[Lightning-dev] Questions on lightning chan closure privacy

[Lloyd Fournier]

Hi Lee,

You are touching on some very relevant privacy challenges for lightning. To
your questions:

1. Is it possible to identify which node funded a lightning channel? (this
tells you who owns the change output)
2. Is it possible to identify who owns which channel close output?

I think that the answer to both these questions hinges on whether you
exclusively use private channels. If you fund private and public channels
with the same wallet then it may be possible to identify your private
channels and the owner of the channel and channel close outputs[1].
I've recently tried to describe what I think needs to happen to turn
lightning into an effective layer-1 privacy tool in the "Removing
cross-layer links" problem on bitcoin-problems.github.io[2].

Cheers

LL

[1] https://arxiv.org/pdf/2003.12470.pdf (section 3.2).[2]
https://bitcoin-problems.github.io/problems/removing-cross-layer-links.html
[2]
https://bitcoin-problems.github.io/problems/removing-cross-layer-links.html

On Sat, 17 Apr 2021 at 12:22, Mr. Lee Chiffre <lee.chiffre at secmail.pro>
wrote:

>
> > Two, if the balances of each side of a
> > channel are different when closing vs. opening, can someone determine
> > which output from the 2 of 2 multisig belongs to who?
>
>
> A thought to add to my last email. In theory it could be determined if the
> output belonging to a certain node later uses that as an input for a non
> private chan opening right? But that would also look the same if it was
> also the same user opening a new chan to that node?
>
> This brings to another question. Not just chan closure but on chan opening
> is it possible to determine which input came from who?
>
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