Low-cost digital signature architecture suitable for radio frequency identification tags

Continuing achievements in hardware technology are bringing ubiquitous computing closer to reality. The notion of a connected, interactive and autonomous environment is common to all sensor networks, biosystems and radio frequency identification (RFID) devices, and the emergence of significant deployments and sophisticated applications can be expected. However, as more information is collected and transmitted, security issues will become vital for such a fully connected environment. In this study the authors consider adding security features to low-cost devices such as RFID tags. In particular, the authors consider the implementation of a digital signature architecture that can be used for device authentication, to prevent tag cloning, and for data authentication to prevent transmission forgery. The scheme is built around the signature variant of the cryptoGPS identification scheme and the SHA-1 hash function. When implemented on 130 nm CMOS the full design uses 7494 gates and consumes 4.72 mu W of power, making it smaller and more power efficient than previous low-cost digital signature designs. The study also presents a low-cost SHA-1 hardware architecture which is the smallest standardised hash function design to date.

The Decline of the Cow: Agricultural and Settlement Change in Early Medieval Ireland

This article considers cows and dairying as the basis a17of value system in early societies, particularly in Ireland. Only in a very few instances is it possible to demonstrate that such systems existed. When it does, it can be shown that cows and dairying were imbedded in the social or religious institutions of these cultures. Cattle had a value and meaning much greater than their economic worth in terms of food, hides, tallow etc. Such a systems, however, does not allow economic development as dairy produce does not easily lend itself to the production, and accumulation, of significant surplus nor is dairy produce particularly suitable for economic expansion based on trade. Its perishable nature militates against both roles. In order to develop political power that is based on economic power and wealth it is necessary to change the emphasis from livestock to cereal production.

Architecture in Cinema: A Relation of Representation Based on Space

Architecture, whether in the foreground or background, is an intrinsic part of any film, and cinema holds a position as a transformative reference in contemporary architecture. This book addresses the role of architecture in cinema, and through a focus on the use of space, it presents a critical overview of the relation between the two. Through framing, flattening and editing, cinematic space, as the representation of architectural space, focuses on its certain qualities, while eliminating others. Thus, cinema emphasizes individual aspects of space that may be overlooked when the whole context is considered. Space 'acts' in the foreground rather than simply filling the background in the films of Peter Greenaway and Wim Wenders, which are used to analyze two significant cinematic approaches to space, space as form and space as symbol. The detailed analysis of Greenaway's The Belly of an Architect and Wenders' Der Himmel über Berlin (Wings of Desire) offers an innovative and original perspective on space to those interested in both fields of architecture and film studies.