Low Cost and Compact Quantum Cryptography

We present the design of a novel free-space quantum cryptography system, complete with purpose-built software, that can operate in daylight conditions. The transmitter and receiver modules are built using inexpensive off-the-shelf components. Both modules are compact allowing the generation of renewed shared secrets on demand over a short range of a few metres. An analysis of the software is shown as well as results of error rates and therefore shared secret yields at varying background light levels. As the system is designed to eventually work in short-range consumer applications, we also present a use scenario where the consumer can regularly 'top up' a store of secrets for use in a variety of one-time-pad and authentication protocols.Comment: 18 pages, 9 figures, to be published in New Journal of Physic

A survey of energy saving techniques for mobile computers

Portable products such as pagers, cordless and digital cellular telephones, personal audio equipment, and laptop computers are increasingly being used. Because these applications are battery powered, reducing power consumption is vital. In this report we first give a survey of techniques for accomplishing energy reduction on the hardware level such as: low voltage components, use of sleep or idle modes, dynamic control of the processor clock frequency, clocking regions, and disabling unused peripherals. System- design techniques include minimizing external accesses, minimizing logic state transitions, and system partitioning using application-specific coprocessors. Then we review energy reduction techniques in the design of operating systems, including communication protocols, caching, scheduling and QoS management. Finally, we give an overview of policies to optimize the code of the application for energy consumption and make it aware of power management functions. Applications play a critical role in the user's experience of a power-managed system. Therefore, the application and the operating system must allow a user to control the power management. Remarkably, it appears that some energy preserving techniques not only lead to a reduced energy consumption, but also to more performance

Low Power system Design techniques for mobile computers

Portable products are being used increasingly. Because these systems are battery powered, reducing power consumption is vital. In this report we give the properties of low power design and techniques to exploit them on the architecture of the system. We focus on: min imizing capacitance, avoiding unnecessary and wasteful activity, and reducing voltage and frequency. We review energy reduction techniques in the architecture and design of a hand-held computer and the wireless communication system, including error control, sys tem decomposition, communication and MAC protocols, and low power short range net works

Context-aware routing system in an indoor scenario

The main aim of this report is to develop, design and analyse a system to simulate a context-aware routing algorithm in an indoor scenario. The context-aware purpose of this project is to take advantage of the interaction of the routing system with an entity when it is relevant. From all the context entities, the spatial environment is one of the most important, and the one which more information can be taken advantage of. Benefits can be obtained from using context-awareness in many ways, which have a special interest in the Information Technologies area. The intention of this report is to create a new application using context information related to the space, to be more precise, the position of the entities within a concrete location, and its preferences. The primary target is to design a supermarket in which benefits can be obtained from the position of the customers, their preferences (concretely the shopping list) and also the location of the products, to create an intelligent and efficient supermarket for the customer (but also for the supermarket in itself) point of view. Knowing the position of the customers and the location of the products in the supermarket can be useful to draw up efficient routes that can guide the customers through the corridors to buy their products quickly, which is the main reason why the system uses a shortest path routing algorithm to find the best route from the customer to the wished product. This algorithm considers the shortest distance and also the position of the rest of the customers so the system is able to guide the customers through another path in cases where they reach congested zones in the supermarket. Bluetooth wireless technology is used to accomplish the localization and system communication task. In addition the routing algorithm is adapted to fit the requirements of the intelligent supermarket. The design and implementation of a GUI simulator written in Java that represents the designed system is the main goal of this project. This simulator serves as a tool to test the system operation offering the possibility to modify parameters such as the rate and distribution type of the arrival of customers, the number of customers, subjective criteria of congestion and speed of the simulation among other parameters. Different types of statistics and the possibility to generate files with the information of the simulation are the main outcomes of this project, besides the GUI. In addition, this information can be translated into a Matlab script using a parser designed for this purpose. Finally the results and conclusions of the system are presented, and the future lines to follow the development of this innovative project

The system architecture of the Pocket Companion

In the Moby Dick project we design the architecture of a so-called Pocket Companion. It is a small personal portable computer with wireless communication facilities for every day use. The typical use of the Pocket Companion induces a number of requirements concerning security, performance, energy consumption, communication and size. We have shown that these requirements are interrelated and can only be met optimal with one single architecture. The Pocket Companion architecture consists of a central switch with a security module surrounded by several modules. The Pocket Companion is a personal machine. Communication, and particularly wireless communication, is essential for the system to support electronic transactions. Such a system requires a good security infrastructure not only for safeguarding personal data, but also to allow safe (financial) transactions. The integration of a security module in the Pocket Companion architecture provides the basis for a secure environment.\ud Because battery life is limited and battery weight is an important factor for the size and the weight of the Pocket Companion, energy consumption plays a crucial role in the architecture. An important theme of the architecture is: enough performance for minimal energy consumption

Codex Enables Secure Offline Micropayments

This paper introduces a new micropayment scheme, suitable for all kinds of transactions, and does not require online transactions for either the payer or payee. The designed method uses an encrypted data structure called Codex which self replicates to represent the current values of both the payer and the payee. The model, while providing fraud detection also guarantees payment & loss recovery