In this paper, we study the opacity property of verifiably encrypted signatures (VES) of Boneh et al. (proposed in Eurocrypt 2003). Informally, opacity implies that although some given aggregate signatures can verified, no useful information about the individual signatures is leaked. However, the very fact that an aggregate signature can be verified leaks certain information- that the individual signature is indeed well-formed. Apart from this, is there any other information leaked? In this paper, we show that there is absolutely no other information leaked about the individual signatures when the aggregation contains only two signatures. In more formal terms, we show that VES are Zero-Knowledge (ZK). We then extend the ZK property of VES to propose efficient Additive Non-Interactive Witness-Indistinguishable (A-NIWI) proofs. Intuitively an A-NIWI proof can be considered as a Proof of Knowledge (PoK) of another A-NIWI proof. 1
Privacy is becoming an increasingly important issue in electronic commerce and other online activities that are growing in popularity. This work introduces a framework, called Peers for Privacy (P4P), for implementing many useful algorithms with provable privacy and adequate efficiency in a realistic adversary model at a reasonably large scale. The basic idea is to decompose an algorithm into a series of addition-only steps, which have very efficient private implementation using cryptographic tools. This simple model is surprisingly general and supports many algorithms prevalent in distributed data mining. Examples include linear algorithms like voting and summation, as well as nonlinear algorithms such as regression, classification, SVD, PCA, <i>k</i>-means, ID3, machine learning algorithms based on Expectation Maximization (EM), etc. In fact all algorithms in the statistical query model are supported. <p> The computation of the sums is based on a highly efficient verifiable secret sharing (VSS) scheme that allows secret-shared arithmetic operations to be done over small fields (e.g. 32 or 64 bits) where private arithmetic operations have the same cost as normal arithmetic. This thesis shows that this paradigm admits efficient zero-knowledge tools that can be used to verify the properties of user data such as equality and boundedness. These tools provide practical mechanisms to deal with cheating users. One such tool is an extremely efficient zero-knowledge proof that verifies the L2-norm of the user data is bounded by a constant. This is to prevent a malicious user from exerting too much influence on the computation. The verification uses a linear number of inexpensive small field operations, and only a logarithmic number of large-field (1024 bits or more) cryptographic operations, and can achieve orders of magnitude reduction in running time over standard techniques (from hours to seconds) for large-scale problems. Concrete examples are given to demonstrate how the framework supports private computation of popular algorithms such as SVD, link analysis and association rule mining. The thesis also includes schemes for scalable multicast encryption and bidirectional group communication. They provide secure data transmission support for the type of communication pattern required by the P4P framework and many other group-oriented applications
To support emerging online activities within the digital information infrastructure, such as commerce, healthcare, entertainment and scientific collaboration, it is increasingly important to verify and protect the digital identity of the individuals involved. Identity management systems manage the digital identity life cycle of individuals which includes issuance, usage and revocation of digital identifiers.
Identity management systems have improved the management of identity information and user convenience; however they do not provide specific solutions to address protection of identity from threats such as identity theft and privacy violation. One major shortcoming of current approaches is the lack of strong verification techniques for issuance and usage of digital identifiers. In the absence of verification mechanisms, digital identifiers can be misused to commit identity theft. Another shortcoming is the inability of individuals to disclose minimal data while satisfying strong identity verification requirements. The extraneous data collected can potentially be aggregated or used in a manner that would lead to violation of an individual's privacy. Finally, current identity management systems do not consider biometric and history-based identifiers. Such identifiers are increasingly becoming an integral part of an individual's identity. Such types of identity data also need to be used with other digital identifiers and protected against misuse.
In this thesis we introduce a number of techniques that address the above problems. Our approach is based on the concept of privacy preserving multi-factor identity verification. The technique consists of verifying multiple identifier claims of an individual, without revealing extraneous identity information. A distinguishing feature of our approach is that we employ identity protection and verification techniques in all stages of the identity life cycle. We also enhance our approach with the use of biometric and history-based identifiers. In particular we provide the following key contributions: (1)Â A new cryptographic primitive referred to as aggregate proof of knowledge to achieve privacy preserving multi-factor verification. This primitive uses aggregate signatures on commitments that are then used for aggregate zero-knowledge proof of knowledge (ZKPK) protocols. Our cryptographic scheme is better in terms of the performance, flexibility and storage requirements than existing efficient ZKPK techniques that may be used to prove, under zero-knowledge, the knowledge of multiple secrets. (2)Â Algorithms to generate biometric keys reliably from an individual's biometric images. These keys are used to create biometric commitments that are subsequently used to perform multi-factor identity verification using ZKPK. Several factors, including various traditional identity attributes, can thus be used in conjunction with one or more biometrics of the individual. We also ensure security and privacy of the biometric data and show how the biometric key is not revealed even if all the data, including cryptographic secrets, stored at the client machine are compromised. (3)Â A series of protocols for the establishment and management of an individual's transaction history-based identifiers encoded as receipts from e-commerce transactions. These receipt protocols satisfy the security and privacy requirements related to the management of the electronic receipts. We also demonstrate how the users receipt protocols can be employed in the context of mobile phones. In particular we provide techniques to manage the portable identity information on such devices, and use them at physical locations of the service providers.
Cryptography and Data Security
Advanced Authentication Protocols Security
Advanced Steganography and Watermarking Techniques
This paper is concerned with the integer quadratic multidimensional knapsack problem (QMKP) where the objective function is separable. Our objective is to determine which expansion technique of the integer variables is the most appropriate to solve (QMKP) to optimality using the upper bound method proposed by Quadri et al. (2007). To the best of our knowledge the upper bound method previously mentioned is the most effective method in the literature concerning (QMKP). This bound is computed by transforming the initial quadratic problem into a 0-1 equivalent piecewise linear formulation and then by establishing the surrogate problem associated. The linearization method consists in using a direct expansion initially suggested by Glover (1975) of the integer variables and in applying a piecewise interpolation to the separable objective function. As the direct expansion results in an increase of the size of the problem, other expansions techniques may be utilized to reduce the number of 0-1 variables so as to make easier the solution to the linearized problem. We will compare theoretically the use in the upper bound process of the direct expansion (I) employed in Quadri et al. (2007) with two other basic expansions, namely: (II) a direct expansion with additional constraints and (III) a binary expansion. We show that expansion (II) provides a bound which value is equal to the one computed by Quadri et al (2007). Conversely, we provide the proof of the non applicability of expansion (III) in the upper bound method. More specifically, we will show that if (III) is used to rewrite the integer variables into 0-1 variables then a linear interpolation can not be applied to transform (QMKP) into an equivalent 0-1 piecewise linear problem.
The secure delivery of data between a source node and a sink node is an open problem in wireless sensor networks. We review the security model used for The University of Kansasâs SensorNet project, and discuss how it might be improved by using a secure routing protocol. In this paper we extend work done in developing multipath extensions to AODV. Unlike previous proposals on multipath extensions to AODV, the scheme proposed in this paper allows each node to use multiple disjoint paths concurrently to reach another node. Each of the paths is validated by using zero-knowledge proofs. Under the new scheme data is protected by traditional cryptography as well as using separate paths for key and data delivery. This increases the resiliency of the network as well as the security of the data.
We propose a cryptographic protocol for biometrics authentication without revealing personal biometrical data against malicious verifier. Our protocol uses a neural network and zero-knowledge interactive proof. In this paper, we developed a sample implementation system of our proposed protocol and we evaluate the performance and the accuracy of the proposed protocol. Especially, we study several algorithms for feature extraction of minutiae of fingerprint which is appropriate to our protocol. We examine false acceptance rates and rejection rates
Biometric Identification and Security
User Authentication and Security Systems
Advanced Steganography and Watermarking Techniques
Secure Multiparty Computation technique plays an important role in the security research of distributed systems.This paper firstly summarizes the advances in theoretical and practical studies on SMC,and then analysis the basic protocols and its related cryptographic algorithms.Secondly,the key tools,secret share,homomorphic public key cryptography,mix network,zero knowledge proof,oblivious transfer and private comparison protocol in implementation SMC are studied deeply.Finally,some research directions in this area are also proposed.
This paper introduces a natural paradigm for fair exchange protocols, called ID-based partial proxy signature scheme. A security model with precise and formal definitions is presented, and an efficient and provably secure partial proxy signature scheme is proposed. This is a full ID-based optimistic fair exchange protocol. Unlike the vast majority of previously proposed protocols, this approach does not use any zero knowledge proofs, and thus avoids most of the costly computations.
The Health Surveillance (Visa) actions decentralization in Brazil was carried out in a slower pace than many other sectors of public health. We can even say that, in national scope, it is a recent event, particularly developed after the National Health Surveillance Agency (Anvisa) creation and the institution of the Settlement and Goals Term (TAM), in 2000, as instrument of agreement of the actions of average and high complexity initially only with the states, and, only in 2003, also agreeing that scope of actions with municipalities. In spite of the achieved advances, we must have a critical position and admit that the number of municipalities with TAM agreement is still low (791 currently), presenting, also, great regional inequity. Therefore, the development of Visa decentralization still lacks of a policy project better structured, that take in account the specificities of this sector, which involves complex questions, as the transcendence of the sanitary risk, the clear definition of actions financing and the establishment of abilities and responsibilities of each one of the system components. This study uses as research techniques bibliographical revision, documentary analysis and the application of half-structured interviews, in the perspective of the methodological triangulation, configuring itself in a qualitative, exploratory-descriptive research, of analytical character, with the objective to describe the current panorama in which is developed decentralization policy for Visa actions in Brazil. In order to do so, it is proceeded an analysis with four interrelated analytical categories, which comprehend all the policy: the context where the policy inserts itself; its process of formulation, implementation, monitoring and evaluation; the content of the policy; and the main subjects involved. What is clear in this debate is that the discussion of system financing is important, but is not depleted in itself. It is necessary, also, that Health Surveillance managers and professionals perceive the necessity to prioritize the Visa actions in Healthâs agenda. Soon, in the consolidation of the National Health Surveillance System (SNVS), the idea of the sanitary commitment must be bigger than the idea of the territorial authority, to let us go, in the scope of the discussion around the decentralization in Health Surveillance, from the debate on the distribution of resources to the commitment with sanitary responsibility.
This paper develops a twoâperiod overlapping generations model with heterogeneous agents aiming at analysing how decentralization in the provision of public education affects growth and personal inequality via human capital investment. Education is financed by a tax levied by either national or local authorities. The tax rate is chosen according to a median voter mechanism. During their working period of life, individuals look after their offspring by providing them with a high level of school education stemming from taxation. In addition parent's contributions to the social security system provide them with retirement income. Heterogeneity accounts for the differences in the optimal taxation mechanism, linking the income distribution to the tax rate, and hence to human capital accumulation, growth and income inequality. In this way we relate differences among agents to the tax rate. We show that decentralization induces growth rate disparities among local communities but it can be ruled out by a proper fiscal substitution between social security and locally provided education. Unlike in the literature, this type of fiscal design allows local economies to grow faster and more equally than the national design.
As Gandhi often pointed out, India lives in villages and unless village life can be revitalized the nation as a whole can hardly come alive. When India became independent in 1947, perhaps one-third of the villages of India had traditional Panchayats and many of them were far from flourishing conditions. The congress government has made a determined effort to promote the creation of Panchayats and to make them effective units of local self- government. Article 40 of the Constitution clearly declares âThe state shall take necessary actions to organize village Panchayats and to endow them with such powers and authority as may be necessary to enable them to function as units of self-governmentâ. The aim was to foster democratic participation, to involve villagers in the development of the community and to reduce the burden of higher level of administration. Though various steps were taken by successive governments to revitalize the system, Gramswaraj through village Panchayats remained as a distant dream till 1992. Bureaucratic apathy, indifference of the people, lack of political will, lack of uniformity etc were the main factors behind the failure of the system. Realizing the potential of the PR system, Rajeev Gandhi government initiated a process of Constitutional amendment to give sanctity and uniformity to Panchayati Raj system so that it can be immune from political interference and bureaucratic indifference. Rajeev Gandhi introduced 64th Constitutional amendment Bill in 1989. But the Bill did not materialize because of the fall of his Ministry. Finally the P.V.Narasimha Rao government introduced Panchayati Raj system in India through the 73rd Constitutional Amendment in 1992. \nThe article mainly focuses on the effectiveness of 73rd Constitutional amendment in securing empowerment of people. The article tries to capture the efforts of various states to implement panchayati Raj system and makes a comparative study of performance of states in terms of peopleâs participation, capacity building, de-bureaucratization and decentralization of powers. The salient features of 73rd Amendment Act including reservation of seats, provision for separate election commission and finance commission, gramsabha, taxes, periodic elections etc are discussed. More over it examines the initiatives of state governments towards democratic decentralization and highlights special programmes initiated by Kerala, Andhra Pradesh, Rajasthan, Karnataka, Madhya Pradesh etc to make the system effective. The article critically evaluates the effectiveness of PRIs as a system of governance for increased peopleâs participation empowerment and social change. Here attempt is made to incorporate the results of impact assessment studies conducted by World Bank. Concluding section highlights the need for revitalizing the system through integrating NREGP [National Rural Employment Guarantee Programme] and NRHM [National Rural Health Mission] etc
Tujuan dari penelitian ini adalah untuk mengidentifikasi tingkat pemberantasan praktik illegal logging yang terjadi setelah otonomi daerah baik sebelum dan sesudah regulasi Keputusan Gubernur Kalimantan Barat Nomor : 02 Tahun 2005, memetakan stakeholder dan konflik kepentingan stakeholder dalam kegiatan pemberantasan praktik illegal logging di Kalimantan Barat dan mengetahui konsistensi dan implementasi regulasi pemberantasan praktik illegal logging. Masalah dalam penelitian ini adalah : ââŹĹApakah regulasi melalui Keputusan Gubernur Kalimantan Barat Nomor : 02 Tahun 2005 sudah efektif dapat menurunkan praktik illegal logging?. ââŹĹBagaimana konflik kepentingan terjadi diantara stakeholder dalam pemberantasan praktik illegal logging?ââŹÂ. ââŹĹKenapa terjadi inkoordinasi dalam implementasi Keputusan Gubernur Kalimantan Barat Nomor : 02 Tahun 2005 tentang pemberantasan praktik illegal logging?ââŹÂ Landasan teori pada penelitian ini dibangun dari berbagai pendapat ahli, terutama dari Fisher, Nurrochmat, Colfer, Resosudarwo, Nurdjana dan Anderson tentang desentralisasi. Salim, Nurjana, Haba, Dudley, Colfer tentang illegal logging dan faktor-faktor yang mempengaruhinya. Sedangkan untuk konflik dibangun dari pendapat Robbins, Stoner dan Freeman, Winardi, Schermerhorn, Kreitner dan Kinicki. Jenis yang digunakan dalam penelitian ini adalah penelitian deskriptif. Ruang lingkup penelitian ini memfokuskan pada pemberantasan praktik illegal logging dan konflik kepentingan yang terjadi diantara stakeholder dalam memberantas praktik illegal logging dan koordinasi dalam tahap regulasi dan implementasi kebijakan pemberantasan praktik illegal logging (Keputusan Gubernur Kalimantan Barat Nomor : 02 Tahun 2005) di Kalimantan Barat. Hasil penelitian diperoleh terdapat peningkatan aktivitas pemberantasan praktik illegal logging yang terjadi sesudah diterbitkannya SK Gubernur Kalimantan Barat No.02 Tahun 2005 dapat dilihat dari adanya : (1) Peningkatan intensitas kegiatan represif razia praktik illegal logging dari kondisi sebelum terbitnya SK dan setelah terbitnya SK (2) Adanya peningkatan upayaââŹâpenanganan secara hukum /tindakan yustisi terhadap pelaku praktik illegal logging dari kondisi sebelum terbitnya SK dan setelah terbitnya SK sebesar 13,36%. Stakeholder yang terlibat konflik secara langsung dalam pemberantasan praktik illegal logging terjadi antara pemilik kayu (yang umumnya masyarakat setempat dan pengusaha kayu yang terlibat praktik illegal logging) dengan pemerintah dalam hal ini Pemerintah Provinsi Kalimantan Barat (Dinas Kehutanan, Polhut dan Aparat Kepolisian/Militer). Konflik tersebut kemudian berlanjut dalam bentuk gugatan yang mereka lakukan kepada pemerintah. Pihak Lembaga Swadaya Masyarakat (LSM), Institusi Perguruan Tinggi dan Lembaga Penelitian merupakan stakeholder yang tidak terlibat langsung dalam konflik pemberantasan praktik illegal logging. Tim Pemberantasan Praktik illegal logging yang dibentuk melalui SK Gubernur Kalimantan Barat No.2 Tahun 2005 telah berhasil menurunkan aktivitas praktik illegal logging sehingga dapat dikatakan telah efektif dalam memberantas praktik illegal logging yang terjadi di Provinsi Kalimantan Barat. Namun kenyataannya di lapangan masing-masing instansi yang merupakan bagian dari Tim Pemberantasan Praktik illegal logging cenderung bekerja secara sendirisendiri dan belum memiliki persepsi yang sama tentang praktik illegal logging. Ini menunjukkan tidak terdapat koordinasi yang baik dalam pelaksanaan pemberantasan praktik illegal logging di lapangan. Fenomena ini terjadi karena terdapatnya konflik kepentingan dari masing-masing instansi yang masuk dalam Tim Pemberantasan Praktik Illegal Logging seperti Dinas Kehutanan, Kepolisian, Bea Cukai dan Kejaksaan/ Kehakiman serta dinas-dinas lainnya yang turut dalam kegiatan pemberantasan. Untuk mengatasi permasalah-permasalahan yang berkaitan dengan pemberantasan praktik illegal logging dan konflik kepentingan di dalam pemberantasan praktik illegal logging dimulai dengan membangun persepsi yang sama dari seluruh pemangku kepentingan di seluruh tingkatan sehingga dapat dicapai visi, misi serta komitmen dalam pemberantasan praktik illegal logging, melibatkan masyarakat sipil termasuk LSM dan Perguruan Tinggi serta melakukan koordinasi antar instansi terkait yang terlibat dalam tim pemberantasan praktik illegal logging sehingga diharapkan akan diperoleh suatu kesepahaman tentang tugas dan fungsi dari masing-masing instansi.
This research was aimed to identify eradications over illegal logging practices before and after local autonomous regulation issuance of the Governor of West Kalimantan No: 02 in 2005, that maps the stakeholders and conflicts of interest among the stakeholders in eradicating illegal logging. The problems in this research were ââŹËHow effective this regulation reduced the illegal logging practices. How this conflict of interest took place among the stakeholders. Why did coordination of implementing this West Kalimantan GovernorââŹâ˘s regulation on eradicating the illegal logging missââŹâ˘. The base of theory was developed from the expertââŹâ˘s opinions, mainly came from Fisher, Nurrochmat, Colfer, Resosudarwo, Nurdjana and Anderson in terms of decentralization. Salim, Nurjana, Haba, Dudley, Colfer noted about meaning of illegal logging and factors that influence it. Whereas conflicts of interest was developed from opinions by Robbins, Stoner, and Freeman, Wanardi, Schermerthorn, Kreitner and Kinicki. The method we had used in this research was descriptive research. The research focused on eradications of illegal logging practices and conflicts of interest among the stakeholders in reducing the illegal logging and coordination of regulation steps and its implementation ( the West Kalimantan GovernorââŹâ˘s regulation No: 2 in 2005 ) in West Kalimantan Province. Results from this research were: (1) repressively trapping the illegal logging actors in fields in effort to eradicate illegal logging in West Kalimantan. (2) quantitatively low enforcement efforts reaching 13,36 % after the GovernorââŹâ˘s regulation issuance than before. Conflict of interest covers the owner ( both communities or forest companies ) against west Kalimantan Offices i.e. Dinas Kehutanan, Polhut, and Aparat Kepolisian/Militer. This conflict brought to suing for the local government. Non Government Organization ( NGO ), Academic Institution and Research Institution are indirectly covered in this conflicts. Illegal logging task force that has been formed by the governor through SK Gubernur Kalimantan Barat No. 2 Tahun 2005 was effective to overcome the illegal logging there. But each team member of illegal logging task force could not work solidly but they did as each wanted because of difference of their perception over it. This showed that the coordination did run well in field. To overcome this problem, illegal logging, conflicts of interest in eradicating the illegal logging activities, was to build an even perception first on pre-regulations and pre-eradications of illegal logging from all the stakeholders, improve political will of local officials to reach vision, mission, and commitment by the local government involving the communities, including non government organization and academics, coordinating the linked officials by establishing a task force to eradicate an illegal logging in order to understand tasks and functions of each institutions
Sucasas Iglesias, Tutor Enrique, Costa Montenegro, Superior Ingenieros ¡ 7 authors
The relevancy that the information security is obtaining in this age, due to the vast amount of services emerged from the demand of such a competitive digital world, have led to a situation where security and privacy are in discord. Nowadays, digital systems face a tradeoff between keeping the security of the system and the privacy rights of their customers. Furthermore, the tendency to store and manage big amounts of personal information, most of the times without the knowledge of the customers, can make users suspect about the misuse of their personal data, and remove their confidence in service providers. In this scenario, new technologies like anonymous credential systems are rising in demand. These technologies make use of zero-knowledge proofs and commitment schemes to allow the authentication of the usersâ attributes and privileges towards service providers, while preserving the userâs privacy and anonymity. At the same time such system provide features that prevent misuses by rogue users that try to take advantage of their anonymity. The goal of this project is the study and implementation of an anonymous credential system. Taking as starting point the existing previous work in this field, we make our own implementation and propose further improvements to build a complete credential system. We explain in detail the main issues that concerns such systems and possible solutions for their implementations.
An important element in considering school finance policies is that households are not passive. Instead they respond to policies with a combination of modified residential choice and political choice of tax levels. The highly stylized decision models of most existing analyses, however, lead to concerns about the policy evaluations. In our general equilibrium model of residential location and community choice, households base optimizing decisions on commuting costs, school quality, and land rents. With both centralized and decentralized employment, the resulting equilibrium has heterogeneous communities in terms of income and tastes for schools. This model is used to analyze a series of conventional policy experiments, including school district consolidation, district power utilization, and different equalization devices. The important conclusion is that welfare falls for all families with the restrictions in choice that are implied by these approaches.
Carlos M. S. Figueiredo, AndrĂŠ L. L. Aquino, AntĂ´nio A. F. Loureiro, Linnyer Beatrys Ruiz
Self-organization is an important concept being applied to modern computer networks to achieve robust autonomous operation. In particular, Wireless Sensor Networks (WSNs) were conceived under this paradigm. With this concept, the network elements interact only among themselves, in a completely decentralized way, to accomplish a function for the proper network operation. However, application and management goals can change along the time, and a scheme for controlling these element interactions to adjust or change the achieved global behavior to a new requirement has not been explicitly addressed yet. In this work, we present a general scheme for managing this kind of network. The proposed scheme is composed by a central idea, which consists of acting over local rules guiding the element interactions according to required goals and/or QoS metrics, and a methodology, which defines a generic procedure and relates important aspects for the design of the management solutions. We demonstrate the applicability of our scheme by presenting a case study. Resumo. Auto-organizacao e um importante conceito sendo aplicado em sistemas de rede modernos para obter funcionamento autonomo e robusto. Particularmente, as Redes de Sensores Sem Fio (RSSFs) foram concebidas sob esse paradigma. Basicamente, em uma rede auto-organizavel, os elementos interagem somente entre si, de forma completamente descentralizada, para executar uma funcao para o correto funcionamento da rede. No entanto, os objetivos determinados por uma entidade de gerencia ou aplicacao podem mudar ao longo do tempo, e um esquema para controlar as interacoes entre os elementos e ajustar ou mudar o comportamento global a ser obtido a um novo requisito nao foi explicitamente abordado na literatura. Neste trabalho, e apresentado um esquema geral para o gerenciamento de redes auto-organizaveis. Sua ideia geral consiste em atuar sobre as regras de interacao locais governando as interacoes entre os elementos e, consequentemente, adequando o comportamento da rede a diferentes objetivos e/ou metricas de QoS necessarias. Uma metodologia tambem e provida, e essa define um procedimento generico e relaciona importantes aspectos para o projeto de solucoes de gerenciamento. A aplicabilidade do esquema proposto e demonstrada atraves da apresentacao de um estudo de caso. SBRC 2007 Cooperacao e Auto-Organizacao. 221
As data generation becomes increasingly inherently distributed, either due to usergenerated (multimedia) content or because of application-specific needs (sensor networks, data streams, etc.), traditional centralized architectures fail to address the new challenges of contemporary data management.A promising solution for the design and deployment of global-scale applications is the exploitation of the peer-to-peer (P2P) paradigm.P2P has emerged as a powerful model for organizing and searching large data repositories distributed over autonomous independent sources.The main topic and contribution of this thesis is the unsupervised organization of content into Semantic Overlay Networks (SONs), in a decentralized and distributed manner, and subsequently a variety of techniques for efficient searching and query processing in unstructured P2P systems.SONs have been proposed in the relevant research literature, as a way to organize peers into thematic groups, thereby enabling query routing to specific peer groups in a deliberate way, instead of blind forwarding.In particular, this work focuses on unstructured P2P networks that preserve peer autonomy.A novel protocol for unsupervised, distributed and decentralized SON construction is proposed, named DESENT [35,38], which employs distributed clustering of peer contents, respecting the requirements imposed by the distributed nature of the environment [138].Exploiting the generated SONs, we propose efficient routing strategies for answering similarity search queries [37,39].The approach is applied and tested in a distributed IR setting, aiming to address some of the limitations of P2P IR/web search.Towards this goal, a distributed dimensionality reduction algorithm is proposed [96], in order to reduce the high-dimensional feature space and improve clustering quality.Assuming a super-peer architecture we propose an approach called SIMPEER [43] that efficiently supports similarity search over data distributed over a large set of peers.We show how range queries and nearest neighbor queries can be processed.We also explore how to support non-traditional queries (such as top-k [141] and skylines [139]) that involve ranking.Furthermore, by relaxing the restriction of completely unsupervised environment and assuming a semi-supervised context, a novel technique for P2P summary caching of hierarchical information is presented, exploiting either predefined taxonomies [104] or XML schema information [36,40], which is applied in mobile P2P context-aware environments to improve query routing [45,44].6.4 Measurements from using different number of querying peers, given as the fraction of peers in the network. . . . . . . . . . . . . . . . .6.5 Measurements from using different skew (represented by increasing values of a) in the query distributions. . . . . . . . . . . . . . . . . .6.6 Measurements for different network
Brent Hecht, Michael Rohs, J. Schoening, Antonio KrĂźger
Traditional paper-based maps are still superior in several ways to their digital counterparts used on mobile devices. Namely, paper-based maps provide high-resolution, largescale information with zero power consumption. Digital maps offer personalized and dynamic information, but suffer from small outer scales and low resolutions. In this paper, we present WikEye, an interdisciplinary project that demonstrates proof-of-concepts of three novel research ideas related to this topic: multi-dimensional interaction with a magic lens device, spatio-temporal Wikipedia data mining, and magic lens markerless tracking. Through its integration of the advantages of static and dynamic maps and its employment of Wikipedia as its primary knowledge repository, we envision WikEye being used to address mobile technology issues in the tourism and education fields. In particular, we focus on the need for effective tourism-related mobile technologies and the demand from educators for new methods that students can use to interact with information. 1.
The recent developments in the mobile technology (mobile phones, middleware) created a need for new methods of protecting the code transmitted through the network. The oldest and the simplest mechanisms concentrate more on integrity of the code itself and on the detection of unauthorized manipulation. The newer solutions not only secure the compiled program, but also the data, that can be gathered during its journey and even the execution state. Some other approaches base on prevention rather than detection. This paper describes a new idea of securing mobile agents. The presented method protects all: the code, the data and the execution state. The proposal is based on a zero-knowledge proof system and a secure secret sharing scheme, two powerful cryptographic primitives. The paper also includes security analysis of the new method and comparison to currently most widespread solutions.
In this paper the main determinants of health care expenditure per capita in Spanish autonomous communities are analyzed. The coexistence of several models concerning the degree of spending power decentralization and financing systems converts Spain in a singular case, allowing to extract interesting conclusions for other countries in ways of decentralizing their health care system. Besides, our results allow to evaluate the incidence of some factors of over-cost underlined by the autonomous communities with a view to future changes in the autonomous communities financing model.
P²D (Personal x Professional Development) is the United Nations Childrenâs Fundâs staff-created non-traditional career development program. It is delivered in the form of two and three-day workshops, with tools and support in place by the organization to support staffâs ongoing development. Its purpose is âto create a self-reliant UNICEF workforce by empowering staff members to realize their potential, and to manage their own careersâŚThis, in turn, provides a sustainable, competitive advantage in the delivery of results for the children of the worldâ (P²D). A P²D unit in New York Headquarters (NYHQ) coordinates the program, but it is actually delivered by volunteer âChampionâ facilitators. The system of delivery is decentralized and events are autonomous, therefore many events go unrecorded resulting in a loss of programmatic memory, as well as a lack of communication, system reporting and accountability. This inquiry asks the following question: What is the most effective way to communicate with Champions about UNICEFâs P²D? The research methods included are a survey and secondary source materials such as case studies, guides, and other scholarly research. Data findings will be applied by the P²D unit in NYHQ in facilitating the creation of a global communications strategy with P²D Champions. While a more in-depth analysis of the survey results in regards to cultural preferences proved to be challenging, the survey yielded useful and practical results and recommendations.
Corruption in higher education has long been neglected as an area of research in the US. The processes of decentralization, commoditization, and privatization in higher education rise questions of accountability, transparency, quality, and access. Every nation solves problems of access, quality, and equity differently. Thus, although prosecuting corruption in higher education is part of the legal process in every country, the ways in which legal actions are undertaken differ. This paper addresses the question: How is corruption in higher education understood and defined in legal cases, what particular cases receive more attention, and how these cases correlate with the major educational reforms, changes, and socio-economic context in the nation? Specifically, it analyses records of selected legal cases devoted to corruption in the US higher education. Decentralized financing of higher education anticipates cost sharing based in part on educational loans. The US higher education sector grows steadily, and so do opportunities for abuse, including in educational loans. The rapid expansion of education sector leaves some grey areas in legislation and raises issues of applicability of certain state and federal laws and provisions to different forms of misconduct, including consumer fraud, deception, bribery, embezzlement, etc. Higher Education Act, False Claims Act, and Consumer Protection Act cover corruption as related to the state and the public sector; corruption as related to client, business owner, and an agent; and corruption as related to consumer-business relations. However, the legal frame is simplistic, while the system of interrelations in the higher education industry is rather complex.
The importance of assessing the impact of microfinance schemes on poverty reduction cannot be overestimated. Poverty reduction is the raison-dâĂŞtre of microfinance. It is because other forms of finance are not usually accessible to the poor (due to high transaction costs, the poorâs lack of collateral, etc) that microfinance has been explored as a possible solution to poverty reduction. But it is more than that. The assumption underlying this argument is that poverty is partly explained by lack of economic opportunities and that microfinance can provide a sustainable path towards viable surviving economic strategies. Therefore, microfinance can be important not only because it can lead to poverty reduction but mainly because it promotes, in a non-patronizing and decentralized way, economic alternatives to the poor that are in principle more sustainable (permanent) in the long-run. Microfinance can be compared with other poverty reduction initiatives based on paternalistic concessions (e.g., basic income programmes) that are a priori unsustainable in the long-run because they are dependent on a continuous inflow of resources. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.