69,406 research outputs found
Quantitative analysis of the leakage of confidential data
Basic information theory is used to analyse the amount of confidential information which may be leaked by programs written in a very simple imperative language. In particular, a detailed analysis is given of the possible leakage due to equality tests and if statements. The analysis is presented as a set of syntax-directed inference rules and can readily be automated
A static analysis for quantifying information flow in a simple imperative language
We propose an approach to quantify interference in a simple imperative language that includes a looping construct. In this paper we focus on a particular case of this definition of interference: leakage of information from private variables to public ones via a Trojan Horse attack. We quantify leakage in terms of Shannon's information theory and we motivate our definition by proving a result relating this definition of leakage and the classical notion of programming language interference. The major contribution of the paper is a quantitative static analysis based on this definition for such a language. The analysis uses some non-trivial information theory results like Fano's inequality and L1 inequalities to provide reasonable bounds for conditional statements. While-loops are handled by integrating a qualitative flow-sensitive dependency analysis into the quantitative analysis
The spatio-temporal spectrum of turbulent flows
Identification and extraction of vortical structures and of waves in a
disorganised flow is a mayor challenge in the study of turbulence. We present a
study of the spatio-temporal behavior of turbulent flows in the presence of
different restitutive forces. We show how to compute and analyse the
spatio-temporal spectrum from data stemming from numerical simulations and from
laboratory experiments. Four cases are considered: homogeneous and isotropic
turbulence, rotating turbulence, stratified turbulence, and water wave
turbulence. For homogeneous and isotropic turbulence, the spectrum allows
identification of sweeping by the large scale flow. For rotating and for
stratified turbulence, the spectrum allows identification of the waves, precise
quantification of the energy in the waves and in the turbulent eddies, and
identification of physical mechanisms such as Doppler shift and wave absorption
in critical layers. Finally, in water wave turbulence the spectrum shows a
transition from gravity-capillary waves to bound waves as the amplitude of the
forcing is increased.Comment: Added new references and analysi
On the influence of social bots in online protests. Preliminary findings of a Mexican case study
Social bots can affect online communication among humans. We study this
phenomenon by focusing on #YaMeCanse, the most active protest hashtag in the
history of Twitter in Mexico. Accounts using the hashtag are classified using
the BotOrNot bot detection tool. Our preliminary analysis suggests that bots
played a critical role in disrupting online communication about the protest
movement.Comment: 10 page
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