. Furthermore, the findings from studying the impact of weather conditions reveal that, as the intensity of rainfall increases, the encrypted image experiences a reduction in its propagation range within the FSO channel. For example, under heavy rain (HR) conditions, the maximum FSO range for high-quality received encrypted images is 1055 m, which extends to 2290 m as rain intensity decreases (for light rain). In terms of the two cities, Jeddah, with its lower average rainfall intensity compared to Alexandria, allows the encrypted image to travel an additional 2400 m.

This study introduces a novel image cryptosystem designed to improve security and reliability within underwater optical wireless communication (UOWC) systems particularly for water bodies that exhibits higher absorption and scattering coefficients. An image encryption scheme, characterized by high security, and consists of a chaotic iteration of dragon fractal shapes (ChDrFr). The system performance is assessed across five distinct water types, each exhibiting unique optical properties. For enhancing the quality of encrypted images received, median and high-pass filters are utilized. To test the ability of this new algorithm to ward off different types of attacks, numerical simulation is applied. Specifically, a correlation coefficient of approximately zero is witnessed between the original images and those generated by encryption. The optimum values for information entropy and unified average changed intensity (UACI) are almost reached for the encrypted images. A comparison is undertaken between different encryption methods and the one proposed in this paper, depending on ChDrFr. Results show that the proposed encryption scheme yields better results and achieves much securer encrypted images, when compared to the images encrypted by other encryption algorithms. Additionally, the encrypted images show enhancement in the underwater transmission distance with 6% for Pure Sea (PS) and Clear Ocean (CL), 4% for Coastal Sea (CS), 0.9% for Harbor I (HI), and 0.8% for Harbor II (HII). Moreover, the utilization of filters results in improvement in the Structured Similarity Index (SSIM), Peak-Signal-to-Noise-Ratio (PSNR), and Signal-to-Noise-Ratio (SNR).

This paper proposes a new cipher image transmission system in free space optics system (FSO). A secure and effective image cryptosystem algorithm based on the Choquet fuzzy integral (CFI) technique and the integer wavelet transform is utilized. Numerical simulations are conducted to examine the efficacy of encrypted images against different attacks. The pixel correlation coefficient is found to be quite small for horizontally, vertically, and diagonally in the ranges 2.0557×10 ^-4 to 0.00057, 9.0256×10 ^-4 to 0.0045, and 0.00035 to 0.00342, respectively. Additionally, the information entropy of the encrypted image is found to be within the range of 7.9991:7.9972, which is very close to the ideal value of 8. As for the unified average changing intensity (UACI) and the number of pixel change rate (NPCR) metrics, they are in the ranges 33.46 to 33.42 and 99.58 to 99.63, respectively, which are also very close to the optimum values. Median and high pass filters are employed for further enhancing the received decrypted image. Different fog conditions are considered during the transmission of the encrypted image over FSO channel. The signal to noise ratio (SNR), FSO propagation range, and structured similarity index method (SSIM) are metrics used for performance evaluation. The results indicate that images transmitted with ciphering exhibit better performance than plain images. The maximum FSO spans over which the image can propagate in the channel while maintaining good quality are 1790 m, 1198 m, and 947 m under light fog (LF), medium fog (MF), and heavy fog (HF), respectively. In contrast, these ranges extend to 1798 m (LF), 1206 m (MF), and 953 m (HF) with good visual quality when ciphered images are transmitted. Furthermore, the employed enhancement technique demonstrates improvements in SNR and SSIM values for the received images. For instance, when the original image is transmitted in an FSO channel affected by MF, the SNR is -21 dB. This value significantly improves to 12.6 dB when median and high pass filters are applied for enhancement. In addition, the SSIM value goes from 0.18 for the original image to 0.29 when enhancement techniques like median and high pass filters are used at a 1206 m FSO range in MF weather. Consequently, the proposed encrypted image transfer improves image quality. This advancement can be attributed to the CFI encryption algorithm’s rigorous security mechanisms, which assure data safety as it travels through the atmosphere.