Two-out-of-two color matching based visual cryptography schemes

International audienceVisual cryptography which consists in sharing a secret message between transparencies has been extended to color prints. In this paper, we propose a new visual cryptography scheme based on color matching. The stacked printed media reveal a uniformly colored message decoded by the human visual system. In contrast with the previous color visual cryptography schemes, the proposed one enables to share images without pixel expansion and to detect a forgery as the color of the message is kept secret. In order to correctly print the colors on the media and to increase the security of the scheme, we use spectral models developed for color reproduction describing printed colors from an optical point of view

On the Security of a Visual Cryptography Scheme for Color Images

In Pattern Recognition, vol. 36, 2003, Hou proposed a four-share visual cryptography scheme for color images. The scheme splits a secret image into four shares, the black mask and the other three shares. It was claimed that without knowing the black mas, no information about the secret image can be obtained even if all the other three shares are known. In this paper, we show that this may be true for a few specific two-color secret images only. In all other cases however, security cannot be guaranteed. We show that an attacker can compromise a randomly chosen two-color secret image from any two of the other three shares with probability 4/7. The advantage will increase to 6/7 if all the other three shares are known. If the secret image has three or four colors, we show that the attacker can compromise it with probability 4/7 and 8/35, respectively. Finally, we show that our technique can be extended to compromising secret images with more than four colors

Text image secret sharing with hiding based on color feature

The Secret Sharing is a scheme for sharing data into n pieces using (k, n) threshold method. Secret Sharing becomes an efficient method to ensure secure data transmission. Some visual cryptography techniques don’t guarantee security transmission because the secret information can be retrieved if the hackers obtain the number of shares. This study present a secret sharing method with hiding based on YCbCr color space. The proposed method is based on hiding the secret text file or image into a number of the cover image. The proposed method passes through three main steps: the first is to convert the secret text file or image and all cover images from RGB to YCbCr, the second step is to convert each color band to binary vector, then divide this band in the secret image into four-part, each part is appended with a binary vector of each cover image in variable locations, the third step is converting the color space from YCbCr to RGB color space and the generated shares, hidden with covers, are ready for transmission over the network. Even if the hackers get a piece of data or even all, they cannot retrieve the whole picture because they do not know where to hide the information. The results of the proposed scheme guarantee sending and receiving data of any length. The proposed method provides more security and reliability when compared with others. It hides an image of size (234x192) pixels with four covers. The MSE result is 3.12 and PSNR is 43.74. The proposed method shows good results, where the correlation between secret and retrieved images is strong ranging from (0.96 to 0.99). In the proposed method the reconstructed image quality is good, where original and reconstructed images Entropy are 7.224, 7.374 respectively