“You won’t get my bitcoins” – Secrets of Mixing Bitcoin and CoinJoin

Anonymity is often a subject of controversy in our societies. Some feel that hiding your identity is only for notorious criminals or other shady characters.

In an era of mass state and corporate surveillance where everyone is watched for their actions, it is perhaps difficult to imagine a world where our identity is not constantly sold to the highest bidder.

However, not all have abandoned themselves to this fate, and some continue to fight for their conviction and the protection of their privacy. The famous whistleblower, Edward Snowden , wisely stated in a 2015 interview :

“Saying you don’t care about privacy because you have nothing to hide is no different from saying you don’t care about freedom of expression because you have nothing to hide. say. “

While the battle for the right to anonymity seems lost to some, others are not ready to give up on this quest .

Anonymity through software – the birth of CoinJoin

The right to anonymity is strongly pushed by the majority of the ideologues of bitcoin . This is a sought after property to ensure a censorship resistant form of money .

The inventor of Bitcoin himself, Satoshi Nakamoto , withdrew completely from the internet without revealing his true identity only 2 years after launching the Bitcoin protocol . This tradition of anonymity appears to carry on beyond Satoshi, as many Bitcoin developers are also anonymous .

Bitcoin mixers

Indeed, some of the most popular software in the Cryptosoft universe is mixing software using CoinJoin technology .

First stated in a 2013 Bitcoin Talk discussion by renowned Bitcoin Core developer Gregory Maxwell , CoinJoin technology has come a long way since then.

Like mixers on the darknet that often ended up being scammed because of their centralized form, mixing technologies using CoinJoin are infinitely more secure than their ancestors.

Businesses and individuals who are concerned with the topic of privacy can now anonymize their digital assets without fear with relatively easy to operate software interfaces.

In today’s article, we will explain and compare the different techniques of Bitcoin technology , but first of all, let’s briefly understand what it is.

What is CoinJoin?
The CoinJoin method consists of creating a special transaction including several participants wishing to anonymize their coins. This transaction groups together several “inputs” coming from several sources (several participants) and includes a set of “outputs” with new addresses for the return of coins.

Transaction CoinJoin

The goal is to break the link between the input that pays the output corresponding to it. The new UTXOs thus created will all have the same value so as not to be able to infer the origin of the inputs.

The anonymity comes from the fact that probabilistically speaking, it is virtually impossible to guess from which address the created output originally came.

The more users who join the game, the more difficult it is to infer any analysis according to the heuristics used by famous Blockchain analysis companies, such as Chain Analysis.

There are many implementations of CoinJoin technology and each of them uses it in a different way. Let’s see which one of you is the best fit!

PayJoin, simple and efficient

PayJoin is one of the most minimalist CoinJoin techniques among all those we will present today, because it only takes place between 2 participants . It is a collaborative transaction that relies on making a payment and a transaction simultaneously.

This technique has many advantages, including that of breaking the supposed heuristic that all inputs in a transaction belong to the same party.

Let’s take a look at how a “normal” transaction can be turned into a PayJoin transaction.