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We present an approach where one can execute user defined SPARQL queries on encrypted graph data. The graph data is only partially revealed to those users authorized for executing a query. The approach is based on eight different types of queries, corresponding to the different binding possibilities in a single SPARQL triple pattern. The allowed queries can(More)
Die Arbeitsberichte aus dem Fachbereich Informatik dienen der Darstellung vorläufiger Ergebnisse, die in der Regel noch für spätere Veröffentlichungen überarbeitet werden. Die Autoren sind deshalb für kritische Hinweise dankbar. Alle Rechte vorbehalten, insbesondere die der Übersetzung, des Nachdruckes, des Vortrags, der Entnahme von Abbildungen und(More)
Es wird ein Referenzmodell ontologisch sinnvoll organisierter Begriffe der IT-Sicherheit vorgestellt und gezeigt, wie dieses eine Begründung zur systematischen Durchführung von IT-Sicherheitsanalysen liefert. Das Referenzmodell besteht aus vier Ebenen: erstens die vorhandene Welt aus Gütern und Interessenkonflikten mit den bestehenden Systemen und ihren(More)
Existing algorithms for signing graph data typically do not cover the whole signing process. In addition, they lack distinctive features such as signing graph data at different levels of granularity, iterative signing of graph data, and signing multiple graphs. In this paper, we introduce a novel framework for signing arbitrary graph data provided, e g., as(More)
When publishing graph data on the web such as vocabularies using RDF(S) or OWL, one has only limited means to verify its authenticity and integrity. Today's approaches require a high signature overhead and do not allow for an iterative signing of graph data. This paper presents a configurable framework for signing arbitrary graph data provided in RDF(S),(More)
Les Halles, Paris's historic marketplace, was once called " the belly of Paris " by Emile Zola. Les Halles was a Parisian institution. The destruction of the marketplace in 1971, especially the famed Baltard pavilions, set off a firestorm of debate and public dissent not seen on an urban issue in nearly a century. Within the debate over Les Halles existed a(More)
Internet filtering is the manipulation of Internet communication in order to prevent the access and exchange of unwanted data. According to the reports of the OpenNet Initiative, Internet filtering emerges all over the world. Although many filtering techniques are legitimated by a similar legal basis, most of them are implemented differently. This paper(More)