Dan Ristea
About
I am a PhD student in the Centre for Doctoral Training in Cybersecurity at University College London. My research interest is differential privacy, specifically how it is verified and validated in real-world use-cases. My supervisor is Professor Steven J. Murdoch.
Publications
CoStricTor: Collaborative HTTP Strict Transport Security in Tor Browser
Killian Davitt, Dan Ristea, Duncan Russell, Steven J. Murdoch
PoPETS 2024, Issue 1Abstract:
HTTP Strict Transport Security (HSTS) is a widely-deployed security feature in modern web browsing. It is also, however, a potential vector for user tracking and surveillance. Tor Browser, a web browser primarily concerned with online anonymity, disables HSTS as a result of this tracking potential. We present the CoStricTor protocol which crowdsources HSTS data among Tor Browser clients. It gives Tor Browser users increased resistance to man-in-the-middle attacks without exposing them to HSTS tracking. Our protocol adapts other privacy-preserving data aggregation algorithms to share data effectively among users with strong local differential privacy guarantees. The CoStricTor protocol resists denial of service attacks by design through our innovative use of Bloom filters to represent complementary data. Our simulations show our protocol can model up to 150,000 websites, providing 10,000 upgrades to HSTS for users.
Teaching
I am currently a Postgraduate Teaching Assistant for the following Masters-level modules at UCL:
COMP0025 - Introduction to Cryptography (term 1 - 2021/2022, 2022/2023, 2023/2024).
I ran tutorial sessions, contributed material to homework and coursework assignments, and marked assignments
COMP0061 - Privacy Enhancing Technologies (term 2 - 2021/2022, 2022/2023, 2023/2024)
I automated lab assignments using GitHub Classroom, provided technical assistance to students with lab assignments, guided discussions in seminars, and marked lab assignments.
- For my teaching activity as a PGTA, I was awarded the UCL Education Award for top Postgraduate Teaching Assistant in the Faculty of Engineering Sciences for the 2021/2022 academic year. UCL Blog
I am also a React coach for Skiller Whale.
Contact
Email: dan at dri.st