Cellular Automata Based Image Authentication Scheme Using Extended Visual Cryptography

Most of the Visual Cryptography based image authentication schemes hide the share and authentication data into cover images by using an additional data hiding process. This process increases the computational cost of the schemes. Pixel expansion, meaningless shares and use of codebook are other challenges in these schemes. To overcome these issues, an authentication scheme is proposed in which no embedding into the cover images is performed and meaningful authentication shares are created using the watermark and cover images. This makes the scheme completely imperceptible. The watermark can be retrieved just by superimposing these authentication shares, thus reducing the computational complexity at receiver's side. Cellular Automata is used to construct the master share that provides self-construction ability to the shares. The meaningful authentication shares help in enhancing the security of the scheme while size invariance saves transmission and storage cost. The scheme possesses the ability of tamper detection. Experimental results demonstrate the improved security and quality of the generated shares of the proposed scheme as compared to existing schemes

A Visual Cryptography Scheme for User Authentication

A new scheme for user authentication is proposed using visual cryptography and invisible digital watermarking. Visual cryptography which allows visual information to be encrypted in such a way that decryption becomes the job of the person to decrypt via a sight reading. In the proposed work, user signature will be embedded within the cover media. It may be text, images, audio, video etc. Here we used cover image for embedding data by using a single bit LSB watermark insertion algorithm. After that the image will be split into two shares. Shares will be later encrypted by using a Column Shift Permutation algorithm. Receiver will decrypt the shares using Column Shift Permutation algorithm. Shares are collected and stamp together by receiver to get cover image. Then signature will be de-embedded from the cover image. Data will be transfer using communication media. Image will be passed in more secure manner without any distortion. This method is very efficient and effective .The method can be implemented with minimum processing. This application used in customer identification in bank and in online voting

Reversible Data Hiding using Visual Cryptography: A Review

ABSTRACT: Data security and data integrity are the two challenging areas for research. There are so many research is progressing on the field like internet security, steganography, cryptography. Data hiding are a group of techniques used to put a secure data in a host media with small deterioration in host and the means to extract the secure data afterwards. Reversible data hiding is a technique to embed additional message into some distortion-unacceptable cover media, such as military or medical images, with a reversible manner so that the original cover content can be perfectly restored after extraction of the hidden message. The reversibility means not only embedding data but also original image can be precisely recovered in the extracting stage. Most hiding techniques perform data embedding by altering the contents of a host media. These types of data hiding techniques are thus irreversible. However in a number of domains such as military, legal and medical imaging although some embedding distortion is admissible, permanent loss of signal fidelity is undesirable. This highlights the need for Reversible (Lossless) data embedding techniques. This paper gives a review on various reversible data hiding techniques and also proposes a novel approach for reversible data hiding using visual cryptography. This involves no use of keys thus keeping the computation cost for encryption/decryption low. This scheme applies a method of vacating the room for data prior to the image encryption used to hide the secret data. By reversing the order of encryption and data hiding we overcome the difficulty of finding the room for data from already encrypted image

Breaking the Binary: Exploring Orality in India through Typography, Cryptography and Craft

This thesis explores the fluidity of language through the fusion of heterogenous visual traditions — creating hybrid forms and coded communication. It voyages through the linguistic landscape of India. Delving into its social, political and cultural identities it finds expression in typography, cryptography, craft arts and poetry. From this body of work emerged the hybrid typeface Latinagari, a character set that fuses the letterforms of the Devanagari and Latin scripts. Embodying both forms it is also neither. Being familiar to readers of either script, yet obscure. It both invites and denies the viewer’s desire to read. Representing the in-between spaces of spoken language in India, it is its own being. Through it, a novel graphic language finds form and with it new opportunities for expression, communication and mis-communication. Like the way Hindi flows to English and back in contemporary Indian culture this visual vocabulary becomes its own thing, An expression of identity, a linguistic code and a way of knowing.Communication designCryptographyEmbroideryCraftCoded communicationMultilingual typographyDownload for optimal viewing experience

Evaluating the usability and security of a video CAPTCHA

A CAPTCHA is a variation of the Turing test, in which a challenge is used to distinguish humans from computers (`bots\u27) on the internet. They are commonly used to prevent the abuse of online services. CAPTCHAs discriminate using hard articial intelligence problems: the most common type requires a user to transcribe distorted characters displayed within a noisy image. Unfortunately, many users and them frustrating and break rates as high as 60% have been reported (for Microsoft\u27s Hotmail). We present a new CAPTCHA in which users provide three words (`tags\u27) that describe a video. A challenge is passed if a user\u27s tag belongs to a set of automatically generated ground-truth tags. In an experiment, we were able to increase human pass rates for our video CAPTCHAs from 69.7% to 90.2% (184 participants over 20 videos). Under the same conditions, the pass rate for an attack submitting the three most frequent tags (estimated over 86,368 videos) remained nearly constant (5% over the 20 videos, roughly 12.9% over a separate sample of 5146 videos). Challenge videos were taken from YouTube.com. For each video, 90 tags were added from related videos to the ground-truth set; security was maintained by pruning all tags with a frequency 0.6%. Tag stemming and approximate matching were also used to increase human pass rates. Only 20.1% of participants preferred text-based CAPTCHAs, while 58.2% preferred our video-based alternative. Finally, we demonstrate how our technique for extending the ground truth tags allows for different usability/security trade-offs, and discuss how it can be applied to other types of CAPTCHAs

Communication Strategy in a NGO

Predmetem diplomove prace je zpresneni komunikacni strategie nejvetsi evropske studentske organizace—Erasmus Student Network AISBL. Prace definuje status quo organizace a po jeho analyze navrhuje zpusob, jakym lze diky tvorbe obsahove strategie z pohledu ciloveho uzivatele (tvorbou person) zvysit zasah a zlepsit cileni obsahu pro jednotlive komunikacni kanaly.The subject of this Master’s thesis is refinement of the communication strategy of the biggest European student organisation—Erasmus Student Network AISBL. The thesis defines the status quo of the organisation and based upon its analysis it proposes an approach of creating content strategy from the point of view of the target groups (by creating personas), leading to strengthening the engagement and clarifying content targeting for individual communication channels.

The Spaces Between: Performance, Individualisation, and the Politics of Global Change

This thesis responds to the difficulty inherent in attempting to address global challenges that require global solutions, such as climate change and extreme poverty, from within an increasingly individualised society. In this context, opening up spaces to engage with the world through alternate frames of reference can be seen to be a powerful political act: inviting response-ability, fostering and deepening connections, and calling the systemic into question. Performance offers one such site of engagement. As a bodied activity that situates the spectator in relation to people, to places, and to the world, performance can expand some of the connections that individualisation and globalisation compress. As such, it can be argued that performance holds the potential to unsettle the globalised and the individualised: to traverse the increasing space between them and to blur, oppose, or look beyond their boundaries. In this thesis I explore that potential, drawing upon cultural theory and performance theory, three case studies of performance works that evoke the global but disrupt the globalised, and a performance-as-research project that shifts the focus to the local and localised connection. Through these creative and theoretical bodies of work I consider the capacity of performance to critically reframe the globalised present, to awaken the cosmopolitan imagination, to invite the spectator to engage and respond, and to suggest the actual possibility of a more equitable and sustainable world. Performance, it becomes evident, can be a productive site for negotiating global change: not by necessarily providing a solution to sustainability concerns or inciting political actions, but rather by creating moments of disruption in the current frames of globalisation and individualisation to act as an opening through which change comes about

Managing to play: the everday lives of adult videogame consumers.

Against a backdrop of videogame producers keen to promote themselves as a 'serious' adult entertainment industry, and persistent media reports on the 'dangers' of videogame play, this research examines the lived experiences of adult videogame players. I start with aconsideration of the nature of play and of consumption in order to assess the ways in whichour consumer society may be seen as becoming more playful, or experiential. I also consider the development of key discourses on videogame use and in particular the problematic waysin which we understand real, virtual and digital spaces. These theoretical contexts provide a background against which I consider a phenomenology of adult videogame consumption. Drawing from extended discussions with 24 adult videogame players I review: the biographical and domestic contexts in which adults play videogames; the various practices that they develop relating to buying, owning and using videogames, and; the nature of experiences produced through play. Adults may have started playing videogames as a result of an educational agenda, or peer pressure whilst as school, but may have continued playing intermittently into adulthood and now find that friends, and especially family influence how and what they play. As a result they have developed a variety of practices that I describe in detail including managing the amount of time and money spent on games and negotiating spaces to play. Within these contexts players aim for 'ideal' experiences of skill and achievement, of escape though the management of their imagination, and of social interaction with family and friends. However these largely positive experiences need to be carefully managed against a risk that their behaviour may be seen as childish, and against the potential for play to cause disruption to work or domestic life. Following these detailed first-person descriptions I consider the 'discourses in practice' during the use of videogames. I note the persistent framing of videogame play as frivolous, but also the way in which games are used to manage everyday life by providing a space that is an escape from routines of work and family life and in particular a space in which the imagination may be actualised. In doing so I also consider the transformatory potential of videogames, concluding that although they may be seen to serve a conservative role, and may be critiqued as part of an over-experienced, yet'futile' life, their ability to aid the management of everyday life is significant