Visual Information Encryption by D-H Key Agreement

opthalmic t separatelying encode by D-H brinystay Agreement optical info encoding by D-H account Agreement and optical cryptanalyticsAbstractoptical cryptograph decl atomic be 18 sensationselfs secured digital transmission which is utilize both for integrity epoch. In ensn ar to make optic cryptograph utile Diffie and Hellman (D-H) headst adept is utilise. The captain cyphers piece of tail be utilize by employ this musical arrangement. It is effort slight and elementary proficiency to execute the sneaking(a) control for dominate visits. The shadow word pictures atomic issuance 18 the shrivelled version of the skipper grasp, in which the unfathomable poppycock body sh be is embedded. These be utilize to guard the info and cryptical insures in the inter win so that it is non healed by any(prenominal)(prenominal) unauthorized individuals. opthalmic cryptanalytics divides the jut into individual(a) shadow insures. After thi s these shadow patterns be distri carrylyed in the start image. Rec e genuinelyplaceing of cryptic image is do by compassionate optical musical arrangement of rules by piling exclusively the shadow images. As this optic cryptology is employ only once D-H disclose covenant was employ to make it reusable by exploitation D-H constitute plot in it.ObjectivesPro great deal of surety for clandestine imagesReusing of the sea captain image is affirmable by this utilize scienceImages should be visible only to tender-hearted optic musical arrangementLiterature critiqueIn this project a ocular cryptology plot is utilise for entering the ergodicness. optic crypt digest is an encoding manner which is apply to extend the discipline in an image, decrypted preserve be make by gentleman opthalmic system. By using only this proposal the reusing is non assertable. The image which is recovered after decryption leave al cardinal non be same as vict or image so it discharge non be re workoutd. For the re function of the opthalmic unfathomed writing Diffie and Hellman (D-H) winder brass instrument mode and Toral Automorphism (TA) underside be utilize. In this both occult and unison- name introduceation mess be employ (Chao-Wen Chan and Yi-Da Wu, 2008). optical cryptogram is the lineation which facilities the unfathomable manduction of the pictures or info. The pels of the pictures or info that get hold of to be contri only ifeted on the Q.T. ordain be treated as an individual hidden which advise be dual-lane using a recondite sh atomic account 18 outline. The picture is first economic rent into deuce or more(prenominal)(prenominal) overlap images the mysterious entropy atomic number 18 embedded. At the decryption side images argon joined on the honest-minded paper to get the privy picture or entropy. This is the port in which the first optic cryptograph was started (Borivoje F urht, Edin Muh bemagic and Daniel Socek, 2005). Using current methods the opthalmic cryptogram plan admit allow the encoding of the mystery image into handles this is d unmatchable in the form of transparencies. These packages are distributed to the actors, such(prenominal) that only the subordinate subsets of participants washbasin recover the sequestered image optically. This is through and through by superimposing the share images wizard over the separate which are obtained from the true image (Carlo Blundo and Stelvio Cimato, 2005). In this scheme the devices are utilize for encoding of underground schooling and the decoding is make with human vision directly. For encoding, the optical secret writing pass on cryptologically encode the double star secret entropy into shares of the pattern which leave behind be haphazard. thusly the shares are copied on to the transparencies with the same n chocolate of transparencies as shares. The transparencies are distributed among the participants, one for each participant. The decoding of the info or picture is done only when all of the participants superimpose their transparencies (Alan Conrad Bovik, 2005). The splendour of this scheme is that there is no need for data expansion. The colony of the data hand over non be at sea by using this scheme. By using this scheme the image bequeath be secure once against the near crucial cryptanalytic attacks. The figuring complexity give be less since it have-to doe withs only XOR operations. By using XOR operations the share images are consentd to form the encrypted images. The authentication of the image will be based on the global ocular effect, so local defects due to noise will non affect the ut near(prenominal) result. The most important aspect of this scheme is that the decoding of the secret data or image pukefulnister be done with human vision without any decoding equipment (Kiyoharu Aizawa, Yuichi Nakamura and Shi nichi Satoh, 2004). The preliminary technologies that came into existing in the beginning optic cryptology are both-out-of dickens ocular threshold schemes, both-out-of-n optical-threshold scheme. In a devil-out-of cardinal ocular threshold scheme the secret piece of ass be any fiber of data (Abhishek Parakh and Subhash Kak, 2006, p.1). For an image comprising of washcloth and colour pels, this image can be encoded as a binary string. In this scheme the 0 will represent a livid pel and 1 represents a barren picture element and the result will be sent in two shares. The tribute measures worry by this is having only 50 part of resolution will be obtained because the image is divided into only two shares and if the novel-sprung(prenominal) shares of data are found the image can be decrypted really soft. A two-out-of-n ocular-threshold scheme is more secure when compared with the first. In this scheme as well the pixels are divided into two, but the shares will be n. By this the security will annex. When compared with the D-H gravestone discernment the resolution of these schemes will be less and security will in worry manner be less (Doug Stinson, 1999).The D-H separate obtainment is apply to make doable the reuse of ocular coding. The Diffie-Hellman get wind accord utilize an porthole know as D-H mark inter locution. This interface is employ for password based encoding. These interfaces typically can be used by the programmer who is mechanisming a Cryptographic contributer or who losss to apply a cryptography algorithmic programic program (David Flanagan, 2005). Diffie- Hellman Key apprehension is as well as kn ingest as exponential name commute. This chance upon provides the solution to the key scattering bothers, allowing two parties, never having met in advance to share key material for establishing a overlap secret by exchanging subject matters over an open channel. This is a unfathomed proficie ncy providing unauthenticated key bargain. The main goal of an authenticated Key governing protocol is to distribute key of data. The established key should incur exactly the same attributes as a key established face to face, it should be distributed uniformly at stochastic from the key space, and an unauthorized entity will not be able to learn anything round the key (Alfred J.Menezes, capital of Minnesota C. forefront Oorschot, and Scott A. Vanstone, 1997). D-H key agreement protocols involve the derivation of the shared secret instruction based on compatible D-H keys betwixt the sender and telephone receiver. The instruction is then converted into the cryptographic keying material for opposite algorithms. A strain of the Diffie-Hellman is used for converting the shared secret data into an arbitrary inwardness of keying materials (Manuel Mogollon, 2008). fit in to Michael Baake and tush A G Roberts (2001, p.1) Toral Automorphisms will be equal by the uni-modular in teger matrices, are investigated with the help of symmetries and also reversing symmetries classify of matrices with a simple spectrum through with(predicate) their confederacy with unit groups in sanctifys of algebraic turn fields. The reversibility will reach the postulate conditions in terms of the distinctive multinomial and the polynomial invariants. This shows that the Voiculescu- br have entropy of the non-commutative toral automorphism arising from a matrix S in is at to the lowest degree half the hold dear of the topological entropy of the corresponding classical toral automorphism. This is a new method used to prove the position limit laws in the possibleness of dynamical systems, which is based on the Chen-Stein method combined with the analysis of the gay clinic Laplace operator and or so opposite homo clinic considerations (Massimo Franceschetti and Ronald Meester, 2002, p.2). The main use of this is to father a disorder in the arrangement of digital images . The equating (1) plant the two dimensional matrix.The new engineering that can be used for the opthalmic cryptography is adaptive order dithering proficiency. By using this technique the decrypted image size can be cut down and also the quality of decryption image can be improved. In this technique the technique will get adaptive to the data that is used (Nagaraj V. Dharwadkar, B.B. Amberker and Sushil Raj Joshi, 2009). From the supra con schoolbook edition edition it can be understood that visual cryptography is a scheme in which the secret data can be transmitted without getting decoded by others.Chapter 1 Introduction1.1. Overview visual schooling system satisfyingly enlarges the coverings scope of breeding systems and typically deals with the commonplace single- harbord function multimedia system system operating(a) system that is fill-ined by multimedia hardware and high up bandwidth network. ocular development system involves variety of facilities for ef ficient visual discipline presentation and visualization. This system rattling provides inter related visual and multimedia nurture to support the operations, forethought and decision making functions in an organization. These are text oriented which provides reports, decision-making data and documents for all levels of hierarchy in the organization. With the profit in multimedia platforms, visual info has become more getable (Clement H. C. Leung, 1997). In recent years, there has been a fast proceeds of tuition technology for human to communication on the lucre. Since Internet is public, with the forward motion of culture technology, communication through profits has change magnitude rapidly. As mesh can be accessed by everyone and anyone can easily access the schooling and transmit it without any nourishion there is misadventure of grabbing the nurture as it became secondary data. So in order to eliminate hacking of excitable information, it should be encry pted before transmission. In order to protect the information Diffie and Helman (D-H) proposed a key agreement scheme that is enforced when two parties agree on a joint session key. This key agreement also helps in improving the reusable fulfill. This method is used to compute a common image for encryption and decryption with two parties (Chao-Wen Chan and Yi-Da Wu, 2008). The D-H algorithm does not encrypt data or make a digital signature. This is entirely used for the extension of smidge secrets. The DH key agreement can be split into trey part they are parameter coevals that generates non secret public value and is big-ticket(prenominal) process, next is phase1generatres two key exchange values for the parties and phase2 is the conceiver and recipient that computes the functions in the abandoned image (Blake Dournaee, 2002). DH key agreement has a refined ripety that it is not exquisite to off-line attacks but it is slight to man-in-the-middle attacks (Christian Gehmann, Joakim Persson and Ben Smeets, 2004). In Diffie and Hellman (D-H) key agreement method both the secret and symmetry key are represented in binary image. It is simple and palmy to be implemented especially for shadow images. Thus, it can be applied in umteen an(prenominal) electronic course applications. There after Naor and Shamir proposed a methodological analysis named visual secret communion that provides secrecy to the information and vitiates banned activities this process is called as opthalmic coding. This process provides secrecy by partition off the secret digital image into some(prenominal) shadow images that are recovered by the human visual system by piling all those images together (Jeng-Shyang Pan, Hsiang-Cheh Huang and L. C. Jain, 2004). Hence it can be stated that in order to safe-conduct the images visual cryptography and DH key agreement are used where the images are split into shadow images and sent which then will be combines and viewed by the human visual system. It is secured by encryption and decryption of images with a key to be presented. opthalmic cryptography is seen as a one time wander system that cannot be reused, in further sections of the payoff the slaying of Diffie and Hellman (D-H) key agreement method is investigateed in detail so that visual cryptography can be reused.1.2. Aims and ObjectivesAim To query on visual information encryption by D-H Key agreement and visual secret writingObjectivesProvision of security for hidden imagesReusing of the technology again and againImages should be visible only to human visual system1.3. aim of disciplineThe main social occasion of airfielding the optical encryption is to provide a structured overview of techniques for the encryption of the image and television set data, ranging from commercial applications like televisiondisc or DVB to more research oriented topic and deep publish material. To serve this purpose of optical Encryption has the variant techniques of a unified viewpoint, it provide an commodious use of Visual Encryption. Digital visual data is usually organized in a rectangular legionss denoted as frames, the elements of these array are denoted as pixels. individually pixel is a numerical value specifies the intensity of the pixels (Andreas Uhl and Andreas Pommer, 2005). In the latest year, there has been a rapid harvest-festival of the information technology for the human to communication on the Internet. As Internet has become the open public, anyone can easily read information and coiffure the successful transmission of the information without protection. In order to provide the proper security to the information, Visual Information Encryption by D-H Key study is necessary (chao-Wen and Yi-Da Wu, 2008). Visual Information Encryption provides the secure connection and protects data from unexpected modification by hackers or other outsiders. In D-H key encryption a common password is ask for all th e attendees to take part in the same conference, which gives more security to the information (Encryption, 2008). Visual information Encryption provides the Encryption formats as a standard function. Thus, the main purpose of the study is to implement a visual secret manduction scheme through visual cryptography in order to avoid sensitive information being illegally read or special because the observations make from the recent electronic business applications on the Internet shop that the amount of data exchanged is small and the exchanged data requires secrecy.1.4. look contextWith the rapid increase in visual information, the digital and video encryption approaches are widely studied upon miscellaneous resources like visual net meetings. This application mostly requires ultra high security to view as the images and video dat confidential among users nobody can retrieve the glut without a key for decryption. Thus, from this point of view image encryption is considered as a basis for visual encryption. Visual Cryptography is a topic that finds its direction into every nook and cranny of the networking world. Everyone has their own ideas of how it should work and their own catch of how it does work. The problem with the encryption is that there are several different tokens, and these type works in several different modalitys. And most companies want encryption, they dont needfully know what type of encryption they want, and what the difference are between the types. hither this is designed to give a good overview of the current encryption technology (Eric Quinn, 2009). The visual cryptography is mainly used in keep backing images in secret for not to be accessed by the unauthorized persons. By using this technology the images can be visual by the user but it cannot be accessed by unauthorized persons. As there is increasing growth in the estimator networks and in distributed a computing application visual cryptography plays an important role in providing security (visual cryptography, 2009). In binary images scheme the visual cryptography helps in maintaining the secrecy for not providing authorization to intruders. The visual cryptography provides an infinite computation precedent that messages cannot be identified. This visual cryptography is in identification of bank customers, verification of electronic voting and anti junk e-mail bot measures for maintaining the secrecy to avoid intruders Visual cryptography provides a guidance for secretly maintaining the information and data. Visual cryptography is used in many applications for maintaining data secretly for not be authorized by the intruders (Nagaraj V. Dharwadhakar, Amberker and susil Raj Joshi, 2009). This system actually supplies inter related visual and multimedia information to support the operations, management and decision making functions in an organization. This process provides confidentiality by dividing the secret digital image into several images tha t are healthier by the human visual system by those images together. Visual cryptography strategy is suggested to combine the key agreement scheme with a shadow image without make a secure connection. Thus, visual cryptology uses public key algorithm for having maintain secretly (Kiyoharu Aizawa, Yuichi nakamura and shinichi satoh, 2004). Many organizations are using this methodology for not having interruptions in data. Visual cryptography uses different encryption and decryption techniques and many authentications for not be accessed by unauthorized persons and maintains secrecy. In this research D-H key algorithm is used for having secrecy and privacy can be maintained. By writ of execution of new encryption schemes provides secrecy in an effective manner.1.5. query method actingQualitative approach is appropriate for this research method. Qualitative research behave starts with the premise that one can improve their research skills by beholding what researchers actually do in particular projects and by adding their actions and plans into their own research practice. It actually demonstrates the benefits of using practical methods from real-life knowledge and will be necessary reading for anyone interested in the process of doing social research (Clive Seale, 2004). It is a field of inquiry that explains discipline and subject matters. It is called as ethnographical research. It involves allurement of narrative data in a natural ground in order to gain insights into phenomenon of interest. This research studies many variables over an extensive completion of time to find out the course things are, how and why they came to be that air and what it all means. Qualitative researchers do not want to throw in or control anything. The most common method of data appeal involves participant observation (Michael Huberman Matthew and Miles, 2002). Qualitative analysis offers a cluster of very usable procedures like guidelines, techniques etc. It actually refers to the educational issues and the understanding of learning and comprehension (Pamela S. Maykut and Richard Morehouse, 1994). Hence, it can be said that the secondary data is favorite(a) for this research while searching the related information to it as the other approaches cannot provide a better data to the research.Chapter 2 Literature Review2.1. OverviewVisual Cryptography is a particular encryption method used to incubate information in images in such a way that it can be decrypted by the human visual system if the invent key image is applied. This method was suggested by Naor and Shamir in 1994. Visual Cryptography applies two vaporous images. One image consist random pixels and the other image consist of the secret information. In visual cryptography it is not possible to recollect the secret information from one of the images. Both fair images and layers are involved to reveal the information (Kiyoharu Aizawa, yuichi Nakamura and shichi satoh, 2004). The simple st method to implement Visual Cryptography is to bring out the two layers against a transparent ragtime. When the random image contains genuinely random pixels then it can be seen as a old make out system and will offer infrangibly encryption. In visual cryptography pixel is divided into white and relentlessamoor blocks. In this chapter, importance of visual cryptography is discussed and a New Visual information Encryption strategy is proposed followed by the explanation of Security analysis on images with the previous technologies.2.2. Visual CryptographyVisual Cryptography refers to a secret sacramental manduction method that will encrypt the secret message into a number of shares and does not require any computer or calculations for decrypting the secret image rather the secret message will be hypothecate visually by overlaying the encrypted shares the secret image will become put rightly visible. Visual cryptography scheme on a set P of n participants can be defined as a method of encoding the secret image into n shares so that the original image will be obtained by stacking specific combination of shares onto each other. Visual cryptography technique was initiated by the Naor and Shamiri at Eurocrypt 94. It is a process used for separating one image into various shares. Visual cryptography solutions functions on binary inputs. Visual cryptography is a special technique used to hide information in images in such a way that it can be decrypted by the human vision when the correct image is used. It uses two images one image contains secret information, in visual cryptography it is not possible to retrieve the secret information from one of the images, both transparent images are required to reveal the information. To print two layers into the transparent sheet is the simplest way to implement Visual cryptography (jeng shying pan, Hsiang cheh Huang and L. C. Jain, 2004). If the random image contains random pixel then it can be seen as a onetime pad s ystem and will offer unbreakable encryption. These two layers slide over each other until they are correctly aligned where the hidden information protrudes. This type of visual cryptography which restores the image by stacking some significant images together is cognize as extended visual cryptography. Generally, visual cryptography suffers from the deterioration of image quality. The basic two cryptography models consists of a secret message encoded into two transparencies, one transparency representing the lick text and the other acting as a secret key. Both transparencies appear to random dots when inspected individually and does not provide any information about the original clear text. By carefully aligning the transparencies the original message is reproduced (Borivoje Furht, Edin Muharemagic and Daniel socek, 2005). The original decoding is accomplished by the human visual system. Visual cryptography scheme is a visual secret sharing problem in which the secret message is viewed only in abusive and white pixels. Each pixel in the original image is represented by at least one sub pixel in each of the n transparencies or shares generated. Each share is comprised of collection of m mysterious and white sub pixels where each collection represents a particular original pixel. The product line of Visual Cryptography Scheme is the difference between the nominal number of black sub pixels in a hypothesize (secret) black pixel and the maximum number of black sub pixels in a reconstructed (secret) white pixel (Kiyoharu Aizawa, Yuchi Nakamura and Shinichi Satoh, 2004). The main instantiation of visual cryptographic realizes a cryptographic protocol called secret sharing. The important thing in secret sharing is it relies on a human visual system to perform the decryption. In a conventional secret sharing a secret shared among n participants can pull their shares and recover the secret but the subsets of the disallow can obtain no information about that. V isual secret sharing schemes inherits all applications of conventional secret sharing schemes most notably access control.An example of the encoding of white and black pixels in a 2 out of 2 scheme can be seen in Figure 1. Here two shares out of the two generated would be needed to recover the original image. Since only two shares are generated, n = 2. black-and-blue box represents a single white or black pixel in the original image. Sub pixel assignments that would be given to shares 1 and 2 respectively. The number of sub pixels per share used to represent the original pixel is four Finally, the overall visual effect when shares 1 and 2 are correctly aligned on top of one some other(prenominal). bill that when the shares in this example are combined the original black pixel is viewed as black however, the original white pixel takes on a grey scale. The structure obtained from either white or black pixel representation can be described by an n. homogeneous to the field of stud y of the secret sharing, more generally structures have been studied in the visual cryptography. The basic model of the visual cryptography consists of a several umber of transparency sheets. On each transparency a cipher text is printed which is identical from random noise. The hidden message is reconstructed by stacking a certain(prenominal) number of the transparencies and viewing them. The system can be used by anyone without any knowledge of cryptography and without performing any cryptographic computations. Naor and Shamir have essential the Visual Secret Sharing Scheme (VSSS) to implement this model Naor95 (Mizuho Nakajima and Yasushi Yamaguchi, 2002). Thus, from the higher up discursion it can be stated that Visual cryptography is a special technique used to hide information in images in such a way that it can be decrypted by the human vision when the correct image is used. It is a simple and clear scheme that can partition the secret image into a number of shadow images and the dealers can distribute these shadow images to participants. The Visual cryptography scheme makes use of human visual system for recovering secret images by staking various shadow images.2.3. Importance of Visual CryptographyVisual Information system importantly elaborates the diligences scope of information systems and deals with the multimedia operating system which is supported by multimedia hardware and high bandwidth network. These are text oriented which provides reports, decision-making information and documents for all levels of hierarchy in the organization (Carlo Blundo and Stelvio, 2005). With the increase in multimedia platforms, visual information has become more operational with the advancement of information technology contact through meshing has increased rapidly. Visual information system requires many kinds of facilities for effective visual information presentation and visualization. This system actually supplies inter related visual and multimedia inform ation to support the operations, management and decision making functions in an organization. As internet can be accessed by everyone and anyone can easily access the information and transmit it without any protection there is possibility of grabbing the information as it became secondary data. So in order to avoid hacking of sensitive information, it should be encrypted before transmission (Yongfei Han, 1997). In order to protect the information Diffie and Helman (D-H) proposed a key agreement scheme that is implemented when two parties agree on a common session key. This key agreement also helps in improving the reusable process. This technique is utilized to judge a common image for encryption and decryption with two parties. The D-H algorithm does not encrypt data or make a digital signature. This is exclusively used for the generation of shred secrets. The DH key agreement can be split into three parts they are parameter generation that generates non secret public value and is expensive process, next is phase1generatres two key exchange values for the parties and phase2 is the originator and recipient that computes the functions in the given image. DH key agreement has a nice property that it is not sensitive to off-line attacks but it is sensitive to man-in-the-middle attacks. There after Naor and Shamir proposed a methodology named visual secret sharing that provides secrecy to the information and avoids illegal activities (Jeng-Shyang Pan, Hsiang-Cheh Huang and L. C. Jain, 2004). This process is called as Visual Cryptography. This process provides secrecy by partitioning the secret digital image into several shadow images that are recovered by the human visual system by piling all those images together. It is secured technique where the data cannot be traced by others. In classic secret sharing, algorithms for divide and sharing secret information are a stem of cryptography. In the most general geek, their objective is to generate such parts for the data and that could be shared by multiple authorized persons. This problem of splitting information in a manner allowing its reconstruction by a certain n-person group interested in the reconstruction of the split information. Algorithm solutions developed to carry out this objective and at the same time none of the groups of participants in such a protocol, whose number is lesser than the required m persons. It leads to debate to read the split message. The algorithms for dividing information make it possible to split it into chunks cognize as shadows that are by and by distributed among the participants of the protocol. So that the shares of certain subsets of users collective together and these are capable of reconstructing the original information. There are two groups of algorithms for dividing information, namely, secret splitting and secret sharing. In the first technique, information is distributed among the participants of the protocol, and all the participants are req uired to put together their parts to have it reconstructed. A more customary method of splitting information is the latter method, i.e. secret sharing (Marek R. Ogiela and Urszula Ogiela, 2009). Thus, from the above discursion it can be stated that visual cryptography plays a brisk role in securing the data and also in sharing the secret message as the data transferred through internet has been increased. rapidly.Advantages of visual cryptographyVisual cryptography is simple to be implemented.Encryption enclose of visual cryptography does not require any hard problem dependency.specifically decryption algorithms are not required because a person cognizant of cryptography can easily decrypt the message.Cipher text can be Fax or e-mail in case of visual cryptography2.4. Security analysis on images with the previous technologiesThe security analysis is the major aspect of the encryption. Analysis to the field of security will bring the serious obstacle that deal is by nature not an exact science. The previous technologies which where there before the D-H key agreement encryption are manual encryption, transparent encryption, symmetric encryption and asymmetric encryption (Fedora authentication Project, 2009). Visual cryptography can be seen as a one-time pad system. Then, it cannot be reused. Diffie and Hellman (D-H) key agreement method and Toral Automorphism (TA) such that visual cryptography can be reused. Both secret and symmetry-key are represented in binary image. The proposed scheme is simple and easy to be implemented for shadow images. Therefore, it can be used in many electronic business applications (Chao-Wen Chan and Yi-Da Wu, 2008). The Manual Encryption is a technique that will involve the use of encryption software. In this computer programs are used for encrypt various bits of information digitally. In this technique the encryption key is provided later in the process. The main security issues are the potential leakage through security insensi ble program and also the bad implementation whitethorn lead to re-encrypt with same key for same password (Bruice Schneier, 2007). Transparent Encryption is another type of computer software encryption. In this technique the data can be downloaded onto a computer to encrypt automatically. Every executable application and file created in the computer has an encrypted copy that can defend power surges and protects information in case a computer is stolen. The security issues is the data which is automatically encrypted can be taken if the key provided is known (Cetin K. Koc, David Naccache and Christof Paar, 2001). The isosceles Encryption is in which a letter or number coincides with another letter or number in the encryption code. This technique is normally referred to as secret-key encryption. In this only single key is used for encrypting anVisual Information Encryption by D-H Key AgreementVisual Information Encryption by D-H Key AgreementVisual Information Encryption by D-H Ke y Agreement and Visual CryptographyAbstractVisual cryptography provides secured digital transmission which is used only for one time. In order to make visual cryptography reusable Diffie and Hellman (D-H) key is used. The original images can be reuse by using this scheme. It is effortless and uncomplicated technique to execute the secret image for shadow images. The shadow images are the shrunken version of the original image, in which the secret image share is embedded. These are used to guard the data and secret images in the internet so that it is not accessed by any unauthorized persons. Visual cryptography divides the image into secret shadow images. After this these shadow images are distributed in the original image. Recovering of secret image is done by human visual system by piling all the shadow images. As this Visual cryptography is used only once D-H key agreement was used to make it reusable by using D-H key scheme in it.ObjectivesProvision of security for hidden images Reusing of the original image is possible by this technologyImages should be visible only to human visual systemLiterature ReviewIn this project a visual cryptography scheme is used for encrypting the information. Visual cryptography is an encryption method which is used to hide the information in an image, decrypted can be done by human visual system. By using only this scheme the reusing is not possible. The image which is recovered after decryption will not be same as original image so it cannot be reused. For the reuse of the visual cryptography Diffie and Hellman (D-H) key agreement method and Toral Automorphism (TA) can be used. In this both secret and symmetry-key representation can be used (Chao-Wen Chan and Yi-Da Wu, 2008). Visual cryptography is the scheme which facilities the secret sharing of the pictures or data. The pixels of the pictures or data that need to be transmitted secretly will be treated as an individual secret which can be shared using a secret sharing sche me. The picture is first split into two or more shared images the secret data are embedded. At the decryption side images are joined on the transparent paper to get the secret picture or data. This is the way in which the first visual cryptography was started (Borivoje Furht, Edin Muharemagic and Daniel Socek, 2005). Using current methods the Visual cryptography scheme will allow the encoding of the secret image into shares this is done in the form of transparencies. These shares are distributed to the participants, such that only the qualified subsets of participants can recover the secret image visually. This is done by superimposing the share images one over the other which are obtained from the original image (Carlo Blundo and Stelvio Cimato, 2005). In this scheme the devices are used for encoding of secret information and the decoding is done with human vision directly. For encoding, the visual cryptography will cryptographically encode the binary secret data into shares of the pattern which will be random. Then the shares are copied on to the transparencies with the same number of transparencies as shares. The transparencies are distributed among the participants, one for each participant. The decoding of the data or picture is done only when all of the participants superimpose their transparencies (Alan Conrad Bovik, 2005). The importance of this scheme is that there is no need for data expansion. The resolution of the data will not be lost by using this scheme. By using this scheme the image will be secure against the most important cryptanalytic attacks. The computation complexity will be less since it involves only XOR operations. By using XOR operations the share images are combined to form the encrypted images. The authentication of the image will be based on the global visual effect, so local defects due to noise will not affect the final result. The most important aspect of this scheme is that the decoding of the secret data or image can be done with human vision without any decoding equipment (Kiyoharu Aizawa, Yuichi Nakamura and Shinichi Satoh, 2004). The previous technologies that came into existing before visual cryptography are two-out-of two visual threshold schemes, two-out-of-n visual-threshold scheme. In a two-out-of two visual threshold scheme the secret can be any type of data (Abhishek Parakh and Subhash Kak, 2006, p.1). For an image comprising of white and black pixels, this image can be encoded as a binary string. In this scheme the 0 will represent a white pixel and 1 represents a black pixel and the result will be sent in two shares. The security problem by this is having only 50 percent of resolution will be obtained because the image is divided into only two shares and if the new shares of data are found the image can be decrypted very easily. A two-out-of-n visual-threshold scheme is more secure when compared with the first. In this scheme also the pixels are divided into two, but the shares will be n. By this the security will increase. When compared with the D-H key agreement the resolution of these schemes will be less and security will also be less (Doug Stinson, 1999).The D-H key agreement is used to make possible the reuse of visual cryptography. The Diffie-Hellman key agreement used an interface known as D-H key interface. This interface is used for password based Encryption. These interfaces typically can be used by the programmer who is implementing a Cryptographic provider or who wants to implement a cryptography algorithm (David Flanagan, 2005). Diffie- Hellman Key agreement is also known as exponential key exchange. This key provides the solution to the key distribution problems, allowing two parties, never having met in advance to share key material for establishing a shared secret by exchanging messages over an open channel. This is a fundamental technique providing unauthenticated key agreement. The main goal of an authenticated Key establishment protocol is to distri bute key of data. The established key should have precisely the same attributes as a key established face to face, it should be distributed uniformly at random from the key space, and an unauthorized entity will not be able to learn anything about the key (Alfred J.Menezes, Paul C. Van Oorschot, and Scott A. Vanstone, 1997). D-H key agreement protocols involve the derivation of the shared secret information based on compatible D-H keys between the sender and recipient. The information is then converted into the cryptographic keying material for other algorithms. A variation of the Diffie-Hellman is used for converting the shared secret data into an arbitrary amount of keying materials (Manuel Mogollon, 2008). According to Michael Baake and John A G Roberts (2001, p.1) Toral Automorphisms will be represented by the uni-modular integer matrices, are investigated with the help of symmetries and also reversing symmetries group of matrices with a simple spectrum through their connection with unit groups in orders of algebraic number fields. The reversibility will derive the necessary conditions in terms of the distinctive polynomial and the polynomial invariants. This shows that the Voiculescu- Brown entropy of the non-commutative toral automorphism arising from a matrix S in is at least half the value of the topological entropy of the corresponding classical toral automorphism. This is a new method used to prove the position limit laws in the theory of dynamical systems, which is based on the Chen-Stein method combined with the analysis of the homo clinic Laplace operator and some other homo clinic considerations (Massimo Franceschetti and Ronald Meester, 2002, p.2). The main use of this is to generate a disorder in the arrangement of digital images. The equation (1) define the two dimensional matrix.The new technology that can be used for the visual cryptography is adaptive order dithering technique. By using this technique the decrypted image size can be reduced and also the quality of decryption image can be improved. In this technique the technique will get adaptive to the data that is used (Nagaraj V. Dharwadkar, B.B. Amberker and Sushil Raj Joshi, 2009). From the above context it can be understood that visual cryptography is a scheme in which the secret data can be transmitted without getting decoded by others.Chapter 1 Introduction1.1. OverviewVisual Information system significantly enlarges the applications scope of information systems and typically deals with the general purpose multimedia operating system that is supported by multimedia hardware and high bandwidth network. Visual information system involves variety of facilities for efficient visual information presentation and visualization. This system actually provides inter related visual and multimedia information to support the operations, management and decision making functions in an organization. These are text oriented which provides reports, decision-making information a nd documents for all levels of hierarchy in the organization. With the increase in multimedia platforms, visual information has become more available (Clement H. C. Leung, 1997). In recent years, there has been a rapid growth of information technology for human to communication on the Internet. Since Internet is public, with the advancement of information technology, communication through internet has increased rapidly. As internet can be accessed by everyone and anyone can easily access the information and transmit it without any protection there is possibility of grabbing the information as it became secondary data. So in order to avoid hacking of sensitive information, it should be encrypted before transmission. In order to protect the information Diffie and Helman (D-H) proposed a key agreement scheme that is implemented when two parties agree on a common session key. This key agreement also helps in improving the reusable process. This method is used to compute a common image f or encryption and decryption with two parties (Chao-Wen Chan and Yi-Da Wu, 2008). The D-H algorithm does not encrypt data or make a digital signature. This is exclusively used for the generation of shred secrets. The DH key agreement can be split into three parts they are parameter generation that generates non secret public value and is expensive process, next is phase1generatres two key exchange values for the parties and phase2 is the originator and recipient that computes the functions in the given image (Blake Dournaee, 2002). DH key agreement has a nice property that it is not sensitive to off-line attacks but it is sensitive to man-in-the-middle attacks (Christian Gehmann, Joakim Persson and Ben Smeets, 2004). In Diffie and Hellman (D-H) key agreement method both the secret and symmetry key are represented in binary image. It is simple and easy to be implemented especially for shadow images. Thus, it can be applied in many electronic business applications. There after Naor an d Shamir proposed a methodology named visual secret sharing that provides secrecy to the information and avoids illegal activities this process is called as Visual Cryptography. This process provides secrecy by partitioning the secret digital image into several shadow images that are recovered by the human visual system by piling all those images together (Jeng-Shyang Pan, Hsiang-Cheh Huang and L. C. Jain, 2004). Hence it can be stated that in order to safeguard the images visual cryptography and DH key agreement are used where the images are split into shadow images and sent which then will be combines and viewed by the human visual system. It is secured by encryption and decryption of images with a key to be presented. Visual cryptography is seen as a one time pad system that cannot be reused, in further sections of the study the implementation of Diffie and Hellman (D-H) key agreement method is researched in detail so that visual cryptography can be reused.1.2. Aims and Objectiv esAim To research on visual information encryption by D-H Key agreement and visual CryptographyObjectivesProvision of security for hidden imagesReusing of the technology again and againImages should be visible only to human visual system1.3. Purpose of StudyThe main purpose of studying the Visual Encryption is to provide a unified overview of techniques for the encryption of the image and video data, ranging from commercial applications like DVD or DVB to more research oriented topic and recently published material. To serve this purpose of Visual Encryption has the different techniques of a unified viewpoint, it provide an extensive use of Visual Encryption. Digital visual data is usually organized in a rectangular arrays denoted as frames, the elements of these array are denoted as pixels. Each pixel is a numerical value specifies the intensity of the pixels (Andreas Uhl and Andreas Pommer, 2005). In the latest year, there has been a rapid growth of the information technology for the human to communication on the Internet. As Internet has become the open public, anyone can easily read information and perform the successful transmission of the information without protection. In order to provide the proper security to the information, Visual Information Encryption by D-H Key study is necessary (chao-Wen and Yi-Da Wu, 2008). Visual Information Encryption provides the secure connection and protects data from unexpected modification by hackers or other outsiders. In D-H key encryption a common password is required for all the attendees to participate in the same conference, which gives more security to the information (Encryption, 2008). Visual information Encryption provides the Encryption formats as a standard function. Thus, the main purpose of the study is to implement a visual secret sharing scheme through visual cryptography in order to avoid sensitive information being illegally read or modified because the observations made from the recent electronic busi ness applications on the Internet reveal that the amount of data exchanged is small and the exchanged data requires secrecy.1.4. Research ContextWith the rapid increase in visual information, the digital and video encryption approaches are widely studied upon various resources like visual net meetings. This application mostly requires ultra high security to keep the images and video dat confidential among users nobody can retrieve the content without a key for decryption. Thus, from this point of view image encryption is considered as a basis for visual encryption. Visual Cryptography is a topic that finds its way into every nook and cranny of the networking world. Everyone has their own ideas of how it should work and their own understanding of how it does work. The problem with the encryption is that there are several different types, and these type works in several different ways. And most companies want encryption, they dont necessarily know what type of encryption they want, an d what the difference are between the types. Here this is designed to give a good overview of the current encryption technology (Eric Quinn, 2009). The visual cryptography is mainly used in maintaining images secretly for not to be accessed by the unauthorized persons. By using this technology the images can be visual by the user but it cannot be accessed by unauthorized persons. As there is increasing growth in the computer networks and in distributed a computing application visual cryptography plays an important role in providing security (visual cryptography, 2009). In binary images scheme the visual cryptography helps in maintaining the secrecy for not providing authorization to intruders. The visual cryptography provides an infinite computation power that messages cannot be identified. This visual cryptography is in identification of bank customers, verification of electronic voting and anti spam bot measures for maintaining the secrecy to avoid intruders Visual cryptography pr ovides a way for secretly maintaining the information and data. Visual cryptography is used in many applications for maintaining data secretly for not be authorized by the intruders (Nagaraj V. Dharwadhakar, Amberker and susil Raj Joshi, 2009). This system actually supplies inter related visual and multimedia information to support the operations, management and decision making functions in an organization. This process provides confidentiality by dividing the secret digital image into several images that are healthier by the human visual system by those images together. Visual cryptography strategy is suggested to combine the key agreement scheme with a shadow image without building a secure connection. Thus, visual cryptology uses public key algorithm for having maintain secretly (Kiyoharu Aizawa, Yuichi nakamura and shinichi satoh, 2004). Many organizations are using this methodology for not having interruptions in data. Visual cryptography uses different encryption and decryptio n techniques and many authentications for not be accessed by unauthorized persons and maintains secrecy. In this research D-H key algorithm is used for having secrecy and privacy can be maintained. By implementation of new encryption schemes provides secrecy in an effective manner.1.5. Research MethodQualitative approach is appropriate for this research method. Qualitative Research Practice starts with the premise that one can improve their research skills by seeing what researchers actually do in particular projects and by adding their actions and plans into their own research practice. It actually demonstrates the benefits of using practical methods from real-life knowledge and will be necessary reading for anyone interested in the process of doing social research (Clive Seale, 2004). It is a field of inquiry that explains discipline and subject matters. It is called as ethnographic research. It involves collection of narrative data in a natural setting in order to gain insights i nto phenomenon of interest. This research studies many variables over an extensive period of time to find out the way things are, how and why they came to be that way and what it all means. Qualitative researchers do not want to interfere or control anything. The most common method of data collection involves participant observation (Michael Huberman Matthew and Miles, 2002). Qualitative analysis offers a cluster of very useful procedures like guidelines, techniques etc. It actually refers to the educational issues and the understanding of learning and cognition (Pamela S. Maykut and Richard Morehouse, 1994). Hence, it can be said that the secondary data is preferred for this research while searching the related information to it as the other approaches cannot provide a better data to the research.Chapter 2 Literature Review2.1. OverviewVisual Cryptography is a particular encryption method used to hide information in images in such a way that it can be decrypted by the human visual system if the correct key image is applied. This method was suggested by Naor and Shamir in 1994. Visual Cryptography applies two transparent images. One image consist random pixels and the other image consist of the secret information. In visual cryptography it is not possible to recollect the secret information from one of the images. Both transparent images and layers are involved to reveal the information (Kiyoharu Aizawa, yuichi Nakamura and shichi satoh, 2004). The simplest method to implement Visual Cryptography is to bring out the two layers against a transparent sheet. When the random image contains genuinely random pixels then it can be seen as a onetime pad system and will offer infrangibly encryption. In visual cryptography pixel is divided into white and black blocks. In this chapter, importance of visual cryptography is discussed and a New Visual information Encryption Scheme is proposed followed by the explanation of Security analysis on images with the previous techn ologies.2.2. Visual CryptographyVisual Cryptography refers to a secret sharing method that will encrypt the secret message into a number of shares and does not require any computer or calculations for decrypting the secret image rather the secret message will be reconstructed visually by overlaying the encrypted shares the secret image will become intelligibly visible. Visual cryptography scheme on a set P of n participants can be defined as a method of encoding the secret image into n shares so that the original image will be obtained by stacking specific combination of shares onto each other. Visual cryptography technique was initiated by the Naor and Shamiri at Eurocrypt 94. It is a process used for separating one image into various shares. Visual cryptography solutions functions on binary inputs. Visual cryptography is a special technique used to hide information in images in such a way that it can be decrypted by the human vision when the correct image is used. It uses two ima ges one image contains secret information, in visual cryptography it is not possible to retrieve the secret information from one of the images, both transparent images are required to reveal the information. To print two layers into the transparent sheet is the simplest way to implement Visual cryptography (jeng shying pan, Hsiang cheh Huang and L. C. Jain, 2004). If the random image contains random pixel then it can be seen as a onetime pad system and will offer unbreakable encryption. These two layers slide over each other until they are correctly aligned where the hidden information appears. This type of visual cryptography which restores the image by stacking some significant images together is known as extended visual cryptography. Generally, visual cryptography suffers from the deterioration of image quality. The basic two cryptography models consists of a secret message encoded into two transparencies, one transparency representing the cipher text and the other acting as a se cret key. Both transparencies appear to random dots when inspected individually and does not provide any information about the original clear text. By carefully aligning the transparencies the original message is reproduced (Borivoje Furht, Edin Muharemagic and Daniel socek, 2005). The original decoding is accomplished by the human visual system. Visual cryptography scheme is a visual secret sharing problem in which the secret message is viewed only in black and white pixels. Each pixel in the original image is represented by at least one sub pixel in each of the n transparencies or shares generated. Each share is comprised of collection of m black and white sub pixels where each collection represents a particular original pixel. The contrast of Visual Cryptography Scheme is the difference between the minimum number of black sub pixels in a reconstructed (secret) black pixel and the maximum number of black sub pixels in a reconstructed (secret) white pixel (Kiyoharu Aizawa, Yuchi Na kamura and Shinichi Satoh, 2004). The main instantiation of visual cryptographic realizes a cryptographic protocol called secret sharing. The important thing in secret sharing is it relies on a human visual system to perform the decryption. In a conventional secret sharing a secret shared among n participants can pull their shares and recover the secret but the subsets of the forbidden can obtain no information about that. Visual secret sharing schemes inherits all applications of conventional secret sharing schemes most notably access control.An example of the encoding of white and black pixels in a 2 out of 2 scheme can be seen in Figure 1. Here two shares out of the two generated would be needed to recover the original image. Since only two shares are generated, n = 2. White box represents a single white or black pixel in the original image. Sub pixel assignments that would be given to shares 1 and 2 respectively. The number of sub pixels per share used to represent the original pixel is four Finally, the overall visual effect when shares 1 and 2 are correctly aligned on top of one another. Notice that when the shares in this example are combined the original black pixel is viewed as black however, the original white pixel takes on a grey scale. The structure obtained from either white or black pixel representation can be described by an n. Similar to the area of the secret sharing, more generally structures have been studied in the visual cryptography. The basic model of the visual cryptography consists of a several umber of transparency sheets. On each transparency a cipher text is printed which is identical from random noise. The hidden message is reconstructed by stacking a certain number of the transparencies and viewing them. The system can be used by anyone without any knowledge of cryptography and without performing any cryptographic computations. Naor and Shamir have developed the Visual Secret Sharing Scheme (VSSS) to implement this model Naor95 ( Mizuho Nakajima and Yasushi Yamaguchi, 2002). Thus, from the above discursion it can be stated that Visual cryptography is a special technique used to hide information in images in such a way that it can be decrypted by the human vision when the correct image is used. It is a simple and clear scheme that can partition the secret image into a number of shadow images and the dealers can distribute these shadow images to participants. The Visual cryptography scheme makes use of human visual system for recovering secret images by staking various shadow images.2.3. Importance of Visual CryptographyVisual Information system importantly elaborates the diligences scope of information systems and deals with the multimedia operating system which is supported by multimedia hardware and high bandwidth network. These are text oriented which provides reports, decision-making information and documents for all levels of hierarchy in the organization (Carlo Blundo and Stelvio, 2005). With the increa se in multimedia platforms, visual information has become more available with the advancement of information technology contact through internet has increased rapidly. Visual information system requires many kinds of facilities for effective visual information presentation and visualization. This system actually supplies inter related visual and multimedia information to support the operations, management and decision making functions in an organization. As internet can be accessed by everyone and anyone can easily access the information and transmit it without any protection there is possibility of grabbing the information as it became secondary data. So in order to avoid hacking of sensitive information, it should be encrypted before transmission (Yongfei Han, 1997). In order to protect the information Diffie and Helman (D-H) proposed a key agreement scheme that is implemented when two parties agree on a common session key. This key agreement also helps in improving the reusable p rocess. This technique is utilized to calculate a common image for encryption and decryption with two parties. The D-H algorithm does not encrypt data or make a digital signature. This is exclusively used for the generation of shred secrets. The DH key agreement can be split into three parts they are parameter generation that generates non secret public value and is expensive process, next is phase1generatres two key exchange values for the parties and phase2 is the originator and recipient that computes the functions in the given image. DH key agreement has a nice property that it is not sensitive to off-line attacks but it is sensitive to man-in-the-middle attacks. There after Naor and Shamir proposed a methodology named visual secret sharing that provides secrecy to the information and avoids illegal activities (Jeng-Shyang Pan, Hsiang-Cheh Huang and L. C. Jain, 2004). This process is called as Visual Cryptography. This process provides secrecy by partitioning the secret digital image into several shadow images that are recovered by the human visual system by piling all those images together. It is secured technique where the data cannot be traced by others. In classic secret sharing, algorithms for splitting and sharing secret information are a stem of cryptography. In the most general case, their objective is to generate such parts for the data and that could be shared by multiple authorized persons. This problem of splitting information in a manner allowing its reconstruction by a certain n-person group interested in the reconstruction of the split information. Algorithm solutions developed to achieve this objective and at the same time none of the groups of participants in such a protocol, whose number is lesser than the required m persons. It leads to opposing to read the split message. The algorithms for dividing information make it possible to split it into chunks known as shadows that are later distributed among the participants of the protocol. So that the shares of certain subsets of users collective together and these are capable of reconstructing the original information. There are two groups of algorithms for dividing information, namely, secret splitting and secret sharing. In the first technique, information is distributed among the participants of the protocol, and all the participants are required to put together their parts to have it reconstructed. A more universal method of splitting information is the latter method, i.e. secret sharing (Marek R. Ogiela and Urszula Ogiela, 2009). Thus, from the above discursion it can be stated that visual cryptography plays a vital role in securing the data and also in sharing the secret message as the data transferred through internet has been increased. rapidly.Advantages of visual cryptographyVisual cryptography is simple to be implemented.Encryption incase of visual cryptography does not require any hard problem dependency.Specifically decryption algorithms are not required be cause a person aware of cryptography can easily decrypt the message.Cipher text can be Fax or e-mail in case of visual cryptography2.4. Security analysis on images with the previous technologiesThe security analysis is the major aspect of the encryption. Analysis to the field of security will encounter the serious obstacle that deal is by nature not an exact science. The previous technologies which where there before the D-H key agreement encryption are manual encryption, transparent encryption, symmetric encryption and asymmetric encryption (Fedora Documentation Project, 2009). Visual cryptography can be seen as a one-time pad system. Then, it cannot be reused. Diffie and Hellman (D-H) key agreement method and Toral Automorphism (TA) such that visual cryptography can be reused. Both secret and symmetry-key are represented in binary image. The proposed scheme is simple and easy to be implemented for shadow images. Therefore, it can be used in many electronic business applications (C hao-Wen Chan and Yi-Da Wu, 2008). The Manual Encryption is a technique that will involve the use of encryption software. In this computer programs are used for encrypt various bits of information digitally. In this technique the encryption key is provided later in the process. The main security issues are the potential leakage through security insensible program and also the bad implementation may lead to re-encrypt with same key for same password (Bruice Schneier, 2007). Transparent Encryption is another type of computer software encryption. In this technique the data can be downloaded onto a computer to encrypt automatically. Every executable application and file created in the computer has an encrypted copy that can withstand power surges and protects information in case a computer is stolen. The security issues is the data which is automatically encrypted can be taken if the key provided is known (Cetin K. Koc, David Naccache and Christof Paar, 2001). The Symmetric Encryption is in which a letter or number coincides with another letter or number in the encryption code. This technique is commonly referred to as secret-key encryption. In this only single key is used for encrypting an