Benjamin Braatz

On an Automated Translation of Satellite Procedures Using Triple Graph Grammars

Model transformation based on triple graph grammars (TGGs) is a general, intuitive and formally well defined technique for the translation of models [5,6,2]. While previous concepts and case studies were focused mainly on visual models of software and systems, this article describes an industrial application of model transformations based on TGGs as a powerful technique for software translation using the tool Henshin [1]. The general problem in this scenario is to translate source code that is currently in use into corresponding source code that shall run on a new system. Up to now, this problem was addressed based on manually written converters, parser generators, compiler-compilers or meta-programming environments using term rewriting or similar techniques (see e. g. [4]).

Letting the puss in boots sweat: detecting fake access points using dependency of clock skews on temperature

The only available IEEE 802.11 network identifiers (i.e., the network name and the MAC address) can be easily spoofed. Consequently, an attacker is able to fake a real hotspot and attract its traffic. By this means, the attacker can intercept, collect, or change users traffic (often even if it is encrypted). In this paper, we describe an efficient method for detecting the replacement of access points (APs) by passive remote physical device fingerprinting. The main feature of our fingerprinting approach is the clock skew - an unavoidable phenomenon that causes clocks to run at minuscule yet remotely observable different speeds - which is extracted from information contained in beacon frames. We are the first to achieve a high discriminability of devices by completely eliminating the fingerprinters influence and considering the clock skews dependency on temperature. Finally, we develop a method for reliable detection of the presence of AP impostors that works without explicit temperature information. Compared to the best state-of-the-art approach, our method improves detection accuracy from about 30% to 90% without generating any traffic and requires less than one minute to collect a sufficient number of observations. Our approach yields a strong feature for passive remote physical device fingerprinting in wireless networks.

Clock skew based remote device fingerprinting demystified

Commonly used identifiers for IEEE 802.11 access points (APs), such as network name (SSID), MAC, or IP address can be easily spoofed. This allows an attacker to fake a real AP and intercept, collect, or alter (potentially even encrypted) data. In this paper, we address the aforementioned problem by studying limits of unique remote physical device identification based on their clock skew—an unavoidable phenomenon that causes clocks to run at marginal but measurably different speed. To this end, we propose an algorithm for passive fingerprinting using timestamps regularly sent by APs in beacon frames. The major advantages of our method are that it is online and that we are able to eliminate the influence of clock skew of the measurement device. Hence, fingerprints performed by different devices become comparable. We calculate the precision of our clock skew measurement algorithm and provide a termination criterion for estimation of the clock skew with arbitrary precision. Moreover, conducting a large scale evaluation, we study the stability and uniqueness of clock skew as a means for remote wireless device identification.

Triple Graph Grammars in the Large for Translating Satellite Procedures

Software translation is a challenging task. Several requirements are important – including automation of the execution, maintainability of the translation patterns, and, most importantly, reliability concerning the correctness of the translation. Triple graph grammars (TGGs) have shown to be an intuitive, welldefined technique for model translation. In this paper, we leverage TGGs for industry scale software translations. The approach is implemented using the Eclipse-based graph transformation tool Henshin and has been successfully applied in a large industrial project with the satellite operator SES on the translation of satellite control procedures. We evaluate the approach regarding requirements from the project and performance on a complete set of procedures of one satellite.

How to delete categorically - Two pushout complement constructions

In category theory, most set-theoretic constructions-union, intersection, etc.-have direct categorical counterparts. But up to now, there is no direct construction of a deletion operation like the set-theoretic complement. In rule-based transformation systems, deletion of parts of a given object is one of the main tasks. In the double pushout approach to algebraic graph transformation, the construction of pushout complements is used in order to locally delete structures from graphs. But in general categories, even if they have pushouts, pushout complements do not necessarily exist or are unique. In this paper, two different constructions for pushout complements are given and compared. Both constructions are based on certain universal constructions in the sense of category theory. More specifically, one uses initial pushouts while the other one uses quasi-coproduct complements. These constructions are applied to examples in the categories of graphs and simple graphs.

Finitary \(\mathcal{M}\)-Adhesive Categories

Finitary (mathcal{M})-adhesive categories are (mathcal{M})-adhesive categories with finite objects only, where the notion (mathcal{M})-adhesive category is short for weak adhesive high-level replacement (HLR) category. We call an object finite if it has a finite number of (mathcal{M})-subobjects. In this paper, we show that in finitary (mathcal{M})-adhesive categories we do not only have all the well-known properties of (mathcal{M})-adhesive categories, but also all the additional HLR-requirements which are needed to prove the classical results for (mathcal{M})-adhesive systems. These results are the Local Church-Rosser, Parallelism, Concurrency, Embedding, Extension, and Local Confluence Theorems, where the latter is based on critical pairs. More precisely, we are able to show that finitary (mathcal{M})-adhesive categories have a unique (mathcal{E})-(mathcal{M}) factorization and initial pushouts, and the existence of an (mathcal{M})-initial object implies in addition finite coproducts and a unique (mathcal{E})-(mathcal{M}) pair factorization. Moreover, we can show that the finitary restriction of each (mathcal{M})-adhesive category is a finitary (mathcal{M})-adhesive category and finitariness is preserved under functor and comma category constructions based on (mathcal{M})-adhesive categories. This means that all the classical results are also valid for corresponding finitary (mathcal{M})-adhesive systems like several kinds of finitary graph and Petri net transformation systems. Finally, we discuss how some of the results can be extended to non-(mathcal{M})-adhesive categories.

Priority Program SoftSpez and the International INT Workshops “Integration of Software Specification Techniques for Applications in Engineering” (DFG-Schwerpunktprogramm SoftSpez und die internationalen INT-Workshops „Integration von Techniken der Softwarespezifikation für ingenieurwissenschaftliche Anwendungen“)

Abstract The research area “Integration of Software Specification Techniques for Applications in Engineering” has been subject of the Priority Program SoftSpez of the German Research Foundation (DFG) in the years 1998–2004 and of the international INT workshops as satellite events of the ETAPS conferences in 2000, 2002, and 2004. In this paper, we present an overview of aims, organization, and results of these activities. Moreover, we present an example for the integration of specification techniques in software engineering and industrial control systems developed within the project IOSIP of SoftSpez.