katzenpost_thinclient

A thin client for sending and receiving messages via the Katzenpost mix network.

This PyPI package provides an async Python thin client library for interacting with a Katzenpost mixnet.

A mix network is a type of anonymous communications network. A thin client library is code you may use as a dependency in your application so that it can anonymously interact with services on the mix network. The Katzenpost client daemon (kpclientd) is a multiplexing client; many applications on the same device may use their thin client libraries to connect to the daemon and interact with mixnet services concurrently. All cryptographic operations, including PQ Noise transport, Sphinx packet construction, and ARQ retransmission, are performed by the daemon, not by this library.

Pigeonhole, in brief

Beyond simple request-response services, Katzenpost provides a storage layer called Pigeonhole. Applications communicate through encrypted, append-only streams composed of fixed-size, padded Boxes, sharded across storage replicas via consistent hashing. Access is governed by cryptographic capabilities: a write capability appends messages or places tombstones, whilst a separate read capability decrypts and verifies without conferring any ability to write. Streams are single-writer, multi-reader, and unlinkable to outside observers. Storage is ephemeral: Boxes are garbage-collected after roughly two weeks, so Pigeonhole is not intended for long-term archival storage. For a developer-oriented introduction, see Understanding Pigeonhole.

Documentation

• Thin Client How-to Guide, task-oriented examples in Go, Rust, and Python.
• Thin Client API Reference, the unified API reference for all three languages.
• Python API reference, pydoc-formatted reference for this package.
• Understanding Pigeonhole, conceptual background on Pigeonhole.
• Build from source, the canonical record of pinned versions for kpclientd and the thin clients.

Installation

Install from PyPI:

pip install katzenpost_thinclient

Or, from a checkout of this repository:

pip install -e .

Compatibility

This package is intended to be used with the version of kpclientd listed in Build from source. That page is the canonical record of currently pinned tags for the whole stack; please consult it before pinning a version of your own.

Running the tests

The tests/ directory contains the integration suite, which doubles as a working reference for the API. The tests expect a running Katzenpost mixnet; the most convenient way to obtain one is the docker test mixnet shipped with the Katzenpost monorepo. Full instructions are in Docker test network; the short form is:

cd katzenpost/docker
make start wait run-ping

The mixnet runs kpclientd inside a container exposed on 127.0.0.1:64331, and writes a thin client configuration to voting_mixnet/client/thinclient.toml. The test suite locates a preconfigured fixture at testdata/thinclient.toml, which dials the daemon on that port:

pytest

Applications using this library

Two larger programs that use this library:

1. stats, a terminal application that prints the current mixnet status.
2. worldmap, which renders an image of the mixnet transposed over a world map.

Contributions

This is a work in progress, and we welcome feedback from developers who try to use it. Pull requests are welcome at https://github.com/katzenpost/thin_client.

License

AGPLv3.