A Review on Various Visual Cryptography Schemes

Visual Cryptography (VC) is recent technology used to the strengthen security of many applications in various fields. It allows visual information like printed text, handwritten notes, and images to be encrypted by dividing it into shares. The most important characteristic of VCS is that one can visually decrypted the secret image by stacking shares without computation. The current paper aims at introducing a descriptive review for VC, which covering the "state-of-the-art" concept, and classification of schemes. In this paper, we have classified the VC schemes and provide some interpretation on the base of some various measures such as pixel expansion, share generated, format of secret image and number of secret image, which actually deemed as valuable contribution in the field of VC studies.

Allied Journals, 2015

Visual cryptography is an encryption technique which is used to hide information of an image in multiple secret shares. These shares make the secrecy levels. For n level region incrementing visual cryptography scheme, image is divided in n regions. Each region consists of one level information. For implementing visual cryptography in n levels we need to encode(n+1) shares in such a way so that any single share is not able to show the information and by combining any two shares, first level information would be visible. Similarly by superimposing any three shares, information upto second level could be seen. In similar way, for revealing whole information all the (n+1) shares are superimposed. In this paper, we are comparing many visual cryptography algorithms. Traditional visual cryptography Algorithms were based on permutation whereas modern approach are based on random column selection. In Proposed algorithm, problem of pixel expansion and poor contrast has been removed and further it is modified to generate the levels automatically which is named as automatic region incrementing visual cryptography.

ijera.com

The Visual cryptography scheme (VCS) is a secure method that encrypts a secret image by breaking it into shares. A distinctive property of VCS is that one can visually decode the secret image by superimposing shares without computation. The project ...

Visual Cryptography Scheme (VCS) is an encryption method that uses combinatorial techniques to encode secret written materials. The idea is to convert the written material into an image and encode this image into n shadow images. The decoding only requires only selecting some subset of these n images, making transparencies of them, and stacking them on top of each other. In this survey paper, we will provide the readers an overview of the basic VCS constructions, as well as several extended work in the area. In addition, we also review several state-of-art applications that take full advantage of such simple yet secure scheme.

International Journal of Computer Applications

In today's world handling and security of information from attacks becomes very important aspect for the individuals. Researchers are innovating new techniques to secure the information from unwanted intrusions. Various cryptography techniques are discovered and many are yet to be revealed. Here in this paper we are going to review an advanced method of information hiding i.e. Visual Cryptography. Visual Cryptography emerged as a special encryption technique for information hiding using images. In way that encrypted image can be decrypted by the human vision if the correct image key is used. By this cryptographic technique we can encrypt visual information (pictures, text, etc.) in a way that human visual system can perform decryption of encrypted information & no aid of computers needed. In visual cryptography a secret image is transformed into several share images. These share images are meaningful but noisy or distorted images. Combination of these share images can reveal the original secret image. This paper reviews two methods for visual cryptography of color images based on Shamir encryption method variants of k-out-of-n i.e.2-out-of-2, 2-out-of-n, n-out-of-n, and k-out-ofn scheme encryption method.

2013

Visual cryptography is a cryptographic technique which encrypt a visual information (e.g. text, handwritten notes and pictures) in such a way that the decryption done by the human visual system. It needs neither cryptography knowledge nor complex computation. For security purposs, it also ensures that hacker cannot obtain any clues about a secret image from individual sharess. Naor and Shamir proposed the basic model of visual cryptography in 1994. Visual cryptography scheme eliminates complex computation problem at the decryption the secret images can be restored by stack operation. The important issue of visual cryptography is quality of relevant image. Performance of visual cryptography scheme depends, such a number of image(single, multiple), types of image(binary, gray, color),share generation(meaningful, meaningless), security, accuracy pixel expansion, complexity,) encrypted by the scheme.

International journal of Emerging Trends in Science and Technology, 2016

Visual cryptography technique allows the visual information to be encrypted in such a way that their decryption can be performed by human visual system. Security has become an inseparable issue as Information Technology is ruling the world now. Cryptography in the study of mathematical techniques related aspects of information security such as confidentialities, data security, entity authentication, but it is not only the means of providing information security, rather one of the techniques. Visual cryptography can be applied for copy right for images, access control to user images ,visual authentication and identification any kind images of images like(normal or digital).Visual cryptography is a new technique which provides information security which user simple algorithm unlike the complex, computationally intensive algorithms used in other techniques like traditional cryptography. This technique allows visual information (pictures, text, etc)to be encrypted in such a way that their decryption can be performed by the human visual system, without any complex cryptographic algorithms. This technique encrypts a secret image into shares such that stacking sufficient number of shares reveals the secret image. Shares are visually presented in transparencies.

Advanced Computer Control, 2009. ICACC' …, 2009

Visual Cryptography is a new cryptographic technique which allows visual information (pictures, text, etc.) to be encrypted in such a way that the decryption can be performed by human, without any decryption algorithm. Here we propose a Data hiding in halftone ...

IJSRD - International Journal for Scientific Research & Development, 2017

Cryptography is a technique used for encryption of data (pictures, text, etc.) which involves key to decrypt the data encrypted which can only be done by desired recipient. It depends on type of key used to decrypt it that is private or public key. It was created for security purpose, but the key used in this can act as a major loophole sometimes. To overcome this, there is a technique called visual cryptography which does not use key. It can only be decrypted by human eye. In this paper proposed information is about visual cryptography methods and schemes.

s-To verify identity of person his /her physical or behavioural characteristics can be use,this strategy is called as Biometrics. Preservation of privacy of digital biometric data such as iris,face images etc. which stored in central database becomes more essential. This paper introduced the new visual cryptographic technique that allows encryption of visual information such that decryption can perform using human visual system hence cryptography computation does not required any extra hardware and software. In visual cryptography secrete image is encrypted into number of shares which independently can not reveal information about original image. For getting information about original image all sheets must be available simultaneously.

2015

Image cryptography is emerging field of the research. There are various techniques has been established for cryptography. The many encryption techniques have been used for hide the visual information (pictures, text, etc.) in images. The main idea of encryption is possibility of decryption by the human vision if the correct key image is used is known as visual cryptography. In this paper, different research has been discussed for Visual Cryptography.

VC is a cryptographic technique that ensures the security of images by dividing a secret image into random shares, which makes the image data unreadable. Then decryption is performed by superimposing the shares, without any special computational power. Intuitively, VC can be categorized as: secret sharing scheme [1] for monochrome images and extended VC (EVC) [2] for color images. In this paper both schemes of VC have been exploited to hide image where image security is essential, such as Bangla text document, handwritten signature, biometric authentication (e.g. human face) etc. These can be exercised in offices for deed, in banking sector for financial document and in examination or election system for authentication respectively. Moreover a minor modification of EVC which can be applied for color image also has been presented.

Communication is a vital aspect of our lives. Due to increasing advancements in technology, several schemes of communication have been introduced and information can be easily transferred across the network. These advancements have given rise to various security related issues. Visual cryptography scheme (VCS) is a secret-sharing scheme which allows the encryption of a secret image into shares that are distributed to participants such that when shares are superimposed, the hidden secret image can be revealed. Such a system may be used for protecting image based secrets.

International Journal of Information Systems and Computer Sciences, 2019

Cryptography is the main pillars of information security. By the arrival of internet, its usage and usefulness has exploded. Cryptography means storing and transmitting data in a form that only targeted people can read and process. It is also an effective way of protecting sensitive data that is stored on media devices or transmitted over an unsecured network communication channel by encrypting it into an unreadable format. Visual cryptography is a cryptographic technique used to encodes a black and white secret image into n shadow image called shares and these shares are distributed among n participants and only qualified subset of participants can visually recover the secret image. DCT is used in the proposed system. It has two encryption methods: lossy encryption and lossless encryption. Lossless encryption is more appropriate because it preserves every single detail in the image.It reduces the transmission risk problem and the quality of image is retained.