Visual cryptography

About: Visual cryptography is a research topic. Over the lifetime, 1724 publications have been published within this topic receiving 25300 citations.

Multiple Secret Sharing Using Natural Language Letter Based Visual Cryptography Scheme

Abstract: Visual cryptography VC is a method used for encrypting visual informations in such a way that it can be easily decrypted by human visual system. Existing visual cryptographic schemes focuses only on using transparencies as shares and the shares appear as noise like pixels. These meaningless shares are not user friendly and create transmission risk problems. And schemes generating meaningful shares are limited to single secret sharing. This paper proposes a Letter-based Visual Cryptography Scheme LVCS, which creates meaningful shares for sharing multiple secrets that can be used for both binary and grayscale images. In this method we use natural language letters for representing pixels of secret images. Here we are generating meaningful text files instead of share images. So here the text files contain meaningful data and an attacker will not recognize them as containing secrets. This method satisfies security conditions since the secret information can be reconstructed by any k shares but with less than k shares reveal nothing.

On the security of multi-secret visual cryptography scheme with ring shares

Abstract: With visual cryptography in mind, the security property of a new scheme is always one of main concerns. However, the ideal security is not taken into account in some visual cryptography schemes sharing multiple secrets. In this paper, the security of a multi-secret visual cryptography scheme proposed by Feng et al. is analyzed. We show that the security of their scheme is not ideal. Precisely, it is insecure since some information of the secret images can be inferred by block attacking the second share alone. The main weak design is proved and shown by means of giving theoretical analysis and conducting some counter experiments.

Highly Trustworthy In-Sensor Cryptography for Image Encryption and Authentication.

Abstract: The prevailing transmission of image information over the Internet of Things demands trustworthy cryptography for high security and privacy. State-of-the-art security modules are usually physically separated from the sensory terminals that capture images, which unavoidably exposes image information to various attacks during the transmission process. Here we develop in-sensor cryptography that enables capturing images and producing security keys in the same hardware devices. The generated key inherently binds to the captured images, which gives rise to highly trustworthy cryptography. Using the intrinsic electronic and optoelectronic characteristics of the 256 molybdenum disulfide phototransistor array, we can harvest electronic and optoelectronic binary keys with a physically unclonable function and further upgrade them into multiple-state ternary and double-binary keys, exhibiting high uniformity, uniqueness, randomness, and coding capacity. This in-sensor cryptography enables highly trustworthy image encryption to avoid passive attacks and image authentication to prevent unauthorized editions.

Visual Cryptography — How to Use Images to Share a Secret

Abstract: In this paper, we give a survey of visual cryptography schemes, a new type of cryptographic schemes which was first introduced by Naor and Shamir [9] in 1994. Visual cryptography schemes can be considered as encryption schemes based on graphical data. In visual cryptography schemes as special instances of secret sharing schemes, the secret information is encoded by the construction of several fragments, called shares which are distributed secretly to different, not necessarily trustworthy parties. In order to reconstruct the secret image, a qualified subset of these parties has to combine their shares. For example, in (K, n)—threshold schemes there are n different parties and each subset of at least k parties is qualified. Visual cryptography schemes are perfect, i.e., forbidden (i.e., not qualified) subsets of parties learn no information at all about the encrypted image (in the information-theoretic sense). In contrast to conventional encryption (resp. secret sharing) schemes, visual cryptography schemes allow the decryption to be done directly by the human visual system, i.e., without performing any sophisticated cryptographic computations.

A Secure and Verifiable Visual Cryptography for Color Images

Abstract: Confidentiality is the most important aspect of information security. Visual Cryptography (VC) is a decryption-less cryptographic technique where human eye is proficient in decrypting the secret information. VC is implemented for binary, gray scale and color images, Color image VC schemes are commonly implemented using Cyan-Magenta-Yellow-Black (CMYK) model that requires a computational device for revealing the secret image but lacks verifiability of the shares. The authenticity of the shares is not assured to the receiver, particularly in color image VC scheme. In case of any alteration, attack or loss in the transmitted data, it cannot be identified by the existing schemes. Unlike the existing models where a device is compulsory for decrypting back color images, the proposed model provides a means to encrypt the color images using Red-Green-Blue (RGB) model where each pixel is processed by its respective RGB components. It enables decryption at the receiver without the assistance of computer or aided devices. In this paper, the above mentioned issues are addressed by the scheme that verifies the integrity of the received shares at the receiver.