A Novel Anti Phishing Based On Visual Cryptography

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A Novel Anti Phishing framework based on Visual Cryptography


With the advent of internet, various online attacks has been increased and among them the most popular attack is phishing. Phishing is an attempt by an individual or a group to get personal confidential information such as passwords, credit card information from unsuspecting victims for identity theft, financial gain and other fraudulent activities. Fake websites which appear very similar to the original ones are being hosted to achieve this. In this paper we have proposed a new approach named as "ANovel Anti-phishing framework based on visual cryptography "to solve the problem of phishing. Here an image based authentication using Visual Cryptography is implemented. The use of visual cryptographyis explored to preserve the privacy of an image captcha by decomposing the original image captcha into two shares (known as sheets) that are stored in separate database servers(one with user and one with server) such that the original image captcha can be revealed only when both are simultaneously available; the individual sheet images do not reveal the identity of the original image captcha. Once the original image captcha is revealed to the user it can be used as the password. Using this website cross verifies its identity and proves that it is a genuine website before the end users.

Enhanced Captcha Bifurcation towards Phishing page Attack Identification


Anti-phishing mechanisms in the websites currently focus on helping users to verify whether a web site is genuine or not. However, prevention-based approaches on this issue will fail due to effectively suppress phishing attacks and protect Internet users from revealing their credentials to phishing websites. Phishing on the web pages is an attempt by an individual or a group to threats/hackers trying to retrieve an individual’s personal confidential information such as passwords, usernames/confidential info, credit card information etc This problem comes under, unsuspecting victims for identity theft, financial gain and other fraudulent web activities. In this project, we are proposing a new approach named as “Based on visual cryptography" to solve the problem of phishing. Textual keyword validation along with visual cryptography is a major advantage of this project .The use of visual cryptography technique is explored to preserve the privacy of image captcha by degenerating the original image captcha into two different image shares by manipulating the pixel value of the image captcha .Part of the image share will be stored in the remote database servers such that the original image captcha can be revealed only when both of the shares are simultaneously available .The individual share images do not reveal the identity of the original image captcha. Once the original image captcha is revealed after merging different shares, which can be used as the password. Dynamically generating the Captcha image by the system is one of the major advantage of the system.






[1]Halftone visual cryptography


Visual cryptography encodes a secret binary image (SI) into n shares of random binary patterns. If the shares are xeroxed onto transparencies, the secret image can be visually decoded by superimposing a qualified subset of transparencies, but no secret information can be obtained from the superposition of a forbidden subset. The binary patterns of the n shares, however, have no visual meaning and hinder the objectives of visual cryptography. Extended visual cryptography was proposed recently to construct meaningful binary images as shares using hypergraph colourings, but the visual quality is poor. In this paper, a novel technique named halftone visual cryptography is proposed to achieve visual cryptography via halftoning. Based on the blue-noise dithering principles, the proposed method utilizes the void and cluster algorithm to encode a secret binary image into n halftone shares (images) carrying significant visual information. The simulation shows that the visual quality of the obtained halft one shares are observably better than that attained by any available visual cryptography method known to date.

[2] Colour visual cryptography schemes


Visual cryptography scheme (VCS) is a kind of secret-sharing scheme which allows the encryption of a secret image into n shares that are distributed to n participants. The beauty of such a scheme is that, the decryption of the secret image requires neither the knowledge of cryptography nor complex computation. Colour visual cryptography becomes an interesting research topic after the formal introduction of visual cryptography by Naor and Shamir in 1995. The authors propose a colour (k, n)-VCS under the visual cryptography model of Naor and Shamir with no pixel expansion, and a colour (k, n)-extended visual cryptography scheme ((k, n)-EVCS) under the visual cryptography model of Naor and Shamir with pixel expansion the same as that of its corresponding black and white (k, n)-EVCS. Furthermore, the authors propose a black and white (k, n)-VCS and a black and white (k, n)-EVCS under the visual cryptography model of Tuyls. Based on the black and white schemes, the authors propose a colour (k, n)-VCS and a colour (k, n)-EVCS under the same visual cryptography model, of which the pixel expansions are the same as that of their corresponding black and white (k, n)-VCS and (k, n)-EVCS, respectively. The authors also give the experimental results of the proposed schemes, and compare the proposed scheme with known schemes in the literature.

[3]Enhanced image secret sharing via error diffusion in halftone visual cryptography


Visual Cryptography is an encryption technique where a secret image is cryptographically encoded into n shares. In visual secret sharing scheme (k, n) the secret images can be visually revealed by stacking together any k or more transparencies of the shares and by inspecting less than k shares one cannot retrieve the secret image. Visual Secret Sharing based on halftone visual cryptography, the continuous-tone image is first transformed into a halftone image, and then encrypted using visual secret sharing schemes. In visual cryptography, meaningless shares are encoded into halftone shares taking meaningful visual information which reduces the suspicion of intruders. These halftone shares are concurrently error diffused to give visually pleasing effect. Error diffusion is computationally efficient with less complexity. Techniques such as classical fixed, edge enhancement, green noise and block error diffusion are performed and a comparative study is made. The quality of the halftone shares enhanced by using Floyd - Steinberg and Jarvis error filters. Secret image is reconstructed by stacking the qualified halftone shares. The simulation results shows that the visual quality of the obtained halftone share are observably better.

[4]Novel authentication system using visual cryptography


An array of encryption techniques has been proposed for providing data security. However, most of the traditional cryptography methods require complex algorithms for encryption and decryption. Visual cryptography is a technique which provides confidentiality without any cryptographic knowledge or complex computations. Visual information (e.g. printed text, hand-written notes, pictures, etc.) is encrypted by decomposing it into several images, called shares, in such a way that decryption can be done by human visual system with stacking of the shares. Some important goals while developing a Visual Cryptography scheme is to have (i)optimum number of shares, (ii)good quality of reconstructed image and (iii)keeping the size of share small. This paper aims to provide a comparative study of various Visual Cryptographic schemes based on pixel expansion, no of shares, size and quality of reconstructed image, etc and some real-life applications of visual cryptography. A new authentication system has been proposed which uses the technique of visual cryptography to improve the security level of existing schemes. The application of the system in financial domain is discussed.

[5] VVCS: Verifiable Visual Cryptography Scheme


Visual cryptography is a cryptographic technique to achieve visual secret sharing. Shares are distributed to every participant and overlapping a number of shares can recover the original secret. The participants' cheating is discussed more in previous literatures. However, the issue of the distribution center's dishonesty exists similarly in visual cryptography. In this paper, a verifiable visual cryptography scheme is proposed to verify whether the share is authorized, in which we introduce the Third Trusted Party (TTP) whose action is guaranteed. The scheme solves the participants distrusting in the center so as to improve the security of visual cryptography schemes.

[6]Extended visual cryptography scheme with an artificial cocktail party effect


Cloud computing has brought new changes and opportunities to IT industry. It is the result of the evolution of a variety of techniques. And the railway department will use the cloud computing technology to achieve the sharing of the railway information resources and to improve the capacity of information processing. But with the development of the cloud computing, it also faced with many difficulties, cloudcomputing security has become the leading cause of impeding its development. Cloud computingsecurity has become a hot topic in industry and academic research. This paper will explore the status of the development of cloud computing security, analyze the data privacy, security auditing, data monitoring and other challenges that the cloud computing security faced with. We will describe the solutions which the industry and academia proposed for some key issues of cloud computing security, such as virtualization security and traffic monitoring between virtual machines and so on. And we analyzed the security of cloud computing in railway environment. We proposed a cloud computing security reference framework. The purpose of this paper is attempted to bring greater clarity landscape about cloud computing security.

[7] Cloud computing security threats and responses


[8] An extended visual cryptography scheme without pixel expansion for halftone images


Visual cryptography is a secret sharing scheme which uses images distributed as shares such that, when the shares are superimposed, a hidden secret image is revealed. In extended visual cryptography, the share images are constructed to contain meaningful cover images, thereby providing opportunities for integrating visual cryptography and biometric security techniques. In this paper, we propose a method for processing halftone images that improves the quality of the share images and the recovered secret image in an extended visual cryptography scheme for which the size of the share images and the recovered image is the same as for the original halftone secret image. The resulting scheme maintains the perfect security of the original extended visual cryptography approach.

[9]On the Relation of Random Grid and Deterministic Visual Cryptography


Visual cryptography is a special type of secret sharing. Two models of visual cryptography have been independently studied: 1) deterministic visual cryptography, introduced by Naor and Shamir, and 2) random grid visual cryptography, introduced by Kafri and Keren. In this paper, we show that there is a strict relation between these two models. In particular, we show that to any random grid scheme corresponds a deterministic scheme and vice versa. This allows us to use results known in a model also in the other model. By exploiting the (many) results known in the deterministic model, we are able to improve several schemes and to provide many upper bounds for the random grid model and by exploiting some results known for the random grid model, we are also able to provide new schemes for the deterministic model. A side effect of this paper is that future new results for any one of the two models should not ignore, and in fact be compared with, the results known in the other model.

[10] Design of hierarchical visual cryptography


This paper describes the concept of hierarchical visual cryptography. The key idea behind hierarchical visual cryptography is to encrypt the secret information in number of levels. As the number of levels in hierarchical visual cryptography increases, the secrecy of data tends to increase. An intelligent authentication system is also proposed using hierarchical visual cryptography. The shares generated out of Hierarchical visual cryptography are found to be random giving no information. The expansion ratio is also reduced to 1:2 from 1:4.

[11] Color Extended Visual Cryptography Using Error Diffusion


Color visual cryptography (VC) encrypts a color secret message into color halftone image shares. Previous methods in the literature show good results for black and white or gray scale VC schemes, however, they are not sufficient to be applied directly to color shares due to different color structures. Some methods for color visual cryptography are not satisfactory in terms of producing either meaningless shares or meaningful shares with low visual quality, leading to suspicion of encryption. This paper introduces the concept of visual information pixel (VIP) synchronization and error diffusion to attain a color visual cryptography encryption method that produces meaningful color shares with high visual quality. VIP synchronization retains the positions of pixels carrying visual information of original images throughout the color channels and error diffusion generates shares pleasant to human eyes. Comparisons with previous approaches show the superior performance of the new method.

[12]Enhancement of security in visual cryptography system using cover image share embedded security algorithm (CISEA)


Visual Cryptography is an encryption technique used to hide visual information in such a way that it can be decrypted by the human visual system, without using any decryption algorithm. There exist various schemes like digital watermarking algorithm etc. In this paper we have proposed a new algorithm to enhance the security in visual cryptography. To achieve this level of security, we have proposed a Cover Image Share Embedded security algorithm (CISEA) to produce the meaningful shares from the secret image. In this algorithm we have applied a new concept for generation of compliment images of a cover image over which the shares of secret image are to be embedded. CISEA provides one more layer of security for the images in communication channel. It is shown that CISEA provides better security compared to security provided by visual cryptography using digital watermarking system and the results are tested using MS visual studio dot net platform.

[13] Steganography using Genetic Algorithm along with Visual Cryptography for wireless network application


Image steganography is an emerging field of research for secure data hiding and transmission over networks. The proposed system provides the best approach for Least Significant Bit (LSB) based steganography using Genetic Algorithm (GA) along with Visual Cryptography (VC). Original message is converted into cipher text by using secret key and then hidden into the LSB of original image. Genetic Algorithm and Visual Cryptography has been used for enhancing the security. Genetic Algorithm is used to modify the pixel location of stego image and the detection of this message is complex. Visual Cryptography is used to encrypt the visual information. It is achieved by breaking the image into two shares based on a threshold. The performance of the proposed system is experimented by performing steganalysis and conducting benchmarking test for analysing the parameters like Mean Squared Error (MSE) and Peak Signal to Noise Ratio (PSNR). The main aim of this paper is to design the enhanced secure algorithm which uses both steganography using Genetic Algorithm and Visual Cryptography to ensure improved security and reliability.

[14]Contrast-Enhanced Visual Cryptography Schemes Based on Additional Pixel Patterns


Visual cryptography is a kind of secret image sharing scheme that uses the human visual system to perform the decryption computations. A visual cryptography scheme allows confidential messages to be encrypted into k-out-of-n secret sharing schemes. Whenever the number of participants from the group (n) is larger than or equal to the predetermined threshold value (k), the confidential message can be obtained by these participants. Contrast is one of the most important parameters in visual cryptography schemes. Usually, the reconstructed secret image will be darker (through contrast degradation) than the original secret image. The proposed scheme achieves better contrast and reduces the noise in the reconstructed secret image without any computational complexity. In this method, additional pixel patterns are used to improve the contrast of the reconstructed secret image. By using additional pixel patterns for the white pixels, the contrast of the reconstructed secret image can be improved than in the case of existing visual cryptography schemes.

[15]A Novel Visual Cryptography Scheme


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 images using conjugate ordered dithering (DHCOD) algorithm which is a modified version of data hiding in halftone images using conjugate error diffusion technique (DHCED). We use this DHOCD algorithm for proposing a new three phase visual cryptography scheme. DHCOD technique is used to hide an binary visual pattern in two or more ordered dither halftone images, which can be from the same or different multi-tone images. In proposed scheme we shall generate the shares using basic visual cryptography model and then embed them into a cover image using a DHCOD technique, so that the shares will be more secure and meaningful.

[16]Halftone Visual Cryptography Via Error Diffusion


Halftone visual cryptography (HVC) enlarges the area of visual cryptography by the addition of digital halftoning techniques. In particular, in visual secret sharing schemes, a secret image can be encoded into halftone shares taking meaningful visual information. In this paper, HVC construction methods based on error diffusion are proposed. The secret image is concurrently embedded into binary valued shares while these shares are halftoned by error diffusion-the workhorse standard of halftoning algorithms. Error diffusion has low complexity and provides halftone shares with good image quality. A reconstructed secret image, obtained by stacking qualified shares together, does not suffer from cross interference of share images. Factors affecting the share image quality and the contrast of the reconstructed image are discussed. Simulation results show several illustrative examples.

[17] Visual cryptography using hybrid halftoning and inter-pixel exchanging


Visual Cryptography is the study of mathematical techniques related aspects of Security which allows Visual information to be encrypted in such a way that their decryption can be performed by the human visual system, without any complex cryptographic algorithms. Visual cryptography scheme is used to encrypt an image into multiple shares and is distributed among different participants. A minimum number of shares if overlapped could reveal the hidden information visually. In a computer a logical OR operation could reveal the same information We propose the significance in use of hybrid halftoning in visual cryptography. We also propose a new technique in hiding the information that the encrypted shares are encrypted by inter-pixel exchanging using a secondary image.

[18] Visual cryptography using hybrid halftoning and inter-pixel exchanging


Visual Cryptography is the study of mathematical techniques related aspects of Security which allows Visual information to be encrypted in such a way that their decryption can be performed by the human visual system, without any complex cryptographic algorithms. Visual cryptography scheme is used to encrypt an image into multiple shares and is distributed among different participants. A minimum number of shares if overlapped could reveal the hidden information visually. In a computer a logical OR operation could reveal the same information We propose the significance in use of hybrid halftoning in visual cryptography. We also propose a new technique in hiding the information that the encrypted shares are encrypted by inter-pixel exchanging using a secondary image.

[19]A Novel Technique for Secret Communication through Optimal Shares Using Visual Cryptography (SCOSVC)


In this paper a novel (2, m + 1) visual cryptographic technique has been proposed, where m number of secret images has been encrypted based on a randomly generated master as a common share for all secrets which is decodable with any of the shares in conjunction with master share out of m + 1 generated shares. Instead of generating new pixels for share except the master share, hamming weight of the blocks of the secret images has been modified using random function to generate shares corresponding to the secrets. The proposed scheme is secure and very easy to implement like other existing techniques of visual cryptography. At the decoding end the secrets are revealed by stacking the master share on any one share corresponding to the secrets in any arbitrary order with proper alignment directly by human visual system where shares are printed on different transparencies which conforms the optimality of using shares. The aspect ratio and dimension of the secret images and the generated shares with respect to the source images remains constant during the process.

[20]Effective recovery technique for halftone images in Visual Cryptography


Security has become an inseparable issue even in the field of space technology. Visual Cryptography is the study of mathematical techniques related aspects of Information Security which allows Visual information 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 represents the secret image by several different shares of binary images. It is hard to perceive any clues about a secret image from individual shares. The secret message is revealed when parts or all of these shares are aligned and stacked together. In this paper we provide an overview of the emerging Visual Cryptography (VC) techniques used in the secure transfer of the thousands of images collected by the satellite which are stored in image library and sent to Google for use on Google Earth and Google maps. The related work is based on the recovering of secret image using a binary logo which is used to represent the ownership of the host image which generate shadows by visual cryptography algorithms. An error correction-coding scheme is also used to create the appropriate shadow. The logo extracted from the half-toned host image identifies the cheating types. Furthermore, the logo recovers the reconstructed image when shadow is being cheated using an image self-verification scheme based on the Rehash technique which rehash the halftone logo for effective self verification of the reconstructed secret image without the need for the trusted third party(TTP).

[21]Resolution variant visual cryptography for street view of Google Maps


Resolution variant visual cryptography takes the idea of using a single share of visual cryptography (VC) to recover a secret from an image at multiple resolutions. That means, viewing the image on a one-to-one basis and superimposing the share will recover the secret. However, if the image is zoomed, using that same share we can recover other secrets at different levels. The same share is used at these varying resolutions in order to recover a large amount of hidden secrets. This process is quite similar to watermarking an image, whereby nothing can be seen while fully zoomed out, but as the zoom level is increased the watermark becomes visible. This would also be associated with a recursive style of secret sharing. This type of secret sharing scheme would be appropriate for recovering specific types of censored information, such as vehicle registration numbers within certain types of images. This adds an additional dimension to our scheme: content based visual cryptography.

[22]Non-expanded visual cryptography scheme with authentication


In recent years, a crucial issue is the manner in which to safely transmit the secret information and prevent the detection of information. An extended visual cryptography with authentication technology for the original image was proposed in previous studies. Fang and Lin's scheme [3] combine the principle of traditional visual cryptography with authentication characteristic, when we fix the first share image and shift the other share image for certain unit, we can obtain the extra confidential data. But in traditional visual cryptography, secret pixels are expanded to cause the size of the recovered image is larger than the original one. So this study combined the non-expanded scheme with the extra ability of hiding confidential data to prevent the detection of information.

[23] Progressive Visual Cryptography With Unexpanded Shares


The basic (k, n)-threshold visual cryptography (VC) scheme is to share a secret image with n participants. The secret image can be recovered while stacking k or more shares obtained; but we will get nothing if there are less than k pieces of shares being overlapped. On the contrary, progressive VC can be utilized to recover the secret image gradually by superimposing more and more shares. If we only have a few pieces of shares, we could get an outline of the secret image; by increasing the number of the shares being stacked, the details of the hidden information can be revealed progressively. Previous research, such as Jin in 2005, and Fang and Lin in 2006, were all based upon pixel-expansion, which not only causes the waste of storage space and transmission time but also gets a poor visual quality on the stacked image. Furthermore, Fang and Lin's research had a severe security problem that will disclose the secret information on each share. In this letter, we proposed a brand new sharing scheme of progressive VC to produce pixel-unexpanded shares. In our research, the possibility for either black or white pixels of the secret image to appear as black pixels on the shares is the same, which approximates to 1/n. Therefore, no one can obtain any hidden information from a single share, hence ensures the security. When superimposing k (sheets of share), the possibility for the white pixels being stacked into black pixels remains 1/n, while the possibility rises to k/n for the black pixels, which sharpens the contrast of the stacked image and the hidden information, therefore, become more and more obvious. After superimposing all of the shares, the contrast rises to (n-1)/n which is apparently better than the traditional ways that can only obtain 50% of contrast, consequently, a clearer recovered image can be achieved.

[24]User-friendly visual cryptography with complementary cover images


User-friendly visual cryptography schemes (denoted as (n, n) - FVCSs) generate meaningful shares to cope the management problem of conventional visual cryptography. However, several issues still remain in this research field, including: pixel expansion, residual traces of cover images, low visual quality of meaningful shares and recovered images, lack of systematic encryption methods, and others. To solve the abovementioned problems, this paper proposes a novel (n, n) - FVCS for sharing binary secret images. We extend the probabilistic (n, n) - VCS and embed complementary cover images in shares to construct the (n, n) - FVCS. The proposed approach provides an adjustable contrast for meaningful shares to satisfy dealers' requirements. Moreover, the experimental results indicate that the proposed (n, n) - FVCS significantly outperforms the previous methods in terms of the quality of the recovered images and meaningful shares.

[25] Colored digital watermarking technology based on visual cryptography


Summary form only given. For a period of time, it was popular to use gray-level and black-and-white authentication logos for digital watermarking. With the changes of times, there are more and more digital watermarking techniques using colored logos for the index of its authentication. However, the algorithm must be more complicated for using colored logos to develop digital watermarking. It depends on a lot of complicated mathematical operations to embed the colored digital watermark. In this paper, an application of using visual cryptography technology on the making of colored digital watermarks is proposed. The proposed scheme is promoted by the great advantage of visual cryptography as it is without complicated mathematical operations. Using the human visual system, the secret can be distinguished. Our approaches not only keep the advantage of visual cryptography, but also will not destroy the protected image while making the colored digital watermark.

[26]Encrypting Informative Color Image Using Color Visual Cryptography


Color Visual Cryptography scheme implemented in this paper encrypts informative color image in such a way that result of encryption is in the form of shares. Shares do not reflect any information directly, information is scrambled instead. Each share carries some information which in unreadable by necked eyes. The decryption is done directly by the human visual system with no special cryptographic calculations. Color visual cryptography uses 2 out of two secret sharing scheme which generates two shares for every input image to be encrypted. The original image is reconstructed by printing the two output shares onto transparencies and superimposing them together. This is X-OR operation between the shares to reveal the original information. The algorithm first generates RED, GREEN, BLUE as well as the ALPHA components of each pixel of an input image and these three components are used to generate the shares using 2 out of 2 secret sharing scheme. This scheme is useful in many applications like in securing information but not useful for visually blind people.

[27]Secret image / message transmission through meaningful shares using (2, 2) visual cryptography (SITMSVC)


In this paper a secret message/image transmission technique has been proposed through (2, 2) visual cryptographic shares which are covered by meaningful images so that a potential eavesdropper won't know there's a message to be read. A binary image is taken as cover image and authenticating message/image has been fabricated into it through a hash function where two bits in each pixel within four bits from LSB of the pixel is embedded and as a result it converts the binary image to gray scale one. (2, 2) visual cryptographic shares are generated from this converted gray scale image and these shares are hidden into separate meaningful images. During decoding shares are fetched from received meaningful images and combined to regenerate the authenticated image from where the secret message/image is obtained through the same hash function along with reduction of noise. Noise reduction is also done on regenerated authenticated image to produce original cover image at destination.

[28]Halftone visual cryptography


Visual cryptography encodes a secret image SI into n shares of random patterns. If the shares are xeroxed onto transparencies, we can visually decode the secret image by superimposing a qualified subset of transparencies, but no secret information can be obtained from the superposition of a forbidden subset. Such a scheme is mathematically secure, however, it produces random patterns which have no visual meaning, raising the suspicion of data encryption. In this paper, to achieve a higher level of security, we propose halftone visual cryptography, where all shares are halftones of grey level images carrying significant visual information. The proposed methods utilize blue-noise dithering principles to construct halftone shares having visually pleasing attributes.

[29]A verifiable visual cryptography scheme based on XOR algorithm


Visual Cryptography is the same as other secret sharing schemes, which also has the problem of deception. The cheater can destroy the recovery of secret image or gain secret information by cheating through making a counterfeiter of share images. In this paper, in order to resolve the problem of deception, we proposed a verifiable visual cryptography scheme can ensure that the secret image can be visually revealed correctly. This scheme can check and verify the accuracy and truthfulness of every share image, which is simple to decrypt and without any pixel expansion.

[30]A known-energy neural network approach for visual cryptography


Visual cryptography is based on cryptography where n images are encoded in a way that only the human visual system can decrypt the hidden message without any cryptographic computations when all shares are stacked together. This paper presents an improved algorithm based on Chang's and Yu visual cryptography scheme for hiding a colored image into multiple colored cover images. This scheme achieves lossless recovery and reduces the noise in the cover images without adding any computational complexity.

[31] extended visual cryptography using error diffusion


This paper introduces a color visual cryptography encryption method that produces meaningful color shares via visual information pixel (VIP) synchronization and error diffusion halftoning. VIP synchronization retains the positions of pixels carrying visual information of original shares throughout the color channels and error diffusion generates shares pleasant to human eyes. Comparisons with previous approaches show the superior performance of the new method.

[32]Color Visual Cryptography Scheme Using Meaningful Shares


Visual cryptography (VC) schemes hide the secret image into two or more images which are called shares. The secret image can be recovered simply by stacking the shares together without any complex computation involved. The shares are very safe because separately they reveal nothing about the secret image. In this paper, a color visual cryptography scheme producing meaningful shares is proposed. These meaningful shares will not arouse the attention of hackers. The proposed scheme utilizes the halftone technique, cover coding table and secret coding table to generate two meaningful shares. The secret image can be decrypted by stacking the two meaningful shares together. Experimental results have demonstrated that the new scheme is perfectly applicable and achieves a high security level.

[33] Steganography and Visual Cryptography in Computer Forensics


Recently, numerous novel algorithms have been proposed in the fields of steganography and visual cryptography with the goals of improving security, reliability, and efficiency. This paper discusses and compares the two methodologies. Some similarities and differences are presented, in addition to discussing some of the best known algorithms for each. Lastly, an idea for a possible algorithm which combines the use of both steganography and visual cryptography is suggested. There are several ways of hiding data in files of different formats, leaving various signs of hidden data. Can data hidden in an original image be detected after it undergoes visual cryptography? Would that be a scenario which computer forensic investigators and forensic software developers have to account for?

[34] Visual Cryptography Based on Void-And-Cluster Halftoning Technique


In this paper, visual cryptography for halftone images is proposed, which uses threshold arrays generated by a void-and-cluster method. The proposed halftone visual cryptography (HFC) using threshold arrays shows great flexibility for a combination of share images in order to decode a secret image. Moreover, it also achieves high quality share images, high speed processing and extensibility to (k,n) the visual cryptography of three share image categories, such as (2,3) or (3,3). Simulation results show that all the above features are achieved, while a secret image is clearly decoded, and the secret image cannot be seen on each share image.

[35] High capacity multi-scale image sharing scheme by combining visual cryptography with data hiding


In this paper we propose a multi-scale image sharing scheme to hide multiple images to two meaningful sharing images. The proposed method combines conventional 2-out-of-2 visual cryptography with data hiding technique. The overall effort of the proposed scheme is the achievement of decrypting/extracting multiple secret images and reference images from sharing images at different scale-levels. Moreover, it is not only applied to monochromatic images but also color halftone images. The experiment results will demonstrate that the proposed scheme indeed increases more capacity of hidden images than the conventional 2-out-of-2 visual cryptography does.

[36]Verifiable Visual Cryptography


The paper presents a verifiable visual cryptography (VC) scheme for checking the validness to the shares engaged in a VC decoding instance. The idea is to stamp a continuous pattern on the shares belonging to the same secret image, and a part of the pattern can be revealed through aligning and stacking half of two shares together. The visual coherent among the revealed patterns of all pair of shares provides evidence to the genuine of the shares engaged in the decoding process. Compare to the reported cheating prevention VC schemes, the proposed scheme maintains the original pixel expansion in VC scheme without cheating prevention ability, and the share verification process is done without resorting to any additional verification image. Besides, the proposed verification mechanism can easily be attached to any VC schemes in the literature to endow legitimate user with the ability to prevent cheating from malicious participants.

[37] Data Hiding in Non-Expansion Visual Cryptography Based on Edge Enhancement Multitoning


This paper proposes a scheme to hide some extra confidential data in transparencies during secret image encryption in visual cryptography. The secret image is multitoned into several levels first. An extended non-expansion visual secret sharing model is employed, i.e. size of transparencies is equal to that of the secret image. Thus less time and space are needed for transparencies transmission and storage.

[38] An Innocuous Visual Cryptography Scheme


An innocuous visual secret sharing scheme over natural images is presented in this paper. Secret sharing scheme allows a group of participants to share a secret (i.e., an image) among them. In case of(k, n) visual cryptography any group of k qualified participants among n (where k les n) can reconstruct the secret. This paper presents (n, n) visual cryptography scheme. This scheme does not apply dithering techniques to hide a secret image. Thus, it does not degrade quality of the secret image and in particular, this scheme is far from negative photo effect. Instead of dithering, this scheme spreads data by applying simple arithmetic operations. The rationale of arithmetic operations is presented.

[39] Digital watermarking and information hiding using wavelets, SLSB and Visual Cryptography method


Watermarking technique is increasingly used in the protection of biometric data against accidental and intentional attacks. Biometric watermarking is a technique that creates a link between a human subject and the digital media by embedding biometric information into the digital object. Among the various biometrics, iris has gained more popularity in the authentication area. The reason behind their popularity is that they unique and hence can be used during personal identification. Another area is information hiding where secret messages are stored inside a message. In this paper, a novel hybrid method to hide an iris image and secret message into a cover image using Discrete Wavelet Transformation (DWT), SLSB (Selected Least Significant Bit) and Visual Cryptography (VC) is proposed. Results show that the recognition rate after dewatermarking is high and the proposed system can resist various attacks while maintaining the visual quality of the cover image and text message.

[40]Based on Binary Encoding Methods and Visual Cryptography Schemes to Hide Data


Encoding data based on binary encoding methods and visual cryptography schemes is presented in this paper. First, a visual cryptography scheme is used to share pixels of a covert data to form two shadow matrices by using a specified sharing matrix. Then, the two shadow matrices are encoded into a host image to form an overt image by using a specific encoding rule. The overt image contains four groups of binary codes (specification codes), i.e. identification codes, covert-data dimension codes, sharing-matrix dimension codes, and information codes, to denote the parameters used for sharing and encoding. According to the test results, the proposed method performs well. Moreover, the overt image and the host image look almost the same, and the decoded covert data is exactly the same as the original covert data.

[41] A new fast and efficient visual cryptography scheme for medical images with forgery detection


In the field of medicine, storing images in a secure way has become a challenge. In order to face this challenge of security, we propose an algorithm based on visual cryptography for black and white medical images. Here, we bring out a new approach to visual cryptography. The main advantage of this system is that there is no necessity for post processing of the image without which a good quality of the image is obtained. More security is provided by using the JPEG Ghost technique, which performs forgery checking on the reconstructed medical image. This paper proposes a technique of processing the medical image and dividing it into two shares in an unpredictable format. These two shares can be overlaid on which the original image is retrieved. This reconstructed medical image undergoes a forgery detection checking and determines whether the obtained image is forged one or not. This technique can be implemented in the medical field for storing images of X-ray, MRI scan, CT scan and Ultrasound scan in a secure way. Research is going on to import these images over networks in a compressed and secure manner.

[42] Visual Cryptography in Internet Voting System


Internet Voting System (IVS) Using Visual Cryptography (VC) aims at providing a facility to cast vote for critical and confidential internal corporate decisions. It has the flexibility to allow casting of vote from any remote place, even when key stakeholders of election process are not available at workplace. This is enabled by leveraging and implementing the features provided by the VC in IVS. The election is held in full confidentiality by applying appropriate security measures to allow the voter to vote for any participating candidate only if he logs into the system by entering the correct password which is generated by merging the two shares (Black & White dotted Images)using VC scheme. Where, Administrator (Election officer) sends share 1 to voter e-mail id before election and share 2 will be available in the voting system for his login during election. Voter will get the secret password to cast his vote by combining share 1 and share 2 using VC. Visual Cryptography (VC) is a secret sharing scheme in which an image is converted into shares. No information can be revealed by observing any share (Black & White dotted Image). The information about the original image (Voter Password) will be revealed only after stacking sufficient number of shares. There are various schemes present in VC, 2 out of 2, k out of n, n out of n, etc. In the proposed method, IVS with 2-out-of-2 VC has been used for an efficient authentication voting system. Even if the hacker gets one share of the password, it is impossible to get the other share of the password, as it will be sent to the E-Mail Id of the voter. Thus IVS provides two way securities to the voting system, which is very much in need.

[43] Visual cryptography based multiparty copyright protect scheme


This paper applies visual cryptography for copyright protection. A multiparty scheme is presented for coowners of digital image. The basic concepts of visual cryptography are explained at first. Then by comparing with reference, a scheme for coowners is described. Next, key points in schemes are listed including halftone and progressive algorithms. At last examples are listed to show the whole procedure.

[44]Automation of business-processes of an Election System


Biometric techniques consists of uniquely identifying a person based on their physical characteristic or behavioral characteristic. It is mainly used for authentication purpose. Iris is one of the most powerful technique among all biometrics because of its uniqueness and stability. For authentication, the feature template in the database and the user template should be the same. Storing the template in the database securely is troublesome, because it can be compromised. In order to overcome this issue, in this paper a new method for securely storing the template in the database is proposed. This method uses Visual Cryptography (VC) concept and will generate shares, that shares will be stored in the database. The proposed Visual Cryptography fashion will generate meaningful shares which overcomes the problem in existing methods. Thus this new operandi will provide a great means of security and an extravagance layer for endorsement.

[45]A new color visual cryptography scheme with perfect contrast


In this paper, we propose a new color visual cryptography scheme based on the modified visual cryptography. This scheme can share a color secret image over n-1 arbitrary natural images and one noise-like share image. Instead of altering the contents of natural images, the encryption process extracts feature images from each natural image. In such a way, the proposed approach can effectively reduce the transmission risk and solve the management problems. Moreover, this approach avoids the pixel expansion problem and makes it possible to recover secret images without any distortion. Thus, the proposed scheme can share b&w, gray-level or color images in a secret way and is easy to implement.

[46]Image Hatching for Visual Cryptography


Image hatching (or non-photorealistic line-art) is a technique widely applied in the printing or engraving of currency. Diverse styles of brush strokes have previously been adopted for different areas of an image to create textures and shading. Because there is no continuous tone within these types of images, we propose a multi-level scheme, which uses different textures based on a threshold level. These textures are then applied to the different levels and are then combined to build up the final image. We propose a technique by which one can hide a secret using visual cryptography (VC) within the hatched images. Visual cryptography provides a very powerful means by which one secret can be distributed into two or more pieces known as shares. When the shares are superimposed exactly together, the original secret can be discovered without computer participation.

[47] An Improved Visual Cryptography Scheme for Secret Hiding


Cloud computing has been widely adopted in a large variety of applications. This brings besides others also many new challenges in the fields of security and reliability. Like any other security and correctness sensitive computer system, it is beneficial to fully verify cloud solutions to ensure their correctness. Verification and validation of distributed systems has been widely studied, however, it has not been analyzed whether verification approaches in distributed systems can be directly applied to cloud computing or not. In this study, we present a comparison of verification requirements for distributed computing and cloud computing to establish the need of a specialized verification model/architecture for cloud computing. We differentiate the verification in distributed and cloud systems based on their business models, architecture models, programming models and security models. We argue that service level agreements (SLAs), which span across the cloud, become more critical in the verification process. Based on our study, we present an abstract verification model focusing specifically on cloud computing, paving the way to an implementation of a viable verification model which can practically verify complex cloud systems.

[48] Generalized Random Grid and Its Applications in Visual Cryptography


Random grid (RG) is a method to implement visual cryptography (VC) without pixel expansion. However, a reconstructed secret with lower visual quality reveals in RG-based VC due to the fact that average light transmission of a share is fixed at 1/2. In this work, we introduce the concept of generalized RG, where the light transmission of a share becomes adjustable, and adopt generalized RG to implement different VC schemes. First, a basic algorithm, a (2,2) generalized RG-based VC, is devised. Based on the (2,2) scheme, two VC schemes including a (2,n) generalized RG-based VC and a (n,n) xor-based meaningful VC are constructed. The two derived algorithms are designed to solve different problems in VC. In the (2,n) scheme, recovered image quality is further improved. In the (n,n) method, meaningful shares are constructed so that the management of shadows becomes more efficient, and the chance of suspicion on secret image encryption is reduced. Moreover, superior visual quality of both the shares and recovered secret image is achieved. Theoretical analysis and experimental results are provided as well, demonstrating the effectiveness and advantages of the proposed algorithms.

[49] Maintaining the secrecy in visual cryptography schemes


Visual cryptography schemes suffer from the drawback of large pixel expansion of share images and bad visual quality of the recovered image. To provide secrecy, we go for pixel expansion and increasing number of shares, this causes the bad visual quality of the recovered image. In this paper, we construct (n, n)-VCS and OR and XOR operations are used for share creation and stacking process, which proves better in contrast and pixel expansion. The proposed method uses additional matrix to increase the secrecy of the message in XOR operation.

[50]Image protection based on visual cryptography and statistical property


In this paper, a novel intellectual property protection scheme for digital images based on visual cryptography and statistical property is proposed. The result of comparing two pixels that are selected randomly from the host image determines the content of the master share. Then, the master share and the watermark are used to generate the ownership share according to the encryption rules of visual cryptography. Our method does not need to alter the original image and can identify the ownership without restoring to the original image. Besides, our method allows multiple watermarks to be registered for a single host image without causing any damage to other hidden watermarks. Moreover, it is also possible for our scheme to cast a larger watermark into a smaller host image. Finally, experimental results will show the robustness of our scheme against several common attacks.

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