Introduction to Mix Networks and Katzenpost a new anonymity movement

David Stainton and mo

47 min

47 min 2019-08-23

2019-08-23 2019-08-24

2019-08-24 380

380 Fahrplan

Playlists: 'camp2019' videos starting here

This talk will introduce the fundamental concepts of mix networks as

well as the Katzenpost mix network free software project. We are not

just implementing a new mix network but starting a new anonymity

movement and we welcome others to join us! Like Tor, mix networks

protect metadata by using layered encryption and routing packets

between a series of independent nodes. Mix networks resist vastly more

powerful adversary models than Tor though, including partial defense

against global passive adversaries. In so doing, mix networks add both

latency and cover traffic. I shall outline the basic components of a

mix network, touch on their roles in resisting active and passive

attacks. In particular I'll mention how mix networks can be used with

encrypted messaging applications and crypto currency to resist global

network surveillance and traffic analysis.

Academics have proposed various anonymity technologies with far

stronger threat models than Tor, but by far the most practical and

efficient option remains mix networks, which date to the founding of

anonymity research by David Chaum in 1981. Tor was inspired by mix

networks and shares some superficial similarities, but mix networks'

are vastly stronger if they judiciously add latency and decoy traffic.

There are several historical reasons why mixnets lost popularity and

why Tor's onion routing won. Namely, Tor is low latency and can be

used to browse the web. This is in contrast to mix networks which are

essentially an unreliable packet switching network. Historically mix

networks achieved enough mix entropy by using long delays whereas it

is becoming more widely understood that there exists a trade off

between legit traffic, decoy traffic and latency. After this

introduction to mix networks I'll talk a bit about the Katzenpost mix

network software project which is based off of the recently published

academic paper "The Loopix Anonymity System". These new insights into

mix network designs allow modern mix networks to make the correct

design trade offs so that we can keep the latency relatively

low. Historically high latency and unreliability has been a major

obstacle to mass adoption. I shall explain how Katzenpost solves both

of these problems and allows developers to easily add network services

to the mix network to support a wide variety of client applications

including but not limited to: encrypted messaging, crypto currency

transaction transport, offline browsing and, transporting client

interactions with Distributed Hash Tables and Conflict Free

Replicating Data Types et cetera.

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