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<h3><img
src="cid:part1.06030205.02050701@ruhr-uni-bochum.de"
alt="HGI" height="106" align="right" width="116"><br>
</h3>
<big><big><big><small>Sehr geehrte Damen und Herren, <br>
<br>
<br>
im Rahmen des HGI-Kolloquiums, organisiert vom
Lehrstuhl Kryptologie und IT-Sicherheit
(CITS), werden<br>
<br>
<big><u> Javier Herranz</u></big></small></big></big></big><br>
<big><big><big><u> <br>
</u><small>von der <br>
<br>
Universitat Politècninca de Catalunya</small></big></big></big><br>
<big><big><big><small> <br>
am <br>
<br>
nächsten <u>Donnerstag, den 10. Mai
2012 um 11.00 Uhr s.t. in Raum ID 04/653<br>
<br>
</u>über folgende Themen referieren:</small><br>
</big></big></big> <br>
<br>
<hr size="2" width="100%">
<h1><small>Restricted Adaptive Oblivious Transfer</small></h1>
<big>In this talk we consider the following primitive,
that we call <i>restricted adaptive oblivious
transfer</i>. On the one hand, the owner of a
database wants to restrict the access of users to
this data according to some policy, in such a way
that a user can only obtain information satisfying
the restrictions imposed by the owner. On the other
hand, a legitimate user wants to privately retrieve
allowed parts of the data, in a sequential and
adaptive way, without letting the owner know which
part of the data is being obtained. </big>
<p><big> After having formally described the
components and required properties of a protocol
for restricted adaptive oblivious transfer, we
propose two generic ways to realize this
primitive. The first one uses a cryptographic tool
which has received a lot of attention from the
literature in the last years: cryptosystems which
are both multiplicatively and additively
homomorphic. Our second generic construction is
based on secret sharing schemes. </big><br>
</p>
<br>
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class="Apple-style-span" style="color: rgb(0, 53,
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class="Apple-style-span" style="color: rgb(0, 53,
96);"><big>Der Vortrag beginnt am Donnerstag um
11.00 Uhr s.t. im ID 04/653.<br>
</big></span></span><br>
<span class="Apple-style-span" style="border-collapse:
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class="Apple-style-span" style="color: rgb(0, 53,
96);"><big>Zu diesem und sämtlichen weiteren
Vorträgen im Rahmen des HGI-Kolloquiums sind
alle Studierenden und Interessierten herzlich
eingeladen! Eine Voranmeldung ist nicht
erforderlich!</big></span></span>
<p><span class="Apple-style-span"
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class="Apple-style-span" style="color: rgb(0, 53,
96);"><big>Weitere Informationen gibt es auf
folgender Webseite:<br>
<br>
<a moz-do-not-send="true"
href="http://hgi.rub.de/hgi/hgi-seminar/aktuelles/">http://hgi.rub.de/hgi/hgi-seminar/aktuelles/</a></big><br>
</span></span><span class="Apple-style-span"
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<big><big>Beste Grüße, <br>
Saqib A. Kakvi</big></big><br>
<br>
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