New blog post! ✨ I argue that AI will make formal verification go mainstream. martin.kleppmann.com/2025/12/08/a... Three reasons for this: 1. LLMs are getting increasingly good at writing proofs using proof assistants. This will make formal verification vastly cheaper than it's been to date.

@arberesford.bsky.social and I are giving a talk on deploying secure whistleblower technology in practice this Wednesday (12th Nov) at the @cst.cam.ac.uk in Cambridge (3pm)—covering the five year journey of CoverDrop. 🙌 Join us online or in-person: www.cst.cam.ac.uk/seminars/lis...

How to trust that the binaries that we deploy are truthfully built from the correct source code? 🤝 Just back from ACM CCS '25 🌏 where we presented Attestable Builds as a solution to this challenge. It complements Reproducible Builds and uses TEEs as a trust anchor. With @coderlime.bsky.social

One of my favourite CoverDrop details: out-of-band verification of the trusted organization key which signs the entire key hierarchy. Its digest is included in the imprint of every printed Guardian newspaper, removing the need to trust CAs 🔑🗞️ more details: www.coverdrop.org

Audits of AI/ML systems while protecting model IP and keeping the audit data confidential 🤫 @inxoy.bsky.social is at the ICML TAIG workshop today, presenting our work on Attestable Audits: arxiv.org/html/2506.23... with Bill Marino and @arberesford.bsky.social

Super excited that Jenny is presenting our new paper on "Web Authentication and Recovery in the Age of E2EE" at PETS today! 🎉🎉 Tons of interesting insights for a world in which we are moving away from passwords, and E2EE data becomes more long-term and critical. petsymposium.org/popets/2025/...

CoverDrop involved users from the very beginning—avoiding the “solution looking for problem” trap. Big shout out to @mansoor.bsky.social , Diana, and @arberesford.bsky.social for getting this right from the very beginning by running two very insightful workshops with journalists and engineers.

This announcement really should have our lead Rustaceans @itsibitzi.dev and @zekehg.bsky.social on top 🦀! CoverDrop's implementation journey has been demonstrating the immense strengths that lie in Rust's type system and the mature tool chain. Looking forward to all the talk in September!

RustConf@rustconf.com · last yr.

🎤 #rustconf Session Announcement: Daniel Hugenroth (@lambda.bsky.social), Sam Cutler, & Zeke Hunter-Green “Secure Messaging: Leveraging Rust to Create the Guardian’s Anonymous Whistleblowing System” → rustconf.com/schedule/#1473 #rustlang

The Guardian app’s own data flows make leaks indistinguishable from regular traffic — cutting off one of the easiest ways for a repressive government or a corporate boss to identify a leaker. www.niemanlab.org/2025/06/the-...

The Guardian’s new whistleblower tool buries leaks to journalists within its own readers’ everyday traffic

Think "I am Spartacus!" — but for leakers.

niemanlab.org

Congratulations @lambda.bsky.social! Today @theguardian.com is launching a new way for whistleblowers to anonymously contact journalists, based on years-long research by Daniel and other colleagues. www.theguardian.com/gnm-press-of...

The Guardian launches Secure Messaging, a world-first from a media organisation, in collaboration with the University of Cambridge

Secure Messaging is a new innovation for confidential story-sharing and source protection, underpinning the Guardian’s commitment to investigative journalism. The Guardian has published the open sourc...

theguardian.com

We launched CoverDrop 🎉 providing sources with a secure and anonymous way to talk to journalists. Having started five years ago as a PhD research project, this now ships within the Guardian app to millions of users—all of which provide cover traffic. Paper, code, and more info: www.coverdrop.org

Greatly enjoyed talking at JKU Linz about our Sloth 🦥 library which uses Secure Enclaves (SEs) for key stretching and deniable encryption. Importantly, it works around Android/iOS API limitations and, therefore, Sloth is available to regular apps on most smartphones without modifications.

It's done! The final lecture slides and notes for "P79 Cryptography and Protocol Engineering" are now online: www.cl.cam.ac.uk/teaching/242... 🎉. This is the first time that @martin.kleppmann.com and I have done this course—we very much welcome feedback, corrections, and suggestions for next time

I am quite excited that our brand-new module "P79: Cryptography and Protocol Engineering" has its first lecture today! @martin.kleppmann.com and I designed the course to bridge the gap between mathematical ideas and the challenge of implementing secure cryptography in the real world. @cst.cam.ac.uk

The PaPoC workshop is once again accepting submissions on distributed consistency. Deadline 15 January papoc-workshop.github.io/2025/cfp.html

My CS department @cst.cam.ac.uk is now on Bluesky, with a properly validated domain handle. Please give them a warm welcome!

I went down a rabbit hole studying HKDF implementations for Android and wrote up some impressions: www.danielhugenroth.com/posts/2024_0...

Android HKDF implementations

This article discusses several open-source implementations of the HKDF scheme for Android. Since HKDF is a relatively simple algorithm, it allows for a good case study of cryptographic code. The prima...

danielhugenroth.com

I'll be speaking at TUM in Munich next week about "🎢 Rollercoaster: An Efficient Group-Multicast Scheme for Mix Networks". Say Hi if you're around, or join online: https://hedgedoc.net.in.tum.de/s/xDwzUxvFV#TUM-Blockchain-Salon

New paper! 📄✨ It turns out that all text collaboration algorithms have an interleaving problem, and we fixed it for the first time. Very proud of this work with Matthew Weidner and Seph Gentle https://arxiv.org/abs/2305.00583

The Art of the Fugue: Minimizing Interleaving in Collaborative Text Editing

Existing algorithms for replicated lists, which are widely used in collaborative text editors, suffer from a problem: when two users concurrently insert text at the same position in the document,...

arxiv.org