Thank you all for being a part of PETS 2025!
Special shoutout to General Chair @adamaviv and @GeorgeWashingtonUniversity for hosting, to Program Chairs @zubair_shafiq and @robgjansen and all the wonderful people in the organizing committee, and the program committee for making it a success. We hope you leave inspired, energized, and with a few new friends. See you next time! ✨
📅 PETS 2026 Issue 2 submission deadline is August 31, 2025 (AOE)
Looking forward to heading to Washington, D.C. for the @PET_Symposium starting tomorrow! It's always a highlight of the year.
This time, I'm especially excited for several reasons: one of my PhD students will be presenting a paper, and we will also be showcasing two posters. On top of that, I have the pleasure of organizing this year’s poster session, which features over 25 high-quality contributions from researchers around the world. I’ll also be chairing the session Web Tracking II.
As always, I’m looking forward to the intense discussions, fresh ideas, and the chance to reconnect with many familiar faces from the PETS community. See you in D.C.!
🚀 Calling all privacy researchers!
The @PET_Symposium 2025 Call for Posters is now open (https://petsymposium.org/2025/cfposters.php)!
Present your new ideas & ongoing research at the Privacy Enhancing Technologies Symposium in Washington, DC (July 14–19).
📅 Submit by June 24 (visa support deadline: May 13).
🏆 News this year: a Best Poster Award!
🔗 Submit now: https://submit.petsymposium.org/posters2025/
#PETS2025 #Privacy #PETS 'Poster #research #PETS25
🔍 New Research on Regional Filter Lists in the Web 🔍
I'm excited to share our latest work, "Understanding Regional Filter Lists: Efficacy and Impact," which has been published at the @PET_Symposium (PETS) 2025! 🚀
Ad blockers and tracking protection mechanisms rely on filter lists to block unwanted content and trackers. In addition to global lists, there are numerous regional filter lists created for specific countries or language regions. But how well do they actually perform?
In our large-scale study, we visited over 1.8 million web pages, analyzed 207 million HTTP requests, and examined 579 GB of data. Our findings reveal:
🔹 Regional lists often block less than expected – and sometimes even perform worse than general lists.
🔹 Only 7% of the rules in these lists are truly effective – showing significant room for optimization.
🔹 Regional lists don’t necessarily enhance privacy where they are intended to – some are even more effective in other regions.
Our results question the actual benefit of regional lists and suggest that the privacy community should work on better, optimized solutions.
📄 Read the full paper: https://petsymposium.org/popets/2025/popets-2025-0063.php
Christian Böttger, Nurullah Demir, Jan Hörnemann, Bhupendra Acharya, @tho, Norbert Pohlmann, @pizzahax
New paper! "Comparing Apples to Androids" deals with matching iOS apps to Android apps from the two biggest stores. Gonna be more interesting once there are more markets 
. Work by Magdalena Steinböck, yours truly, Mikka Rainer, Tobias Urban (@_tobiasu), Christine Utz, and Martina Lindorfer.
We use seven metadata features for matching: name, ID, icon, description, developer, privacy URL, and deep links. The average similarity of those works very well, but it can be tweaked for your use case.
But how do we evaluate this? Thanks, Google, for providing an undocumented migration API that returns Android apps to be installed based on the iOS apps you have. It's good enough, but it's a black box and might end up on the Google graveyard 
.
Our code will be open-sourced soon; we're documenting and testing it, so it's not your usual academiaware. The scraped & matched apps are available for research upon request.
We look forward to presenting this at MSR in April in Lisbon 🇵🇹! If you're interested, the details are in the paper and the paper's already available here: https://themoep.at/research/2024-comparing-apples-to-androids.pdf
Are you planning to attend (virtually or physically) #IMC23 next week? Be sure to attend our (@nrllah @thorstenholz @chwress @pizzahax @ProfPohlmann ) talk on the similarity of Web measurements in the Security and Privacy session on Wednesday, the 25th!
In our paper, we perform a large-scale web measurement (1.7M page visits) and discuss the differences and similarities between multiple measurements. We find that differences in the result exist even if a website is crawled using the same setup in parallel from two machines.
However, we found significant differences between first- and third-party components. While first-party components are loaded relatively stable and similar, third-party elements (e.g., trackers) make up a significant part of the cases of observed variances.
Finally, what we learned in our study that (1) Drawing conclusions based on loading dependencies is error-prone, (2) An understanding of whether the phenomenon of interest is present in the dynamic or static content of a page is vital for planning the experiments, and (3) Our approach confirms that researchers should use different profiles and execute multiple measurements to assess the potential of ‘randomized’ findings.
PET Symposium
jakob