There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

This work proposes a novel reversible data hiding scheme for encrypted image. After encrypting the entire data of an uncompressed image by a stream cipher, the additional data can be embedded into the image by modifying a small proportion of encrypted data. With an encrypted image containing additional data, one may firstly decrypt it using the encryption key, and the decrypted version is similar to the original image. According to the data-hiding key, with the aid of spatial correlation in natural image, the embedded data can be successfully extracted and the original image can be perfectly recovered.

Reversible Data Hiding in Encrypted Image

This work proposes a novel scheme for separable reversible data hiding in encrypted images. In the first phase, a content owner encrypts the original uncompressed image using an encryption key. Then, a data-hider may compress the least significant bits of the encrypted image using a data-hiding key to create a sparse space to accommodate some additional data. With an encrypted image containing additional data, if a receiver has the data-hiding key, he can extract the additional data though he does not know the image content. If the receiver has the encryption key, he can decrypt the received data to obtain an image similar to the original one, but cannot extract the additional data. If the receiver has both the data-hiding key and the encryption key, he can extract the additional data and recover the original content without any error by exploiting the spatial correlation in natural image when the amount of additional data is not too large.

Separable Reversible Data Hiding in Encrypted Image

This letter proposes an improved version of Zhang's reversible data hiding method in encrypted images. The original work partitions an encrypted image into blocks, and each block carries one bit by flipping three LSBs of a set of pre-defined pixels. The data extraction and image recovery can be achieved by examining the block smoothness. Zhang's work did not fully exploit the pixels in calculating the smoothness of each block and did not consider the pixel correlations in the border of neighboring blocks. These two issues could reduce the correctness of data extraction. This letter adopts a better scheme for measuring the smoothness of blocks, and uses the side-match scheme to further decrease the error rate of extracted-bits. The experimental results reveal that the proposed method offers better performance over Zhang's work. For example, when the block size is set to 8 8, the error rate of the Lena image of the proposed method is 0. 34%, which is significantly lower than 1.21% of Zhang's work.

An Improved Reversible Data Hiding in Encrypted Images Using Side Match

With the increasing importance of images in people’s daily life, content-based image retrieval (CBIR) has been widely studied. Compared with text documents, images consume much more storage space. Hence, its maintenance is considered to be a typical example for cloud storage outsourcing. For privacy-preserving purposes, sensitive images, such as medical and personal images, need to be encrypted before outsourcing, which makes the CBIR technologies in plaintext domain to be unusable. In this paper, we propose a scheme that supports CBIR over encrypted images without leaking the sensitive information to the cloud server. First, feature vectors are extracted to represent the corresponding images. After that, the pre-filter tables are constructed by locality-sensitive hashing to increase search efficiency. Moreover, the feature vectors are protected by the secure kNN algorithm, and image pixels are encrypted by a standard stream cipher. In addition, considering the case that the authorized query users may illegally copy and distribute the retrieved images to someone unauthorized, we propose a watermark-based protocol to deter such illegal distributions. In our watermark-based protocol, a unique watermark is directly embedded into the encrypted images by the cloud server before images are sent to the query user. Hence, when image copy is found, the unlawful query user who distributed the image can be traced by the watermark extraction. The security analysis and the experiments show the security and efficiency of the proposed scheme.

A Privacy-Preserving and Copy-Deterrence Content-Based Image Retrieval Scheme in Cloud Computing

In this paper a commutative watermarking and ciphering scheme for digital images is presented. The commutative property of the proposed method allows to cipher a watermarked image without interfering with the embedded signal or to watermark an encrypted image still allowing a perfect deciphering. Both operations are performed on a parametric transform domain: the Tree Structured Haar transform. The key dependence of the adopted transform domain increases the security of the overall system. In fact, without the knowledge of the generating key it is not possible to extract any useful information from the ciphered-watermarked image. Experimental results show the effectiveness of the proposed scheme.

A commutative digital image watermarking and encryption method in the tree structured Haar transform domain

A novel method for watermarking and ciphering color images, based on the joint use of a key-dependent wavelet transform with a secure cryptographic scheme, is presented. The system allows to watermark encrypted data without requiring the knowledge of the original data and also to cipher watermarked data without damaging the embedded signal. Since different areas of the proposed transform domain are used for encryption and watermarking, the extraction of the hidden information can be performed without deciphering the cover data and it is also possible to decipher watermarked data without removing the watermark. Experimental results show the effectiveness of the proposed scheme.

/pdf/joint-watermarking-and-encryption-of-color-images-in-the-34micdxruj.pdf

Joint watermarking and encryption of color images in the Fibonacci-Haar domain

In this paper a joint watermarking and ciphering scheme for digital images is presented. Both operations are
performed on a key-dependent transform domain. The commutative property of the proposed method allows to
cipher a watermarked image without interfering with the embedded signal or to watermark an encrypted image
still allowing a perfect deciphering. Furthermore, the key dependence of the transform domain increases the
security of the overall system. Experimental results show the effectiveness of the proposed scheme.

http://www.comlab.uniroma3.it/Marco/Articoli%20Battisti/A%20Joint%20Digital%20Watermarking%20and%20Encryption%20Method.pdf

A joint digital watermarking and encryption method

In this paper a novel method for watermarking and ciphering color images is presented. The aim of the system is
to allow the watermarking of encrypted data without requiring the knowledge of the original data. By using this
method, it is also possible to cipher watermarked data without damaging the embedded signal. Furthermore, the
extraction of the hidden information can be performed without deciphering the cover data and it is also possible
to decipher watermarked data without removing the watermark. The transform domain adopted in this work is the Fibonacci-Haar wavelet transform. The experimental results show the effectiveness of the proposed scheme.

http://www.comlab.uniroma3.it/Marco/Articoli%20Battisti/Watermarking%20and%20encryption%20of%20color%20images%20in%20the%20Fibonacci%20domain.pdf

Watermarking and encryption of color images in the Fibonacci domain

In this paper a novel, fast, and robust data hiding technique based on key-dependent basis functions is presented.
The particular domain chosen for the embedding is built on the Tree-Structured Haar basis. A weight
function, based on Human Visual System features, is used as a mask for selecting the coefficients to be marked.
Experimental results show the effectiveness of the proposed method.

Michela Cancellaro

Papers

A commutative digital image watermarking and encryption method in the tree structured Haar transform domain

Joint watermarking and encryption of color images in the Fibonacci-Haar domain

A joint digital watermarking and encryption method

Watermarking and encryption of color images in the Fibonacci domain

Perceptual data hiding in tree structured Haar transform domain