A free and open-source post-quantum mix network that hides who is talking to whom from network-level observers, including adversaries who record traffic today to decrypt on a future quantum computer. A mix network is made of mix nodes that act as cryptographic packet-switching routers, mixing many messages together, transforming them and adding shuffling or delay so that incoming and outgoing messages cannot be linked. Katzenpost also provides Pigeonhole, an anonymous storage layer on top of the mixnet in which applications exchange encrypted, append-only streams of fixed-size padded boxes sharded across replicas and governed by write and read capabilities, with thin clients in Go, Rust and Python and a Qt group-chat client. Its design is described in a paper on the Echomix anonymity system, and a public Katzenpost network called Namenlos is listed as coming next .
OwnerKatzenpost (the project's own name in its site footer; the cited sources do not name a legal entity)
Governing BodyNot described in the cited sources
Country Not stated by the project.
Start Year 2021
StackGo (the repository's main language), with post-quantum key exchange in its design; Pigeonhole storage with thin clients in Go, Rust and Python; katzenqt (Qt) and a client daemon
OriginsTraffic-analysis-resistant, post-quantum anonymous communication, based on mix network research and, more recently, the Echomix design and the Pigeonhole storage protocol
Database N/A
Data FormatsMix-network packets and Pigeonhole boxes (fixed-size, padded, encrypted) as described in the repository README
Mobile SupportNo application; thin clients are libraries
Web SupportNo browser client was described in the cited sources
Native Appskatzenqt (a Qt group-chat client) and the kpclientd client daemon, buildable from source
TermsFree and open source (AGPL-3.0); the site links a donation page
Funds Not stated by the project.
Based OnMix network research, including the Echomix design in the project's paper, and post-quantum cryptography
P2P ArchitectureA mix network of mix nodes with directory authorities and storage replicas; a deployer runs a network, and clients connect to it. A public network (Namenlos) is announced but not yet available
Overlay NetworkYes: a mixnet overlay with its own routing and storage replicas
Content Addressing No.
Local-First No: network infrastructure rather than a data layer.
E2EEYes for Pigeonhole streams: encrypted append-only streams governed by write and read capabilities
Byzantine Fault Tolerance Not stated by the project.
SignatureCapabilities for writing and reading are cryptographic; the cited sources do not detail signing
PermissionsCryptographic capabilities: a write capability can append or place tombstones, and a separate read capability decrypts and verifies without conferring write access
Protocol Maturity / StandardizationResearch-grade, pre-release (v0.0.x) with a published paper and an evolving threat-model document; no standards-body involvement
Infrastructure FunctionAnonymous messaging and storage resistant to traffic analysis, including by quantum-capable adversaries
Threat ModelGlobal passive adversaries and record-now-decrypt-later quantum attackers; the site notes that the published threat-model document is a work in progress
Volunteer / Node ModelNot stated: the cited sources describe deployers who run mix nodes, and a public Namenlos network that is announced but not yet running
Traffic VisibilityDesigned so that observers cannot link senders and recipients through mixing, padding and delay
Active Deployment ScaleNo public network yet: Namenlos is listed as coming next
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