Applied batch cryptography

The material presented in this thesis may be viewed as comprising two key parts, the first part concerns batch cryptography specifically, whilst the second deals with how this form of cryptography may be applied to security related applications such as electronic cash for improving efficiency of the protocols. The objective of batch cryptography is to devise more efficient primitive cryptographic protocols. In general, these primitives make use of some property such as homomorphism to perform a computationally expensive operation on a collective input set. The idea is to amortise an expensive operation, such as modular exponentiation, over the input. Most of the research work in this field has concentrated on its employment as a batch verifier of digital signatures. It is shown that several new attacks may be launched against these published schemes as some weaknesses are exposed. Another common use of batch cryptography is the simultaneous generation of digital signatures. There is significantly less previous work on this area, and the present schemes have some limited use in practical applications. Several new batch signatures schemes are introduced that improve upon the existing techniques and some practical uses are illustrated. Electronic cash is a technology that demands complex protocols in order to furnish several security properties. These typically include anonymity, traceability of a double spender, and off-line payment features. Presently, the most efficient schemes make use of coin divisibility to withdraw one large financial amount that may be progressively spent with one or more merchants. Several new cash schemes are introduced here that make use of batch cryptography for improving the withdrawal, payment, and deposit of electronic coins. The devised schemes apply both to the batch signature and verification techniques introduced, demonstrating improved performance over the contemporary divisible based structures. The solutions also provide an alternative paradigm for the construction of electronic cash systems. Whilst electronic cash is used as the vehicle for demonstrating the relevance of batch cryptography to security related applications, the applicability of the techniques introduced extends well beyond this.

Expressive cryptography : lattice perspectives

The invention of asymmetric encryption back in the seventies was a conceptual leap that vastly increased the expressive power of encryption of the times. For the first time, it allowed the sender of a message to designate the intended recipient in an cryptographic way, expressed as a “public key” that was related to but distinct from the “private key” that, alone, embodied the ability to decrypt. This made large-scale encryption a practical and scalable endeavour, and more than anything else—save the internet itself—led to the advent of electronic commerce as we know and practice it today.

Los determinantes de la confianza del comprador online. Comparación con el caso de subasta

[ES] Los trabajos de investigación sobre comercio electrónico en Internet ocupan gran parte de la investigación de marketing, pero son pocos aún los que se han ocupado de estudiar el sistema de subasta. Ante las peculiares características de una compra online, transmitir confianza al consumidor en este contexto es uno de los retos más importantes y difíciles en comparación con la compra offline. No obstante, es de esperar que las señales generadoras de confianza sean diferentes en la compra online por subasta que en la compra online en otros sitios web.

Enhancing Agent Mediated Electronic Markets with Ontology Matching Services and Social Network Support

Os Mercados Eletrónicos atingiram uma complexidade e nível de sofisticação tão elevados, que tornaram inadequados os modelos de software convencionais. Estes mercados são caracterizados por serem abertos, dinâmicos e competitivos, e constituídos por várias entidades independentes e heterogéneas. Tais entidades desempenham os seus papéis de forma autónoma, seguindo os seus objetivos, reagindo às ocorrências do ambiente em que se inserem e interagindo umas com as outras. Esta realidade levou a que existisse por parte da comunidade científica um especial interesse no estudo da negociação automática executada por agentes de software [Zhang et al., 2011]. No entanto, a diversidade dos atores envolvidos pode levar à existência de diferentes conceptualizações das suas necessidades e capacidades dando origem a incompatibilidades semânticas, que podem prejudicar a negociação e impedir a ocorrência de transações que satisfaçam as partes envolvidas. Os novos mercados devem, assim, possuir mecanismos que lhes permitam exibir novas capacidades, nomeadamente a capacidade de auxiliar na comunicação entre os diferentes agentes. Pelo que, é defendido neste trabalho que os mercados devem oferecer serviços de ontologias que permitam facilitar a interoperabilidade entre os agentes. No entanto, os humanos tendem a ser relutantes em aceitar a conceptualização de outros, a não ser que sejam convencidos de que poderão conseguir um bom negócio. Neste contexto, a aplicação e exploração de relações capturadas em redes sociais pode resultar no estabelecimento de relações de confiança entre vendedores e consumidores, e ao mesmo tempo, conduzir a um aumento da eficiência da negociação e consequentemente na satisfação das partes envolvidas. O sistema AEMOS é uma plataforma de comércio eletrónico baseada em agentes que inclui serviços de ontologias, mais especificamente, serviços de alinhamento de ontologias, incluindo a recomendação de possíveis alinhamentos entre as ontologias dos parceiros de negociação. Este sistema inclui também uma componente baseada numa rede social, que é construída aplicando técnicas de análise de redes socias sobre informação recolhida pelo mercado, e que permite melhorar a recomendação de alinhamentos e auxiliar os agentes na sua escolha. Neste trabalho são apresentados o desenvolvimento e implementação do sistema AEMOS, mais concretamente: • É proposto um novo modelo para comércio eletrónico baseado em agentes que disponibiliza serviços de ontologias; • Adicionalmente propõem-se o uso de redes sociais emergentes para captar e explorar informação sobre relações entre os diferentes parceiros de negócio; • É definida e implementada uma componente de serviços de ontologias que é capaz de: • o Sugerir alinhamentos entre ontologias para pares de agentes; • o Traduzir mensagens escritas de acordo com uma ontologia em mensagens escritas de acordo com outra, utilizando alinhamentos previamente aprovados; • o Melhorar os seus próprios serviços recorrendo às funcionalidades disponibilizadas pela componente de redes sociais; • É definida e implementada uma componente de redes sociais que: • o É capaz de construir e gerir um grafo de relações de proximidade entre agentes, e de relações de adequação de alinhamentos a agentes, tendo em conta os perfis, comportamento e interação dos agentes, bem como a cobertura e utilização dos alinhamentos; • o Explora e adapta técnicas e algoritmos de análise de redes sociais às várias fases dos processos do mercado eletrónico. A implementação e experimentação do modelo proposto demonstra como a colaboração entre os diferentes agentes pode ser vantajosa na melhoria do desempenho do sistema e como a inclusão e combinação de serviços de ontologias e redes sociais se reflete na eficiência da negociação de transações e na dinâmica do mercado como um todo.

Comportamento do consumidor brasileiro no e-commerce

Este é um estudo sobre o perfil do e-consumidor brasileiro. Através de um enquadramento do ecommerce no Brasil e de uma pesquisa qualitativa, o trabalho busca identificar quem é este consumidor, o que ele compra, porque ele compra online, como coleta as informações necessárias para escolher um produto ou serviço, quais são os fatores determinantes da compra e quais os locais escolhidos.

Arbitrage en ligne et les litiges du commerce électronique

"Mémoire présenté à la Faculté des études supérieures en vue de l'obtention du grade de Maîtrise en droit (LLM)"

L'encadrement juridique du traitement des données personnelles sur les sites de commerce en ligne

"Thèse en vue de l'obtention du grade de docteur en droit de l'Université Panthéon-Assas (Paris II) et de docteur en droit de la faculté de droit de l'Université de Montréal en droit privé"

Rôle et travaux au sein de l’Union européenne et de l’Allemagne en matière de la protection des consommateurs en Commerce Électronique

Cet article délivre un bref aperçu de la nouvelle législation européenne et allemande relative au commerce électronique et à la protection des consommateurs. Il décrit le développement du commerce électronique, de la législation et de la jurisprudence au cours des dernières années. Une distinction est établie entre les niveaux européen et allemand. La nouvelle Directive sur le commerce électronique a été adoptée le 8 juin 2000 et doit être transposée dans la loi nationale avant le 17 janvier 2002. Elle sera décrite et succinctement analysée avant d’aborder la nouvelle loi allemande portant sur les contrats à distance qui vient d’être adoptée par le Parlement allemand pour transposer la Directive sur les contrats à distance de 1997. Le cadre juridique existant avant l’entrée en vigueur de la nouvelle loi sur les contrats à distance sera également exposée en tenant compte de la protection des consommateurs. Alors que l’Union européenne vient de créer une nouvelle Directive sur le commerce électronique, les États membres sont encore occupés à transformer celle de 1997 en loi nationale. En comparant la législation européenne et allemande, nous soulignerons donc le point faible de la législation européenne : le temps nécessaire pour établir un cadre juridique efficace et fonctionnel peut facilement atteindre plusieurs années. L’article s’achèvera sur une courte présentation du « powershopping » ou « community shopping », en passe de devenir un nouveau modèle pour le consommateur européen, qui a fait l’objet de décisions restrictives ces derniers temps.

Dissolution of Dynamic Electronic Institutions, a first approach: Relevant factors and causes

In the context of the digital business ecosystems, small organizations cooperate between them in order to achieve common goals or offer new services for expanding their markets. There are different approaches for these cooperation models such as virtual enterprises, virtual organizations or dynamic electronic institutions which in their lifecycle have in common a dissolution phase. However this phase has not been studied deeply in the current literature and it lacks formalization. In this paper a first approach for achieving and managing the dissolution phase is proposed, as well as a CBR process in order to support it in a multi-agent system

Utilidad de los conceptos y estrategias comunitarias en el marketing online para la prevención de la copia ilegal en el mercado musical

Esta investigación se dirige a determinar cuál es la utilidad de los conceptos y estrategias comunitarias en el marketing online para la prevención de la copia ilegal en el mercado musical. Con este proyecto se desea que por medio de una nueva disquera enfocada en el comercio online, y usando los conceptos del mercadeo comunitario y el mercadeo relacional, se pueda desarrollar nuevas estrategias de mercadeo en donde se logre incentivar y promover la compra de música original por medio de la creación de una relación más estrecha entre la compañía y el cliente, en la cual pueda afectar de forma positiva a la comunidad a la que este pertenece. El objetivo general es determinar cuál es la utilidad de los conceptos y estrategias comunitarias en el marketing online para la prevención de la copia ilegal en el mercado musical. Los objetivos específicos son: 1. Mostrar la utilidad de los conceptos y estrategias del marketing comunitario en la prevención de la copia ilegal del mercado musical y 2. Implementar las estrategias logradas en la investigación en un plan de creación de empresa. Se utilizará el método de investigación y análisis de caso, utilizando el plan de empresa en la creación de una empresa del mercado musical, tomando la relación estratégica comunitaria y el marketing dentro del plan de mercadeo como estrategia para la prevención de la copia ilegal. Mediante este proyecto se desea que por medio del marketing relacional y de los conceptos del mercadeo hacia comunidades, enfocado en une- marketing sepuedanestablecerestrategiasparalaprevencióndelacopiailegalydelacomprade estos productos Además, se busca implementar dichos resultados en la empresa que se pretende crear en el sector de la industria musical, puesto que la seguridad que tendrán los productos a la venta, serán la ventaja competitiva de la empresa.

Persuasive technology and users acceptance of e-commerce: users perceptions of website persuasiveness

Persuasive technologies have been extensively applied in the context of e-commerce for the purpose of marketing, enhancing system credibility, and motivating users to adopt the systems. Recognising that persuasion impacts on consumer behaviour to purchase online have not been investigated previously. This study reviews theories of technology acceptance, and identifies their limitation in not considering the effect of persuasive technologies when determining user online technology acceptance. The study proposes a theoretical model that considers the effect of persuasive technologies on consumer acceptance of e-commerce websites; with consideration of other related variables, i.e. trust and technological attributes. Moreover the paper proposes a model based on the UTAUT2, which contains relevant contributing factors; including the concept of perceived persuasiveness.

Mudanças na Natureza do Comércio no Mundo conectado através do E-commerce

The Internet has taken the world by storm. It has eliminated the barriers of technology, and unlocked the doors to electronic commerce and the 'Virtual Economy'. It has given us a glimpse into the future of 'Business' itself, and it has created a bewildering variety of choices in our personal and professional lives. It has taken on a life of its own, and we are all frantically trying to keep up. Many overwhelmed companies are asking questions like: 'What should our Internet Strategy be?' Or 'How do we put our business on the Internet like everybody else is doing?' or 'How do we use this thing to make money without spending any?'. These questions may seem reasonable on the surface, but they miss the point because they focus on the technologies rather than the core issues of conducting day-to-day business. The Internet can indeed offer fast returns in marketing reach, speed, director consumer sales and so on, and many companies are using it to good advantage, but the highest and best use of any such technology is to support, enhance and even re-invent the fundamentals of general business practice. When the initial excitement is over, and companies gain experience and confidence with the new business models, this larger view will begin to assert itself. Companies will then start to position their 'Internet Strategies' in context of where the business world itself is going over time, and how they can prepare for what is to come. Until now, the business world has been very fragmented, its collective progress limited (in part) by the inability to communicate within and between companies. Now that the technical remedy seems to be at hand and standards are beginning to emerge, we are starting to see a trend toward consolidation, cooperation, and economic synergy. Companies are improving their internal business processes with Intranets, and Electronic Commerce initiatives have sprung up using EDI, the World Wide Web, E-Mail, secure credit card payments and other tools. Companies are using the Internet to talk to each other and to sell their goods and services to the end consumer. Like Berlin, the walls are coming down because they have to. Electronic 'Communities of Common Interest' are beginning to surface, with the goal of supporting and aligning similar industries (such as Government, Insurance, Transportation and Health care) or similar business functions (such as Purchasing, Payments, and Human Resources). As these communities grow and mature, their initial scope will broaden and their spheres of influence will expand. They will begin to overlap into other communities, creating a synergistic effect and reshaping the conduct of business. The business world will undergo a gradual evolution toward globalization, driven by economic imperatives and natural selection in the marketplace, and facilitated by Electronic Commerce and Internet technologies. The business world 'beyond 2000' will have a substantially different look and feel than that which we see today.

E-commerce environment and trade promotion for Latin America: policy implications from East Asian and advanced economies' experiences

Includes bibliography