Topic
Visual cryptography
About: Visual cryptography is a research topic. Over the lifetime, 1724 publications have been published within this topic receiving 25300 citations.
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01 Jan 1998
TL;DR: A survey of visual cryptography can be found in this paper, where the secret information is encoded by the construction of several fragments, called shares which are distributed secretly to different, not necessarily trustworthy parties.
Abstract: In this paper, we give a survey of visual cryptography schemes, a new type of cryptographic schemes which was first intro duced 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 frag ments, called shares which are distributed secretly to different, not nec essarily 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, Le., forbidden (Le., 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, Le., without performing any sophisticated cryptographic computations.
01 Dec 2005
TL;DR: This paper presents three simple methods alternatives to visual cryptography for colored images that takes a bit by bit for each pixel from the red, green, blue bands and inserts them in the LSB in each of the key image.
Abstract: This paper presents three simple methods alternatives to visual cryptography for colored images. In the first method, an RGB colored image is converted to HSI image generating 8 sub-images. Then each sub-image is divided to an arbitrary number of slides (8 slides) sub-images and encrypted using XOR operation with HSI random keys. A substitution process is applied for decryption followed by HIS/RGB conversion. With the second method and after RGB/HIS conversion, a bit by bit is taken from the original image and inserted them in each key image (8 images). The third method converts the original image and the key image into 3 sub-images (R,G,B) and takes a bit by bit for each pixel from the red, green, blue bands and insert them in the LSB in each of the key image (8 images). Finally the results of the three methods are compared.
02 Dec 2017
01 Jan 2013
TL;DR: This paper proposes an extended VC scheme with unlimited based on basis matrices and a prospect mold, and the maximal contrasts with two are explicitly solved in this paper.
Abstract: The visual cryptography is a secret sharing scheme where a secret image is encoded into transparencies, and the stacking of any out of transparencies reveals the secret image. The stacking of or fewer transparencies is unable to extract any information about the secret. We discuss the additions and deletions of users in a dynamic user group. To reduce the overhead of generating and distributing transparencies in user changes, this paper proposes a VC scheme with unlimited based on the prospect mold. The proposed scheme allows changing dynamically in order to include new transparencies without regenerating and redistributing the original transparencies. Specifically, an extended VC scheme based on basis matrices and a prospect mold is proposed. An equation is derived from the fundamental definitions of the VC scheme, and then the VC scheme achieving maximal contrast can be designed by using the derived equation. The maximal contrasts with two are explicitly solved in this paper.
01 Jan 2015
TL;DR: A new model is proposed called as “A Secure Mail Application using Steganography and Visual Cryptography” that ensures security of the shares by using AES algorithm, a symmetric key encryption method, which provides secure email messaging.
Abstract: Although there are recent advancements in the development of messengers, Emails are the most widely used and popular messaging system used by the Internet users, which helps them to communicate in a short span of time. Security to the Email messages is an important issue as no Internet Standards provides security to the message content. The existing system, PGP (Pretty Good Privacy) used to encrypt and decrypt email messages, has a drawback of adaptive chosen cipher text attack as it works in CFB encryption mode as used by OpenPGP. To improve the security of email messages, a new model is proposed called as “A Secure Mail Application using Steganography and Visual Cryptography”. The email message to be transmitted is converted to an image and shares are generated using (2, 2) Visual Cryptographic Technique. One of the shares is kept with the server and other is sent to the receiver’s mail box. Man in the middle attack is not possible as these shares are transmitted through different medium. At the receiver side, two shares are fetched and decrypted to get the image. From this image, the original message is reconstructed. One added advantage of the system is that it ensures security of the shares by using AES algorithm, a symmetric key encryption method. The use of Image Steganography to construct an image from the message and use of Visual Cryptography provides secure email messaging.