341 research outputs found
Verification in Privacy Preserving Data Publishing
Privacy preserving data publication is a major concern for both the owners of data and the data publishers. Principles like k-anonymity, l-diversity were proposed to reduce privacy violations. On the other side, no studies were found on verification on the anonymized data in terms of adversarial breach and anonymity levels. However, the anonymized data is still prone to attacks due to the presence of dependencies among quasi-identifiers and sensitive attributes. This paper presents a novel framework to detect the existence of those dependencies and a solution to reduce them. The advantages of our approach are i) privacy violations can be detected, ii) the extent of privacy risk can be measured and iii) re-anonymization can be done on vulnerable blocks of data. The work is further extended to show how the adversarial breach knowledge eventually increased when new tuples are added and an on the fly solution to reduce it is discussed. Experimental results are reported and analyzed
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Decentralised computer systems
The architecture of the Web was designed to enable decentralised exchange of information. Early architects envisioned an egalitarian yet organic society thriving in cyberspace. The reality of the Web today, unfortunately, does not bear out these visions: information networks have repeatedly shown a tendency towards consolidation and centralisation with the current Web split between a handful of large corporations.
The advent of Bitcoin and successor blockchain networks re-ignited interest in developing alternatives to the centralised Web and paving a way back to the earlier architectural visions for the Web. This has led to immense hype around these technologies with the cryptocurrency market valued at several hundred billions of dollars at the time of writing. With great hype, apparently, come great scams. I start off by analysing the use of Bitcoin as an enabler for crime and then present both technical solutions as well as policy recommendations to mitigate the harm these crimes cause.
These policy recommendations then lead us on to look more closely at cryptocurrency's tamer cousin: permissioned blockchains. These systems, while less revolutionary in their premise, nevertheless aim to provide sweeping improvements in the efficiency and transparency of existing enterprise systems. To see whether they work in practice, I present the results of my work in delivering a production permissioned blockchain system to real users. This involves comparing several permissioned blockchain systems, exploring their deficiencies and developing solutions for the most egregious of those.
Lastly, I do a deep dive into one of the most persistent technical issues with permissioned blockchains, and decentralised networks in general: the lack of scalability in their consensus mechanisms. I present two novel consensus algorithms that aim to improve upon the state of the art in several ways. The first is designed to enable existing permissioned blockchain networks to scale to thousands of nodes. The second presents an entirely new way of building decentralised consensus systems utilising a trie-based data structure at its core as opposed to the usual linear ledgers used in current systems
Hairwork in Victorian Literature and Culture: Matter, Form, Craft
This thesis is a study of hairwork—the crafting of decorative objects from human hair—in Victorian literature and culture. Hairwork constitutes not only the hair of an individual, but is hair worked into a suggestive form for a particular purpose, whether commemorative, mournful, romantic, reconciliatory or aesthetic and which may be exchanged to reify a relationship. I argue that, in this way, hairwork is a means and process of representation in which hair at once figures its donor while its working signifies a more complex set of associations that are frequently in tension with one another. Hairwork expresses seemingly conflicting or incompatible ideas but holds them in equipoise: body and object; present and past; life and death; presence and absence; nature and craft; sentiment and fashion; authenticity and artifice. This set of antithetical qualities are specific to hairwork, emphasised in forms of hairwork that became popular in the mid-nineteenth century, and represent its unique place in Victorian material culture. As hair was physically worked and worn, it imaginatively shaped and framed the tensions between the affects, relationships, and identities of its donor, maker, and wearer, which rendered it a compelling subject of representation in Victorian fiction. The thesis begins with a chapter addressing the history of hairwork in Britain which is followed by studies of the writings of Charlotte and Emily Brontë, Robert and Elizabeth Barrett Browning, Wilkie Collins, and Margaret Oliphant. Through analysis of how hairwork was represented in the fiction of these authors, I demonstrate that hairwork was not just a relatively frequently represented object in Victorian literature but a rich subject of representation in its matter, form, and craft. Considerations of hairwork artefacts are positioned throughout this thesis at points at which they aid and develop my reading of literary texts: they prompt or emphasise ideas latent in textual representations or illuminate something of hairwork’s significations. Thus, as I analyse representations of hairwork in literature, I trace the tensions underlying hairwork, whether real or represented
Advances in knowledge discovery and data mining Part II
19th Pacific-Asia Conference, PAKDD 2015, Ho Chi Minh City, Vietnam, May 19-22, 2015, Proceedings, Part II</p
Distributed Cryptographic Protocols
[ES] La confianza es la base de las sociedades modernas. Sin embargo, las relaciones basadas en confianza son difÃciles de establecer y pueden ser explotadas
fácilmente con resultados devastadores. En esta tesis exploramos el uso
de protocolos criptográficos distribuidos para construir sistemas confiables
donde la confianza se vea reemplazada por garantÃas matemáticas y criptográficas. En estos nuevos sistemas dinámicos, incluso si una de las partes
se comporta de manera deshonesta, la integridad y resiliencia del sistema
están garantizadas, ya que existen mecanismos para superar este tipo de
situaciones. Por lo tanto, hay una transición de sistemas basados en la confianza, a esquemas donde esta misma confianza es descentralizada entre un
conjunto de individuos o entidades. Cada miembro de este conjunto puede ser
auditado, y la verificación universal asegura que todos los usuarios puedan
calcular el estado final en cada uno de estos métodos, sin comprometer la
privacidad individual de los usuarios.
La mayorÃa de los problemas de colaboración a los que nos enfrentamos
como sociedad, pueden reducirse a dos grandes dilemas: el votar una propuesta, o un representante polÃtico, ó identificarnos a nosotros mismos como
miembros de un colectivo con derecho de acceso a un recurso o servicio. Por
ello, esta tesis doctoral se centra en los protocolos criptográficos distribuidos
aplicados al voto electrónico y la identificación anónima.
Hemos desarrollado tres protocolos para el voto electrónico que complementan y mejoran a los métodos más tradicionales, y además protegen la
privacidad de los votantes al mismo tiempo que aseguran la integridad del
proceso de voto. En estos sistemas, hemos empleado diferentes mecanismos
criptográficos que proveen, bajo diferentes asunciones, de las propiedades de
seguridad que todo sistema de voto debe tener. Algunos de estos sistemas son
seguros incluso en escenarios pos-cuánticos. También hemos calculado minuciosamente la complejidad temporal de los métodos para demostrar que son
eficientes y factibles de ser implementados. Además, hemos implementado
algunos de estos sistemas, o partes de ellos, y llevado a cabo una detallada
experimentación para demostrar el potencial de nuestras contribuciones.
Finalmente, estudiamos en detalle el problema de la identificación y proponemos tres métodos no interactivos y distribuidos que permiten el registro
y acceso anónimo. Estos protocolos son especialmente ligeros y agnósticos
en su implementación, lo que permite que puedan ser integrados con múltiples propósitos. Hemos formalizado y demostrado la seguridad de nuestros
protocolos de identificación, y hemos realizado una implementación completa
de ellos para, una vez más, demostrar la factibilidad y eficiencia de las soluciones propuestas. Bajo este marco teórico de identificación, somos capaces
de asegurar el recurso custodiado, sin que ello suponga una violación para el
anonimato de los usuarios.[CA] La confiança és la base de les societats modernes. No obstant això, les relacions basades en confiança són difÃcils d’establir i poden ser explotades fà cilment amb resultats devastadors. En aquesta tesi explorem l’ús de protocols
criptogrà fics distribuïts per a construir sistemes de confiança on la confiança es veja reemplaçada per garanties matemà tiques i criptogrà fiques. En
aquests nous sistemes dinà mics, fins i tot si una de les parts es comporta
de manera deshonesta, la integritat i resiliència del sistema estan garantides,
ja que existeixen mecanismes per a superar aquest tipus de situacions. Per
tant, hi ha una transició de sistemes basats en la confiança, a esquemes on
aquesta acarona confiança és descentralitzada entre un conjunt d’individus o
entitats. Cada membre d’aquest conjunt pot ser auditat, i la verificació universal assegura que tots els usuaris puguen calcular l’estat final en cadascun
d’aquests mètodes, sense comprometre la privacitat individual dels usuaris.
La majoria dels problemes de colůlaboració als quals ens enfrontem com
a societat, poden reduir-se a dos grans dilemes: el votar una proposta, o un
representant polÃtic, o identificar-nos a nosaltres mateixos com a membres
d’un colůlectiu amb dret d’accés a un recurs o servei. Per això, aquesta tesi
doctoral se centra en els protocols criptogrà fics distribuïts aplicats al vot
electrònic i la identificació anònima.
Hem desenvolupat tres protocols per al vot electrònic que complementen
i milloren als mètodes més tradicionals, i a més protegeixen la privacitat
dels votants al mateix temps que asseguren la integritat del procés de vot.
En aquests sistemes, hem emprat diferents mecanismes criptogrà fics que
proveeixen, baix diferents assumpcions, de les propietats de seguretat que
tot sistema de vot ha de tindre. Alguns d’aquests sistemes són segurs fins i tot en escenaris post-quà ntics. També hem calculat minuciosament la complexitat temporal dels mètodes per a demostrar que són eficients i factibles
de ser implementats. A més, hem implementats alguns d’aquests sistemes, o
parts d’ells, i dut a terme una detallada experimentació per a demostrar la
potencial de les nostres contribucions.
Finalment, estudiem detalladament el problema de la identificació i proposem tres mètodes no interactius i distribuïts que permeten el registre i
accés anònim. Aquests protocols són especialment lleugers i agnòstics en
la seua implementació, la qual cosa permet que puguen ser integrats amb
múltiples propòsits. Hem formalitzat i demostrat la seguretat dels nostres
protocols d’identificació, i hem realitzat una implementació completa d’ells
per a, una vegada més, demostrar la factibilitat i eficiència de les solucions
proposades. Sota aquest marc teòric d’identificació, som capaces d’assegurar
el recurs custodiat, sense que això supose una violació per a l’anonimat dels
usuaris.[EN] Trust is the base of modern societies. However, trust is difficult to achieve
and can be exploited easily with devastating results. In this thesis, we explore the use of distributed cryptographic protocols to build reliable systems
where trust can be replaced by cryptographic and mathematical guarantees.
In these adaptive systems, even if one involved party acts dishonestly, the
integrity and robustness of the system can be ensured as there exist mechanisms to overcome these scenarios. Therefore, there is a transition from
systems based in trust, to schemes where trust is distributed between decentralized parties. Individual parties can be audited, and universal verifiability
ensures that any user can compute the final state of these methods, without
compromising individual users’ privacy.
Most collaboration problems we face as societies can be reduced to two
main dilemmas: voting on a proposal or electing political representatives,
or identifying ourselves as valid members of a collective to access a service
or resource. Hence, this doctoral thesis focuses on distributed cryptographic
protocols for electronic voting and anonymous identification.
We have developed three electronic voting schemes that enhance traditional methods, and protect the privacy of electors while ensuring the integrity of the whole election. In these systems, we have employed different
cryptographic mechanisms, that fulfill all the desired security properties of
an electronic voting scheme, under different assumptions. Some of them are
secure even in post-quantum scenarios. We have provided a detailed time-complexity analysis to prove that our proposed methods are efficient and
feasible to implement. We also implemented some voting protocols, or parts
of them, and carried out meticulous experimentation to show the potential of our contributions.
Finally, we study in detail the identification problem and propose three
distributed and non-interactive methods for anonymous registration and access. These three protocols are especially lightweight and application agnostic, making them feasible to be integrated with many purposes. We formally
analyze and demonstrate the security of our identification protocols, and
provide a complete implementation of them to once again show the feasibility and effectiveness of the developed solutions. Using this identification
framework, we can ensure the security of the guarded resource, while also
preserving the anonymity of the users.Larriba Flor, AM. (2023). Distributed Cryptographic Protocols [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19810
LIPIcs, Volume 261, ICALP 2023, Complete Volume
LIPIcs, Volume 261, ICALP 2023, Complete Volum
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
A Knowledge Mining Approach for Effective Customer Relationship Management
The problem of existing customer relationship management (CRM) system is not lack of information but the ability to differentiate useful information from chatter or even disinformation and also maximize the richness of these heterogeneous information sources. This paper describes an improved text mining approach for automatically extracting association rules from collections of textual documents. It discovers association rules from keyword features extracted from the documents. The main contributions of the technique are that, in selecting the most discriminative keywords for use in association rules generation, the system combines syntactic and semantic relevance into its Information Retrieval Scheme which is integrated with XML technology. Experiments carried out revealed that the extracted association rules contain important features which form a worthy platform for making effective decisions as regards customer relationship management. The performance of the improved text mining approach is compared with existing system that uses the GARW algorithm to reveal a significant reduction in the large itemsets, leading to reduction in rules generated to more interesting ones due to the semantic analysis component being introduced. Also, it has brought about reduction of the execution time, compared to the GARW algorithm.</p
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