Reversible data hiding in encrypted images

The objective of this research is to develop a novel image encryption method that can be used to considerably increase the security of encrypted images. To solve this image security problem, we propose a distributed homomorphic image encryption scheme where the images of interest are those in the visible electromagnetic spectrum. In our encryption phase, a red green blue (RGB) image is first separated into its constituent channel images, and then the numerical intensity value of a pixel from each channel is written as a sum of smaller pixel intensity sub-values, leading to having several component images for each of the R, G, and B-channel images. A homomorphic encryption function is used to separately encrypted each of the pixel intensity sub-values in each component image using an encryption key, leading to a distributed image encryption approach. Each of the encrypted component images can be compressed before transmission and/or storage. In our decryption phase, each encrypted component image is decompressed if necessary, and then the homomorphic property of the encryption function is used to transform the product of individually encrypted pixel intensity sub-values in each encrypted component images, to the encryption of their sum, before applying the corresponding decryption function with a decryption key to recover the original pixel's intensity values for each channel image, and then recovering the original RGB image. Furthermore, a special case of an RGB image encryption and decryption where a pixel's intensity value from each channel is written as a sum of only two sub-values is implemented and simulated with a software. The resulting cipher-images are subject to a range of security tests and analyses. Results from these tests shown that our proposed homomorphic image encryption scheme is robust and can resist security attacks, as well as increases the security of the associated encrypted images. Our proposed homomorphic image encryption scheme has produced highly secure encrypted images.

This paper proposes an image retrieval approach in encrypted images that are outsourced to the cloud network using LSB (Least significant bit) elimination based feature extraction. To preserve the privacy of the image that is outsourced to the cloud, the images are encrypted. Retrieving the encrypted images that are outsourced to cloud is considered as a challenging task. The proposed method eliminates the LS B’ $s$ , and the histogram is estimated to obtain the necessary features. Initially, the image owner encrypts the original image by using a key and uploads the encrypted image to the cloud. The cloud server extracts the features from the encrypted original image and stores the features in the cloud. To perform image retrieval, the user has to encrypt the Query image using a key, and it must be uploaded to the cloud. The cloud server extracts the features from the Query image and matches with the features that are already stored in the cloud server. The encrypted images correspond to the top-k matched features are returned to the user, from which the user has to decrypt it using the key. The performance of the proposed method was measured in terms of Precision, time of feature extraction, time of index construction and time of image retrieval. Experimental results reveal that the proposed feature extraction outperforms than the traditional methods.

Adaptive embedding combining LBE and IBBE for high-capacity reversible data hiding in encrypted images

With the extensive use of cloud services in different applications, it's a problem for the cloud service provider to manage or process the privacy data that are encrypted by the content owner. Therefore, signal processing technology in the encrypted domain has attracted the attention of researchers. In this paper, we propose a new reversible data hiding method for encrypted images based on two-phase histogram shifting. In the proposed method, the original image is encrypted by using special image division and additive homomorphic encryption. After image encryption, the encrypted image can partially maintain spatial correlation for data embedding while the content security of the encrypted image is ensured. Due to the spatial correlation, the data hider can generate two difference histograms from the encrypted image, which provide high embedding capacity. A two-phase histogram shift scheme is used to embed the secret data into the two difference histograms. At the receiver side, the secret data can be extracted from the encrypted image or the decrypted image, and the image can be recovered to its original version without any error. The experimental results demonstrated that the proposed method can efficiently improve the capacity of data embedding and outperform other related methods, while the visual quality of the marked image can be maintained.

Reversible Watermarking (RW) in encrypted images helps to reconstruct the original content and embedded data without distortion while protecting the owner’s privacy. The security and integrity of embedded data is very much demanding. In this paper, an efficient RW method is proposed that recovers the embedded data from the marked encrypted color palette images in the presence of attacks. In this method, embeddable color-triples are constructed by employing color partitioning. Next, the cryptographic SHA-256 hash and Bose–Chaudhuri–Hocquenghem (BCH) are applied over the secret information to ensure the authenticity and integrity. The hash authenticated secret data is embedded into the encrypted color palette image. The secret data is extracted using the separable color partitioning method and authenticated with cryptographic hash function. The proposed method has higher embedding capacity when compared to other relative schemes. The BCH codes helps to recover the secret data and cover image in the presence of noise and attacks.

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.

Protection to classified digital data becomes so important in avoiding data manipulation and alteration. The focus of this paper is in data and information protection of digital images form. Protection is provided in the form of encrypted digital image. The encryption process uses a new map, , which is called MS map. This paper will show: the results of digital image encryption using MS map and how the performance is regarding the average time needed for encryption/decryption process; randomness of key stream sequence with NIST test, histogram analysis and goodness of fit test, quality of the decrypted image by PSNR, initial value sensitivity level, and key space. The results show that the average time of the encryption process is relatively same as the decryption process and it depends to types and sizes of the image. Cipherimage (encrypted image) is uniformly distributed since: it passes the goodness of fit test and also the histogram of the cipherimage is flat; key stream, that are generated by MS map, passes frequency (monobit) test, and runs test, which means the key stream is a random sequence; the decrypted image has same quality as the original image; and initial value sensitivity reaches 10−17, and key space reaches 3.24 × 10634. So, that encryption algorithm generated by MS map is more resistant to brute-force attack and known plaintext attack.

Reversible data hiding in encrypted images using Pixel Shifting Approach (PSA)

Image encryption (IE) is a very useful and popular technology to protect the privacy of users. Most algorithms usually encrypt the original image into an image similar to texture or noise, but texture and noise are an obvious visual indication that the image has been encrypted, which is more likely to cause the attacks of enemy. To overcome this shortcoming, many image encryption systems, which convert the original image into a carrier image with visual significance have been proposed. However, the generated cryptographic image still has texture features. In line with the idea of improving the visual quality of the final password images, we proposed a meaningful image hiding algorithm based on prediction error and discrete wavelet transform. Lots of experimental results and safety analysis show that the proposed algorithm can achieve high visual quality and ensure the security at the same time.

Chaos and compressive sensing based novel image encryption scheme

Reversible data hiding in encrypted images using adaptive reversible integer transformation

With the convenient and rapid development of cloud storage, data privacy violations have become increasingly prominent. Reversible Data Hiding (RDH) can be used to embed additional data in encrypted data stored in the cloud. Most encrypted RDH algorithms are performed in uncompressed images and are not widely employed in popular JPEG images. Therefore, an effective RDH scheme in encrypted JPEG images is proposed in the paper. This algorithm first extracts the distribution characteristics of DCT coefficients, and chaotic encryption is utilized to encrypt the DC coefficients. Then the number of AC coefficients “0” is calculated in each DCT block to generate the embedded sequence in descending order. The paillier encryption and the homomorphic encryption is employed the multiplication feature to embed for the AC coefficient. During the embedding process, the range of the encrypted ciphertexts is determined according to the paillier parameter and the embedding threshold. It ensures that the ciphertexts do not out the range of the DCT coefficient while maintaining a small file increment. The experimental results show that the scheme effectively improves the data embedding capacity and image encryption quality compared to other state-of-the-art encrypted RDH schemed. The scheme also realizes the synchronization of data extraction between the ciphertext image and the original image. The experimental analysis further shows that this scheme has high embedding capacity and good image quality. The scheme can be applied to application scenarios with high embedded capacity and high-security requirements.KeywordsDCT coefficientChaotic encryptionPaillier homomorphic encryptionReversible data hiding

Many digital services require a reliable security for saving and sending images. Security of images has attracted the attention of many because of the rapid growth of the Internet in today's digital world. In this study a new combined model of encrypting images was used that is made of genetic algorithm and Mandelbrot algorithm. In the early proposed stages, by combining original image with built Mandelbrot algorithm a number of encrypted images were created and these images were used as initial population for the genetic algorithm in following stages. At each stage of the genetic algorithm the response of the previous iteration was optimized until we reach the best encrypted image. Also in our proposed method we can reach to the encrypted image from a reverse operation of genetic algorithm. The best encrypted image is an image with high entropy and low correlation coefficient. Considering the entropy and correlation coefficient that is obtained from our proposed method compared to other methods, our method had better results.

A novel compact image encryption system is proposed based on Arnold transformation (AT). In general, AT is a pixel-scramble tool in image encryption, but its security is not high enough as an independent cryptosystem because of its periodicity. Hence, extra diffusion operations are needed to diffuse the pixel values to acquire the higher security. Here an encryption algorithm is proposed by AT. Firstly, the corresponding coordinates of each pixel in original image are calculated by AT. Secondly, the pixel values of the two corresponding coordinates are disturbed by another AT. These two processes can diffuse the pixel values of the original image. At last, the diffused image is pixel scrambled by AT with different parameters. This is the confusion process. In proposed scheme, the diffusing and confusing operations are both realized by AT. At the same time, the image is encrypted as a pixel distribution instead of a data stream. The key space, key sensitivity, the correlation, the cost time and the security of proposed cryptosystem are analyzed and the results confirm that the proposed image encryption algorithm demonstrates extraordinary performance.

This paper proposes a scheme of separable reversible information hiding (RIH) for encrypted images (EIs) in which hidden information can be extracted from an EI carrying information without image decryption. The proposed scheme firstly encrypts an image and simultaneously prepares room for RIH by two permutation ways. Information are, then, hidden into the EI by a RIH technique, and the EI carrying information is sent to a receiver. According to keys which the receiver has, he/she is allowed to take seven different actions, whereas the conventional scheme offers only three. This feature of the proposed scheme extends applicable scenarios. Moreover, the proposed scheme always recover the original image, whereas the conventional scheme sometimes fails to do.