Date: Sat, 13 Jun 2020 00:45:12 +0000
To: Antoine Riard <antoine.riard@gmail.com>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] CoinPool,
	exploring generic payment pools for Fun and Privacy
Precedence: list

Good morning Antoine,


> Yes, that's part of future research, defining better *in-pool* observer. =
Sadly, right now, even if you use mask construction inside, it's quite easy=
 to trace leaves by value weight. Of course, you can enforce equal-value le=
aves, as for a regular onchain CoinJoin. I think it comes with a higher onc=
hain cost in case of pool breakage.


Perhaps not necessarily.

An advantage of WabiSabi is I can pretend to be two or more participants.

For example, I can pretend to be "Alice" and "Bob", and pretend that "Alice=
" owes a life debt to "Bob".

At initial state setup, I put a 1.0 BTC coin as "Alice" and a 0.5 BTC coin =
as "Bob".

Now, at each state update I need to sign as "Alice" and "Bob".
However, after the first initial state, I can use a new persona "Bobby" to =
*own* my coins, even though I still have to sign as "Alice" and "Bob" in ev=
ery state update.

What the other pool participants see is that the 1.0 BTC "Alice" coin and t=
he 0.5 BTC "Bob" coin are merged into the 1.5 BTC "Bobby" coin.
What they cannot be sure of is:

* "Alice" paid to "Bob", who is now pretending to be "Bobby".
* "Bob" paid to "Alice", who is now pretending to be "Bobby".
* "Alice" and "Bob" are the same person, and is also pretending to be "Bobb=
y".

All the other participants know is that whoever owns the coin *now* is stil=
l part of the pool, but cannot be sure which participant *really* owns whic=
h coin, and whether participants are sockpuppets (which is why it should us=
e n-of-n at each state update, incidentally).

In effect, it "imports" the possibility of PayJoin inside the CoinPool cons=
truction.


Regards,
ZmnSCPxj