More On Mixnets...

cMixx is a very fast mixnet.  More generally, mixnets, also known as mixing networks, were first described by xx network Founder David Chaum in 1979. A mixnet lays down cryptographic rules for messages or transactions to be relayed by a sequence of trusted intermediaries known as mix nodes. These mix nodes receive a batch of encrypted pieces of data from users, randomly permute or “mix” them, and then send the reordered, encrypted data forward to the next mix node.

This “mixing” obscures the metadata associated with user activity, creating a privacy-protecting communication system. Metadata is the​ who​,what​, ​when​, ​where​, and ​how​ details associated with any message or activity. 

The main drawback to existing mixnets is that the public key operations necessary for the mixing operation require intensive computing.  In fact, in 1979, the computations originally described in Chaum’s paper exceeded the power of most existing computers.  Even now, the required computation for typical mixnets is resource intensive and time-consuming.  As a result, when performed at scale, mixnets are too slow for most consumer uses.

In 2016, Chaum and a team of researchers published a design for an “accelerated” mix net called “cmix”.  “Precomputation” was proposed as the solution to the slowness of typical mix nets.

Precomputation allows mix nodes to execute the time-consuming public key cryptography before the real-time phase of handling messages or data transmission between senders and recipients. The result is a very efficient type of mixnet that allows users to send and receive in real-time without compromising security or privacy.

Part of the initial research project was an academic reference implementation that served as a proof of concept for cmix; it included a backend team of mix nodes and a rudimentary smartphone client.

In August 2017, under Chaum’s leadership, a development group began creating a decentralized, secure and scalable implementation called cMixx.  The  team included pioneers who developed early  practical, anonymous, and verifiable cryptographic systems. Its members were among  the first to propose and deploy digital currencies, mix networks, un-permissioned  cryptography, verifiable voting systems, and many other advances in cryptography.