Too Close for Comfort? Measuring Success of Sampled-Data Leakage Attacks Against Encrypted Search

The well-defined information leakage of Encrypted Search Algorithms (ESAs) is predominantly analyzed by crafting so-called leakage attacks. These attacks utilize adversarially known auxiliary data and the observed leakage to attack an ESA instance built on a user\u27s data. Known-data attacks require the auxiliary data to be a subset of the user\u27s data. In contrast, sampled-data attacks merely rely on auxiliary data that is, in some sense, statistically close to the user\u27s data and hence reflect a much more realistic attack scenario where the auxiliary data stems from a publicly available data source instead of the private user\u27s data. Unfortunately, it is unclear what statistically close means in the context of sampled-data attacks. This leaves open how to measure whether data is close enough for attacks to become a considerable threat. Furthermore, sampled-data attacks have so far not been evaluated in the more realistic attack scenario where the auxiliary data stems from a source different to the one emulating the user\u27s data. Instead, auxiliary and user data have been emulated with data from one source being split into distinct training and testing sets. This leaves open whether and how well attacks work in the mentioned attack scenario with data from different sources. In this work, we address these open questions by providing a measurable metric for statistical closeness in encrypted keyword search. Using real-world data, we show a clear exponential relation between our metric and attack performance. We uncover new data that are intuitively similar yet stem from different sources. We discover that said data are not close enough for sampled-data attacks to perform well. Furthermore, we provide a re-evaluation of sampled-data keyword attacks with varying evaluation parameters and uncover that some evaluation choices can significantly affect evaluation results

Exploring time like tranistions in pp, πp and AA reactions with HADES

Radiative transition of an excited baryon to a nucleon with emission of a virtual massive photon converting to dielectron pair (Dalitz decays) provides important information about baryon-photon coupling at low q2 in timelike region. A prominent enhancement in the respective electromagnetic transition Form Factors (etFF) at q2 near vector mesons ρ/ω poles has been predicted by various calculations reflecting strong baryon-vector meson couplings. The understanding of these couplings is also of primary importance for the interpretation of the emissivity of QCD matter studied in heavy ion collisions via dilepton emission. Dedicated measurements of baryon Dalitz decays in proton-proton and pion-proton scattering with HADES detector at GSI/FAIR are presented and discussed. The relevance of these studies for the interpretation of results obtained from heavy ion reactions is elucidated on the example of the HADES results