ABSTRACT In the recent times, due to the increasing rate of global warming, the Southern African region, especially, Lesotho has been experiencing continuous climatic change characterized by drastic reduction in rainfall, increase in the rate of dryness and heat, with depletion of the amount of water, flora and fauna resources. The situation has been so for years without many questions and answers with regard to how it affects food production and security in the country. Against this background, this paper investigates the chain of interactions between climatic change, expressed in the rate of rainfall and drought condition, the indigenous adaptation mechanisms and food production in Lesotho. The paper addresses the estimate of drought condition in Lesotho, Southern Africa, the nature of food production activities in the area and the extent to which continuous climatic change has affected the state of food production.

Promoting household food security and reducing malnutrition rates of a growing population with the same amount of water is a challenge facing South African nutritionists and agriculturalists alike. Apart from non-food related effects of agriculture in general, the crop and livestock production practices of the South African smallholder farmer may have nutritional implications, primarily when practised on residential land and resulting in home consumption. Yet, few studies have systematically investigated the impact thereof. It appears that crop diversification, gender issues and nutrition education are among the important factors that strengthen the link between agriculture and nutrition. Since food production is the most water-intensive activity in society, nutritional water productivity (i.e. nutrition per volume water) of foods and the nutritional water footprint of diets should be investigated in order to achieve a sustainable solution. This implies that both the demand for a diet consisting predominantly of water-productive plant products, as well as the supply thereof, be addressed.

The contribution of own food production to the nutrition of households in two neighbouring, rural, semi-arid settlements was investigated. A survey of a 10% probability sample (n=131) of households in Sekuruwe and Ga-Molekane in the Mokgalakwena Local Municipality, Waterberg District Municipality, Limpopo Province, South Africa, conducted in 2001, provided data on household composition, income (cash and kind), poverty status, expenditure and agriculture, including a detailed account of the types and quantities of food that were purchased during the month preceding the date of the interview. For each household the food obtained from the different types of agriculture they practised was quantified. Protein, iron and Vitamins A and C were selected as indicators to assess the contribution of purchased and own produced food to the food intake of households. Food composition tables were used to estimate the nutrient content of the different foods. To assess the contribution of irrigated home gardening to food intake of households, Drum & Drip micro-irrigation systems which enabled irrigated vegetable production on an area of 36 m2 were installed on the residential sites of 10 volunteer households in the study area. The results confirmed that income is the most important determinant of household food security in rural South Africa. However, food obtained from various types of dry-land agriculture contributed significantly to household nutrition and without farming the food security of households would be reduced, especially among the ultra-poor. Small-scale irrigated vegetable production was shown to have the potential to substantially raise the amount of the Vitamins A and C available to households but did not address the lack of protein in the diet of ultra-poor households and the lack of iron in the diet of all households.

Every single one of us have heard ones or know someone who have had a badexperience with a motorbike, maybe it was his or her fault, perhaps it was originateddue to the mistake of other vehicle or just was a simple distraction that caused as aresult that small fright or that horrible accident.All the people who ride motorcycles assume that when an impact comes, our body isthe chassis, our own body is in jeopardy to the unexpected just protected with a helmetand some protection clothes.The main goal of this project will be to try to reduce the possibilities of motorcycleusers of having a fatality accident or at least reduce the gravity of them.I will talk further on about why I decided to do this study and which kind of accidentsI am trying to prevent however I will like to say that my personal objective developingthis thesis has been to save lives, maybe sound quite hard to archive but I would bereally proud of myself if I could safe at least one life on the road the day of tomorrow.

The explosive growth in network based applications and distributed systems allows the deployment of critical applications such as e-commerce, tele-banking, electronic government, etc. On the other hand, attacking networks and distributed systems becomes easier with the support of public cracking tools and the information sharing between hackers. Consequently, security is a crucial topic. Authentication is considered as one of the major components in security and, in fact, represents the front door for any secure system. It is an important requirement to ensure that the network resources are accessed only by authorized users, meanings that strong access control mechanisms are needed. Most existing authentication protocols are centralized such that a single authentication entity controls the authentication process. These traditional authentication protocols suffer from certain drawbacks pertaining to security, availability and trust. This thesis proposes and evaluates a novel authentication protocol: Secure Network Access Protocol (SNAP) that attempts to overcome some of the drawbacks of centralized authentication protocols. SNAP is a distributed authentication protocol and is based on secret sharing schemes which have a quorum access structure. Another significant contribution of this thesis has been to consider not only the security analysis of SNAP but also the implementation issues. SNAP is studied and found to be robust in term of its security, availability, overhead and performance. The implementation of SNAP is considered and the application of SNAP to a wireless networks undertaken. The research conducted has shown the need for distributed authentication protocols and the importance of studying the network implementation issues for any novel security protocol.

published_or_final_version / abstract / History / Master / Master of Philosophy

Σε αυτό το πρώτο κεφάλαιο αναλύονται βασικές αρχές της κρυπτογραφίας ιδιωτικού και δημοσίου κλειδιού. Επίσης γίνεται μελέτη επιπλέον τεχνικών όπως συναρτήσεις κατακερματισμού και γεννήτριες ψευδοτυχαίων αριθμών. Τέλος τα χαρακτηριστικά των πιο διαδεδομένων κατηγοριών πρωτοκόλλων πιστοποίησης που χρησιμοποιούνται στη κρυπτογραφία. Στο Κεφάλαιο 2 γίνεται μια παρουσίαση της τεχνολογίας RFID. Αρχικά αναλύεται κάθε κομμάτι του συστήματος και ποιά είναι η λειτουργία του καθενός. Στη συνέχεια παρουσιάζονται οι αρχές λειτουργίας των συσκευών που αποτελούν το σύστημα. Τέλος γίνεται μια ιστορική αναδρομή των RFID συστημάτων και αναφέρονται μερικά από τα πρότυπα που έχουν κυριαρχήσει σήμερα. Στο Κεφάλαιο 3 αναλύονται οι κίνδυνοι που έρχεται αντιμέτωπο ένα RFID σύστημα και γίνεται μια παρουσίαση των επιθέσεων που μπορούν να προσβάλλουν ένα τέτοιο σύστημα. Στο Κεφάλαιο 4 συζητάμε τις κατευθυντήριες γραμμές που πρέπει να ακολουθήσουμε για την προστασία των RFID συστημάτων και τους ελέγχους που πρέπει να γίνουν σε αυτά. Επίσης αναλύουμε τις διάφορες τεχνικές που χρησιμοποιούνται για την ασφαλή επικοινωνία, καθώς και συγκεκριμένα παραδείγματα χαρακτηριστικά για κάθε κατηγορία. Στο Κεφάλαιο 5 γίνεται ανάλυση κάποιων συγκεκριμένων πρωτοκόλλων που πιστεύω υπογραμμίζουν το συμπέρασμα που καταλήγω με τη μελέτη που έκανα. Δηλαδή ότι τα RFID συστήματα πρέπει ακόμα και για το παράγοντα της ασφάλειας να σχεδιάζονται κατάλληλα έτσι ώστε να προβλέπουν την εξέλιξη του συστήματος και ότι ο πρέπει να γίνει ο συνδυασμός τεχνικών για την αποδοτικότερη υλοποίηση μέτρων ασφαλείας στα RFID. Το Κεφάλαιο 6 είναι ο επίλογος όπου επισημαίνουμε τα συμπεράσματα που βγαίνουν από την εργασία αυτή. / In the first chapter we analyze some basic cryptographic primitives drawn from private and public key cryptography. We also study the functionality of hash functions and Pseudorandom Number Generators. Also some Message Authentication Codes and the importance of digital signatures. In Chapter 2 we present briefly the RFID technology. Firstly we analyze each component of the system and the function that it has. We continue mentioning the working principles of those components. Finally the Chronology of the RFID technology is presented, along with some basic standards for the technology. In Chapter 3 we discuss all the dangers that a RFID system faces and also a list of the most popular attacks against those systems. In Chapter 4 at first some basics directions that someone must follow in order to design a secure RFID system are given. Some basic controls that we have in our disposal in order to defend our systems as well as some more advanced topics. Specific examples of those techniques are anlyzed and it is checked in what level they qualify for implementation on RFID systems/ In Chapter 5 we chose some implementations with specific properties that highlight in my opinion some important matters that need to be considered in RFID security. Chapter 6 is the epilogue which highlights the results of this dissertation.

No description available.

Package managers are a common tool for installing, removing, and updating software on modern computer systems. Unfortunately existingpackage managers have two major problems. First, inadequate security leads to vulnerability to attack. Thereare nine feasible attacks against modern package managers, many of which are enabled by flaws in the underlying security architecture. Second, in Virtual Machine (VM) environments such as Xen, VMWare, and VServers,different VMs on the same physical machine are treated as separate systemsby package managers leading to redundant package downloads and installations.This dissertation focuses on the design, development, and evaluation ofa package manager called Stork that does not have these problems. Stork provides a security architecture that prevents the attacks other package managers are vulnerable to. Stork also is efficient in VM environments and reduces redundant package management actions. Stork is a real system thathas been in use for four years and has managed half a million VM instantiations.

Communication in a sensor network needs guaranteed reception of data without fail and providing security to it. The authenticity and confidentiality of the data has to be ensured as sensors have limited hardware resources as well as the bandwidth. This thesis addresses the security aspects in wireless sensor networks. The main task of the project is to identify the critical security parameters for these distributed embedded systems. The sensors have extremely limited resources: small amount of memory, low computation capability and poor bandwidth. For example, a sensor platform can have 8KB of flash memory, a 4MHz 8-bit Atmel processor, and a 900MHz radio interface. Various security threats posed to these small wireless sensor networks has been made and solutions proposed. Secure communication between these communicating partners is to be achieved using cryptography.