Visual cryptography

Visual cryptanalysisIntroductionOne of the habitual solutions for plan encryption is opthalmic cryptography. Secret manduction concepts are use to encrypt a unavowed figure into the shares (customized versions of the original moving picture) which sight be transmitted over an undeveloped communication leave and by overlap shares, the secret message is scramed Visual cryptanalytic solutions are based on binary star or binaries inputs. Due to this, natural images moldiness be counterbalance trans work angiotensin converting enzymed into halft ace (this is a technique which uses different density of dots to video display the image) images to simulate the original patriarchal or colour levels in the rump binary image To create the shares, the halftone version of the input image is use instead of the original image. The decrypted image is made by stacking the shares together. Because binary selective information skunk be displayed in an apparent form when printed on transparencies or viewed on the screen and overlapping shares that contain apparently haphazard information can expose the secret image. to a greater extentover, the decrypted image is darker, contains a b break of opthalmic damages due to the algorithm that is employ for the process and the final result of secret image is incr heartseased by close of visual cryptography solutions (Lukac at el,2005) and(Lukac 2006).1.1 ObjectivesThe base of fostered communication among users using insecure channel is known as cryptography. In order for cryptologic security to strike place, an algorithm is involved for the practice of encrypting and decrypting messages In its basic form, one image is split into cardinal separate images c completelyed shares. When the shares are busty on slip by of from each one other, the unique image is retrieved A general n out of n visual cryptography intrigue involves n participants in which a secret image is split into n random looking shares and all n shares are required to recover the original image.1.2 Aims The important topic lav Visual steganography is to encrypt information in the form of images in a secure and flawless way The information must be encrypted before it is send, so that it cannot be illegally read or modified in the middle of transmission. Suppose 4 persons cause deposited their funds in a bank account. These persons obviously do not affirm each other. In particular, they do not want a champion member of themselves to withdraw the money. However, they assume that withdrawing money by both members of the group is not considered a conspiracy rather it is considered to have received authorizations Therefore, they clear-cut to set the bank regulation (with a trusted computer) into 4 partitions so that any two or much partitions can be used to reconstruct the code. Since the persons encounteratives forget not have a computer with them to rewrite the bank code when they come to withdraw the mone y, they want to be fitting to decode visually each thief gets a enhancer The transparency should yield no information about the bank code (even implicitly). However, by taking any two transparencies, stacking them together and aligning them, the secret proceeds should pop out. How can this be done? (Naor and Shamir, 1994) proposed a solution and introduced a simple but perfectly secure way that allows secret sharing without any cryptographic computation, which they termed as Visual cryptanalytics Scheme. The simplest Visual Cryptography Scheme is given by the following setup. A secret image consists of a collection of black and clean-living pels where each pel is tough independently To encode the secret, the original image is split into n customized versions (referred as shares). To decode the image, a subset S of those n shares is picked and display each of them onto a transparency In this throw, a new visual cryptography end is intended for shadow images. The proposed scheme willing be flexible, easily implemented, and more secure for shadow images. Moreover, shadow image structure is augmented to pare the chances for an attacker to guess the secret. Literature Survey2.1 introductionVisual Cryptography was introduced by (Naor and Shamir, 1994) at Eurocrypt, an annual conference sponsored by the International tie-up for Cryptographical Research (IACA) to encourage discourses and seminars among cryptologists all over the world In that, the description is about a new cryptographic scheme that encodes a black and white image into n shares. Decoding is done with the pitying visual arranging when the n shares are placed on transparencies and stacked on top of each other. They included several schemes to implement a visual cryptography system in their presentation Since that time, the paradigm of visual cryptography has attracted wide attention all over the world. Several papers and projects have been presented to extend visual cryptography. Sche mes have been invented for a general k out of n sharing scheme and to cover gray outmatch and colour images as well(Jim Cai and Zhou,2000) Even today, research continues in the field of visual cryptography and papers regarding contrast, extended schemes are being published regularly This research addresses the few questions concerning visual cryptography, and will attempt to answer these questions in the context of the research by using experimental approach into the difficulty of visual cryptography, these questions are what is cryptography? What set of features should be used in visual cryptography? How to reduce chances for attackers to get the secret of shadow images? 2.2 surmisalThis section will attempt to explain the basic theory behind visual cryptography. Consider a black and white image (not gray scale). It is made up of black pixels and white pixels grouped such that when viewed with the gentle eye, the picture (or word, symbol etc.) can be seen. To encrypt this ima ge, each pixel from the original image is taken and converted into sub pixels. For sake of this discussion and for simplicity, let us assume that each pixel will be converted into two sub pixels and there will be two shares If a pixel is white, then one of two combinations of sub pixels will be randomly chosen to represent the pixel on each of the shares. When the shares are stacked and properly lined up, the sub pixels for the white pixel produce the result In both sets of sub pixels for the white pixel, it can be seen the result is one black sub pixel and one white sub pixel following to each other. When viewed with the human visual system, the result appears to be gray (combined effect of white and black next to each other) On the other hand, if a pixel is black, then one of the two combinations of sub pixels will be randomly chosen to represent the pixel in each of the shares (same idea as the white pixel). However with black pixels gives two sub pixels next to each other. To t he human eye, this appears as a share by itself gives no visible information from the original image because the sub pixels are evenly distributed on each share (one black sub pixel and one white sub pixel for each pixel in the original image). These combinations (black/white and white/black) kick the bucket with probability 1/ 2 providing a share with randomized pixels and and so not revealing any hint of the original image. When the shares are stacked, the white pixels are seen as gray, while the black areas remain black (Naor at el, 1994 ,Lee at el,2003 and Voyatzis,1996) (Naor and Shamir, 1995) thought about the problem of encrypting material such as printed text, handwritten notes, pictures, etc in an absolutely secure way which can be interpreted directly by the human visual system Furthermore, they have explained that the basic model includes a printed page of cipertext (which can be sent by mail of faxed) and a printed transparency. The system they developed can be used by anyone who lacks knowledge of cryptography and without dischargeing any cryptographic commutations. Moreover, they noted that the best way to visualize the visual cryptographic scheme is to consider a concrete example In cryptography, the process of transforming data (referred to as plaintext) where the process uses an algorithm (called cipher) is called encryption. The encrypting process make the information un legible to anyone except those possessing special knowledge, usually referred to as a key. The encrypting process results encrypted data (in cryptography, referred to as cipher text). To read encrypted data, the encrypted data should be made readable. So the reverse process is called decryption. In real world, the package for encryption can typically also perform decryption to make the encrypted information readable again (ElGamal,1985 and Rivest,1978) encryption has long been used by militaries and governments to facilitate secret communication. Encryption is now used i n protecting information at heart many kinds of civilian systems, such as computers, storage devices (e.g. USB flash drives), net profitworks (e.g. the Internet, e-commerce), nomadic telephones, wireless microphones, wireless intercom systems, Bluetooth devices and bank automatic teller machines. Encryption is also used in digital rights management to obstruct unlicenced use or reproduction of copyrighted material and in software also to protect against reverse engineering (Encryption) Encryption, by itself, can protect the confidentiality of messages, but other techniques are still needed to protect the rectitude and authenticity of a message for example, verification of a message documentation codes (MAC) or a digital signature. Standards and cryptographic software and hardware to perform encryption are widely available, but success soundy using encryption to ensure security may be a challenging problem. A single slip-up in system design or executing can allow successful attacks. Sometimes an adversary can obtain unencrypted information without directly undoing the encryption. (Maurer,1994 and Diffie,1976) Moreover, The optimality of VC is determined mostly by its pixel expansion and the relative contrast and, the relative contrast needs to be as large as possible to ensure visibility (Alvarez at el,2005). In the scope of this research, the works related to contrast optimization will be explored. Works related to deriving lower bound of pixel expansion m can be found in (Naor and Shamir, 1995), (Rivest at el,1984) etc. The research on contrast optimization was motivated by the problem of extra graying erect introduced to decoded image. This occurs because the decoded image is not an exact reproduction of the original image, but an expansion of the original, with extra black pixels. Research methods-Doing a thorough investigation into basic visual cryptography -Careful study of algorithms used in visual cryptography -Checking out a suitable growth e nvironment and a suitable frame work that can ease the image processing tasks -investigating shadow image structure for visual cryptographic practices such as pixel expansion and the relative contrast -This project emphasizes, intends and evaluates a computer-based system using appropriate processes and tools, as follows Front destroy coffee bean Back End Microsoft SQL Server OS Windows XP and Windows vista IDE net beans 6.7 The net bean IDE is used for following features In this project, net beans structured Development Environment (IDE) is used because its tools, debugging and performance monitoring. Net bean IDE for create applications saves the time by managing windows, settings, and data. In addition, an IDE can store repetitive tasks by macros and abbreviations. Drag-and-drop features make creating graphical user interface (GUI) components or accessing databases easy and highlighted code and debugging features alert to errors in the code The application is developed b y coffee bean because of following features Java is a graphical user interface schedule language Java supports to programme independent mechanism Java is a general purpose and object oriented programming language The most striking features of the language are that it is platform neural language Java program is under the control of JVM the JVM can contain the program and prevent it from generating side effects outside the system. Thus safety is included in Java language.Java is mainly adopted for two reasons Security Portability These two features are available in java because of the byte code. Byte code is a extremely optimized set of instructions to be executed by the Java flow time system called JVM. The features of Java which are adopted for the network system explore are Multithreading Socket programming span Multithreading Users perceive that their world is full of multiple events all happenings at once and wants their computers to do the same. Unfortunately, wr iting programs that steal with many things at once can be much more difficult than writing conventional single threaded programs in C or C++. Thread safe in multithreading means that a given library functions is implemented concurrent threads of execution quiver Swing refers to the new library of GUI controls (buttons, sliders, checkboxes etc). Swing is a quick GUI outgrowth tool that is part of the standard Java development kit. Swing is a set of classes that provides more powerful and flexible components. Swing components are not implemented by platform specific code. sooner they are written in Java and therefore are platform independent (java doc).