How does coinjoin work?

[EchiHearthstone]

I was doing some tests for coinjoin on the testnet and I'm not sure I understand how it works. Build from source code so maybe its too early to be working well.
1.) Why am I getting so many different coins?
2.) Why would one coin be banned?
3.) As for the fee for coinjoin is it 0.003 x 200 anon set, or only to start?

Some info for people looking to learn would be great.

[yahiheb]

Build from source code so maybe its too early to be working well.

Wasabi has been in production since 3 years.

1.) Why am I getting so many different coins?

Wasabi CoinJoin creates multiple equal value outputs + change, and by participating in many CoinJoin rounds you might end up with many coins.

Note that coinjoin on testnet is configured differently so you need to participate in many rounds to reach the anonymity set target which and that will create even more coins.

2.) Why would one coin be banned?

https://docs.wasabiwallet.io/FAQ/FAQ-UseWasabi.html#why-do-my-coins-occasionally-get-banned-from-participating-in-coinjoin

3.) As for the fee for coinjoin is it 0.003 x 200 anon set, or only to start?

CoinJoin fee = coordinator fee + mining/transaction fee

This is how the coordinator fee is calculated:

https://docs.wasabiwallet.io/FAQ/FAQ-UseWasabi.html#what-are-the-fees-for-the-coinjoin

If for example you CoinJoin 0.1 btc which is the minimum, then the coordinator fee is 0.003% * 200 (=0.6%) of 0.1 btc: 0.0006 btc.

[EchiHearthstone]

Thank you for the good info, it did help me understand. If I understand correctly the more participants in the coinjoin the less rounds needed?

[yahiheb]

Yes.

[EchiHearthstone]

Do we know what the min of the coinjoins will be in 2.0? Some of us don't have 0.1 BTC.

[BTCparadigm]

There's no minimum in 2.0 other than uneconomical outputs, such as for example 100sats, because it would cost more to spend them than what they are worth.

[EchiHearthstone]

That will be amazing.

[EchiHearthstone]

In 2.0 will we be able to control the coinjoin as given in 1.0? Looking at the new layout all I see is auto coinjoin/wallet privacy. Am I missing anything or will there be more coming, say for power users or ones wanting more control over coins?

[yahiheb]

In 2.0 will we be able to control the coinjoin as given in 1.0?

No CoinJoin will not be like in 1.0. Coinjoins will be done behind the scene without the user interaction.

Am I missing anything or will there be more coming, say for power users or ones wanting more control over coins?

AFAIK currently there is no plan to add such feature.

[EchiHearthstone]

So users will have to have another wallet to use with exchanges or other places that ban coinjoin coins, if that ban actually happens? I've heard of it and was wondering if there is a plan against that.

[nopara73]

That seems to me the easiest way. There's no plan B though, if there's social consensus on criminalizing privacy then coinjoins are dead to begin with. The least we can do is to not leak this despicable concept into considerations in the codebase.