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From: Jeffrey Paul <jp@eeqj.com>
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Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Serialised P2SH HD chains
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> On 20141204, at 07:42, Luke Dashjr <luke@dashjr.org> wrote:
>=20
> Is anyone working on a serialisation format to convey P2SH HD chains? =
For=20
> example, to give someone who wants to make recurring payments a single =
token=20
> that can be used to generate many P2SH addresses paying to a multisig =
script.
>=20
> I'm thinking of something along the lines of a simple series of =
tokens, each=20
> indicating either a HD chain or literal script content. For all HD =
chains in=20
> the data, a child key would be generated based on the payment number, =
and all=20
> tokens concatenated to form the P2SH serialised script. Eg, for a =
simple 2-
> of-2, you would do something like this:
>    literal(OP_2) HDChain HDChain literal(OP_2 OP_CHECKMULTISIG)
> Does this sufficiently cover all reasonable use cases?


What is the use case for something like this?  It=E2=80=99s my =
impression that a single token that can be used to obtain many P2SH =
addresses paying to a multisig script looks something like

   =
bitcoin:?r=3Dhttps://payee.com/customer12345/recurring/paymentrequest/new

As it=E2=80=99s impossible to actually transmit a tx without network =
access, why would it be necessary to, at payment time, not contact the =
payee and use the existing bip70 authenticated payment request protocol =
to find out exactly what multisig address they=E2=80=99d like paid at =
that moment?

The model that you describe where a payer can, without communication =
with the payee, generate additional multisig p2sh addresses based on a =
set of xpubs presumes that the payee would never want to e.g. cycle =
their own keys or change their cooperating multisig participants=E2=80=99 =
keys.  Is this wise?

Lately I=E2=80=99ve been thinking of bitcoin addresses (even multisig) =
as sort of MX records - something that the paying user shouldn=E2=80=99t =
depend on being static, because they are derived from keys that may =
change (or be lost or compromised) over time.  The canonical =E2=80=9Cpay =
me at this address forever QR code=E2=80=9D should be a bitcoin: URI =
that points to a payment request generating URL, should it not?

Best,
-jp

--
Jeffrey Paul                                                      EEQJ
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