Projects, papers, and talks

Here I collect recent projects, papers, and talks. Most projects stem from work in the industry or were part of my PhD. I enjoy specialised, under-explored, and niche areas while keeping an eye on the final product. Few things get me more excited than tackling challenging technical problems that result in large impact. You find many open-source projects on my GitHub profile and full list of academic publications on Google Scholar.

Projects 📦

Sloth

Sloth is a library for key-stretching and plausibly-deniable encryption using the Secure Element on smartphones. By using the Secure Element, Sloth can provide effective rate-limiting against adversaries with physical access to the device and large computational resources. It is implemented for Android and iOS.

Steuerlotse

Steuerlotse is a prototype website created during the Tech4Germany fellowship. It integrates with the official German tax API Elster through ERiC and Python’s ctypes. We presented it to the Federal Minister of Finance, Olaf Scholz, in 2020 and its successor was deployed to production in 2021.

Spectrum

Spectrum is a cross-platform, declarative image transcoding library written in C++ with bindings for Android and iOS. The release blog post provides a good introduction. I am one of its original authors.

Argon2Kt

Argon2Kt is an Android/Kotlin binding for the Argon2 password hash algorithm (winner of the PHC). This is a personal project of mine. I have written this blog article which explains more about password hashing on Android.

Fresco

Fresco is an image management library for Android with a special focus on supporting low-end devices. It incorporates manual memory management and C routines to use the available resources efficiently. I have been one of its maintainers for a many years.

Papers 📚

SoK: Web Authentication in the Age of End-to-End Encryption.

Jenny Blessing, Daniel Hugenroth, Alastair R. Beresford, and Ross Anderson. SoK: Web Authentication in the Age of End-to-End Encryption. To be published in Proceedings on Privacy Enhancing Technologies (PETS), July 2025.

The pre-print is available on arxiv. The full paper will become available on the PETS.

Sloth: Key Stretching and Deniable Encryption using Secure Elements on Smartphones.

Daniel Hugenroth, Alberto Sonnino, Sam Cutler, and Alastair R. Beresford. Sloth: Key Stretching and Deniable Encryption using Secure Elements on Smartphones. Proceedings on Privacy Enhancing Technologies (PETS), July 2024.

The paper is available on the PETS website.

Pudding: Private User Discovery in Anonymity Networks.

Ceren Kocaoğullar, Daniel Hugenroth, Martin Kleppmann, and Alastair R. Beresford. Pudding: Private User Discovery in Anonymity Networks. Proceedings of IEEE Symposium on Security and Privacy (S&P), May 2024.

The paper is available on the IEEE S&P website and as an open-access archived repository copy.

Powering Privacy: On the Energy Demand and Feasibility of Anonymity Networks on Smartphones.

Daniel Hugenroth and Alastair R. Beresford. Powering Privacy: On the Energy Demand and Feasibility of Anonymity Networks on Smartphones. Proceedings of the 32nd USENIX Security Symposium (USENIX Security 23), August 2023.

The paper is available on the USENIX Security ‘23 website.

CoverDrop: Blowing the Whistle Through A News App.

Mansoor Ahmed-Rengers, Diana A. Vasile, Daniel Hugenroth, Alastair R. Beresford, Ross Anderson. CoverDrop: Blowing the Whistle Through A News App. Proceedings on Privacy Enhancing Technologies (PETS), February 2022.

The paper is available on the PETS website.

Rollercoaster: An Efficient Group-Multicast Scheme for Mix Networks.

Daniel Hugenroth, Martin Kleppmann, Alastair R. Beresford. Rollercoaster: An Efficient Group-Multicast Scheme for Mix Networks. Proceedings of the 30th USENIX Security Symposium (USENIX Security 21), August 2021.

The paper and the presentation are available on the USENIX Security ‘21 website.

Key Agreement for Decentralized Secure Group Messaging with Strong Security Guarantees.

Matthew Weidner, Martin Kleppmann, Daniel Hugenroth, Alastair R. Beresford. Proceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security (ACM CCS), November 2021.

The paper is available on the ACM CCS ‘21 website. It is also available as a preprint. We did a live discussion for a wider audience via Zoom and the recording is available on YouTube.

Talks & Podcasts ✨

Rollercoaster

2023-05 – I gave a longer talk about Rollercoaster at the Blockchain Salon at the Technical University of Munich. It is available on Youtube.

Interview: CoverDrop

2022-07 – I did a short interview with the folks at Session about CoverDrop (see above). You can watch it on Youtube. There is also a transcript on their blog.

Podcast: Inside Facebook Mobile

2019-06 – The first minutes contain a short introduction to Spectrum (see above). It is available on Spotify and iTunes.

Londroid: Mastering the Images Spectrum

2018-12 – At the Londroid meet-up we talk about Spectrum and share the challenges that motivated its creation.

droidcon San Francisco: Mastering the Images Spectrum

2018-11 – This is the announcement talk during which we released the Spectrum library.

droidcon New York: Efficient Processing of Images

2018-08 – In this talk I talk about the technical challenges that later motivated the Spectrum library.

droidcon Beijing: Great Images for Everyone, Everywhere

2017-11 – This was my first keynote and I covered high-level considerations for mobile image performance including compression, memory management, and performance metrics.