Date: Tue, 10 May 2022 12:31:00 +0000
To: Chris Belcher <belcher@riseup.net>,
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: AdamISZ <AdamISZ@protonmail.com>
Reply-To: AdamISZ <AdamISZ@protonmail.com>
Message-ID: <dI-CkifjUyQssT-JzKmv09W6NggL89orF78qz1AOFlBL7Kmxo6z5BVBEr6aZha_nbnBQHFcN1hqC5EZM7lB0U0jiBtE3ZWCiIR_dGBJMsDA=@protonmail.com>
In-Reply-To: <82948428-29a3-e50a-a54a-520a83f39bba@riseup.net>
References: <22c80504-e648-e021-866e-ca5a5db3b247@riseup.net>
 <bsOJ-OnnA4FutVmPqtg1xY-k0notwX4OqqIpdMsymXR9-KnS2iXGUE8o7kDVeYBMCqAX0v3oEAmiVMhUIB25gupx6l_bLff2_CNsLK_sk-U=@protonmail.com>
 <82948428-29a3-e50a-a54a-520a83f39bba@riseup.net>
Feedback-ID: 11565511:user:proton
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Subject: Re: [bitcoin-dev] BIP proposal: Timelocked address fidelity bond
	for BIP39 seeds
Precedence: list

------- Original Message -------
On Sunday, May 1st, 2022 at 11:01, Chris Belcher via bitcoin-dev <bitcoin-d=
ev@lists.linuxfoundation.org> wrote:


> Hello ZmnSCPxj,
>
> This is an intended feature. I'm thinking that the same fidelity bond
> can be used to running a JoinMarket maker as well as a Teleport
> (Coinswap) maker.
>
> I don't believe it's abusable. It would be a problem if the same
> fidelity bond is used by two makers in the same application, but
> JoinMarket takers are already coded to check for this, and Teleport
> takers will soon as well. Using the same bond across different
> applications is fine.
>
> Best,
> CB
>

Hi Chris, Zmn, list,
I've noodled about this a few times in the past (especially when trying to =
figure out an LSAG style ring sig based FB for privacy, but that does not s=
eem workable), and I can't decide the right perspective on it.

A user sacrifices X amount of time-value-of-money (henceforth TVOM) by comm=
itting in Joinmarket with FB1. He then uses the same FB1 in Teleport, let's=
 say. If he gets benefit Y from using FB1 in Joinmarket, and benefit Z in T=
eleport, then presumably he'll only do it if (probabilistically) he thinks =
Y+Z > X.

But as an assessor of FB1 in Joinmarket, I don't know if it's also being us=
ed for Teleport, and more importantly, if it's being used somewhere else I'=
m not even aware of. Now I'm not an economist I admit, so I might not be in=
tuit-ing this situation right, but it fees to me like the right answer is "=
It's fine for a closed system, but not an open one." (i.e. if the set of po=
ssible usages is not something that all participants have fixed in advance,=
 then there is an effective Sybilling problem, like I'm, as an assessor, th=
inking that sacrificed value 100 is there, whereas actually it's only 15, o=
r whatever.)

As I mentioned in https://github.com/JoinMarket-Org/joinmarket-clientserver=
/issues/993#issuecomment-1110784059 , I did wonder about domain separation =
tags because of this, and as I vaguely alluded to there, I'm really not sur=
e about it.

If it was me I'd want to include domain separation via part of the signed m=
essage, since I don't see how it hurts? For scenarios where reuse is fine, =
reuse can still happen.

Cheers,
waxwing/AdamISZ