Walletwasabi: Same address = same coin

[nopara73]

https://twitter.com/NicolasDorier/status/1105785459060334592

[nopara73]

https://twitter.com/NicolasDorier/status/1105787922198851584

[nopara73]

In other words: update the coin concept. One coin should be able to have multiple UTXOs.

[NicolasDorier]

This will not prevent somebody sending dust to an address which already spent everything. But at least, it would prevent the user to lose anonymity if he has several UTXO to the same address.

1 line in coin selection would be actually a coin group of every UTXO having same address.

[NicolasDorier]

Btw, the TransactionBuilder already by default select all the coins with the same addresses.

[nopara73]

I know, dust attack is already fixed by hiding the dust, regardless it's still a great concept, if something comes to the same address, there's really no reason from a privacy point of view to consider them multiple coins.

[NicolasDorier]

Hiding the coin is risky though. One day there might have screw up.

[NicolasDorier]

Another idea:

Sometimes I have a coin of 0.9978 when I need 0.9979 for the round.

It would be great to reserve the use of dust utxos to bump small missing amount and send no change back to one or several user. Basically using the dust to increase privacy by decreasing the chances to have change back at you.

[Transisto]

... send no change back to several user.

Does not compute.

I would not count on that dust to amount to much in the long run. Spending or mixing them along same address is a good way to get rid of it but that doesn't work after legit funds are sent.