Projects and papers

Here I collect recent projects and papers. 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 📦

CoverDrop & SecureMessaging

CoverDrop (or SecureMessaging) is a whistleblowing system that integrates into a news app and provides a highly secure channel for whistleblowers to submit information to journalists. It launched in June 2025 and is based on previous academic research (see below). The implementation white paper and the coverdrop.org website provide many details about the system and its design.

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 and deployed to hundreds of thousands of devices through CoverDrop.

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.

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.

Spectrum & Fresco

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.

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 📚

Attestable Audits: Verifiable AI Safety Benchmarks Using Trusted Execution Environments

Christoph Schnabl, Daniel Hugenroth, Bill Marino, and Alastair R. Beresford. Attestable Audits: Verifiable AI Safety Benchmarks Using Trusted Execution Environments. Technical AI Governance (TAIG) Workshop at ICML 2025.

The paper is available on the TAIG ICML website.

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. Proceedings on Privacy Enhancing Technologies (PETS), July 2025.

The paper is available on the PETS website.

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.