A post-quantum mix network providing strong metadata privacy against global passive adversaries.

📄 Paper · 🌐 Website · 📚 Docs · 💬 Community

• katzenpost — monorepo:
  • Mix network: mix server, directory authority
  • Pigeonhole protocol: courier, replica. Uses the mixnet as transport for clients to talk to couriers.
  • Client daemon (kpclientd): mixnet client used by applications, including to reach Pigeonhole couriers.
• hpqc — hybrid post-quantum cryptography library. Provides KEM, NIKE, and signature schemes behind clean interfaces, plus the pieces that make them composable:
  • a KEM combiner that is provably IND-CCA2 in the QROM, based on the KEM Combiners paper
  • a NIKE-to-KEM adapter (an ad-hoc ElGamal construction) so any NIKE can be used as a KEM, and combined with other KEMs via the combiner
  • a signature scheme combiner
  • BACAP, a blinding-and-capability scheme used by Pigeonhole

• kpclientd — the Katzenpost client daemon. Lives in the monorepo at cmd/kpclientd; build with make kpclientd from the repo root. Required by katzenqt.
• katzenqt — Qt group chat client. Talks to kpclientd.

Language bindings for building applications that talk to kpclientd:

• Go — in the monorepo at client2/thin
• Rust and Python — thin_client

• website — source for katzenpost.network

• Use it: build katzenqt and kpclientd (see Clients above) — pre-built packages coming
• Run a node: Admin Guide
• Build on it: Thin Client API
• Contribute: katzenpost/katzenpost — issues and PRs
• Research: Echomix paper and Threat Model

The sections above are the curated front door. Below is every repository in the organisation, grouped by purpose, so a newcomer can find the right place quickly and so dead wood is plainly labelled.

Live dependencies of hpqc:

• circl: fork of Cloudflare's CIRCL, carried for use with hpqc.
• falcon: Go bindings for the Falcon padded post-quantum signature (C vendored from PQClean).
• sphincsplus: fork of the SPHINCS+ reference code.
• sntrup4591761: Go Streamlined NTRU Prime 4591^761.

Live dependencies of `katzepost':

• nyquist: fork of Yawning Angel's Nyquist Noise library, from the pqnoise branch; supplies the PQ Noise wire protocol.
• trunnel: actively maintained Go port of Tor's trunnel binary-serialisation code generator; used for Sphinx and Pigeonhole wire types.

Standalone crypto:

• NoiseFramework: fork of the Python Noise Protocol Framework. Not yet used.

• cryptoproofs: machine-checkable ProVerif models and measurement data.
• formal_specifications: ProVerif/Noise models for BACAP, client2, MKEM, Sphinx and the Noise handshakes.
• CryptWalker: a Lean cryptography library for prototyping protocols and proving properties about them.
• lean-ffi: Lean FFI examples (to Rust and C), supporting the Lean modelling work.
• reunion: the REUNION PAKE rendezvous protocol.
• napkin-math: back-of-the-envelope latency and sizing calculations.
• talek: fork of the Talek PIR private publish/subscribe system, kept for reference.
• echo: small Rust example service built on the thin_client library.

• ansible-playbooks: Ansible playbooks for deploying Katzenpost mix networks.
• status: mixnet diagnostics and status page (uses the thin client).
• worldmap: draws a world map with mix-network nodes overlaid (uses the thin client).

• website: source for katzenpost.network.
• .github: this organisation profile and shared community files.
• diagrams: design diagrams and conceptual imagery.
• zine: LaTeX source for the Katzenpost zine.

These repositories are dormant or superseded or obsolete. We should think about deleting them.

• katzen: former Gio messaging client, superseded by katzenqt.
• client: old client library, superseded by the monorepo client2/kpclientd.
• mixnet_uprising: historical task tracker.
• slides: old presentation slides.
• nixops / nixpkgs: abandoned Nix deployment configuration (last touched 2018).

• quic-go: fork of quic-go.
• katzen.chat: website for the retired katzen app; obsolete with katzen.
• fdroiddata: stale fork of F-Droid metadata for the old katzen Android build.
• bfg: unlabelled Rust experiment, no README, untouched since 2024; purpose unclear.
• mceliece, chacha20, chacha20poly1305: standalone crypto that hpqc/circl appear to have superseded; verify no remaining dependants before archiving.
• qrterminal: fork with no current consumer.

GNU AGPL-3.0 across the org. A small number of submodules use different licenses; see the LICENSE file inside each repository.