Auflistung nach Autor:in "Wolf, Christopher"
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- KonferenzbeitragApplications of multivariate quadratic public key systems(Sicherheit 2005, Sicherheit – Schutz und Zuverlässigkeit, 2005) Wolf, Christopher; Preneel, BartIn this article, we investigate the class of multivariate quadratic (MQ) public key systems. These systems are becoming a serious alternative to RSA or ECC based systems. After introducing the main ideas and sketching some relevant systems, we deal with the advantages and disadvantages of these kinds of schemes. Based on our observations, we determine application domains in which MQ-schemes have advantages over RSA or ECC. We concentrate on product activation keys, electronic stamps and fast one-way functions.
- KonferenzbeitragThe belgian electronic identity card (overview)(Sicherheit 2006, Sicherheit – Schutz und Zuverlässigkeit, 2006) Cock, Danny de; Wolf, Christopher; Preneel, Bart
- KonferenzbeitragContinuous authentication on mobile devices by analysis of typing motion behavior(Sicherheit 2014 – Sicherheit, Schutz und Zuverlässigkeit, 2014) Gascon, Hugo; Uellenbeck, Sebastian; Wolf, Christopher; Rieck, KonradSmartphones have become the standard personal device to store private or sensitive information. Widely used as every day gadget, however, they are susceptible to get lost or stolen. To protect information on a smartphone from being physically accessed by attackers, a lot of authentication methods have been proposed in recent years. Each one of them suffers from certain drawbacks, either they are easy to circumvent, vulnerable against shoulder surfing attacks, or cumbersome to use. In this paper, we present an alternative approach for user authentication that is based on the smartphone's sensors. By making use of the user's biometrical behavior while entering text into the smartphone, we transparently authenticate the user in an ongoing-fashion. In a field study, we asked more than 300 participants to enter some short sentences into a smartphone while all available sensor events were recorded to determine a typing motion fingerprint of the user. After the proper feature extraction, a machine learning classifier based on Support Vector Machines (SVM) is used to identify the authorized user. The results of our study are twofold: While our approach is able to continuously authenticate some users with high precision, there also exist participants for which no accurate motion fingerprint can be learned. We analyze these difference in detail and provide guidelines for similar problems.
- KonferenzbeitragSchritt für Schritt zum Welt-weites Wählen – das Beispiel der IACR(INFORMATIK 2013 – Informatik angepasst an Mensch, Organisation und Umwelt, 2013) Wolf, ChristopherDer Welt-Kryptographenverband (IACR - International Association for Cryptologic Research) verwendet seit 2010 ein System für eine Online-Wahl. Die Erfahrungen sind durchweg positiv. Der Einführung ging eine intensive Diskussion innerhalb der Mitgliederschaft voran. Ziel war, möglichst alle Belange zu berücksichtigen und durch einen offenen Prozess von Anfang an Vertrauen in das neue System zu schaffen. Wichtiger Baustein hierzu war eine Demo-Wahl im Jahre 2009, in dem die Mitglieder das System ausprobieren konnten bevor es letztendlich Ende 2010 erstmalig eingesetzt wurde.
- KonferenzbeitragSicherheitsanalyse von Kreditkarten am Beispiel von EMV(Informatik 2009 – Im Focus das Leben, 2009) Wang, Zidu; Wolf, Christopher; Schwenk, Jörg