Original Secret Image Research Articles

ENGLISH

Visual Cryptography is a special type of encryption technique to obscure image-based secret information which can be decrypted by Human Visual System. There have various approaches developed for encrypting image. The former being encrypting the images through encryption algorithms using keys, and the later approach involves dividing the image into random shares without the use of keys. But unfortunately there has heavy computation cost and key management and the poor quality of the recovered image from the random shares limit the applications. In this paper we propose a novel approach with the use of random share and key share. The approach employs generating two shares of the original image. One random share and the other key share. The original secret image can be recovered from the two shares simply by Xoring the two shares without any loss of image quality.

Data Hiding Method Replacing LSB of Hidden Portion for Secret Image with Run-Length Coded Image

Data hiding method based on steganography improving secret image invisibility through replacing Least Significant Bit: LSB with run-length coded Image is proposed. Although, the proposed method is based on Discrete Wavelet Transformation: DWT, run-length coded secrete image is embedded in the LSB of the high frequency component before reconstruction of the image for opening to the public for improvement of the secrete image invisibility. Before embedding the coded secret image, the coded secret image bits are rearranged the order by using random number. Therefore, secret image invisibility is much improved. Through experiments, it is confirmed that secret images are almost invisible in distribute images. Data hiding performance in terms of invisibility of secret images which are embedded in distribute images is evaluated with the Peak Signal to Noise Ratio: PSNR and the Root Mean Square: RMS difference between the original secret image and extracted one from the distribute images. Meanwhile the conventional Multi-Resolution Analysis: MRA based data hiding is attempted with a variety of parameters, level of MRA and the frequency component location of which secret image is replaced to it and is compared to the proposed method. It is found that the proposed data hiding method is superior to the conventional method.

Sharing a Large Secret Image Using Meaningful Shadows Based on VQ and Inpainting

This paper proposes a novel progressive secret image-hiding scheme based on the inpainting technique, the vector quantization technique (VQ) and the exploiting modification direction (EMD) technique. The proposed scheme first divides the secret image into non-overlapping blocks and categorizes the blocks into two groups: complex and smooth. The blocks in the complex group are compressed by VQ with PCA sorted codebook to obtain the VQ index table. Instead of embedding the original secret image, the proposed method progressively embeds the VQ index table into the cover images by using the EMD technique. After the receiver recovers the complex parts of the secret image by decoding the VQ index table from the shadow images, the smooth parts can be reconstructed by using the inpainting technique based on the content of the complex parts. The experimental results demonstrate that the proposed scheme not only has the advantage of progressive data hiding, which involves more shadow images joining to recover the secret image so as to produce a higher quality steganography image, but also can achieve high hiding capacity with acceptable recovered image quality.

A Novel XOR-based Visual Secret Sharing Scheme with Random Grid

The basic concept of secret image sharing is to encrypt a secret image into a number of meaningless share images. Except for all the images, no information should leak out from any of the share images. The original secret image is printed onto transparencies, and stacking these transparencies directly reveals the original image. The advantage lies in the fact that no computational cost is encountered, and only the human visual system is required to decode the secret image. The visual secret sharing scheme is to encrypt a secret image into a set of share images to increase the encryption capacity. However, the schemes available use a codebook, and used pixel expansion to encrypt secret images into share images. In general, pixel expansion of twice the original order is seen. It is neither practical nor the best solution when secret images are more in number. This paper proposes a novel visual secret sharing scheme that can share a binary secret image on two share images with no codebook requirement. The experimental result reveals that the proposed approach has high contrast and also has an excellent recovery quality of the secret image. The recovered secret image type is lossless.

A New Simple Non-Expansion Algorithm for (2,2) - Visual Secret Sharing Scheme

Visual cryptography (VC) is a powerful encryption technique which combines perfect secrecy and secret sharing in cryptography with respect to images. VC takes a binary image (the secret) and divides it into two or more pieces known as shares (transparencies). When the shares are superimposed, the secret can be recovered. One of the distinguishing features of VC is that it needs no computational power for decryption. All what VC needs for decryption is the human visual system (the human eye). Two main factors affect the quality of a visual cryptography scheme; the pixel expansion and the contrast. In this papers we propose a new simple non-expansion algorithm for (2,2)-visual secret sharing scheme (VSS). The shares produced by this algorithm and the reconstructed image are not expanded in size, and all have the same size as the original (secret) image. It encodes the original (secret) image a 4-pixel blockwise to 4-pixel blocks in each share.

English

Visual Cryptography is an encryption technique where a secret image is cryptographically encoded into n meaningless share images. A basic model for visual cryptography for natural images was proposed by Naor and Shamir. Security has gained a lot of importance as information technology is widely used. Cryptography refers to the study of mathematical techniques and related aspects of Information Security like data confidentiality, data Integrity, and of data authentication. Visual cryptography is a process where a secret image is encrypted into shares which refuse to divulge information about the original secret image. Its strength is a fact that the decryption of the secret image is through human visual system without computation. This paper provides a formulation of encryption for multiple secret images, which is a generalization of the existing ones, and also a general method of constructing visual secret sharing schemes encrypting multiple secret images.

General Access Structure Secret Sharing in Matrix Projection

Image Secret Sharing is a technique which provides security to confidential images by dispersed storages. General access structure image secret sharing provides flexibility for deciding qualified subsets of participants which can reconstruct the original secret image. Non qualified subsets of participants cannot get any information about original secret image. This paper proposes general access structure image secret sharing based on matrix projection. The experimental results show high accuracy, high security and less overhead in the network due to highly reduced size of image shares.

Steganography Technique for JPEG2000 Compressed Images Using Histogram in Wavelet Domain

In this work, a steganography technique using histogram shifting for JPEG2000 compressed images is proposed. Histogram of the wavelet coefficients of each wavelet subband is calculated and shifted to embed secret image data. This embedding is performed on the peak wavelet coefficients during wavelet decomposition process of JPEG2000 encoder using Lifting scheme. Optimal Pixel Adjustment Process (OPAP) is performed on stego images to enrich their visual quality. The results given in this work show that proposed technique provide large embedding capacity and better visual quality of stego images than existing steganography techniques for JPEG2000 compressed images. Extracted secret image using proposed technique is similar to its original secret image.

3-Level DWT Image Watermarking Against Frequency and Geometrical Attacks

This paper introduces a robust image watermarking technique for the copyright protection. The proposed method is based on 3-level discrete wavelet transform (DWT). Encoded secret image using spiral scanning is hidden by alpha blending technique in LL sub bands. During embedding process, secret image is dispersed within LL band depending upon alpha value. Encoded secret images are extracted and decoded to recover the original secret image. The experimental results demonstrate that the watermarks generated with the proposed algorithm are invisible and the quality of watermarked image and the recovered image are improved. The scheme is found robust to various image processing attacks such as JPEG compression, Gaussian noise, blurring, median filtering and rotation. Index Terms—Image watermarking, 3-level DWT, wavelet transform, attacks, mean square error (MSE), peak signal to noise ratio (PSNR).

A new (k, n) verifiable secret image sharing scheme (VSISS)

In this paper, a new (k,n) verifiable secret image sharing scheme (VSISS) is proposed in which third order LFSR (linear-feedback shift register)-based public key cryptosystem is applied for the cheating prevention and preview before decryption. In the proposed scheme the secret image is first partitioned into several non-overlapping blocks of k pixels. Every k pixel is then used to form m=⌈k/4⌉+1 pixels of one encrypted share. The original secret image can be reconstructed by gathering any k or more encrypted shared images. The experimental results show that the proposed VSISS is an efficient and safe method.

Correlated-imaging-based chosen plaintext attack on general cryptosystems composed of linear canonical transforms and phase encodings

We introduce a chosen-plaintext attack scheme on general optical cryptosystems that use linear canonical transform and phase encoding based on correlated imaging. The plaintexts are chosen as Gaussian random real number matrixes, and the corresponding ciphertexts are regarded as prior knowledge of the proposed attack method. To establish the reconstruct of the secret plaintext, correlated imaging is employed using the known resources. Differing from the reported attack methods, there is no need to decipher the distribution of the decryption key. The original secret image can be directly recovered by the attack in the absence of decryption key. In addition, the improved cryptosystems combined with pixel scrambling operations are also vulnerable to the proposed attack method. Necessary mathematical derivations and numerical simulations are carried out to demonstrate the validity of the proposed attack scheme.

Multiple-image encryption based on optical asymmetric key cryptosystem

We propose a multiple-image encryption scheme with asymmetric keys and demonstrate it by optical experiments. The original secret images are multiplexed and encoded into a real-valued ciphertext using only one public encryption key. In the decryption process, each secret image can only be de-multiplexed by its corresponding private decryption key. The multiplexing capacity is analyzed through examining the distribution of cross-talk noise and the key space of private decryption key. Numerical simulations and optical experiments have been carried out to demonstrate the validity, high security, and large multiplexing capacity of the proposed method.

Analysis and Design of Multi Share Secret Message Sharing using Visual Cryptography

Cryptography is a special encryption technique to hide information in images in such a way that it can be decrypted by the human visual system. It is secret sharing scheme which uses images distributed as shares such that, when the shares are superimposed, the original image is revealed. In last decade Visual Cryptography has evolved as an entity which divides the data into different shares and then embedding is done. This technique is also is less secured. In this paper we propose an encryption algorithm, which is applied on the different shares of the images. Before embedding the image into the cover image, shares are also encrypted for which the size of share images and the recovered image is the same as for the original secret image. Pixel expansion and the quality of the reconstructed secret image has been a major issue of visual secret sharing (VSS) schemes. The proposed scheme maintains the perfect security and the size of the original image. Keywordssecret sharing, Visual Cryptography.

Visual multi secret sharing by cylindrical random grid

Visual secret sharing (VSS) is the process of encoding a secret image into several share images in which the original secret image can be reconstructed and recognized by stacking all of the share images together. VSS has two categories: visual cryptography (VC) and Random Grid (RG). The VC is affected by various drawbacks such as: enlarging the size of original image, need for a codebook and the limitation to encode only one secret image at a time. RG solves the first two drawbacks of VC. To solve the third drawback and provide a solution to optimize recent algorithms, we propose a novel RG-based VSS scheme which encodes several secret images at a time. Instead of using only (2, 2) visual secret sharing, (2, n) and (n, n) is employed. This scheme has the ability to encode one or multiple secret images into multiple shares in place of two shares. In our proposed scheme, instead of Circular Random Grid, a new algorithm named Cylindrical Random Grid is used. It encrypts multiple secret images into two or more shares. To decrypt the first secret image, shares are stacked together. For decrypting of other secret images, one of the stacked shares is rotated in a fixed size over other shares based on the number of secret images which are encrypted. This algorithm is simple to implement and less time consuming.

RKO Technique for Color Visual Cryptography

To maintain the secrecy and confidentiality of images two different approaches are being followed, Image Encryption and Visual Cryptography. The former being encrypting the images through encryption algorithms using keys, and the later approach involves dividing the image into random shares without the use of keys. Unfortunately heavy computation cost and key management limit the employment of the first approach and the poor quality of the recovered image from the random shares limit the applications of the second approach. In this paper we propose a novel approach with the use of random share and key share. The approach employs generating two shares of the original image. One random share and the other key share. The original secret image can be recovered from the two shares simply by Xoring the two shares without any loss of image quality.

Secret Image Sharing for General Access Structures using Random Grids

This paper presents a visual secret sharing (VSS) scheme for general access structures by using random grids. Compared to the existing VSS schemes for general access structures, the proposed scheme generates the shares of same size as that of the original secret image and does not require any codebook prior to encryption process. With these advantages, the proposed scheme broadens the potential applicability of random-grid based VSS. We prove that the proposed scheme gives the strong access structure. Formal proofs, security analysis and experimental results are given to demonstrate both the feasibility and the correctness of the proposed scheme.

Meaningful image sharing scheme using toral automorphism

In recent years, image sharing scheme has attracted much attention for researchers due to the characteristics of security and easy implementation. In 2011, Wang and Lee proposed a random grid-based sharing scheme with identifiable shares to protect the security of the secret images. Their method has several disadvantages that must be improved. First, the constructed shares are meaningless ones which are difficult to manage. Second, the original secret image cannot be completely recovered which can cause the misjudgment of information. Wang et al. proposed a sharing method with verification ability in 2011. However, the constructed shares are also meaningless ones. This paper proposes a meaningful image sharing scheme to improve the above-mentioned disadvantages. Furthermore, we utilize toral automorphism to enhance the security of the secret image. Experimental results can show the feasibility of the proposed method.

A mixed scrambling operation for hiding image

A mixed scrambling operation is defined by the use of Arnold transform and Baker mapping. Following a designed sequence, the combined scrambling operation is utilized for changing the pixel position of secret image under the control of a random matrix. At the same time, the pixel value is altered by random bit shift for obtaining an encrypted image encoded in N-bit data. The operations mentioned above are employed for all pixels of original secret image. Finally an encrypted image is obtained and encoded into N-bit data being from the input image. Some numerical simulations have been achieved for checking the performance of the image hiding scheme.

Pixel expansion-free grey-scale image sharing method

In recent years, many visual secret sharing technologies have been proposed to protect the security of secret images (black and white, grey scale or colour images). In 2005, Lukac and Plataniotis used the concept of the Naor–Shamir method to propose a visual secret sharing technology for sharing secret grey-scale images based on bit-plane decomposition. Although their method can avoid pixel-value cutting problem, it still suffers from the pixel expansion problem. In this paper, we propose a new secret grey-scale image sharing method to improve this situation. In the proposed sharing image creation phase, two sharing images (one is grey-scale and the other is binary) are created and later shared by two protectors. The original secret image can be easily reconstructed if both sharing images are obtained. However, one cannot obtain the original secret image from each of the sharing images. Experimental results also show that the proposed method can effectively solve the pixel expansion problem.

Threshold visual secret sharing based on Boolean operations

ABSTRACTWe design a new (k,n)‐threshold visual secret sharing scheme on the basis of Boolean operations. We propose two different algorithms to encrypt a secret image into n meaningless shares such that no secret information can be obtained by having any k − 1 or fewer shares. However, the secret image can be reconstructed easily by XOR of any k (≤n) or more shares. Both the algorithms have used simple Boolean operations such as OR and XOR. The proposed scheme broadens the potential applicability of Boolean operation‐based visual secret sharing by generating the shares of size same as that of the original secret image. Formal proofs, security analysis, and the experimental results are given to demonstrate the correctness and feasibility of the proposed scheme. Copyright © 2013 John Wiley & Sons, Ltd.