Pseudo Random Generator Based Public Key Cryptography

Advances in communication technology have seen strong interest in digital data transmission. However, illegal data access has become more easy and prevalent in wireless and general communication networks. In order to protect the valuable data from illegal access, different kinds of cryptographic systems have been proposed. In this paper, a new integrating channel coding and cryptography design communication systems is proposed. So we use cryptography as an error detection tool. In order to preserve the advantages of encryption and to improve its disadvantages, we place the encryptor before the encoder. The hamming encoder is used to select the generator matrix to be used as a block code to form the new system .In this the security of common cryptographic primitive i.e a key stream generator based on LFSR can be strengthened by using the properties of a physical layer.So, a passive eaves dropping will experience great difficulty in cracking the LFSR based cryptography system as the computational complexity of discovering the secret key increases to large extent. The analysis indicates that the proposed design possesses the following feature. Its security is higher than the conventional one with the channel encoder only. Privacy is more due to unknown random codes. As the applied codes are unknown to a hostile user, this means that it is hardly possible to detect the message of another user. Anti-jam performance is good. It overcomes the disadvantage of Chaos based cryptography system as input data is not extended and hence bandwidth is not wasted. Moreover, the computer simulation shows that the proposed system has a good ability in error detection especially when the SNR per bit is moderate high, and the detection ability is enhanced when the increased length of Hamming code is employed

A di alogue logic

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Architecture, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 63-66).The history of computation owes a major debt to the traditional crafts, and the worlds of design and computation have been interlinked since the development of mechanical computing systems during the 19 th century. As computing systems became digital, the connections between craft and computation have become more abstract, though they are still there. The regime between the analogue world of craft, and more generally design practice, and the digital world of computation, here referred to as the "di-alogue" world has barely been explored. By challenging our notions of both craft and computation, how can excursions into the di alogue world help us to re-define or re-conceive of our traditional understanding of craft and of computation? In this thesis, I examine the shared history of traditional craft and computation as well as cover several examples of how these worlds have been combined. Additionally, I argue that by capitalizing on the procedural backbone of a particular craft, one can create unique "logics" that blur the perceived line between craft and computation.by Henry George Skupniewicz.S.B

Digital Communication System with Multi-carrier Modulation (OFDM) for Power Lin

Projecte realitzat en col.laboració amb el centre Instituto Superior Técnico (UTL)Se propone el un diseño para un receptor OFDM. El esquema de sincronismo esta dividido en cuatro partes para estimar el sincronismo de los simboles, el offset frecuencial y el canal de transmision. Se implementa un esquema conjunto de ecualizacion y decodificacion basados en un algoritmo MMSE con informacion a priori y codigos LDPC, respectivamente. La asignacion de la carga de los subcanales sigue el criterio Water-filling

Information in formation: Power and agency in contemporary informatic assemblages

This dissertation critically examines the concept of "information" in an effort to understand the ways it participates in contemporary relations of power. Chapter 1 surveys the contemporary social, political, and economic conditions under which information operates today, and elaborates four "grammars" of information prominent in popular discourse. It also unpacks various assumptions implicit in these discourses, and explains the limitations of such popular accounts for theorizing information's role in various social formations. Chapter 2 performs an historical genealogy of information, tracing the concept's articulation in the American context, especially during the postwar period. This chapter discusses the work of Claude Shannon and Norbert Wiener, who formalized and mathematized the notion of information during this time, their reasons for and aims in doing so, and these theories' implications for conceptualizing information today. Chapter 3 builds on this analysis in order to pinpoint the particular problematic an historical account of information discloses: namely, that of "agency." This chapter traces this problematic's motivating influence through writing in first- and second-wave cybernetics. It demonstrates that critical social theory's current preoccupation with nonhumanistic theories of agency has conceptual roots in this writing, and offers a schematic for assessing accounts of agency that problematize accounts of the phenomenon inherited from the Enlightenment. Chapter 4 offers a "cartography" of contemporary theories of nonhumanistic agency in order to concretely connect these accounts with their forebearers in cybernetics and information theory; it then re-situates Shannonian and Wienerian theories of information in relation to this cartography. Chapter 5 concludes the dissertation by returning to information's popular articulations. It explains how a "mixed semiotic" approach to information and information technologies might enhance critical discussions of information politics, and attends specifically to the ways in which various figures of agency shape accounts of these politics.Doctor of Philosoph