Modern computer networks allow server resources to be shared. While this multiplexing is the unsung hero of scalability and performance, the fact that clients are sharing resources and each client’s network traffic is transmitted in a larger pool of the total network traffic, poses distinct challenges for security. By adopting multiplexing so broadly, the networking and systems communities have implicitly favored performance over security. When servers multiplexing clients are compromised, the attack is able to spread by exploiting unsuspecting clients sharing the resource. Drive-by-downloads are an example of an attack where a Web server is compromised and begins distributing malware to connecting clients. As a result of using today’s many-to-one client-server network model, current approaches are inadequate at protecting the network and its resources. We propose a redesign of the modern network infrastructure. Our approach involves moving from the current many-to-one client-server model to a one-to-one client-server model. In redesigning the network, we provide a means of better accountability for traffic between clients and servers. With accountability, we enable the ability to quickly determine which client is responsible for an attack. This allows us to quickly repair the affected entities. To accomplish this accountability, we separate each client’s communication into separate flows. A flow is identified by various network features, such as IP addresses and ports. Further, instead of allowing multiple clients to be multiplexed at the same server, we use a technique that allows each client to communicate with a server that is logically separate from all other clients. Accordingly, a server compromise only effects a single client. We create a one-to-one client-server model using virtualization techniques and OpenFlow, a software-defined network (SDN) protocol. We complete our model in three phases. In the first, we deploy a physical SDN using physical machines and a commodity network switch that supports OpenFlow to gain an initial understanding of SDNs. The next phase involves implementation of Choreographer, a DNS access control mechanism, in a virtualized SDN environment for better scalability over our physical configuration. Finally, we leverage Choreographer to dynamically instantiate a server for each client and create network flows that allow a client to reach the requested server.

No description available.

The diploma thesis deals with the universal mobile client-server application of Android and iOS devices solved in the native environment of the given operating systems. The work explores approaches to solving the problem in both environments. The application solution will display, store and process a variety of data sent to the server in a unified form as well as customize the look given the conditions addressed conditions and equipment. The aim of the thesis is to show and compare the native potential of the mobile device as well as to design a unified application of frequently asked issues - to view and access a large amount of stored data to the user.

No description available.

基於通行碼之認證金鑰交換協定(Password-based Authenticated Key Exchange)為一項使要進行交換訊息之雙方做相互驗證並產生一把共享金鑰的技術。藉由通訊雙方共享一組通行碼做為身份驗證的依據，並且在驗證結束後產生一把僅有雙方才知道的祕密通訊金鑰，往後進行傳遞機密資訊時即可透過此金鑰建立安全的通訊管道。 本篇論文提出一個在主從式架構(Client/Server model)下基於晶格(lattice)之通行碼認證金鑰交換協定，用戶端只需記錄與伺服器共享之通行碼，而伺服器端除了通行碼外擁有屬於自己的公私鑰對，雙方間透過共享之通行碼進行相互驗證，並且在兩個步驟內完成認證及金鑰交換。在安全性上基於晶格密碼系統之難問題，若未來量子電腦問世能夠抵擋其強大運算能力之攻擊，達到安全且有效率之通行碼認證金鑰協議。 / The password-based authenticated key exchange is a technology that allows both parties to perform mutual authentication and generate a shared session key. They through the shared password as the basis for authentication and generate a session key that is only known by both parties. At last, they can use this key to establish a secure channel to transmit secret message. We propose a password-based authenticated key exchange from lattices for Client-Server model. The client only need to remember the password rather than the private key, and the server except keep the password and its own public/private key pair. Both parties execute the mutual authentication via the shared password and accomplish the key exchange within two steps. The security of our protocol is based on LWE problem for lattices, so it is secure even an attacker uses a quantum computer.

L'objectif de cette thèse est l'étude d'un environnement d'exécution pour machines parallèles sans mémoire commune. Elle comprend la définition d'un modèle de programme parallèle, basé sur l'échange de message offrant une forme restreinte de mémoire partagée. La communication est indirecte, via des portes; les processus utilisent les barrières pour la synchronisation. Les entités du système. processus, portes et barrières, sont créées dynamiquement, et placées sur un processeur quelconque du réseau de processeurs de façon explicite. Nous proposons une implantation de ce modèle comme la mise en oeuvre systématique d'une architecture client/serveur. Cette implantation a été efféctuée sur une machine Supemode. La base est un Micro Noyau Parallèle, où le composant principal est un mécanisme d'appel de procédure à distance minimal. / This thesis describes an execution environment for parallel machines without shared memory. A parallel programming model based on message passing, with a special shared memory. In this model, process communication occurs indirectly, via ports, and the processes use barriers for synchronization. All the entities of the system, such as processes, ports and barriers, are created dynamically and loaded on any processor of the network of processors. The implementation architecture of our model is a systematic realization of the client/server model. An implementation is proposed in a Supernode parallel machine as a parallel micro kernel. The principal parallel micro kernel component is a minimal remote procedure call mechanism.

L'objectif de cette thèse est l'étude d'un environnement d'exécution pour machines parallèles sans mémoire commune. Elle comprend la définition d'un modèle de programme parallèle, basé sur l'échange de message offrant une forme restreinte de mémoire partagée. La communication est indirecte, via des portes; les processus utilisent les barrières pour la synchronisation. Les entités du système. processus, portes et barrières, sont créées dynamiquement, et placées sur un processeur quelconque du réseau de processeurs de façon explicite. Nous proposons une implantation de ce modèle comme la mise en oeuvre systématique d'une architecture client/serveur. Cette implantation a été efféctuée sur une machine Supemode. La base est un Micro Noyau Parallèle, où le composant principal est un mécanisme d'appel de procédure à distance minimal. / This thesis describes an execution environment for parallel machines without shared memory. A parallel programming model based on message passing, with a special shared memory. In this model, process communication occurs indirectly, via ports, and the processes use barriers for synchronization. All the entities of the system, such as processes, ports and barriers, are created dynamically and loaded on any processor of the network of processors. The implementation architecture of our model is a systematic realization of the client/server model. An implementation is proposed in a Supernode parallel machine as a parallel micro kernel. The principal parallel micro kernel component is a minimal remote procedure call mechanism.

L'objectif de cette thèse est l'étude d'un environnement d'exécution pour machines parallèles sans mémoire commune. Elle comprend la définition d'un modèle de programme parallèle, basé sur l'échange de message offrant une forme restreinte de mémoire partagée. La communication est indirecte, via des portes; les processus utilisent les barrières pour la synchronisation. Les entités du système. processus, portes et barrières, sont créées dynamiquement, et placées sur un processeur quelconque du réseau de processeurs de façon explicite. Nous proposons une implantation de ce modèle comme la mise en oeuvre systématique d'une architecture client/serveur. Cette implantation a été efféctuée sur une machine Supemode. La base est un Micro Noyau Parallèle, où le composant principal est un mécanisme d'appel de procédure à distance minimal. / This thesis describes an execution environment for parallel machines without shared memory. A parallel programming model based on message passing, with a special shared memory. In this model, process communication occurs indirectly, via ports, and the processes use barriers for synchronization. All the entities of the system, such as processes, ports and barriers, are created dynamically and loaded on any processor of the network of processors. The implementation architecture of our model is a systematic realization of the client/server model. An implementation is proposed in a Supernode parallel machine as a parallel micro kernel. The principal parallel micro kernel component is a minimal remote procedure call mechanism.

This thesis describes a development of a modern client-server application for text recognition on iOS platform. The reader is acquainted with common principles of a client-server model, including its known architecture styles, and with a distribution of logical layers between both sides of the model. After that the thesis depicts current trends and examples of suitable technologies for creating an application programming interface of a web server. Possible ways of text recognition on the server side are discussed as well. In context of a client side, the thesis provides an insight into iOS platform and a few important concepts in iOS application development. Following implementation of the server side is stressed to be reusable as much as possible for different kinds of use cases. Last but not least, the thesis provides a simple iOS framework for a direct communication with the recognition server. Finally, an application for evaluation of food ingredients from a packaging material is implemented as an example of usage.

This thesis describes a process of creating a mobile application using deep convolutional neural networks. The process starts with proposal of the main idea, followed by product and technical design, implementation and evaluation. The thesis also explores the technical background of image recognition, and chooses the most suitable options for the purpose of the application. These are object detection and multi-label classification, which are both implemented, evaluated and compared. The resulting application tries to bring value from both user and technical point of view.