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【BAYES COFFEE HOUSE TECH TALK SERIES】The True Concurrency of ePassport Privacy

Ross Horne from the University of Strathclyde will give a talk, in person and online, for the Coffee House Tech Talk Series. Details of the talk are below.

Speaker: Ross Horne, University of Strathclyde

Title: The True Concurrency of ePassport Privacy

When: 11am Tue 27 Feb

Where: 4th floor Bayes Centre

External link:

Meeting ID: 97614068

Passcode: 825964


The problem of unlinkability of ePassports is whether an ePassport holder can avoid being tracked from one usage of their ePassport to the next. The debate surrounding this problem has led to several formulations due to Arapinis et al., Hirschi et al., Cheval et al., and Horne & Mauw. Each formulation is similar – unlinkability is formulated in each case as a process equivalence problem – yet each formulation can give different answers to whether or not unlinkability holds. We have known since 2019 that a key difference is whether trace equivalence or bisimilarity is used as the equivalence. This is already interesting since we have a real-world threat model where branching-time plays a role. It would be natural then to assume that, if all the above mentioned work had used bisimilarity then all models of unlinkability would agree. This, to our surprise, is not the case. We show that awareness of true concurrency – specifically the use of history-preserving bisimilarity due to Winskel, van Glabbeek, and others – is necessary to find attacks consistently regardless of stylistic modelling preferences.


Ross Horne is a senior lecturer in cyber security at University of Strathclyde. His priority is the analysis of security and privacy properties of protocols, which encompasses foundational research in concurrency theory and interdisciplinary thinking. Prior to Strathclyde, he was a researcher in cyber security labs at University of Luxembourg and NTU, Singapore.


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