David Stainton's technical writing

Writing

Papers

• Echomix: a strong-adversary mix network design. arXiv preprint, self-published January 2025: https://arxiv.org/abs/2501.02933. Describes the Katzenpost mix network, the Pigeonhole storage protocol, BACAP, the PQ hybrid Sphinx variants, and the threat model.

Katzenpost mix network specifications

• Pigeonhole protocol spec: unlinkable message storage with sharded replicas and blinded couriers.
• Pigeonhole explained: narrative overview.
• Group chat design: how group conversations are built on top of Pigeonhole.
• Classical Sphinx packet format spec.
• KEM Sphinx packet format spec: post-quantum hybrid variant.
• Mixnet wire protocol spec: PQ Noise handshake for mix network transport.
• Thin client howto and thin client API reference.
• Full Katzenpost specifications index.

Many of these specs originated from a three-month collaboration with Yawning Angel, George Danezis, Claudia Diaz, Ania Piotrowska, and myself as part of the H2020 EU Panoramix project (Privacy and Accountability in Networks via Optimized Randomized Mix-nets).

Blog posts and essays

• Introduction to Mix Networks and Anonymous Communication Networks, published on Least Authority’s blog.
• How to detect TCP injection attacks: comprehensive classification of TCP injection attacks from my 2014-2015 research on Honeybadger.
• Catshadow design and threat model: anonymous messaging client for Katzenpost (NLnet-funded).

Reference material

• Mix Network Syllabus: papers I recommend to build a deep understanding of mix networks.
• Mix Network Bibliography. I was one of the founders. Source code.
• My Google Scholar profile.