Visual Cryptography Algorithm Research Articles

Triple Layered Security for Data Hiding Using Steganography and Visual Cryptography

The proposed system makes use of steganographic method along with visual cryptography for hiding data in images and to provide better security. Even though extensive research work has been done previously, but most of the research work gives no robust security for the image that has been encrypted. The method proposed in this paper is capable of hiding some secret message in least significant bits of the original image, thereby hiding the secret message in way to make its detection difficult. The secret image is then under went to visual cryptography algorithm. Thereby, creating shares of the secret image, which are noise like structures. Further, the method proposes to hide these shares in least significant bits of different images so as to create three levels of security for the message. The main objective of the proposed method is to combine the use of data hiding techniques, steganography and visual cryptography algorithms for designing a secure algorithm so that security, reliability and efficiency of secret message can be improved. The framework is implemented in matlab.

Gray Visual Cryptography Algorithm for Secret Sharing

Gray Visual Cryptography Algorithm for Secret Sharing

Meliorated Multi Layered Key Less Mechanism in Visual Cryptography

Visual Cryptography algorithm primarily ensures lossless recovery of the secret image, by breaking the secret message into multiple shares before sending through a channel, which increases the bandwidth requirement of the channel due to increase in the size. The proposed algorithm deals with this problem by using two exclusive locks on the image to be shared which are applied once on the sender side and once on the receiver side. Thereafter sender and receiver open’s their individual locks to finally retrieve the secret image at the receiver end.

Enhanced-visual-cryptography-based optical information hiding system

Recent years, with the rapid development of information technology, the information security has received more and more attention. A variety of encryption methods to protect the information have been reported. Visual cryptography is one of the encryption methods, which has highly security because of its threshold feature. And the cryptographic information can be explained by a naked eye in the decryption process. In the application of visual cryptography, however, each shared image is limited to transparency films and overlapping on computer. In our previous work, we proposed the scheme of invisible visual cryptography and developed the visual-cryptography-based optical hiding system (VCOH), which transformed the conventional visual cryptography shares into diffraction optical elements (DOEs). It not only increases the application range of visual cryptography, but also enhances security. In this paper, we propose an optical information hiding system based on the extended visual cryptography, which inherits the concept of invisible visual cryptography. In contrast to our previous work, the method proposed in this work can hide a meaningful image instead of text messages. Meanwhile, the capacity and imperceptibility of the method are greatly increased. The hiding process of the system contains two steps. Firstly, the secret image is converted into meaningful shares through the extended visual cryptography algorithm. Secondly, the meaningful shares are able to hide in phase-keys through an iterative phase retrieval algorithm, such as Gerchberg-Saxton algorithm and Yang-Gu iterative algorithm. Then the phase-keys can be made into diffraction optical elements (DOEs) to store and transport in a physical way. In the decryption process, DOEs are illuminated with the laser beam to reconstruct the meaningful shares. The secret image can be explained by the direct overlapping of the reconstructed shares without any optical or cryptographic knowledge. The simulation and optical experimental results show that the proposed method has good performance of security and validate the feasibility of the proposed method. Besides, in this paper the robustness and security issues are also analyzed. This system has a high security because of its indistinguishability under adaptive chosen ciphertext attack (IND-CCA2) security. Additionally, this system is relatively less robust than the VCOH because it shares meaningful images with highly complex and detailed structures.

Visual-cryptographic image hiding with holographic optical elements.

In this paper, we propose a visual-cryptographic image hiding method based on visual cryptography (VC) and volume grating optics. The secret image is converted to the encrypted visual keys (VKs) according to the normal VC algorithm. Then the VKs are further embellished to the QR-code-like appearance and hidden as the holographic optical elements (HOEs), which are fabricated by the holographic exposure of photopolymer. In the decryption process, the fabricated HOE-VKs are illuminated with the laser beam. The reconstructed VKs are overlaid to extract the hidden information directly in the optical facility, without additional computation. Optical experiments verify that the VKs in HOE mode improves the system with high security and good robustness on the random noise attack. Besides, the volume grating nature also enlarges the system bandwidth by using the multiplexing technique. The proposed method may provide a promising potential for the practical image hiding systems.

Improving the Visual Quality of Size-Invariant Visual Cryptography for Grayscale Images: An Analysis-by-Synthesis (AbS) Approach.

In visual cryptography (VC) for grayscale image, size reduction leads to bad perceptual quality to the reconstructed secret image. To improve the quality, the current efforts are limited to the design of VC algorithm for binary image, and measuring the quality with metrics that are not directly related to how the human visual system (HVS) perceives halftone images. We propose an analysis-by-synthesis (AbS) framework to integrate the halftoning process and the VC encoding: the secret pixel/block is reconstructed from the shares in the encoder and the error between the reconstructed secret and the original secret images is fed back and compensated concurrently by the error diffusion process. In doing so, the error between the reconstructed secret and original secret is pushed to high frequency band, thus producing visually pleasing reconstructed secret image. This framework is simple and flexible in that it can be combined with many existing size-invariant VC algorithms, including probabilistic VC, random grid VC and vector/block VC. More importantly, it is proved that this AbS framework is as secure as the traditional VC algorithms. Experimental results demonstrate the effectiveness of the proposed AbS framework.

An Efficient ROI Image Watermarking on Geometric Attacks

Watermarking is raised to apparatus for the Privacy of Intellectual Property Rights (IPR) of combination dates. In this paper, in the starting we have to fill the user name field and password field which will be secure afterwards that it will be make QR-code using zxing library and it is transformed into binary patterns for share-1 that is called Visual cryptography algorithm. Now share-2 is store into server database and it will be furthered use in future situation at receiver way. Now share-1 is hiding into the LL-Band with the help of DWT-SVD into block manner with Pseudo Zernike moment. Then it is sent to the network or internet. As in network there are many unlike attackers whose apply any Rotation, Scaling or Translation attacks on the hiding image. Attack image is expected at the end side or receiver side. To get prevent against attacks here at the starting stage use Pseudo Zernike moment then after Surf based feature extraction and it will recover the attacks pixel and scaling parameters value and using affine transformation recover the rotational parameters value. So then scale value and angle value is apply on attack image recovered watermark image. Now using DWT+SVD block method extract the water mark share-1. So on system with share-1 and another share-2 will be in server side so now by using EX-OR process for getting QR-Code. At the last stage QR-code is translated and fill field user name and password vale to login the system successfully.

Extended Capabilities for XOR-Based Visual Cryptography

The XOR-based visual cryptography (VC) is a possible methodology to solve the poor visual quality problem without darkening the background in VC. However, investigations on XOR-based VC are not sufficient. In this paper, we exploit some extended capabilities for XOR-based VC. Actually, two XOR-based VC algorithms are proposed, namely XOR-based VC for general access structure (GAS) and adaptive region incrementing XOR-based VC. The first algorithm aims to implement complicated sharing strategy using GAS, while maintaining merits such as perfect reconstruction of secret, no pixel expansion, and no code book requirement. In the second algorithm, the concept of adaptive security level is first introduced, where the security levels are recovered in accordance with the qualified sets instead of the quantity of stacked shares. Adaptive region incrementing XOR-based VC further enriches the application scenarios. Theoretical analysis on the proposed algorithms are provided, as well as extensive experimental results and evaluations for demonstrating the effectiveness and advantages of the two methods.

EXTENDING THE VISUAL CRYPTOGRAPHY ALGORITHM USING IMAGE WATERMARKING TECHNIQUE

Visual cryptography is a secret information sharing technique which shares the information in the form of images. It generates noise-like random pixels on share images to hide secret information which on overlay decrypt the information. This technique is known as conventional visual secret sharing schemes. It suffers a management problem, because of which dealers cannot visually identify each share. This problem is solved by the extended visual cryptography scheme (EVCS), which adds a meaningful cover image in each share. While removing the extra cover image it produces extra noise or degrades the hidden image quality. So we propose a new image watermarking technique in this Visual Cryptography Algorithm that places a small image on the noisy image pair at the bottom right corner. So that the cover images need not be removed and it doesn't degrade  resolution of the secret image.

Block Based Symmetry Key Visual Cryptography

Visual cryptography is a method for protecting image-based secrets that has a computation- free decoding process. In this technique, numbers of shares have been generated from one image. The shares are sent through any channel to the receiver and the receiver can again produce original image by stacking all the shares in proper order. But, this method wastes a lot of bandwidth of the network. The techniques of generating shares have been used in several existing methods which are not unique. The different methods have been used in different types of images like binary, gray and color images. In this paper, a block based symmetry key visual cryptography algorithm has been proposed to convert image in encrypted form and decrypt the encrypted image into original form. The symmetric key has been generated from a real number. The encryption and decryption algorithm have been designed based on symmetry key. The algorithm with key has been used to encrypt image into single share and decrypt the single share into original image. The real number has been used to form the key may be predefined or may be sent by secure channel to the receiver. The proposed algorithm can be applied to any type images i.e. binary, gray scale and color images. A comparison has been made of the proposed algorithm with different existing algorithms like Ceaser cipher, transpose of matrix, bit comp, and transposition cipher based on the performance. The pixels distributed in original and share images have also been tested. Finally, it has shown that breaking of security level of proposed algorithm i.e. to guess the real number is huge time consuming.

An Extended Visual Cryptography Algorithm for General Access Structures

Conventional visual secret sharing schemes generate noise-like random pixels on shares to hide secret images. It suffers a management problem, because of which dealers cannot visually identify each share. This problem is solved by the extended visual cryptography scheme (EVCS), which adds a meaningful cover image in each share. However, the previous approaches involving the EVCS for general access structures suffer from a pixel expansion problem. In addition, the visual cryptography (VC)-based approach needs a sophisticated codebook design for various schemes. In this paper, we propose a general approach to solve the above- mentioned problems; the approach can be used for binary secret images in noncomputer-aided decryption environments. The pro- posed approach consists of two phases. In the first phase, based on a given access structure, we construct meaningless shares using an optimization technique and the construction for conventional VC schemes. In the second phase, cover images are added in each share directly by a stamping algorithm. The experimental results indicate that a solution to the pixel expansion problem of the EVCS for GASs is achieved. Moreover, the display quality of the recovered image is very close to that obtained using conventional VC schemes.