New Visual Cryptography Algorithm For Colored Image

Visual Cryptography is a special encryption technique to hide information in image in such a way that it can be decrypted by the human vision if the correct key image is used. Visual Cryptography uses two transparent images one image contains random pixels and the other image contains the secret information. It is impossible to retrieve the secret information from one of the image. Both transparent images and layers are required to reveal the information. The beauty of the Visual secret sharing scheme is its decryption process i.e. to decrypt the secret using Human Visual System (HVS) without any computation

As a result of rapid advancement of various kinds of Internet technologies, more and more information are to be transmitted to all parts of the world from everywhere through the Net. In such cases the senders have to take into consideration the information security issues so that they can trustingly enjoy the speed and convenience that is offered by an Internet. The data sent through an Internet may include some important secret images. " Visual Cryptography " is the technique developed to provide security and authentication to these images. Many attempts have been made from within the cryptographic community to provide security to these secret images. In this paper we will make a review Cryptography Schemes that are used store and transmit the secret images. We will also compare the respective algorithms of all the schemes with respect to the parameters such as PSNR and perceived error.

In this paper, we propose a new color visual cryptography scheme which is based on modified 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. In this scheme sender can share n-1 natural images and one secrete image of variable size with the server and it make the encryption with extraction of feature of natural images without altering the contents of natural images. When the receiver identification is done that time server make the decryption process and send the secrete image with transmitted by highly secure secret channel. Moreover, this approach avoids the pixel expansion problem and makes it possible to recover secret images without any distortion.

23rd Biennial Symposium on Communications, 2006, 2000

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.

2013

Visual Cryptography is a special type of encryption technique to obscure image-based secret information which can be decrypted by Human Visual System (HVS).A digital envelope is data container that is used to protect a message through encryption and data authentication. A digital envelope allows users to encrypt data with the speed of secret key encryption and the convenience and security of public key encryption. At first this cryptographic system divide the secret image by partitioning it into n number of split images.In this current work we have proposed a variable lengthSymmetric Key based Visual Cryptographic Scheme for colorimages where a Secret key is used to encrypt the every images and the Encrypted images are again encrypted by the fingerprints images. Finally every encrypted images are enveloped in other images using invisible digital watermarking.

—Visual Cryptography (VC), a cryptographic technique which allows visual information to be encrypted in such a way that the decryption can be performed by the Human Visual System (HVS), without the help of computers. Visual Cryptography Scheme (VCS) eliminates complex computation problem in decryption process, by stacking operation we can restore the secret image. This property makes VC especially useful for the low computation load requirement. During encryption, the image is encrypted and then it is divided into two shares. Two shares are superimposed to reveal the secret image in the decryption process. The objective of our project is to get the better quality of decrypted image with the same size as the original image. The OR based VCS degrades the contrast by its monotone property. In XOR based scheme, the share images are superimposed with the help of XOR operation which results in perfect reconstruction. Hence, the XOR operation is proposed in decoding process to enhance the contrast, quality, and to reduce noise.

Visual Cryptography is a special encryption technique that encrypts the secret image into n number of shares to hide information in images in such a way that it can be decrypted by the human visual system. It is imperceptible to reveal the secret information unless a certain number of shares (k) or more are superimposed. Simple visual cryptography is very insecure. Variable length key based visual cryptography for color image uses a variable length Symmetric Key based Visual Cryptographic Scheme for color images where a secret key is used to encrypt the image and division of the encrypted image is done using Random Number. Unless the secret key, the original image will not be decrypted. Here secret key ensures the security of image. This paper describes the overall process of above scheme. Encryption process encrypts the Original Image using variable length Symmetric Key, gives encrypted image. Share generation process divides the encrypted image into n number of shares using random number. Decryption process stacks k number of shares out of n to reconstruct encrypted image and uses the same key for decryption.

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.

International Journal of Science and Research (IJSR)

Secret sharing is a method for distributing a secret among a group of participants. Visual Cryptography is a form of Visual Secret Sharing proposed by Moni Naor and Adi Shamir. Visual Cryptography 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. Color Visual Cryptography encrypts a color secret message into color halftone image shares. In this paper the various Visual Cryptography schemes are discussed and try to summarize the recent developments in Color Visual Cryptography technology.

iaeme

Visual cryptography is a method for protecting image based secrets that has a computation-free decoding process. In this paper, we propose a new visual cryptography scheme for color images based on CMY model, half toning technique and the traditional binary image sharing scheme. The image shares generated by our method are transmitted to the destination through a network and the image is decrypted by stacking any two transparencies. The image can be in any standard format. This scheme provides an efficient way to hide the natural image among different shares. Furthermore, the size of the shares and the implementation complexity do not depend on the number of colors appearing in the secret image.

IRJET, 2021

Visual cryptography is a secret sharing technique for securing visual contexts like images or texts by encoding into multiple number of shares. In decryption process, one can decrypt the secret image (SI) by stacking the shares without any additional computations. Color visual cryptography (CVC) encodes a color secret image (SI) into several shares in which each color pixels are separately handled using RGB or CMY models. In this paper we proposed CVC technique for secret color images encoding schemes with multiple encryption algorithm to make the secret image highly secured. In this method, a color secret image is encrypted by extracting R, G, B component from the original secret image and halves of each of them into two separate matrices. Each of these matrices are then XORed with a randomly generated key matrices (Ki) to generate six different shares for each of the three color planes. By using Hou's scheme, share 1 and share 2 are then constructed by stacking the three first level shares and three second level shares of each color components respectively. The generated two shares are further encrypted by hybrid security algorithm called AES and Blowfish. On the recipient side, color SI is retrieved form these shares with the equivalent quality as that of original image by performing all the operations that we accomplished in the encryption processes in reverse order. The proposed method is then evaluated by using performance measures such as PSNR and SSIM. The result obtained by these two evaluation parameters show that the reconstructed image retain the quality of the original image. Therefore the proposed method is excellent for hiding secrets in the form color images confidently compared to the existing VCS schemes.

2013

Color visual cryptography (VC) encrypts a color secret image into n halftone image shares. The secret image can be recovered simply by stacking these shares together without any complex computations involved. The shares are very safe because separately they reveal nothing about the secret image. This paper introduces a faster and easier color visual cryptography encryption method that produces meaningful color shares via error diffusion halftoning. An error diffusion technique for halftoning produces shares which are more pleasant to human eyes. The algorithm proposed by this scheme reduces a considerable time for encryption and decryption in a much easier way. Comparisons with previous approaches show the superior performance of the new method. Keywords—Color meaningful shares, digital halftoning, error diffusion, secret sharing, visual cryptography (VC).

IRJET, 2020

As the increase of information transmission over the internet is increasing across World Wide Web, protection of the private as well as public information or data to be transmitted has become a challenging task. Over the years, encryption technique included many steps with different calculations to help avoid the unauthorized access to data transmitted over the internet communication inverse process of the encryption technique is decryption in which the original secret information could be retrieved, hence both the encryption And decryption process required their own algorithms to be completed. Thus, this shows that both the encryption as well as the decryption is not only time consuming but also resource consuming too. But the visual cryptography (VC) provides an effective way for the solution of this problem by including fewer steps and lesser complexity. In VC the main focus is on the encryption were as the decryption is a simple procedure to be taken out. As there will be an algorithm needed just for encryption of picture or information decryption could perform by human vision system. In the proposed method , the encryption algorithm uses an 16 standard color code format is taken which helps in generation of shares from original picture as well as halftoning to picture is done by using XOR operation and decryption could be performed by just stacking the shares and with human vision without any extra needed efforts. Key Words: Visual Cryptography, XOR based scheme, RGB 16 color code model, and halftoning to picture, human vision.

The effective and secure protections of sensitive information are primary concerns in commercial, medical and military systems. To address the reliability problems for secret images, a visual cryptography scheme is a good alternative to remedy the vulnerabilities. Visual cryptography is a very secure and unique way to protect secrets. Visual cryptography is an encryption technique which is used to hide information which is present in an image. Unliketraditional cryptographic schemes, it uses human eyes to recover the secret without any complex decryption algorithms and the facilitate of computers. It 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 this paper we represent various cryptography technique and research work done in this field.

Visual cryptography is one of the cryptographic techniques which divide the original image (or) data into 'n' number of shares. Each share contains a part of original information, for the reconstruction process 'k' number of shares is required to reconstruct the data. Here we propose the visual cryptographic scheme for color images using threshold level determination. If the threshold level is higher in particular pixel for the particular color that pixel gains the transparency value (white shares) and the remaining other colors having black pixel values. The proposed method satisfy the visual cryptographic properties such as there will be no pixel expansion, it requires only few shares to reconstruct the image, there will be no lose in the data share.