From: Sjors Provoost <sjors@sprovoost.nl>
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Date: Thu, 28 Sep 2017 18:45:47 +0300
References: <20170927160654.GA12492@savin.petertodd.org>
	<oqihpf$5gc$1@blaine.gmane.org>
	<B5DE4E92-C5B3-4C01-A148-E3C46C897323@sprovoost.nl>
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	<14496C9C-E291-4415-B07E-859853579D20@sprovoost.nl>
	<oqj369$18u$1@blaine.gmane.org>
To: Andreas Schildbach <andreas@schildbach.de>,
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
In-Reply-To: <oqj369$18u$1@blaine.gmane.org>
Message-Id: <4745C5CF-AA3A-4614-99DA-DE3C985F3D69@sprovoost.nl>
Subject: Re: [bitcoin-dev] Address expiration times should be added to
	BIP-173
Precedence: list


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Op 28 sep. 2017, om 18:06 heeft Andreas Schildbach via bitcoin-dev =
<bitcoin-dev@lists.linuxfoundation.org> het volgende geschreven:
>=20
> On 09/28/2017 04:41 PM, Sjors Provoost via bitcoin-dev wrote:
>=20
>>> The payment request message is just as one-way as an address is. It =
is
>>> already being emailed and printed on an invoice, in fact it often =
acts
>>> as the invoice.
>>=20
>> True and the more complicated fields, like a digital signature, are =
optional. Are you suggesting BIP-70 payment requests should be rendered =
with bech32? How long would those be if it's just the address and =
expiration date?
>=20
> I've not yet progressed that far in segwit support, but I can't think =
of
> a reason why not. You can request coins to any script using the =
payment
> protocol.
>=20
> Regarding size, I've had no problems putting (unsigned) payment =
request
> messages into QR codes. I doubt paying to a native segwit address will
> change much in size. Protobuf is very efficient.

Bech32 is just a replacement for Base58. It's not strictly SegWit =
related. If I understand correctly the only reason it won't be used for =
legacy addresses is to prevent confusion:

https://www.youtube.com/watch?v=3DNqiN9VFE4CU
https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki

Regarding size I'm mostly curious how big it is on a screen or a =
physical paper, as text, not as a QR code. This would involve =
deserializing the protobuf and rendering the result in bech32.

I does sound like there's overlap between BIP-70 and BIP-173 that should =
be resolved.

Perhaps any payment request can be rendered as bech32 and any bech32 =
address can converted to a payment request. Maybe only for a limited set =
of fields (address, expiration, amount). This would be a matter of =
agreeing how the protobuf should be serialized and deserialized. In that =
case the protobuf would not contain the literal bech32 address as a =
string, but instead it would contain the underlying data (public key / =
script hash, network, etc).

Sjors

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