10 resultados para Public-key

em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland


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Arvokasta tai luottamuksellista tietoa käsittelevien palveluiden, kuten pankki- ja kauppa-palveluiden, tarjoaminen julkisessa Internet-verkossa on synnyttänyt tarpeen vahvalle todennukselle, eli käyttäjien tunnistuksen varmistamiselle. Vahvassa todennuksessa käytetään salaus-menetelmien tarjoamia keinoja todennus-tapahtuman tieto-turvan parantamiseen heikkoihin todennusmenetelmiin nähden. Todennusta käyttäjätunnus-salasana-yhdistelmällä voidaan pitää heikkona menetelmänä. Julkisen avaimen järjestelmän varmenteita voidaan käyttää WWW-ympäristössä toimivissa palveluissa yhteyden osapuolten todentamiseen. Tässä työssä suunniteltiin vahva käyttäjän todennus julkisen avaimen järjestelmällä WWW-ympäristössä tarjottavalle palvelulle ja toteutettiin palvelun tarjoavan sovelluksen komponentiksi soveltuva yksinkertainen varmentaja OpenSSL-salaustyökalupaketin avulla. Työssä käydään läpi myös salauksen perusteet, julkisen avaimen järjestelmä ja esitellään olemassaolevia varmentajatoteutuksia ja mahdollisia tieto-turva-uhkia Vahva todennus tulee suunnitella siten, että palvelun käyttäjä ymmärtää, mikä tarkoitus hänen toimillaan on ja miten ne edistävät tietoturvaa. Internet-palveluissa käyttäjän vahva todennus ei ole yleistynyt huonon käytettävyyden vuoksi.

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Lyhyen kantaman radiotekniikoiden hyödyntäminen mahdollistaa uudenlaisten paikallisten palveluiden käytön ja vanhojen palveluiden kehittämisen. Kulunvalvonta on päivittäisenä palveluna valittu työn esimerkkisovellukseksi. Useita tunnistus- ja valtuutustapoja tutkitaan, ja julkisen avaimen infrastruktuuri on esitellään tarkemmin. Langattomat tekniikat Bluetooth, Zigbee, RFID ja IrDA esitellän yleisellä tasolla langattomat tekniikat –luvussa. Bluetooth-tekniikan rakennetta, mukaan lukien sen tietoturva-arkkitehtuuria, tutkitaan tarkemmin. Bluetooth-tekniikkaa käytetään työssä suunnitellun langattoman kulunvalvontajärjestelmän tietojen siirtoon. Kannettava päätelaite toimii käyttäjän henkilökohtaisena luotettuna laitteena, jota voi käyttää avaimena. Käyttäjän tunnistaminen ja valtuuttaminen perustuu julkisen avaimen infrastruktuuriin. Ylläpidon allekirjoittamat varmenteet sisältävät käyttäjän julkisen avaimen lisäksi tietoa hänestä ja hänen oikeuksistaan. Käyttäjän tunnistaminen kulunvalvontapisteissä tehdään julkisen ja salaisen avaimen käyttöön perustuvalla haaste-vastaus-menetelmällä. Lyhyesti, järjestelmässä käytetään Bluetooth-päätelaitteita langattomina avaimina.

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The basic goal of this study is to extend old and propose new ways to generate knapsack sets suitable for use in public key cryptography. The knapsack problem and its cryptographic use are reviewed in the introductory chapter. Terminology is based on common cryptographic vocabulary. For example, solving the knapsack problem (which is here a subset sum problem) is termed decipherment. Chapter 1 also reviews the most famous knapsack cryptosystem, the Merkle Hellman system. It is based on a superincreasing knapsack and uses modular multiplication as a trapdoor transformation. The insecurity caused by these two properties exemplifies the two general categories of attacks against knapsack systems. These categories provide the motivation for Chapters 2 and 4. Chapter 2 discusses the density of a knapsack and the dangers of having a low density. Chapter 3 interrupts for a while the more abstract treatment by showing examples of small injective knapsacks and extrapolating conjectures on some characteristics of knapsacks of larger size, especially their density and number. The most common trapdoor technique, modular multiplication, is likely to cause insecurity, but as argued in Chapter 4, it is difficult to find any other simple trapdoor techniques. This discussion also provides a basis for the introduction of various categories of non injectivity in Chapter 5. Besides general ideas of non injectivity of knapsack systems, Chapter 5 introduces and evaluates several ways to construct such systems, most notably the "exceptional blocks" in superincreasing knapsacks and the usage of "too small" a modulus in the modular multiplication as a trapdoor technique. The author believes that non injectivity is the most promising direction for development of knapsack cryptosystema. Chapter 6 modifies two well known knapsack schemes, the Merkle Hellman multiplicative trapdoor knapsack and the Graham Shamir knapsack. The main interest is in aspects other than non injectivity, although that is also exploited. In the end of the chapter, constructions proposed by Desmedt et. al. are presented to serve as a comparison for the developments of the subsequent three chapters. Chapter 7 provides a general framework for the iterative construction of injective knapsacks from smaller knapsacks, together with a simple example, the "three elements" system. In Chapters 8 and 9 the general framework is put into practice in two different ways. Modularly injective small knapsacks are used in Chapter 9 to construct a large knapsack, which is called the congruential knapsack. The addends of a subset sum can be found by decrementing the sum iteratively by using each of the small knapsacks and their moduli in turn. The construction is also generalized to the non injective case, which can lead to especially good results in the density, without complicating the deciphering process too much. Chapter 9 presents three related ways to realize the general framework of Chapter 7. The main idea is to join iteratively small knapsacks, each element of which would satisfy the superincreasing condition. As a whole, none of these systems need become superincreasing, though the development of density is not better than that. The new knapsack systems are injective but they can be deciphered with the same searching method as the non injective knapsacks with the "exceptional blocks" in Chapter 5. The final Chapter 10 first reviews the Chor Rivest knapsack system, which has withstood all cryptanalytic attacks. A couple of modifications to the use of this system are presented in order to further increase the security or make the construction easier. The latter goal is attempted by reducing the size of the Chor Rivest knapsack embedded in the modified system. '

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The objective of the dissertation is to examine organizational responses of public actors to customer requirements which drive the transformation of value networks and promote public-private partnership in the electricity distribution industry and elderly care sectors. The research bridges the concept of offering to value networks where capabilities can be acquired for novel product concepts. The research contributes to recent literature, re-examining theories on interactions of customer requirements and supply management. A critical realist case study approach is applied to this abductive the research which directs to describe causalities in the analyzed phenomena. The presented evidence is based on three sources, which are in-depth interviews, archival analysis and the Delphi method. Service provision requires awareness on technology and functionalities of offering. Moreover, service provision includes interactions of multiple partners, which suggests the importance of the co-operative orientation of actors. According to the findings,portfolio management has a key role when intelligent solutions are implemented in public service provision because its concepts involve a variety of resources from multiple suppliers. However, emergent networks are not functional if they lack leaders who have access to the customer interface, have power to steer networks and a capability to build offerings. Public procurement policies were recognized to focus on a narrow scope in which price is a key factor in decisions. In the future, the public sector has to implement technology strategies and portfolio management, which mean longterm platform development and commitment to partnerships. On the other hand, the service providers should also be more aware of offerings into which their products will be integrated in the future. This requires making the customer’s voice in product development and co-operation in order to increase the interconnectivity of products.

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Unsuccessful mergers are unfortunately the rule rather than the exception. Therefore it is necessary to gain an enhanced understanding of mergers and post-merger integrations (PMI) as well as learning more about how mergers and PMIs of information systems (IS) and people can be facilitated. Studies on PMI of IS are scarce and public sector mergers are even less studied. There is nothing however to indicate that public sector mergers are any more successful than those in the private sector. This thesis covers five studies carried out between 2008 and 2011 in two organizations in higher education that merged in January 2010. The most recent study was carried out two years after the new university was established. The longitudinal case-study focused on the administrators and their opinions of the IS, the work situation and the merger in general. These issues were investigated before, during and after the merger. Both surveys and interviews were used to collect data, to which were added documents that both describe and guide the merger process; in this way we aimed at a triangulation of findings. Administrators were chosen as the focus of the study since public organizations are highly dependent on this staff category, forming the backbone of the organization and whose performance is a key success factor for the organization. Reliable and effective IS are also critical for maintaining a functional and effective organization, and this makes administrators highly dependent on their organizations’ IS for the ability to carry out their duties as intended. The case-study has confirmed the administrators’ dependency on IS that work well. A merger is likely to lead to changes in the IS and the routines associated with the administrators’ work. Hence it was especially interesting to study how the administrators viewed the merger and its consequences for IS and the work situation. The overall research objective is to find key issues for successful mergers and PMIs. The first explorative study in 2008 showed that the administrators were confident of their skills and knowledge of IS and had no fear of having to learn new IS due to the merger. Most administrators had an academic background and were not anxious about whether IS training would be given or not. Before the merger the administrators were positive and enthusiastic towards the merger and also to the changes that they expected. The studies carried out before the merger showed that these administrators were very satisfied with the information provided about the merger. This information was disseminated through various channels and even negative information and postponed decisions were quickly distributed. The study conflicts with the theories that have found that resistance to change is inevitable in a merger. Shortly after the merger the (third) study showed disappointment with the fact that fewer changes than expected had been implemented even if the changes that actually were carried out sometimes led to a more problematic work situation. This was seen to be more prominent for routine changes than IS changes. Still the administrators showed a clear willingness to change and to share their knowledge with new colleagues. This knowledge sharing (also tacit) worked well in the merger and the PMI. The majority reported that the most common way to learn to use new ISs and to apply new routines was by asking help from colleagues. They also needed to take responsibility for their own training and development. Five months after the merger (the fourth study) the administrators had become worried about the changes in communication strategy that had been implemented in the new university. This was perceived as being more anonymous. Furthermore, it was harder to get to know what was happening and to contact the new decision makers. The administrators found that decisions, and the authority to make decisions, had been moved to a higher administrative level than they were accustomed to. A directive management style is recommended in mergers in order to achieve a quick transition without distracting from the core business. A merger process may be tiresome and require considerable effort from the participants. In addition, not everyone can make their voice heard during a merger and consensus is not possible in every question. It is important to find out what is best for the new organization instead of simply claiming that the tried and tested methods of doing things should be implemented. A major problem turned out to be the lack of management continuity during the merger process. Especially problematic was the situation in the IS-department with many substitute managers during the whole merger process (even after the merger was carried out). This meant that no one was in charge of IS-issues and the PMI of IS. Moreover, the top managers were appointed very late in the process; in some cases after the merger was carried out. This led to missed opportunities for building trust and management credibility was heavily affected. The administrators felt neglected and that their competences and knowledge no longer counted. This, together with a reduced and altered information flow, led to rumours and distrust. Before the merger the administrators were convinced that their achievements contributed value to their organizations and that they worked effectively. After the merger they were less sure of their value contribution and effectiveness even if these factors were not totally discounted. The fifth study in November 2011 found that the administrators were still satisfied with their IS as they had been throughout the whole study. Furthermore, they believed that the IS department had done a good job despite challenging circumstances. Both the former organizations lacked IS strategies, which badly affected the IS strategizing during the merger and the PMI. IS strategies deal with issues like system ownership; namely who should pay and who is responsible for maintenance and system development, for organizing system training for new IS, and for effectively run IS even during changing circumstances (e.g. more users). A proactive approach is recommended for IS strategizing to work. This is particularly true during a merger and PMI for handling issues about what ISs should be adopted and implemented in the new organization, issues of integration and reengineering of IS-related processes. In the new university an ITstrategy had still not been decided 26 months after the new university was established. The study shows the importance of the decisive management of IS in a merger requiring that IS issues are addressed in the merger process and that IS decisions are made early. Moreover, the new management needs to be appointed early in order to work actively with the IS-strategizing. It is also necessary to build trust and to plan and make decisions about integration of IS and people.

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Social media has become a part of many people’s everyday lives. In the library field the adoption of social media has been widespread and discussions of the development of “Library 2.0” began at an early stage. The aim with this thesis is to study the interface between public libraries, social media, and users, focusing on information activities. The main research question is: How is the interface between public libraries and social media perceived and acted upon by its main stakeholders (library professionals and users)? The background of Library 2.0 is strongly associated with the development of the Web and social media, as well as with the public libraries and their user-centered and information technological development. The theoretical framework builds on the research within the area of Library and Information Science concerning information behavior, information practice, and information activities. Earlier research on social media and public libraries is also highlighted in this thesis. The methods survey and content analysis were applied to map the interface between social media and public libraries. A questionnaire was handed out to the users and another questionnaire was sent out to the library professionals. The results were statistically analyzed. In the content analysis public library Facebook pages were studied. All the empirical investigations were conducted in the area of Finland Proper. An integrated analysis of the results deepens the understanding of the key elements of the social media and public library context. These elements are interactivity, information activities, perceptions, and stakeholders. In this context seven information activities were distinguished: reading, seeking, creating, communicating, informing, mediating, and contributing. This thesis contributes to develop the research concerning information activities and draws a realistic picture of the challenges and opportunities in the social media and public library context. It also contributes with knowledge on library professionals and library users, and the existing differences in their perceptions of the interface between libraries and social media.

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Renewable energy investments play a key role in energy transition. While studies have suggested that social acceptance may form a barrier for renewable energy investments, the ways in which companies perceive and attempt to gain the acceptance have received little attention. This study aims to fill the gap by exploring how large electric utilities justify their strategic investments in their press releases and how do the justifications differ between renewable and non-renewable energy investments. The study bases on legitimacy theory and aims at contributing to the research on legitimation in institutional change. As its research method, the study employs an inductive mixed method content analysis. The study has two parts: a qualitative content analysis that explores and identifies the themes and legitimation strategies of the press releases and a quantitative computer-aided analysis that compares renewable and non-renewable energy investments. The sample of the study consists of 396 press releases representing the strategic energy investments of 34 electric utilities from the list of the world’s 250 largest and financially most successful energy companies. The data is collected from the period of 2010–2014. The study reveals that most important justifications for strategic energy investments are fit with the strategy and environmental and social benefits. Justifications address especially the expectations of market. Investments into non-renewable energy are justified more and they use more arguments addressing the proprieties and performance of power plants whereas renewable energy investments are legitimized by references to past actions and commonly accepted morals and norms. The findings support the notion that validity-addressing and propriety-addressing legitimation strategies are used differently in stable and unstable institutional settings.

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The investments have always been considered as an essential backbone and so-called ‘locomotive’ for the competitive economies. However, in various countries, the state has been put under tight budget constraints for the investments in capital intensive projects. In response to this situation, the cooperation between public and private sector has grown based on public-private mechanism. The promotion of favorable arrangement for collaboration between public and private sectors for the provision of policies, services, and infrastructure in Russia can help to address the problems of dry ports development that neither municipalities nor the private sector can solve alone. Especially, the stimulation of public-private collaboration is significant under the exposure to externalities that affect the magnitude of the risks during all phases of project realization. In these circumstances, the risk in the projects also is becoming increasingly a part of joint research and risk management practice, which is viewed as a key approach, aiming to take active actions on existing global and specific factors of uncertainties. Meanwhile, a relatively little progress has been made on the inclusion of the resilience aspects into the planning process of a dry ports construction that would instruct the capacity planner, on how to mitigate the occurrence of disruptions that may lead to million dollars of losses due to the deviation of the future cash flows from the expected financial flows on the project. The current experience shows that the existing methodological base is developed fragmentary within separate steps of supply chain risk management (SCRM) processes: risk identification, risk evaluation, risk mitigation, risk monitoring and control phases. The lack of the systematic approach hinders the solution of the problem of risk management processes of dry port implementation. Therefore, management of various risks during the investments phases of dry port projects still presents a considerable challenge from the practical and theoretical points of view. In this regard, the given research became a logical continuation of fundamental research, existing in the financial models and theories (e.g., capital asset pricing model and real option theory), as well as provided a complementation for the portfolio theory. The goal of the current study is in the design of methods and models for the facilitation of dry port implementation through the mechanism of public-private partnership on the national market that implies the necessity to mitigate, first and foremost, the shortage of the investments and consequences of risks. The problem of the research was formulated on the ground of the identified contradictions. They rose as a continuation of the trade-off between the opportunities that the investors can gain from the development of terminal business in Russia (i.e. dry port implementation) and risks. As a rule, the higher the investment risk, the greater should be their expected return. However, investors have a different tolerance for the risks. That is why it would be advisable to find an optimum investment. In the given study, the optimum relates to the search for the efficient portfolio, which can provide satisfaction to the investor, depending on its degree of risk aversion. There are many theories and methods in finance, concerning investment choices. Nevertheless, the appropriateness and effectiveness of particular methods should be considered with the allowance of the specifics of the investment projects. For example, the investments in dry ports imply not only the lump sum of financial inflows, but also the long-term payback periods. As a result, capital intensity and longevity of their construction determine the necessity from investors to ensure the return on investment (profitability), along with the rapid return on investment (liquidity), without precluding the fact that the stochastic nature of the project environment is hardly described by the formula-based approach. The current theoretical base for the economic appraisals of the dry port projects more often perceives net present value (NPV) as a technique superior to other decision-making criteria. For example, the portfolio theory, which considers different risk preference of an investor and structures of utility, defines net present value as a better criterion of project appraisal than discounted payback period (DPP). Meanwhile, in business practice, the DPP is more popular. Knowing that the NPV is based on the assumptions of certainty of project life, it cannot be an accurate appraisal approach alone to determine whether or not the project should be accepted for the approval in the environment that is not without of uncertainties. In order to reflect the period or the project’s useful life that is exposed to risks due to changes in political, operational, and financial factors, the second capital budgeting criterion – discounted payback period is profoundly important, particularly for the Russian environment. Those statements represent contradictions that exist in the theory and practice of the applied science. Therefore, it would be desirable to relax the assumptions of portfolio theory and regard DPP as not fewer relevant appraisal approach for the assessment of the investment and risk measure. At the same time, the rationality of the use of both project performance criteria depends on the methods and models, with the help of which these appraisal approaches are calculated in feasibility studies. The deterministic methods cannot ensure the required precision of the results, while the stochastic models guarantee the sufficient level of the accuracy and reliability of the obtained results, providing that the risks are properly identified, evaluated, and mitigated. Otherwise, the project performance indicators may not be confirmed during the phase of project realization. For instance, the economic and political instability can result in the undoing of hard-earned gains, leading to the need for the attraction of the additional finances for the project. The sources of the alternative investments, as well as supportive mitigation strategies, can be studied during the initial phases of project development. During this period, the effectiveness of the investments undertakings can also be improved by the inclusion of the various investors, e.g. Russian Railways’ enterprises and other private companies in the dry port projects. However, the evaluation of the effectiveness of the participation of different investors in the project lack the methods and models that would permit doing the particular feasibility study, foreseeing the quantitative characteristics of risks and their mitigation strategies, which can meet the tolerance of the investors to the risks. For this reason, the research proposes a combination of Monte Carlo method, discounted cash flow technique, the theory of real options, and portfolio theory via a system dynamics simulation approach. The use of this methodology allows for comprehensive risk management process of dry port development to cover all aspects of risk identification, risk evaluation, risk mitigation, risk monitoring, and control phases. A designed system dynamics model can be recommended for the decision-makers on the dry port projects that are financed via a public-private partnership. It permits investors to make a decision appraisal based on random variables of net present value and discounted payback period, depending on different risks factors, e.g. revenue risks, land acquisition risks, traffic volume risks, construction hazards, and political risks. In this case, the statistical mean is used for the explication of the expected value of the DPP and NPV; the standard deviation is proposed as a characteristic of risks, while the elasticity coefficient is applied for rating of risks. Additionally, the risk of failure of project investments and guaranteed recoupment of capital investment can be considered with the help of the model. On the whole, the application of these modern methods of simulation creates preconditions for the controlling of the process of dry port development, i.e. making managerial changes and identifying the most stable parameters that contribute to the optimal alternative scenarios of the project realization in the uncertain environment. System dynamics model allows analyzing the interactions in the most complex mechanism of risk management process of the dry ports development and making proposals for the improvement of the effectiveness of the investments via an estimation of different risk management strategies. For the comparison and ranking of these alternatives in their order of preference to the investor, the proposed indicators of the efficiency of the investments, concerning the NPV, DPP, and coefficient of variation, can be used. Thus, rational investors, who averse to taking increased risks unless they are compensated by the commensurate increase in the expected utility of a risky prospect of dry port development, can be guided by the deduced marginal utility of investments. It is computed on the ground of the results from the system dynamics model. In conclusion, the outlined theoretical and practical implications for the management of risks, which are the key characteristics of public-private partnerships, can help analysts and planning managers in budget decision-making, substantially alleviating the effect from various risks and avoiding unnecessary cost overruns in dry port projects.

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Today, companies need to mind the environment in all their actions. Policies, regulations and growing pressure from environmentally conscious public are driving corporations to invest increasingly in their green images. Communication plays a key role in forming and maintaining that image. This thesis explores how six selected companies communicate about their environmental efforts and activities, and its linkage to their green images, in annual and sustainability reports and in Facebook. The companies come from the U.S. and Europe and operate in three different industries: ICT, oil and gas, and aerospace & defense. Qualitative and quantitative content analyses are conducted to examine 36 reports and 121 Facebook messages, collected from the period of 2010-2014, and from 2005 for comparison. The results show that although the quality and quantity of environmental disclosure is increasing, there is still room for improvement. Overall, disclosure in the ICT sector is on the highest level. The European companies disclose more and on average have stronger green images than the American ones. Emissions and ways to reduce them is by far the most covered topic in both continents and in all three industry sectors. The messages in Facebook are closer to advertising, and overall the platform is utilized surprisingly little.

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Russian e-commerce has drawn a lot of attention in academic publications as well as in public media lately. The market is growing with a speed of rocket offering companies enormous business opportunities. However, combination of Russian culture, consumer online purchasing and decision-making process forms a subject yet completely unknown. From international online business perspective it is vital for companies to know how a culture affects consumer’s purchase decision and what are the key elements that need to be modified in order to successfully expand online operations to Russian market. Here, the main purpose is to define the key factors affecting Russian consumer’s online purchase intention. In order to answer the main research question, firstly the role of culture in purchase intention context is researched. Secondly, focus is drawn to the factors that affect online purchase intention. Lastly, it is researched how Russian culture is affecting e-commerce attributes modification. The objective is not only to expand the theoretical understanding of the subject but also to provide companies with a clear vision on how the online operations should be conducted in Russian online market. Ranganathan’s and Jha’s conceptual framework was chosen as a ground theory in this study. Here, three main categories Computer Self-Efficacy and Past Online Experience, Website Quality and Costumer Concerns form basis for the study. Various articles and academic literature supplemented this theoretical approach. Qualitative research method was adapted and the study was conducted through five expert interviews. As a conclusion it can be stated that culture forms a ground for entire purchase decision-making process in online context. Results from the interviews were grouped according to main three theoretic categories and placed with Ranganathan’s and Jha’s original framework. This formed a new theoretical framework that defines diverse factors affecting specifically Russian consumer’s online purchase intention. This study suggests that following factors need to be taking into serious consideration in Russian online context: photography style, detailed product and company information, colors, language, product variety, reviews, recommendations, strong social media presence, fast check out and minimalistic order information, counterfeit fear, cash on delivery payment, training and guidance, extensive customer service, consumers’ insecurity, inexperience, high interest for technology and their individualistic personality.