29.12.2018 –, Clarke
Sprache: English
Mix networks are a kind of communications network that greatly reduce our metadata leakage and exposure to traffic analysis. Mixnets are suitable for certain low bandwidth message oriented use cases such as encrypted messaging for client to server or peer to peer decentralized systems. The main advantages mixnets offer is location hiding and anonymity properties which are strong enough to resist global adversaries while scaling to hundreds of millions of users.
I will give an introduction to some basic mixnet theory and concepts. The second half of this talk will discuss the Katzenpost mix network software system we are actively developing; including live demonstrations that showcase various cryptographic network protocols being performed over the mix network such as: a PANDA transaction, a Zcash transaction submission, encrypted chat et cetera.
message oriented anonymity for resisting global adversaries
I shall explain the renewed interest in mix networks. 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 shares some superficial similarities, but mix networks are vastly stronger if they judiciously add latency and cover traffic. We shall outline the basic components of a mix network and touch on their roles in resisting active and passive attacks.
The comparison to Tor isn't fair at all given that mixnets and Tor solve for differing use cases: Tor has many advantages over mixnets and is suitable for high bandwidth, low latency application network usage with stream orientation. Therefore we ask you to consider that the world needs more than one anonymity network to solve for different problems. We strongly believe that for specific message oriented use cases mix networks are by far the very best choice. We now find ourselves living in the Snowden apocalypse where near global world surveillance is a reality and people deserve to use traffic analysis resistance that is strong enough to resist NSA, GCHQ, "five eyes", drug cartels, greedy corporations, etc.
There are several historical reasons why mixnets lost popularity and why Tor's onion routing won. Namely, Tor is low latency and really good for browsing the web. This is in contrast to mix networks which are essentially an unreliable packet switching network, usually closed networks with no exit relays. 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 free software project which is a free software project that started off as a European Union academic grant project known as The Panoramix Project. Katzenpost incorporates many sophisticated design elements from the mix network literature as well as modern cryptographic protocol design. Many of the Katzenpost mixnet design comes directly from Ania Piotrowska who is the main author behind the recently published academic paper "The Loopix Anonymity System". I will explain why Ania's work on mix networks is cutting edge and truly inspiring. The Katzenpost project was also fortunate to have received help from Yawning Angel who designed and implemented the most sophisticated Noise based cryptographic protocol the world has seen; our cryptographic link layer uses a post quantum cryptographic key encapsulation mechanism in a hybrid forward secret handshake pattern allowing our mix network's link layer transport protocol to resist attacks from quantum computers.
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 and provide a good user experience. 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 to server and peer to peer systems including but not limited to: messaging/chat, crypto currency transaction transport, offline browsing, file sharing, bulletine board systems et cetera.
