Walletwasabi: Remove `Select All Private` Box

[MaxHillebrand]

Problem

In the Send tab, there is a button Select All Private which automatically selects all green checkmark coins. In general, coin consolidation decreases anonset and privacy. This button makes it very easy to [maybe by accident] consolidate all the private coins - and thus drastically decrease their privacy.

Solution

Remove the Select All Private check box, and force the user to manually select EVERY coin he wants to spend. Yes, this is not as usable as the automatic selection - but that is a feature, not a bug. We should do more to prevent users from coin consolidation.

This is the same effort as #1958.

[Transisto]

I oppose this change.

The main problem is when the merged coins are part of a uninterrupted series of coinjoins.

For example someone takes 24h to partake in every CJ with 2 BTC then send those 2 BTC back all at once.

The reality is that if someone select all privates UTXO it doesn't mean they will all be used, most of the time a smaller amount than the sum of all utxo will be sent and if that person really want to sent them all they will select them all manually anyways.

I don't think it's a good idea to remove that feature, In my opinion it's easier to replace it with an improved version.

[MaxHillebrand]

Agreed @Transisto, many users like to consolidate large sums of coin join outputs in one transaction.
But this is very bad for privacy.

Of course, users should have the ability to do such a consolidation transaction, but I do not think that it should be encouraged in the UX.

Right now it is too tempting to make a horrible privacy mistake. I think that it is more important to protect user privacy, than it is to keep convenience for some users who do these consolidation transactions.

Again, you can still select each utxo individually and consolidate - but this way you are much more careful with which coins you select.

[MaxHillebrand]

I think this issue can be expanded with the feature request to remove BOTH Send All Private & Send All Non-Private, even in the Coin Join tab.

Coin consolidation is always bad - especially assuming that everyone knows what the coordinator knows.
Thus I think coin consolidation should at least not be encouraged [remove the button], and even better warned against [add pop-up double confirmation #1958].

[BTCparadigm]

How about a notification box popping up when you're about to consolidate outputs?

Like:
"You're about to consolidate one or more mixed outputs, hence degrading the UTXOs anonymity set.
Do you want to send anyway?"

[MaxHillebrand]

Yes - that is in issue #1958 - but I think we should do both.

[nopara73]

I agree with Max, but it doesn't worth a user revolt.