What is Katzenpost?

Katzenpost is an open-source mix network which offers traffic analysis resistant messaging and utilizes post-quantum cryptopgraphy.

Katzenpost is a free software project. We write mix network protocol libraries. What is a mix network? It is an anonymous communications system… however the word anonymous is problematic because some government authorities equate anonymity with terrorism. We prefer to instead call it “network security” because you can feel more secure when you communicate using traffic analysis resistant communications protocols.

However we realize we cannot simply write a mix network and core protocol libraries and expect people to use them. Therefore we are working towards a demonstration encrypted chat client which will communicate over our mix network.

Traffic analysis helps governments, corporations and Internet service providers learn more information about the communication even if it is encrypted. The goal of protecting the confidentiality of messages is in fact an orthogonal concern to that of resisting traffic analysis. In particular we are interested in developing mix network based communications systems that can be used by everyone to hide these kinds of communications metadata:

  • geographic location
  • message sender
  • message receiver
  • message sent time
  • message receive time
  • message size
  • ordering of messages
  • frequency of sent messages
  • frequency of received messages

There are many message oriented applications and protocols that could benefit from using our mix network. For example our mix network is not only good for chat clients but also other types of applications:

  • transporting interactions between CRDTs
  • transporting interactions to DHTs
  • database transaction anonymization
  • ‘crypto currency’ anonymization