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Chapter and Conference Paper
Synchronous Universally Composable Computer Networks
Designers of modern IT networks face tremendous security challenges. As systems grow ever more complex and connected it is essential that they resist even previously-unknown attacks. Using formal models to analys...
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Chapter and Conference Paper
Closing the Gap: A Universal Privacy Framework for Outsourced Data
We study formal privacy notions for data outsourcing schemes. The aim of our efforts is to define a security framework that is applicable to highly elaborate as well as practical constructions. First, we defin...
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Chapter and Conference Paper
A Formal Treatment of Privacy in Video Data
Video surveillance has become prevalent both in public spaces, e.g. to prevent crimes, and in private areas, e.g. in order to assist the staff in assisted living communities. This leads to privacy concerns reg...
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Article
Daten verschlüsselt speichern und verarbeiten in der Cloud
Neue Anwendungsformen kryptografi scher Verfahren erlauben es, personenbezogene Daten über unterschiedliche Vertrauenszonen hinweg verschlüsselt zu verarbeiten und speichern. Die oft als heiliger Gral der Kryp...
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Article
Information-theoretically secure oblivious polynomial evaluation in the commodity-based model
Oblivious polynomial evaluation (OPE) consists of a two-party protocol where a sender inputs a polynomial \(p(x)\) ...
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Chapter and Conference Paper
Wireless Key Exchange Using Frequency Impairments
Security methods have traditionally been deployed in the upper layers of the protocol stack. Therefore, the properties of the physical layer, like the wireless channel, have remained unexplored for authenticat...
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Chapter and Conference Paper
General Statistically Secure Computation with Bounded-Resettable Hardware Tokens
Universally composable secure computation was assumed to require trusted setups, until it was realized that parties exchanging (untrusted) tamper-proof hardware tokens allow an alternative approach (Katz; EURO...
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Chapter and Conference Paper
From Stateful Hardware to Resettable Hardware Using Symmetric Assumptions
Universally composable multi-party computation is impossible without setup assumptions. Motivated by the ubiquitous use of secure hardware in many real world security applications, Katz (EUROCRYPT 2007) propos...
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Chapter and Conference Paper
Universally Composable Firewall Architectures Using Trusted Hardware
Network firewalls are a standard security measure in computer networks that connect to the Internet. Often, ready-to-use firewall appliances are trusted to protect the network from malicious Internet traffic. ...
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Article
Das Kryptologikum
Die Kryptographie war über Jahrhunderte eine Geheimwissenschaft. Das hat sich erst mit der Entwicklung des Internet und des daraus resultierenden Bedarfs an allgemeiner Verfügbarkeit kryptographischer Mechanis...
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Article
Polynomial Runtime and Composability
We devise a notion of polynomial runtime suitable for the simulation-based security analysis of multi-party cryptographic protocols. Somewhat surprisingly, straightforward notions of polynomial runtime lack ex...
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Chapter and Conference Paper
Implementing Resettable UC-Functionalities with Untrusted Tamper-Proof Hardware-Tokens
Resettable hardware tokens, usually in the form of smart cards, are used for a variety of security-critical tasks in open environments. Many of these tasks require trusted hardware tokens. With the complexity ...
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Chapter and Conference Paper
Lossy Codes and a New Variant of the Learning-With-Errors Problem
The hardness of the Learning-With-Errors (LWE) Problem has become one of the most useful assumptions in cryptography. It exhibits a worst-to-average-case reduction making the LWE assumption very plausible. Thi...
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Chapter
Defining Privacy Based on Distributions of Privacy Breaches
In contrast to classical cryptography, the challenge of privacy in the context of databases is to find a trade-off between a security guarantee and utility. Individuals in a database have to be protected while...
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Chapter and Conference Paper
IND-CCA Secure Cryptography Based on a Variant of the LPN Problem
In 2003 Michael Alekhnovich (FOCS 2003) introduced a novel variant of the learning parity with noise problem and showed that it implies IND-CPA secure public-key cryptography. In this paper we introduce the fi...
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Chapter and Conference Paper
Universally Composable Oblivious Transfer from Lossy Encryption and the McEliece Assumptions
Oblivious transfer (OT) is a primitive of great importance in two-party and multi-party computation. We introduce a general construction of universally composable (UC) oblivious transfer protocols based on los...
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Chapter and Conference Paper
Statistically Secure Linear-Rate Dimension Extension for Oblivious Affine Function Evaluation
Consider the following natural generalization of the well-known Oblivious Transfer (OT) primitive, which we call Oblivious Affine Function Evaluation (OAFE): Given some finite vector space
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Chapter and Conference Paper
Completeness Theorems with Constructive Proofs for Finite Deterministic 2-Party Functions
In this paper we present simple but comprehensive combinatorial criteria for completeness of finite deterministic 2-party functions with respect to information-theoretic security. We give a general protocol co...
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Chapter and Conference Paper
Vulnerabilities of Wireless Key Exchange Based on Channel Reciprocity
Wireless key exchange on the physical layer is a key exchange protocol independent of computational assumptions. It relies only on the physical properties of the wireless channels to generate a common secret k...
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Chapter and Conference Paper
Efficient Reductions for Non-signaling Cryptographic Primitives
Tamper-proof devices, especially one-time memories (OTMs), are very powerful primitives. They can, e.g., implement one-time programs, i.e. circuits that can be evaluated only once. Furthermore they exhibit a non-...
