Date: Tue, 18 Oct 2022 22:46:13 +0000
To: Andrew Poelstra <apoelstra@wpsoftware.net>
From: rot13maxi <rot13maxi@protonmail.com>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev]
	=?utf-8?q?Trustless_Address_Server_=E2=80=93_Outsou?=
	=?utf-8?q?rcing_handing_out_addresses_to_prevent_address_reuse?=
Precedence: list

Hello Andrew and Bryan,

> No, as I understand the proposal, the "public key" held by the wallet is =
simply
> a signing key used to authenticate addresses, and never leaves the wallet=
.=20

That's right (or at least, that's the intent). Think of importing someone's=
 GPG key and then using it to validate future signed messages from them. In=
 this case, the public key stays in your "address book" entry for a person =
and then whenever you need to fetch a fresh address for them from the Addre=
ss Server, your wallet can validate that it's for their wallet.=20

Making sure that you import a legitimate/authentic public key is a problem,=
 but you only need to do it once per recipient, instead of doing it every t=
ime you need to transact with that person. Maybe that's something you solve=
 in UI (i.e. Signal has you compare strings with your counter-party), or so=
mething you can solve through other metadata (GPG had WoT, or if you're alr=
eady using an address server maybe there's some PKI scheme that's appropria=
te, etc.).=20


Rubin, I think you responded on another branch of the thread, but thanks fo=
r the podcast link. I'll check it out!

Cheers,

Rijndael

------- Original Message -------
On Tuesday, October 18th, 2022 at 8:42 AM, Andrew Poelstra <apoelstra@wpsof=
tware.net> wrote:


> On Mon, Oct 17, 2022 at 07:07:07PM -0500, Bryan Bishop via bitcoin-dev wr=
ote:
>
> > Isn't this the same problem but now for copy-pasting pubkeys instead of=
 an
> > address?
>
>
> No, as I understand the proposal, the "public key" held by the wallet is =
simply
> a signing key used to authenticate addresses, and never leaves the wallet=
. Yes,
> if the wallet's own memory is compromised, it can be tricked into accepti=
ng bad
> addresses, but this is much much harder than compromising data on the cli=
pboard,
> which basically any application can do without any "real" exploits or spe=
cial
> permissions.
>
> As an extreme, this proposal could be run on a hardware wallet which had =
some
> out-of-band way to obtain and authenticate public keys (similar to Signal=
 QR
> codes).
>
> --
> Andrew Poelstra
> Director of Research, Blockstream
> Email: apoelstra at wpsoftware.net
> Web: https://www.wpsoftware.net/andrew
>
> The sun is always shining in space
> -Justin Lewis-Webster