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Collaborative Transaction (Coinjoin) Strategy
46 sats \ 6 comments \ @cicero 2 May 2022 bitcoin
I have read all the different guides on Samourai/Wasabi/Sparrow coinjoins and setting them up, but I have yet to find the perfect guide for understanding what to do with your remaining UTXOs once you've gone through the several mixes.
Combining the UTXOs from the post-mix to send to cold storage seems like bad practice (at least from what the whirpool guides say), and, of course, you don't mix in the badbank portion (preferably you send somewhere to lightning or spend somewhere else), but how exactly is one supposed to send your mixed UTXOs to cold storage in the best way to keep the unbroken links? Multiple cold wallets? Leave them in the mixer forever? Or perhaps you should only ever mix a greater amount so it isn't broken up into smaller sat totals?
Any guides or quick thoughts would be very appreciated!
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22 sats \ 1 reply \ @Majjin 2 May 2022
Sparrow Wallet has a feature that lets you use Samourai's Whirpool service and mix directly to your cold storage without combining the postmix UTXOs
https://sparrowwallet.com/docs/mixing-whirlpool.html#mixing-to-cold-storage
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11 sats \ 0 replies \ @cicero OP 2 May 2022
Great feature
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2 sats \ 1 reply \ @2bithits 2 May 2022
Why not keep each mix separate in cold storage?
If they are in small denominations and you need to spend a larger amount, perhaps send a couple mixes into liquid at different times, then peg back out into a new mix?
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0 sats \ 0 replies \ @2big2fail 2 May 2022
yes or do a coinjoin transaction with the already coinjoined inputs as joinmarket allows
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0 sats \ 1 reply \ @kilianbuhn 2 May 2022
Combining the UTXOs from the post-mix to send to cold storage seems like bad practice
Why? As long as you keep the post-coinjoin identity separated you are good! It doesn't matter if it's a hot or cold wallet in the end.
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1 sat \ 0 replies \ @Majjin 2 May 2022
Let's say you are mixing right after you move your funds off an exchange. Said exchange uses chain analysis to keep track of its customer's funds. It knows how much you have bought from them and which premix UTXOs belong to you. When you mix your funds and don't combine them, you blend into other people's mixed UTXOs. The exchange can't tell with any certainty which UTXO is yours.
However, if you combine UTXOs, they know that all those UTXOs belong to one person. They can estimate the mix fee and transaction fees to see if the amounts for your original, premix UTXOs match up with this new one. Its not that likely that another person has mixed and recombined the same amount of sats as you did. So they can conclude with some certainty that the new UTXO is yours if the amounts match up.
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