Reversible data hiding in encrypted images with separability and high embedding capacity

In this paper, a high-capacity reversible data hiding (RDH) scheme for encrypted images with separability is proposed. The image is first divided into non-overlapping blocks, and each block is encrypted with the same random value. The advantage is that the correlation between adjacent pixels can be preserved. Utilizing the preserved correlation, the prediction difference in encrypted domain is exactly the same as that of plaintext domain, so that the separability can be achieved. Without accessing the original image content, the data-hider can embed additional data into encrypted image through histogram shifting and difference expansion. At the receiving end, the embedded additional data and the original image can be recovered without any error in separable manner. Experimental results are presented to demonstrate the feasibility and efficiency of the proposed scheme.     

High-capacity reversible data hiding in encrypted image based on Huffman coding and differences of high nibbles of pixels

In this paper, we propose a new reversible data hiding method in encrypted images. Due to spatial correlation, there is a large probability that the adjacent pixels of the image have small differences, which is especially obvious on the high four most significant bits (high nibbles) of the pixels. If the high nibble of each pixel is regarded as a 4-bit value, the differences between the high nibbles of the adjacent pixels are mostly concentrated in a small range. Based on this fact, Huffman coding was used to encode all the differences between the high nibbles of the adjacent pixels in order to compress the four most significant bit (MSB) planes efficiently and create a large-capacity room. After creating room, a stream cipher is used to encrypt the image, and the room is reserved in the encrypted image for data hiding without losing information. The experimental results showed that the proposed method can achieve a larger embedding rate and better visual quality of the marked decrypted image than other related methods.     

Efficient reversible data hiding in encrypted images

This paper proposes a novel scheme of reversible data hiding in encrypted images based on lossless compression of encrypted data. In encryption phase, a stream cipher is used to mask the original content. Then, a data hider compresses a part of encrypted data in the cipher-text image using LDPC code, and inserts the compressed data as well as the additional data into the part of encrypted data itself using efficient embedding method. Since the majority of encrypted data are kept unchanged, the quality of directly decrypted image is satisfactory. A receiver with the data-hiding key can successfully extract the additional data and the compressed data. By exploiting the compressed data and the side information provided by the unchanged data, the receiver can further recover the original plaintext image without any error. Experimental result shows that the proposed scheme significantly outperforms the previous approaches.     

Separable reversible data hiding in encrypted image based on pixel value ordering and additive homomorphism

This work proposes a separable reversible data hiding scheme in encrypted images based on pixel value ordering (PVO). After the original image is encrypted using homomorphism encryption by the content owner, the data hider embeds the secret data in encrypted domain. The PVO strategy realizes hiding data in each block. Additive homomorphism guarantees the performance of PVO in encrypted domain is close to that in plain domain. Besides, the homomorphism encryption does not cause data expansion, and the payload can be further improved. With the watermarked encrypted image, if the receiver has only the data hiding key, he can extract the additional data. If the receiver has only the encryption key, he can obtain a decrypted image similar to the original one. If the receiver has both the data hiding key and the encryption key, he can extract the additional data without any error and recover the original image losslessly.     

A ROI-based reversible data hiding scheme in encrypted medical images

A novel ROI-based reversible data hiding scheme in encrypted medical images is proposed. Firstly, a content owner partitions an original medical image into the region of interest (ROI) and the region of noninterest (RONI), and then encrypts the image using an encryption key. A data-hider concatenates the least significant bits (LSB) of the encrypted ROI and Electronic Patient Record (EPR), and then embeds the concatenated data into the encrypted image by LSB substitution algorithm. With the encrypted medical image containing the embedded data, the receiver can extract the embedded data with the data-hiding key; if the receiver has the encryption key, a medical image similar to the original image can be obtained by directly decrypting the encrypted medical image; if the receiver has both the data-hiding key and the encryption key, the embedded data can be extracted without any error and ROI can be losslessly recovered after extracting the embedded data.     

Encrypted signal-based reversible data hiding with public key cryptosystem

Encrypted image-based reversible data hiding (EIRDH) is a well-known method allowing that (1) the image provider gives the data hider an encrypted image, (2) the data hider embeds the secret message into it to generate the encrypted image with the embedded secret message to the receiver, and (3) finally the receiver can extract the message and recover the original image without encryption. In the literature, the data hider and image provider must be specific parties who know the shared key with the receiver in traditional encrypted image-based reversible data hiding. In this paper, we propose an encrypted signal-based reversible data hiding (ESRDH) with public key cryptosystem, not only for images. The proposed scheme is secure based on Paillier homomorphic encryption. Finally, the experimental results show that the proposed scheme has much payload and high signal quality.     

High-capacity reversible data hiding in encrypted image based on specific encryption process

This paper proposes a novel reversible data hiding method in encrypted images based on specific encryption process. In the proposed specific encryption algorithm, the stream cipher and prediction error are combined to vacate room for data embedding. After that, a permutation operation is performed on the encrypted image to improve the security. In the embedding process, we can embed a large amount of secret data in the encrypted image by pixel value expansion because most of the pixel values are less than 128 by the specific encryption process. At the receiver end, the encrypted image can be recovered from the marked encrypted image without knowing the secret data. Therefore, even if the recipient only has the encryption key, the original image will be perfectly recovered. If the recipient only has the data-hiding key, the secret data will be extracted. And if the recipient has both keys, the original image and the secret data are both available. The proposed method achieves a higher embedding capacity than that of methods based on vacating room after encryption. It does not require the image owner to perform reversible data hiding techniques on the original image, which is more convenient than methods based on reserving room before encryption. Experimental results demonstrate that the proposed method outperforms other state-of-the-art methods.     

On the multi-level embedding of crypto-image reversible data hiding

Crypto-space reversible image steganography has attracted increasing attention, given its ability to embed authentication information without revealing the image content. This paper presents an efficient reversible data hiding scheme for crypto-images: a block predictor is applied to compute prediction errors, then an adaptive block mapping algorithm is utilized to compress them whose amplitudes are within a small threshold, finally, this strategy can be applied in a multi-level manner to achieve a higher embedding capacity. Due to the correlations among adjacent pixels in the block, images can be sufficiently compressed to reserve abundant space for additional data embedding. Different from the prior arts, the compression code of the image is fully encrypted. Experimental results verify that the embedded data and original image can be perfectly recovered, the security is higher compared with the state-of-the-arts, and a significant improvement in the average embedding rate is achieved on two large-scale image datasets.     

基于块容量标签的密文图像可逆数据隐藏方法

密文图像的可逆数据隐藏技术既能保证载体内容不被泄露,又能传递附加信息。本文提出了一种基于块容量标签(block capacity label, BCL)的高容量密文图像可逆数据隐藏算法。该方案在图像加密之前进行预处理,首先将图像分为两个区域：参考像素区域和预测像素区域。然后将预测像素区域分为不重叠的块,根据所提出的算法确定分块的BCL,在对图像进行加密之后嵌入BCL,生成加密图像;在秘密数据嵌入阶段,根据BCL和数据隐藏密钥嵌入秘密数据。实验测试了BOWS-2数据集,平均嵌入容量为3.806 8 bpp,与现有方法相比,该方法可以获得更高的秘密数据嵌入容量,并可以实现原始图像的完美重建。     

Improved joint reversible data hiding in encrypted images

This paper proposes an improved method of reversible data hiding in encrypted images (RDH-EI). Three parties constitute the proposed system: the image owner, the remote server and the recipient. To preserve privacy, an image owner encrypts the original image using a stream cipher algorithm and uploads the ciphertext to a remote server. On server side, a data-hider is allowed to embed additional message into the encrypted image using a swapping/shifting based algorithm. After downloading the marked encrypted image from the server and implementing the decryption, a recipient can extract the hidden messages and losslessly recover the original image. Experimental results show that the proposed method achieves a larger payload than the related works. Meanwhile, a limitation in the related works that few bits can be embedded into the encrypted medical images is also eliminated in the proposed method.     

基于编码压缩和加密的图像可逆信息隐藏算法

提出一种编码压缩和加密的图像可逆信息隐藏算 法。计算载体像素预测值与其像素值的差值, 对差值进行哈夫曼编码压缩,通过压缩数据和随机数据加密重构图像,得到载体数据。将哈 夫曼编码的码 表和秘密信息隐藏在载体数据中,实现信息隐藏。在载密数据中提取码表数据和秘密信息, 对加密压缩数 据进行解密,结合码表和预测方法恢复原始图像。实验结果表明,本文算法具有较大的隐藏 容量,不仅能 正确提取秘密信息,还能无损恢复原始图像。     

基于压缩感知的鲁棒可分离的密文域水印算法

为了满足密文域水印嵌入的需要,该文基于压缩感知技术,提出一种鲁棒可分离的密文域水印算法。首先,内容拥有者将图像进行不重叠分块,利用边缘检测手段划分重要块和非重要块。重要块用传统加密方式进行加密,非重要块用压缩感知技术进行加密,同时为水印嵌入留出一定空间,然后根据嵌入密钥,实现二值水印的密文嵌入。在接收端获取图像内容和水印的方式是可分离的,同时根据含水印的密文图像块的像素分布特性可重新判断块的属性,避免了传输块属性信息。此外,水印信息重复4次嵌入在密文图像的不同区域,保证了水印的鲁棒性。实验结果显示所提方案在抵抗适度攻击时具有鲁棒性和安全性。     

A Novel High Capacity Reversible Information Hiding Scheme Based on Side-Match Prediction and Shortest Spanning Path

In recent years, information hiding techniques have attracted increased attention owing to the growing demand for the ability to exchange large amounts of information. In addition, hiding information in compressed messages is very practical in improving transmission efficiency and saving large amounts of storage space. However, the damage caused by hiding data in compressed messages reduces image quality more than the damage caused by hiding data in uncompressed messages. Hence, this paper proposes a data hiding scheme based on side-match prediction and declustering techniques for vector quantization (VQ) compressed images. The appropriate side-match prediction not only embeds secret information into the VQ index but also reverses the original compressed index. In addition, the capacity for secret information can be varied adaptively depending on the requirements of different applications. As experimental results indicate, the proposed scheme indeed outperforms previous work in hiding capacity and in the image quality of stego-images.     

Reversible data hiding in encrypted color images using cross-channel correlations

In recent years, the increasing requirements in cloud storage and cloud computing have made it necessary to encrypt digital images for privacy protection. Meanwhile, many reversible data hiding (RDH) algorithms in the encrypted domain have been proposed. However, most of these algorithms are for gray-level images, and the intrinsic cross-channel correlations of color images cannot be utilized to improve the embedding capacity. In this paper, we propose a novel data hiding method for encrypted color images. In the encryption stage, the homomorphic property of encryption is achieved by basic modular addition. During the data hiding process, the cross-channel correlations between R, G and B channels are generated in encrypted domain, and data hiding is performed by the difference histogram shifting. Analysis and experiments demonstrate that the proposed method is secure and the RDH performance is superior.     

基于多项式秘密共享的图像密文域可逆信息隐藏

针对密文域可逆信息隐藏在多用户场景下算法嵌入率低、载体图像容灾性能较弱等问题，该文提出一种基于多项式秘密共享的图像密文域可逆信息隐藏方案。通过将图像分割成多幅影子图像并存储在不同的用户端，可以增强图像的容灾性，为了实现额外信息在图像重构前后提取的可分离性，该方案包括两种嵌入算法:算法1在图像分割的过程中，将额外信息嵌入多项式的冗余系数中得到含有额外信息的影子图像，该算法支持在图像重构之后提取额外信息；算法2针对图像分割后的任一影子图像，利用秘密共享的加法同态特性实施嵌入，该算法支持直接从影子图像中提取额外信息。实验在不同门限方案和影子图像压缩率的条件下进行测试，当压缩率为50%时，(3, 4)门限方案的嵌入率达4.18 bpp(bit per pixel)，(3, 5)门限方案的嵌入率达3.78 bpp。结果表明，两种嵌入算法分别支持从影子图像与重构图像中提取额外信息，实现了方案的可分离性；与现有方案相比，所提算法嵌入率较高、计算复杂度较低，具有较强的实用性。     

Grey-level image hiding scheme based on vector quantisation

A novel image hiding scheme capable of hiding multiple grey-level images into another grey-level cover image is proposed. To reduce the volume of secret images to be embedded, the vector quantisation scheme is employed to encode the secret images. The compressed message is then encrypted by the DES cryptosystem to ensure security. Finally, the encrypted message is hidden into the cover image using the greedy least significant bit substitution technique.     

Reversible data embedding for indices based on histogram analysis

Reversible data hiding is a technique that not only protects the hidden secrets but also recovers the cover media without any distortion after the secret data have been extracted. In this paper, a new reversible data hiding technique for VQ indices which are compressed streams based on the mapping function and histogram analysis of transformed VQ indices is introduced to enhance the performance of some earlier reversible data hiding schemes that are based on VQ indices. As a result, the proposed scheme achieves high embedding capacity and data compression simultaneously. Moreover, the original VQ-compressed image can be perfectly reconstructed after secret data extraction. To estimate the performance of the proposed scheme, variety of test images are used in the experimental testing. As can be seen in the experimental result, our scheme is superior to some previous schemes in term of compression rate and embedding rate while maintaining the reversibility.     

基于异或运算和图像融合的盲数字水印嵌入和检测方法

数字水印隐藏是将一个版权识别标志(水印信号)嵌入到图像中的技术。本文提出的一种新的隐藏水印的方法是将水印看作是二值图像,运用小波变换,异或运算,图像融合的方法以及中值滤波来隐藏和提取数字水印。这种方法的优点是不需要原始图像就可以提取出水印图像,可以加密码,对椒盐噪声,剪切攻击具有鲁棒性。     

Efficient multi-secret image sharing based on Boolean operations

(n,n) visual secret sharing (VSS), first proposed by Naor and Shamir (1995) [4], is used to encode (encrypt) a secret image into n meaningless share images to be superimposed later to decode (decrypt) the original secret by human visual system after collecting all n secret images. In recent years, VSS-based image sharing (encryption) and image hiding schemes, two of a variety of applications based on VSS, have drawn much attention. In this paper, an efficient (n+1,n+1) multi-secret image sharing scheme based on Boolean-based VSS is proposed to not only keep the secret images confidential but also increase the capacity of sharing multiple secrets. The Boolean-based VSS technology, used to encode the secret images, generates n random matrices; then the n secret images are subsequently encoded into the n+1 meaningless share images. It is worthwhile to note that n secret images can be hidden by means of sharing only n+1 share images in the proposed scheme instead of 2n share images. Thus, the present scheme thus benefits from (1) reducing the demand of image transmission bandwidth, (2) easing the management overhead of meaningless share images, and (3) involving neither significant extra computational cost nor distortion for reconstructed secret images. The experimental results show the performance in terms of feasibility and image sharing capacity. Applied into image hiding schemes, the proposed scheme can enhance the hiding capacity.     

High capacity reversible data hiding in encrypted images using SIBRW and GCC

In this paper, a reversible data hiding in encrypted images (RDHEI) method combining GCC (group classification encoding) and SIBRW containing sixteen image-based rearrangement ways is proposed to achieve high-capacity data embedding in encrypted images. Each way of SIBRW aims at bringing strongly-correlated bits of each higher bit-plane together by rearranging each higher bit-plane. For each higher bit-plane, the optimal way achieving the most concentrated aggregation performance is selected from SIBRW to rearrange this bit-plane, and then, GCC compresses the rearranged bit-plane in group-by-group manner. By making full use of strong-correlation between adjacent groups, GCC can compress not only consecutive several groups whose bits are valued 1 (or 0) but also a single group so that a large embedding space is provided. The encryption method including the bit-level XOR-encryption and scrambling operations enhances the security. The experimental results show that the proposed scheme can achieve large embedding capacity and high security.