5 research outputs found
Secure fingerprinting on sound foundations
The rapid development and the advancement of digital technologies open a variety of opportunities to consumers and content providers for using and trading digital goods. In this context, particularly the Internet has gained a major ground as a worldwiede platform for exchanging and distributing digital goods. Beside all its possibilities and advantages digital technology can be misuesd to breach copyright regulations: unauthorized use and illegal distribution of intellectual property cause authors and content providers considerable loss. Protections of intellectual property has therefore become one of the major challenges of our information society. Fingerprinting is a key technology in copyright protection of intellectual property. Its goal is to deter people from copyright violation by allowing to provably identify the source of illegally copied and redistributed content. As one of its focuses, this thesis considers the design and construction of various fingerprinting schemes and presents the first explicit, secure and reasonably efficient construction for a fingerprinting scheme which fulfills advanced security requirements such as collusion-tolerance, asymmetry, anonymity and direct non-repudiation. Crucial for the security of such s is a careful study of the underlying cryptographic assumptions. In case of the fingerprinting scheme presented here, these are mainly assumptions related to discrete logarithms. The study and analysis of these assumptions is a further focus of this thesis. Based on the first thorough classification of assumptions related to discrete logarithms, this thesis gives novel insights into the relations between these assumptions. In particular, depending on the underlying probability space we present new reuslts on the reducibility between some of these assumptions as well as on their reduction efficency.Die Fortschritte im Bereich der Digitaltechnologien bieten Konsumenten,
Urhebern und Anbietern große Potentiale für innovative Geschäftsmodelle
zum Handel mit digitalen GĂĽtern und zu deren Nutzung. Das Internet stellt
hierbei eine interessante Möglichkeit zum Austausch und zur Verbreitung
digitaler GĂĽter dar. Neben vielen Vorteilen kann die Digitaltechnik jedoch
auch missbräuchlich eingesetzt werden, wie beispielsweise zur Verletzung
von Urheberrechten durch illegale Nutzung und Verbreitung von Inhalten,
wodurch involvierten Parteien erhebliche Schäden entstehen können. Der
Schutz des geistigen Eigentums hat sich deshalb zu einer der besonderen
Herausforderungen unseres Digitalzeitalters entwickelt.
Fingerprinting ist eine SchlĂĽsseltechnologie zum Urheberschutz. Sie hat
das Ziel, vor illegaler Vervielfältigung und Verteilung digitaler Werke abzuschrecken, indem sie die Identifikation eines Betrügers und das Nachweisen
seines Fehlverhaltens ermöglicht. Diese Dissertation liefert als eines ihrer Ergebnisse die erste explizite, sichere und effiziente Konstruktion, welche die
BerĂĽcksichtigung besonders fortgeschrittener Sicherheitseigenschaften wie
Kollusionstoleranz, Asymmetrie, Anonymität und direkte Unabstreitbarkeit
erlaubt.
Entscheidend für die Sicherheit kryptographischer Systeme ist die präzise
Analyse der ihnen zugrunde liegenden kryptographischen Annahmen. Den
im Rahmen dieser Dissertation konstruierten Fingerprintingsystemen liegen
hauptsächlich kryptographische Annahmen zugrunde, welche auf diskreten
Logarithmen basieren. Die Untersuchung dieser Annahmen stellt einen weiteren
Schwerpunkt dieser Dissertation dar. Basierend auf einer hier erstmals
in der Literatur vorgenommenen Klassifikation dieser Annahmen werden
neue und weitreichende Kenntnisse über deren Zusammenhänge gewonnen.
Insbesondere werden, in Abhängigkeit von dem zugrunde liegenden Wahrscheinlichkeitsraum, neue Resultate hinsichtlich der Reduzierbarkeit dieser
Annahmen und ihrer Reduktionseffizienz erzielt
Design and Analysis of Fair Content Tracing Protocols
The work in this thesis examines protocols designed to
address the issues of tracing illegal distribution of digital content in a fair manner.
In digital content distribution, a client requests
content from a distributor, and the distributor sends content to the client.
The main concern is misuse of content by the client,
such as illegal distribution.
As a result, digital watermarking schemes that enable the distributor
to trace copies of content and identify the perpetrator were proposed.
However, such schemes do not provide a mechanism for the distributor
to prove to a third party that a client illegally distributed copies of content.
Furthermore, it is possible that the distributor falsely
accuses a client as he has total control of the tracing mechanisms.
Fair content tracing (FaCT)
protocols were thus proposed to allow tracing of content that
does not discriminate either the distributor or the client.
Many FaCT protocols have been proposed, mostly without an appropriate
design framework, and so there is no obvious and systematic way to evaluate them.
Therefore, we propose a framework that provides a definition
of security and which enables classification of FaCT protocols so
that they can be analysed in a systematic manner.
We define, based on our framework, four main categories of FaCT
protocols and propose new approaches to designing them.
The first category is protocols without trusted third parties.
As the name suggests, these protocols do not rely on a
central trusted party for fair tracing of content.
It is difficult to design such a protocol without drawing on
extra measures that increase communication and computation costs.
We show this is the case by demonstrating flaws in two recent proposals.
We also illustrate a possible repair based on relaxing
the assumption of trust on the distributor.
The second category is protocols with online trusted third parties,
where a central online trusted party is deployed.
This means a trusted party must always be available during
content distribution between the distributor and the client.
While the availability of a trusted third party may simplify
the design of such protocols, efficiency may suffer due to the
need to communicate with this third party.
The third category is protocols with offline trusted third parties,
where a central offline trusted party is deployed.
The difference between the offline and the online trusted party is
that the offline trusted party need not be available during content distribution.
It only needs to be available during the initial setup and
when there is a dispute between the distributor and the client.
This reduces the communication requirements compared to using an online trusted party.
Using a symmetric-based cryptographic primitive known as
Chameleon encryption, we proposed a new approach to
designing such protocols.
The fourth category is protocols with trusted hardware.
Previous protocols proposed in this category have abstracted away from
a practical choice of the underlying trusted hardware.
We propose new protocols based on a Trusted Platform Module (TPM).
Finally, we examine the inclusion of payment in a FaCT protocol,
and how adding payment motivates the requirement for
fair exchange of buying and selling digital content
The Real Economy
This collection highlights a key metaphor in contemporary discourse about economy and society. The contributors explore how references to reality and the real economy are linked both to the utopias of collective well-being, supported by real monies and good economies, and the dystopias of financial bubbles and busts, in which people’s own lives “crash” along with the reality of their economies.
An ambitious anthropology of economy, this volume questions how assemblages of vernacular and scientific realizations and enactments of the economy are linked to ideas of truth and moral value; how these multiple and shifting realities become present and entangle with historically and socially situated lives; and how the formal realizations of the concept of the “real” in the governance of economies engage with the experiential lives of ordinary people
Soil Water Properties of Kerangas Forest Soil after Invasion by Acacia
Soil water is important for forest ecosystems as infiltration and percolation process use soil water for plant growth. The presence of invasive Acacia species may limit the availability of soil water because these species absorb more water than native species. Hence, the objective was to investigate the effect of Acacia invasion on the soil water properties of Kerangas forests. In each invaded and non-invaded Acacia plots, holes a lysimeter was installed into the holes and used to extract soil water by direct contact to the soil. The results shows the invasion of Acacia has affected the Kerangas forest by higher absorption of water and higher fixation of nitrate