Date: Tue, 10 May 2022 19:28:05 +0000
To: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>,
 ZmnSCPxj <ZmnSCPxj@protonmail.com>
From: AdamISZ <AdamISZ@protonmail.com>
Reply-To: AdamISZ <AdamISZ@protonmail.com>
Message-ID: <PFBgbTn4_7JXQaRMlMjZDVrGBIr4OKfMK1ftW38cY-8Qu6tm_GllxDOWEj7K4zHkmQz9jA9NO_9rT_UzTSw9rr3RneEKTNhz826LmEIWF7w=@protonmail.com>
In-Reply-To: <6IPqvNW2vQcHQLhUgSmQQLqtnV0RGrsUfnoUMKgv0SDQpVvKh7PIqJOKNazzgEzGE2W5OHHrlEtmg9lapjbiSjTpUuxqPmsiFua2P_ZN_FY=@protonmail.com>
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>
 <dI-CkifjUyQssT-JzKmv09W6NggL89orF78qz1AOFlBL7Kmxo6z5BVBEr6aZha_nbnBQHFcN1hqC5EZM7lB0U0jiBtE3ZWCiIR_dGBJMsDA=@protonmail.com>
 <Xjq4gzy3me86tG6sYumDq16JE8EpRSnC90Ao-02Fyz3i55vRlLY7QKbW9TdaSJg8hiclxpBqhW93CtNgeCzVmbN3CDaW35P3BZwYp1o54H0=@protonmail.com>
 <6IPqvNW2vQcHQLhUgSmQQLqtnV0RGrsUfnoUMKgv0SDQpVvKh7PIqJOKNazzgEzGE2W5OHHrlEtmg9lapjbiSjTpUuxqPmsiFua2P_ZN_FY=@protonmail.com>
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

> I suppose ultimately this brings up the question of the scope of this BIP=
. The abstract points out that the BIP contains both a definition of addres=
s derivation, but also how to sign fidelity bond certificates.
>
> My feeling is that the latter might be better not included? I note that t=
he 'Motivation' section gives motivation for standardisation of derivation =
(this includes things like time schedule), but not the second area - certif=
icate signing. I think the second area is much more tricky, but much more t=
o the point is, isn't it the case that that second area, can be interpreted=
 without consensus between wallet developers? So say you were a hardware wa=
llet provider, or a "node in a box" provider - your customers want you to p=
rovide the ability move funds around, including e.g. moving funds out of an=
 old Joinmarket wallet (in which say there is a now expired timelock addres=
s utxo) by just entering its BIP39 seed. If this BIP addresses that, it sho=
uld be enough.
>
> I don't doubt that there's gains to be had from a broader community discu=
ssing and agreeing the details of how to create a fidelity bond certificate=
, but it's a separate, and more difficult, task.
>
> Cheers,
> waxwing/AdamISZ

Further to that last point, as the BIP draft currently says:

" Almost all wallets implementing this standard can use their
already-existing "Sign Message" function to sign the certificate
message. As the certificate message itself is always an ascii string,
the wallet may not need to specially implement this section at all but
just rely on users copypasting their certificate message into the
already-existing "Sign Message" user interface. This works as long as
the wallet knows how to use the private key of the timelocked address
for signing messages."

So, isn't that an argument that we don't need to specify the certificate me=
ssage format here?

On the other hand, I can hardly disagree that it's worth presenting a kind =
of 'default' way of doing it. But I fear it is not at all simple to decide =
what a secure, general format should be (as per the discussion we started h=
aving here about domain separation tags).

Cheers,
waxwing/AdamISZ