Construction of General (k, n) Probabilistic Visual Cryptography Scheme

Visual cryptography scheme （VCS） is a secure method that encrypts a secret image by subdividing it into shadow images. Due to the nature of encryption VCS is categorized into two types： the deterministic VCS （DVCS） and the probabilistie VCS （PVCS）. For the DVCS, we use m （known as the pixel expansion） subpixels to represent a secret pixel. The PVCS uses only one subpixel to represent a secret pixel, while the quality of reconstructed image is degraded. A well-known construction of （k, n）-PVCS is obtained from the （k, n）-DVCS. In this paper, we show another construction of （k, n）-PVCS by extending the （k, k）-PVCS.

Securing Technique Using Pattern-Based LSB Audio Steganography and Intensity-Based Visual Cryptography

With the increasing need of sensitive or secret data transmission through public network,security demands using cryptography and steganography are becoming a thirsty research area of last few years.These two techniques can be merged and provide better security which is nowadays extremely required.The proposed system provides a novel method of information security using the techniques of audio steganography combined with visual cryptography.In this system,we take a secret image and divide it into several subparts to make more than one incomprehensible sub-images using the method of visual cryptography.Each of the sub-images is then hidden within individual cover audio files using audio steganographic techniques.The cover audios are then sent to the required destinations where reverse steganography schemes are applied to them to get the incomprehensible component images back.At last,all the sub-images are superimposed to get the actual secret image.This method is very secure as it uses a two-step security mechanism to maintain secrecy.The possibility of interception is less in this technique because one must have each piece of correct sub-image to regenerate the actual secret image.Without superimposing every one of the sub-images meaningful secret images cannot be formed.Audio files are composed of densely packed bits.The high density of data in audio makes it hard for a listener to detect the manipulation due to the proposed time-domain audio steganographic method.

RGB Based Multiple Share Creation in Visual Cryptography with Aid of Elliptic Curve Cryptography

In visual cryptography, many shares are generated which are illogical containing certain message within themselves. When all shares are piled jointly, they tend to expose the secret of the image. The notion of visual secret sharing scheme is to encrypt a secret image into n illogical share images. It is unable to reveal any data on the original image if at least one of the shares is not achieved. The original image, in fact, is realized by overlapping the entire shares directly, in order that the human visual system is competent to identify the collective secret image without employing any complicated computational tools. Therefore, they are communicated steadily as number of shares. The elliptic curve cryptography approach, in turn, is employed to augment the privacy and safety of the image. The new.fangled technique is utilized to generate the multiple shares which are subjected to encryption and decryption by means of the elliptic curve cryptography technique. The test outcomes have revealed the fact that the peak signal to noise ratio is 58.0025, Mean square error value is 0.1164 and the correlation coefficient is 1 for the decrypted image without any sort of distortion of the original image.

MULTI-WATERMARKING SCHEME FOR GROUP USERS BASED ON VISUAL CRYPTOGRAPHY

All watermarks are shared into shadow images using VCS(Visual Cryptography Scheme). Only one specific shadow (as a new watermark) is embedded into the host signal and the other ones are distributed to every user in each group as a key. In the watermarking extraction procedure, users in different group can obtain different watermark by combining their shadows with the extracted one from the watermarked signal. Analysis and experimental results show that the new watermarking method is novel, secure and robust.

A DIGITAL SIGNATURE-BASED VISUAL CRYPTOGRAPHY SCHEME FOR IMAGE DISCRIMINATION AND MANAGEMENT

Visual cryptography is a cryptographic technique which emerges in the information security domain in recent years. Each of the sharing sub-keys may be a stochastic noise image or a significative image with no information on the original key. But a mass of sub-keys have to be saved actually, which faces the problem of inconvenient discrimination and management. This paper presents a visual cryptography scheme based on the digital signature for image discrimination and management, applying the digital signature and the time-stamp technology to the visual cryptography scheme. The scheme both solves the problem on the storage and management of the sharing sub-keys, increases the verification of image contents, thus enhances the validity of storage and management without security effect.

Secret Image Communication Scheme Based on Visual Cryptography and Tetrolet Tiling Patterns

Visual cryptographic scheme is specially designed for secret image sharing in the form of shadow images.The basic idea of visual cryptography is to construct two or more secret shares from the original image in the form of chaotic image.In this paper,a novel secret image communication scheme based on visual cryptography and Tetrolet tiling patterns is proposed.The proposed image communication scheme will break the secret image into more shadow images based on the Tetrolet tiling patterns.The secret image is divided into 4×4 blocks of tetrominoes and employs the concept of visual cryptography to hide the secret image.The main feature of the proposed scheme is the selection of random blocks to apply the tetrolet tilling patterns from the fundamental tetrolet pattern board.Single procedure is used to perform both tetrolet transform and the scheme of visual cryptography.Finally,the experimental results showcase the proposed scheme is an extraordinary approach to transfer the secret image and reconstruct the secret image with high visual quality in the receiver end.

Secret Sharing Using Visual Cryptography

Compared with the traditional crypto- graphy, visual cryptography （VC） decrypts secret images referring to the characteristics of human vision, rather than the cryptography knowledge or complex computations. Furthermore, seeing to the freeness of the secret key, the whole process of encryption as well as deeryption for the visual cryptography meets a fast dealing course. As to the security concern, it is able to guarantee that no one can have access to any clues about the content of a secret image from individual cover images. Thus, owing to the studies on this area, the target of light-weighted cryptography is reached. Now the visual cryptography has been developed from the meaningless shadows to the meaningful ones. Seeing to the highly developed technique, some advanced VC techniques are introduced in this survey, respectively.

Usability and Security of Arabic Text-based CAPTCHA Using Visual Cryptography

Recently,with the spread of online services involving websites,attack-ers have the opportunity to expose these services to malicious actions.To protect these services,A Completely Automated Public Turing Test to Tell Computers and Humans Apart(CAPTCHA)is a proposed technique.Since many Arabic countries have developed their online services in Arabic,Arabic text-based CAPTCHA has been introduced to improve the usability for their users.More-over,there exist a visual cryptography(VC)technique which can be exploited in order to enhance the security of text-based CAPTCHA by encrypting a CAPTCHA image into two shares and decrypting it by asking the user to stack them on each other.However,as yet,the implementation of this technique with regard to Arabic text-based CAPTCHA has not been carried out.Therefore,this paper aims to implement an Arabic printed and handwritten text-based CAPTCHA scheme based on the VC technique.To evaluate this scheme,experi-mental studies are conducted,and the results show that the implemented scheme offers a reasonable security and usability levels with text-based CAPTCHA itself.

Video Identification Based on Watermarking Schemes and Visual Cryptography

Related to the growth of data sharing on the Internet and the wide-spread use of digital media,multimedia security and copyright protection have become of broad interest.Visual cryptography(VC)is a method of sharing a secret image between a group of participants,where certain groups of participants are defined as qualified and may combine their share of the image to obtain the original,and certain other groups are defined as prohibited,and even if they combine knowledge of their parts,they can’t obtain any information on the secret image.The visual cryptography is one of the techniques which used to transmit the secrete image under the cover picture.Human vision systems are connected to visual cryptography.The black and white image was originally used as a hidden image.In order to achieve the owner’s copy right security based on visual cryptography,a watermarking algorithm is presented.We suggest an approach in this paper to hide multiple images in video by meaningful shares using one binary share.With a common share,which we refer to as a smart key,we can decrypt several images simultaneously.Depending on a given share,the smart key decrypts several hidden images.The smart key is printed on transparency and the shares are involved in video and decryption is performed by physically superimposing the transparency on the video.Using binary,grayscale,and color images,we test the proposed method.

Preventing Phishing Attack on Voting System Using Visual Cryptography

Phishing is one of the most common social engineering attacks that users over the internet fall for. An example is voting systems, and because such systems should be accurate and error free, phishing prevention techniques are crucial. Visual Cryptography (VC) is utilized for efficient voting system authentication to cast votes. VC is one of the most secure approaches for privacy protection as it ensures the confidentiality of the voting system. This paper discusses proposed phishing prevention methods and compares different proposed methods.

Web Application Authentication Using Visual Cryptography and Cued Clicked Point Recall-based Graphical Password

Alphanumerical usernames and passwords are the most used computer authentication technique.This approach has been found to have a number of disadvantages.Users,for example,frequently choose passwords that are simple to guess.On the other side,if a password is difficult to guess,it is also difficult to remember.Graphical passwords have been proposed in the literature as a potential alternative to alphanumerical passwords,based on the fact that people remember pictures better than text.Existing graphical passwords,on the other hand,are vulnerable to a shoulder surfing assault.To address this shoulder surfing vulnerability,this study proposes an authentication system for web-applications based on visual cryptography and cued click point recall-based graphical password.The efficiency of the proposed system was validated using unit,system and usability testing measures.The results of the system and unit testing showed that the proposed system accomplished its objectives and requirements.The results of the usability test showed that the proposed system is easy to use,friendly and highly secured.

Magic sheets:Visual cryptography with common shares

Visual cryptography(VC) is an encryption technique for hiding a secret image in distributed and shared images(referred to as shares). VC schemes are employed to encrypt multiple images as meaningless,noisy patterns or meaningful images. However,decrypting multiple secret images using a unique share is difficult with traditional VC. We propose an approach to hide multiple images in meaningful shares. We can decrypt multiple images simultaneously using a common share, which we refer to as a magic sheet. The magic sheet decrypts multiple secret images depending on a given share. The shares are printed on transparencies, and decryption is performed by physically superimposing the transparencies. We evaluate the proposed method using binary, grayscale,and color images.

Cheater identifiable visual secret sharing scheme

The visual secret sharing scheme proposed by Naor and Shamir provides a way to encrypt a secret black-white image into shares. A qualified group of participants can recover the secret message without using any cryptographic computation. But the original scheme can easily be corrupted by malicious participant. We propose an extension of VSS(visual secret sharing) to identify cheaters before the secret is recovered. Without the need for any additional information and cryptographic computation, every participant can verify the validity of shares of other participants, thus the security of VSS is enhanced.

Visual Multi-Secret Sharing with Friendliness

Visual secret sharing(VSS) was used in the literature to encode and decode secret images until visual multi-secret sharing(VMSS) was proposed. Distinctly, multiple secret images can be encoded or decoded at a time in VMSS; however, only one secret image can be done in VSS. In VMSS, secrets are encoded into noise-like shares which have finally been stacked altogether so as to disclose each of the secrets by specific operations, such as rotating, flipping and sliding. Though the noise-like shares can be decoded by those operations, it is just like a fly in the ointment since they are hard to manage, to recognize and even to stack orderly. Based on some researches about user-friendly VSS for generating meaningful shares, a new friendly VMSS scheme is presented in this paper for achieving two main goals. One is trying to encode multiple secrets at a time and the other is making the decoding process easy to manage. The experimental results prove that our proposed scheme does work.