Free coinjoin coordination \ stacker news ~bitcoin

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52.3k sats \ 26 comments \ @kruw 22 Jun bitcoin

A coinjoin is a non custodial privacy enhancing transaction. I'm coordinating coinjoins for Wasabi Wallet and BTCPay Server. I'm not charging any service fee, you only pay for your own mining fees. Opening Lightning channels using coinjoined funds provides an extra layer of privacy: Even invoices that reveal your channel's on chain UTXO won't leak any extra information from on chain analysis.

Larger coinjoin transactions with many participants provide more privacy and greater on chain efficiency than smaller coinjoin transactions. So far, my coordinator has the most liquidity out of the current coinjoin providers: https://x.com/LiquiSabi/status/1804198233301770567 / https://primal.net/e/note1cg4csv523667wq732qfnjqd08g9anfj46aewc9tnyy5u0gksfmaqthracm

To participate using Wasabi Wallet, paste this coordinator info into the settings field and click "Restart Wasabi":

https://btcpay.kruw.io/plugins/wabisabi-coordinator/

https://m.stacker.news/36417

Largest coinjoins so far: Most inputs (164): https://mempool.space/tx/3d2234434745d227cc03177d44a47519e084dd1a342eabc376fa4d1ea41f2a6f Most outputs (180): https://mempool.space/tx/df79e7cc214d4d8908b0abc078ef261ab5956211ed69be19942e75d4b811853f Highest value with no change output (18.46 BTC): https://mempool.space/tx/4a7bb513dfaaec66bc0721e6762ceaad759b6fd15e22995ffe05eef396c16cd4 Highest value with change output (50.71 BTC): https://mempool.space/tx/d87f70403f8e945d7144508467cad0039310b8a608aa8b85725c6c6cf641d4f0

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105 sats \ 0 replies \ @0xbitcoiner 22 Jun

Well done! We need more of these kinds of initiatives.

58 sats \ 0 replies \ @jakoyoh629 22 Jun

Awesome

63 sats \ 4 replies \ @SwapMarket 22 Jun freebie

What happens if a fee is not enough? Who will CPFP the transaction (that will cost a lot)?

Also, I think for channel opening there won't be a privacy benefit, because gossip announcement channel size can be easily correlated with coinjoin input.

42 sats \ 1 reply \ @petertodd 22 Jun

because gossip announcement channel size can be easily correlated with coinjoin input.

Public channels reveal to the world exactly which UTXO was associated with the channel; private channels do not. This is why mempool.space can label public LN channel opens with node IDs. For example: https://mempool.space/tx/37b07c1917fe814c4b504bd5a6746dd05d8140d6012d7d8b0e4321d91620db8d

LN does this as an anti-DoS measure. Without something similar to this you'd be able to advertise an infinite number of channels to the gossip network.

0 sats \ 0 replies \ @SwapMarket 25 Jun

Exactly that. Private channels already hide finding UTXO, and the public ones cannot even with coinjoin. Unless all inputs will be equal.

1021 sats \ 1 reply \ @kruw OP 22 Jun freebie

What happens if a fee is not enough? Who will CPFP the transaction (that will cost a lot)?

Any participant can CPFP a stuck coinjoin, but it's disproportionately costly to attempt since they pay for the other participants. If you have a stuck coinjoin, you can double spend it by using a Libre relay node to duck under the BIP125 pools pinning your transaction: https://github.com/petertodd/bitcoin/tree/libre-relay-v27.1

Also, I think for channel opening there won't be a privacy benefit, because gossip announcement channel size can be easily correlated with coinjoin input.

The privacy benefit of coinjoining before onboarding to Lightning is that your channel UTXO can be known to anyone without them being able to see where you originally received funds on chain.

If you have a channel opened to you from an LSP, then you coinjoin after you close it so no one can link your previously used addresses or future on chain payments to your Lightning activity.

63 sats \ 0 replies \ @petertodd 22 Jun

Re: Libre Relay, people might be interested in my bitcoindev mailing list write-up on how it has been used by LN nodes to get pinned transactions unstuck: https://groups.google.com/g/bitcoindev/c/n2GNmnz0btw The Lightning protocol does have a few remaining transaction pinning vulnerabilities, so anyone running a LN node should consider running Libre Relay.

F2Pool has, so far, been the main pool fixing transaction pinning. I believe this is due to them having a shorter than usual transaction expiration time on their nodes; I don't think they're running replace-by-fee-rate itself.

A coinjoin with a fee that is too low is basically a case of accidental transaction pinning.

42 sats \ 2 replies \ @grayruby 22 Jun

If someone wanted to test this service what amount of sats would you recommend using to try it out?

71 sats \ 1 reply \ @kruw OP 22 Jun

Normally the recommended amount is 0.01 or more, but on chain fees are very low right now, so even 0.0025 is still pretty economical.

21 sats \ 0 replies \ @grayruby 22 Jun

Thanks

42 sats \ 0 replies \ @BitcoinAbhi 22 Jun

Nice.

42 sats \ 0 replies \ @riberet19 22 Jun

I'm going to take a look at it

21 sats \ 8 replies \ @Coinsreporter 22 Jun

The more I look at coinjoin, the more it feels like it's a pleb thing, not for normal users. Am I right? Or, is there something that a normal user can actually get out of it?

162 sats \ 1 reply \ @kruw OP 22 Jun freebie

The purpose of a coinjoin is to protect your on chain privacy, it's not difficult, the client does all the construction and signing of the transaction for you.

Normies who aren't interested in privacy would be able to benefit by using the coinjoin transaction as a non custodial scaling layer. The inputs registered to a coinjoin round are converted to an ephemeral ecash token that you can respend before the round ends and the coins are settled on chain. You can read more about this technique from this thread: https://x.com/MrKukks/status/1619294492854747138

21 sats \ 0 replies \ @028559d218 14 Dec

This is really interesting... i've never heard of this

11 sats \ 5 replies \ @TNStacker 22 Jun

Can and should, but won't.

21 sats \ 4 replies \ @Coinsreporter 22 Jun

How? Please guide..

182 sats \ 3 replies \ @kruw OP 22 Jun

Coinjoin is automatic using Wasabi or the BTCPay plugin. A new coinjoin round takes place every hour on my coordinator, all you have to do is wait.

21 sats \ 1 reply \ @Coinsreporter 22 Jun

Do you have wasabi for mobile?

63 sats \ 0 replies \ @kruw OP 22 Jun

No, it's available for Linux, Mac, and Windows only. Make sure to use the official website ( wasabiwallet.io) since there are many phishing links that appear in search engine results.

0 sats \ 0 replies \ @TNStacker 22 Jun

That's awesome.

210 sats \ 0 replies \ @anon 23 Jun

Nice

21 sats \ 0 replies \ @SatsMate 22 Jun

Love to see it, we need more coinjoin options. Privacy is one of the more important things I care about as it comes to btc.

21 sats \ 0 replies \ @16d86e9daa 23 Jun

one of the reason i prefer coinjoin is due to the fact that the level of privacy afforded by CoinJoins remains unmatched going forward.

0 sats \ 0 replies \ @rafael_xmr 23 Jun

Honest question are you at any risk by being the number one "go-to" coordinator?

0 sats \ 0 replies \ @WeAreAllSatoshi 22 Jun

What is your motivation for running this for free? Just to spread awareness and increase adoption?