There are at least two reasons why Darkcoin is so interesting to me:

It is the most popular privacy-centric crypto-currency to date, with the largest market capitalization. The privacy technology is based primarily on the CoinJoin protocol first proposed for implementation in Bitcoin. Much of the technology included in Darkcoin’s privacy approach, Darksend+ is adaptable to Bitcoin clients. It is the best funded and most actively developed CoinJoin implementation in the world, currently.

This is the first deliverable from my crowd-funded analysis of Darkcoin’s privacy technology, Darksend+. This paper discusses the design of Darksend+, identifies strengths and weaknesses of the technology, and proposes potential mitigations and improvements to any weaknesses identified.

Since much of the design of Darksend+ can inform other CoinJoin implementations, I hope that this paper will not only shed light on the current state of Darksend+, but provide insight into how to analyze future CoinJoin implementations in general.

I would like to thank Evan Duffield and Justus Ranvier for generously giving their time to review the paper and providing feedback.

Currently I consider the document to be an early version, and request public comment. As mistakes are identified and clarifications are required, I will continue to update the document.

[Download the paper]

-Kristov