An Effective Color Image Encryption Based on Henon Map, Tent Chaotic Map, and Orthogonal Matrices

Secure image transmission is one of the most challenging problems in the age of communication technology. Millions of people use and transfer images for either personal or commercial purposes over the internet. One way of achieving secure image transmission over the network is encryption techniques that convert the original image into a non-understandable or scrambled form, called a cipher image, so that even if the attacker gets access to the cipher they would not be able to retrieve the original image. In this study, chaos-based image encryption and block cipher techniques are implemented and analyzed for image encryption. Arnold cat map in combination with a logistic map are used as native chaotic and hybrid chaotic approaches respectively whereas advanced encryption standard (AES) is used as a block cipher approach. The chaotic and AES methods are applied to encrypt images and are subjected to measures of different performance parameters such as peak signal to noise ratio (PSNR), number of pixels change rate (NPCR), unified average changing intensity (UACI), and histogram and computation time analysis to measure the strength of each algorithm. The results show that the hybrid chaotic map has better NPCR and UACI values which makes it more robust to differential attacks or chosen plain text attacks. The Arnold cat map is computationally efficient in comparison to the other two approaches. However, AES has a lower PSNR value (7.53 to 11.93) and has more variation between histograms of original and cipher images, thereby indicating that it is more resistant to statistical attacks than the other two approaches.

The majority of imaging techniques use symmetric and asymmetric cryptography algorithms to encrypt digital media. Most of the research works contributed in the literature focus primarily on the Advanced Encryption Standard (AES) algorithm for encryption and decryption. This paper propose an analysis for performing image encryption and decryption by hybridization of Elliptic Curve Cryptography (ECC) with Hill Cipher (HC), ECC with Advanced Encryption Standard (AES) and ElGamal with Double Playfair Cipher (DPC). This analysis is based on the following parameters: (i) Encryption and decryption time, (ii) entropy of encrypted image, (iii) loss in intensity of the decrypted image, (iv) Peak Signal to Noise Ratio (PSNR), (v) Number of Pixels Change Rate (NPCR), and (vi) Unified Average Changing Intensity (UACI). The hybrid process involves the speed and ease of implementation from symmetric algorithms, as well as improved security from asymmetric algorithms. ECC and ElGamal cryptosystems provide asymmetric key cryptography, while HC, AES, and DPC are symmetric key algorithms. ECC with AES are perfect for remote or private communications with smaller image sizes based on the amount of time needed for encryption and decryption. The metric measurement with test cases finds that ECC and HC have a good overall solution for image encryption.

Security of image data is essential during communication from various security attacks. This paper proposed a new technique for RGB color image encryption and decryption by the combination of shuffling and masking. The chaotic Baker map is used for first layer of image encryption by randomizing the pixels of each components of color image such as red, green and blue and then applying the diffusion process i.e. fractional dual random phase masks (FDRPM) technique which is applied on each component to increase the security level of given method. The order of Discrete Fractional Fourier Transform (DFRFT) act as a key for the process which provides extra degree of security to the proposed system. Matlab simulations are performed to check the security robustness of proposed scheme. Performance of proposed scheme is verified by noise analysis such as mean square error (MSE) and various differential analysis such as Unified Average Change Intensity (UACI) and Number of Pixels Change Rate (NPCR). Results of various analysis shows that the novel proposed encryption technique shows high efficiency and security for color images.

ABSTRACTRecently, in chaotic cryptography several new techniques have been suggested to develop efficient and secure image encryption algorithm for communication of image over insecure/public channels. Some of these techniques are computationally less complex but fails to provide sufficient security, and some techniques are though highly secured but increases computational overhead for encryption and decryption. This paper presents an efficient bit-plane encryption algorithm using chaotic, quadratic, and cubic maps. The proposed algorithm is based on the confusion, diffusion, and pixel randomisation processes. The encryption security of this technique for different bit-plane has been tested through key space analysis, statistical analysis, entropy analysis, and sensitivity analysis for real time image encryption and transmission. The presented algorithm shows the strength of security in terms of information entropy, peak signal-to-noise ratio (PSNR), number of pixels change rate (NPCR), unified average changing intensity (UACI), and correlation coefficient with the number of encrypted bit planes. It is clear that the strength of security increases with the number of encrypted bit planes, but the presented results demand that the level of security reached to the requirements (expected theoretically according to [C. Fu, et al., Optic Express, 20, 2363–78, Jan. 2012]) after encryption of four to six bit planes with reasonable small encryption/decryption time. This features proved the novelty of the proposed work. The algorithm is tested by the random and pseudo-random sequence of test standard SP 8000-22 released by National Institute of Standard and Technology Commission (NIST).

In today’s world of critical global connectivity, satellite communication plays a vital role for businesses, governments, and individuals. Key applications, including climate change monitoring, military surveillance, and real-time event broadcasting, heavily rely on transmitting image data rather than text. As a result, ensuring the secure transmission of images through efficient and robust encryption techniques has become a focal point of interest for both academia and industry. Image encryption is essential for securing sensitive visual data, protecting privacy, and making certain that only authorized users are able to access the required content. It prevents unauthorized access, tampering, and misuse of images, which is crucial for confidential and secure communications. The work in this paper develops a satellite image encryption scheme that employs a novel 1D Cosine Sinusoidal Chaotic (1DCSC) map, and two earlier proposed Sine-Tangent Chaotic (STC) and Improved Cosine Fractional Chaotic (ICFCM) maps, in conjunction with Deoxyribonucleic Acid (DNA) operations. The proposed scheme encrypts a given input image in four steps. In the initial step, 384-bit shared key and a 128-bit initial vector are used to create three different keys. In step two, three different chaotic sequences are produced using these keys and 1DCSC, STC, and ICFCM maps. These chaotic sequences chosen randomly to encrypt red, blue or green components of the given input image. In step three, these three chaotic sequences and the three components of the input image are DNA encoded. In the final step, DNA XOR based diffusion operation is applied between these DNA-encoded color image components and DNA encoded chaotic sequences to create green, red, and blue components of the cipher image. The proposed scheme obtains entropy value 7.9997, Unified Average Changing Intensity (UACI) value 33.32, and Number of Pixels Change Rate (NPCR) value 99.67%.

The security of information and digital images has become a major issue during the last three decades. A large number of algorithms for data and image encryptions are reported in the literature. However, many of the proposed algorithms are not suitable in the fields of application, because they are cryptographically weak. In the present work, a novel algorithm for encoding digital images by using a circle map with 3 parameters has been proposed. In this article different images are used for testing the validity of the proposed algorithm. The algorithm has increased the strength of security of the image encryption against cipher-text-only, chosen-plaintext and chosen-cipher-text attacks. The analysis of cryptographic strength has also been performed to confirm the fact. The results of several experimental tests, such as, key space analysis, key sensitivity analysis and statistical analysis show that the proposed algorithm for image cryptosystems provides an efficient and secure way for image encryption. A comparison in terms of correlation between the initial and transformed images, number of pixels change rate (NPCR) and unified average changing intensity (UACI) is also done. Keywords: Circle map, Chaos, Lyapunov exponent, anti-differential attack, NPCR, UACI.

The present scenario of the medical field is that sending the healthcare images through the internet is so far exposed to security threats. Hence, there is a need for an efficient and secure procedure to exchange healthcare images over the Internet. The Digital Image and Communication in Medicine (DICOM) provides security features for image header information but not for the pixel information. Hence to send the pixel information in a highly secured manner, the pixels need to be encrypted by using a suitable encryption algorithm. The number of pixel changing rate (NPCR) and the unified averaged changed intensity (UACI) are well-known encryption evaluation metrics to analyse the differential attack in image encryption. These two values are used to calculate the average number of pixel changes and intensity changes between two encrypted images before and after modifying any one pixel in a plaintext image respectively. If these two values are high, then the image encryption can resist the differential attacks. In this paper, a theoretical value of NPCR and UACI are computed for DICOM image encryption concerning different significant levels. An encryption algorithm with Gould transform, RC5, logistic map and DNA Diffusion is proposed for DICOM image to increase the NPCR, and UACI value and this method offered an efficient security strategy for DICOM pixel information. Finally, the computed theoretical value of NPCR and UACI are compared with the existing and proposed algorithm.

Image encryption has been an attractive research field in recent years. The chaos-based cryptographic algorithms have suggested some new and efficient ways to develop secure image encryption techniques. This paper proposes a novel image encryption scheme, which is based on the chaotic tent map. Image encryption systems based on such map show some better performances. Firstly, the chaotic tent map is modified to generate chaotic key stream that is more suitable for image encryption. Secondly, the chaos-based key stream is generated by a 1-D chaotic tent map, which has a better performance in terms of randomness properties and security level. The performance and security analysis of the proposed image encryption scheme is performed using well-known ways. The results of the fail-safe analysis are inspiring, and it can be concluded that the proposed scheme is efficient and secure.

Image encryption is an evolving technique in the arena of data communication. In the last decade, many encryption schemes have been suggested. Unfortunately, most of the current schemes are unable to maintain a balance between security and computational complexity. To overcome this challenge, this paper introduces a novel encryption scheme that effectively maintains the trade-off between security and computational complexity. Initially, the plain image is randomized and scrambled by the Logistic map and Arnold’s scrambling technique. The intermediate image found above, is then encrypted by the special word-oriented feedback shift register (wfsr) to get the final cipher image. Wfsr is inherently suitable for high-quality pseudorandom number generation with good statistical properties. It usually posses high throughput. Further, the elliptic curve Diffie-Hellman (ECDH) is used for sharing the keys required for encryption and decryption process. The performance of the proposed cryptosystem is evaluated based on several statistical properties of the cipher image, the resistance of the cipher image to various attacks, and time required for encryption and key sharing process. The statistical properties of the encrypted image are found out through histogram analysis, correlation and entropy finding, key sensitivity analysis, chi-square test, and NIST randomness test. The resistance of the encrypted image to various attacks is either found out experimentally or indirectly by using metrics like Unified Average Changing Intensity (UACI), Number of Pixel Changing Rate (NPCR). The proposed encryption method compares favorably with similar image encryption schemes.

Optimized Chaotic encrypted image based on continuous raster scan method

Recently, there is an increasing demand for efficient and secure transreception of medical images in telemedicine applications. Though a fixed spectrum is allocated to each user, most of the time it remains unused by the concerned user. Cognitive Radio (CR) is a technology that utilizes the unused spectrum efficiently by adopting spectrum sensing concept. This paper proposes an efficient and secure transmission of medical images by adopting CR technology and image encryption technique. Firstly, the novel medical image encryption algorithm is proposed to encrypt the DICOM (Digital Imaging and Communications in Medicine) image effectively. Then, the spectrum sensing technique is carried out via Universal Software Radio Peripheral (USRP) to sense the unused frequency band to transmit the encrypted bio signal. The proposed encryption algorithm combines DNA (Deoxyribo Nucleic Acid) sequence operation and chaotic maps to successfully encrypt the DICOM image pixels. Experimental results are done and various analysis such as Unified Average Changing Intensity (UACI), Number of Pixel Changing Rate (NPCR), entropy estimation and chi-square tests are carried out to validate the sternness of the encryption algorithm.

In this paper, a cryptosystem is proposed to encrypt 16-bit monochrome DICOM image using enhanced chaotic economic map. A new enhanced chaotic economic map (ECEM) is designed from the chaotic economic map which has better bifurcation nature and positive Lyapunov exponent values. In order to improve the sternness of the encryption algorithm, the enhanced chaotic map is employed to generate the pixel permutation, masking, and swapping sequences. The substitution operation is introduced in-between the standard permutation and diffusion operations. The robustness of the proposed image encryption algorithm is measured by various analyses such as histogram, key sensitivity, key space, number of pixel change rate (NPCR), unified average change intensity (UACI), information entropy and correlation coefficient. The results of the security analyses are compared with existing algorithms to validate that the proposed algorithm is better in terms of larger key space to resist brute force attacks and other common attacks on encryption.

A wrist-based photoplethysmography (PPG) tool offers a simple and non-invasive approach for applications in vital sign monitoring and healthcare. However, in a telecare network, these physiological signals ensure the authorisation demands for the domain of medical applications. Hence, this study proposes an intelligent method for PPG signal encryption and decryption. This method combines chaotic map and radial basis function network (RBFN) into symmetric cryptography with an adaptive scheme. The sine-power chaotic map is used as a key generator of 256 non-ordered numbers (key space) to set the private cipher codes. Two RBFNs are used to train an encryptor and a decryptor with the authorised cipher codes. Its substitution-based infosecurity scheme can change the numerical values of PPG raw data for each encrypted communication, and the decrypted PPG data are further applied for time- and frequency-domain analyses in clinical applications, such as heart and respiration rate analysis and arterial stiffness and upper extremity vascular disease evaluations. Through experimental results, the security levels are validated using the number of pixel change rate (NPCR), unified averaged changed intensity (UACI), and correlation analysis. The average NPCR, UACI, and correlation coefficient (CC) are 96.57%, 35.43%, and 0.005, respectively, between the plain PPG and the encrypted PPG data against hacker attacks. The larger-the-better of NPCR and UACI indexes and the smaller-the-better of CC index are obtained to evaluate the efficiency of the proposed cryptography method. The encrypted PPG also guarantees physiological signals of good quality in clinical applications. In addition, the performance of RBFN-based method is superior in adaptive learning capability than that of the traditional learning method in real-time applications.

The widespread use of images, especially color images and rapid advancement of computer science, have led to an emphasis on securing these images and defending them against intruders. One of the most popular ways to protect images is to use encryption algorithms that convert data in a way that is not recognized by someone other than the intended user. The Advanced Encryption Standard algorithm (AES) is one of the most protected encryption algorithms. However, due to various types of theoretical and practical assaults, like a statistical attack, differential analysis, and brute force attack, its security is under attack.
 In this paper, a modified AES coined as (M-AES) is proposed to improve the efficiency of the AES algorithm by increasing the algorithm's security to make the algorithm more suitable for color image encryption, and make it more resistant to many attacks. The modification is conducted on ShiftRows transformation of the original AES algorithm. To test the efficiency of the proposed M-AES algorithm, several images are drawn from the Signal and Image Processing Institute's (SIPI) image dataset. Moreover, the Mean Square Error (MSE), Peak Signal-to-Noise Ratio (PSNR), Entropy (H), Correlation Coefficient (CC), visual evaluation of histogram, Number of Pixels Change Rate (NPCR) and Unified Average Changing Intensity (UACI) are used as an evaluation metric. The results show that proposed modification to the AES algorithm makes the algorithm more appropriate to image and surpasses the original AES. 
 The modification is conducted on ShiftRows step of the original AES algorithm. To test the efficiency of the proposed M-AES algorithm, several images are drawn from the signal and image processing institute's (SIPI) image dataset. Moreover, the mean square error (MSE), peak signal-to-noise ratio (PSNR), entropy (H), correlation coefficient (CC), visual evaluation of histogram, number of pixels change rate (NPCR) and unified average changing intensity (UACI) are used as an evaluation metrics. The results show that the suggested modification to AES makes it's more appropriate to the image and surpasses the original AES.

A novel image encryption scheme using both pixel level and bit level permutation with chaotic map