Measures on probabilistic automata

In questa tesi consideriamo i processi probabilistici non-deterministici modellati attraverso automi. Il nostro obiettivo \`e l'analisi dei problemi di bisimulazioni approssimate. Queste relazioni sono usate, generalmente, per semplificare i modelli di alcuni sistemi e per modellare agenti e attaccanti nei protocolli di sicurezza. In questo ultimo campo ci sono diversi proposte di utilizzo di metriche, le quali sono l'analogo quantitativo della bisimulazione probabilistica e permettono una miglior precisione. Una metrica \`e grossomodo un grado di similarit\`a tra stati. Iniziando dalla formalizzazione di (bi)simulazione approssimata data nel lavoro di Turrini, definiamo due metriche su stati e su distribuzioni. Queste metriche sono basate sul concetto di errore ammesso durante la simulazione di uno stato rispetto un altro stato. Investigheremo la relazione tra queste metriche con una metrica largamente utilizzata, la metrica di Kantorovich, e scopriremo che esse sono equivalenti. Poi riadatteremo per gli automi probabilistici il trasformatore di misure proposto da De Alfaro e al., ottenendo un nuovo funzionale F che \`e una estensione conservativa dei trasformatori proposti in letteratura. Mostreremo che il minimo punto fisso di F coincide con la sua sovra-approssimazione dalle misure derivate dal lavoro di Turrini, attraverso la dimostrazione dell'esistenza di una stretta relazione tra le bisimulazioni approssimate di Turrini con le metriche in letteratura.In this thesis we consider nondeterministic probabilistic processes modeled by automata. Our purpose is the analysis of the problem of approximated bisimulations. These relations are used, generally, to simplify the models of some systems and to model agents and attackers in security protocols. For the latter field there are several proposals to use metrics, which are the quantitative analogue of probabilistic bisimilarity and allow a greater precision. A metric is about a degree of similarity between states. Starting from the formalisation of approximate (bi)simulation given in Turrini's work, we define two metrics on states and on distributions. These metrics are based on the concept of error allowed during the simulation of a state with respect to another one. We investigate the relation between these metrics with a largely used one, the Kantorovich metric, and discover that they are equivalent. Then we recast for probabilistic automata the transformer of measures proposed by De Alfaro et al., obtaining a new functional F that is a conservative extension of the transformers proposed in the literature. We show that the minimum fix point of F coincides with its over-aproximated by the measures derived from Turrini's work thus showing the existence of a strict relation between the Turrini\u2019s approximate bisimulations with the literature on metrics

Static analysis of android apps interaction with automotive CAN

Modern car infotainment systems allow users to connect an Android device to the vehicle. The device then interacts with the hardware of the car, hence providing new interaction mechanisms to the driver. However, this can be misused and become a major security breach into the car, with subsequent security concerns: the Android device can both read sensitive data (speed, model, airbag status) and send dangerous commands (brake, lock, airbag explosion). Moreover, this scenario is unsettling since Android devices connect to the cloud, opening the door to remote attacks by malicious users or the cyberspace. The OpenXC platform is an open-source API that allows Android apps to interact with the car’s hardware. This article studies this library and shows how it can be used to create injection attacks. Moreover, it introduces a novel static analysis that identifies such attacks before they actually occur. It has been implemented in the Julia static analyzer and finds injection vulnerabilities in actual apps from the Google Play marketplace

Incidental Findings Suggestive of COVID-19 in Asymptomatic Patients Undergoing Nuclear Medicine Procedures in a High-Prevalence Region

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A Calculus of Anyons

Recent developments in theoretical physics have highlighted interestingtopological features of some two-dimensional particles, so-called anyons, thatcan be used to realise robust quantum computation. In this paper we show howan anyon system can be defined as a calculus of quantum functions, i.e. lineartransformations on the space of all possible physical configurations of a set ofanyons. A computation in this calculus represents the braiding of anyons and thefinal term of a computation corresponds to the outcome of a measurement of theanyons final fusion state, i.e. in general a probability distribution on the set ofall possible outcomes. We show that this calculus describes a universal anyonicquantum computer provided that the space of terms satisfies some topologicalproperties