Ralf Küsters

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We provide a method for deciding the insecurity of cryptographic protocols in presence of the standard Dolev-Yao intruder (with a finite number of sessions) extended with so-called oracle rules, i.e., deduction rules that satisfy certain conditions. As an instance of this general framework, we obtain that protocol insecurity is in NP for an intruder that(More)
Computing the least common subsunier (les) is an inference task that can be used to support, the "bot tom-up" construction of knowledge bases for KR systems based on description logics. Previous work on how to compute the lcs has concentrated on description logics that allow for universal value restrictions, but not for existential restrictions. The main(More)
Verifiability is a central property of modern e-voting systems. Intuitively, verifiability means that voters can check that their votes were actually counted and that the published result of the election is correct, even if the voting machines/authorities are (partially) untrusted. In this paper, we raise awareness of a simple attack, which we call a clash(More)
We present an NP decision procedure for the formal analysis of protocols in presence of modular exponentiation with products allowed in exponents. The number of factors that may appear in products is unlimited. We illustrate that our model is powerful enough to uncover known attacks on the A-GDH.2 protocol suite.
Many cryptographic tasks and protocols, such as non-repudiation, contract-signing, voting, auction, identity-based encryption, and certain forms of secure multi-party computation, involve the use of (semi-)trusted parties, such as notaries and authorities. It is crucial that such parties can be held accountable in case they misbehave as this is a strong(More)
A newly developed technique based on image sequence analysis allows automatic and precise quantification of the dynamics of the growth velocity of the root tip, the distribution of expansion growth rates along the entire growth zone and the oscillation frequencies of the root tip during growth without the need of artificial landmarks. These three major(More)