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From: Gregory Maxwell <greg@xiph.org>
Date: Sat, 6 Jan 2018 00:44:20 +0000
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To: Luke Dashjr <luke@dashjr.org>, 
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
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Subject: Re: [bitcoin-dev] =?utf-8?q?Bech32_and_P2SH=C2=B2?=
Precedence: list

P2SH^2 wasn't a serious proposal-- I just suggested it as a thought
experiment. I don't think it offers much useful in the context of
Bitcoin today. Particularly since weight calculations have made output
space relatively more expensive and fees are at quite non-negligible
rates interest in "storing data" in outputs should at least not be
increasing.

Moreover, unfortunately, people already rushed bech32 to market in
advance of practically any public review-- regrettable but it is what
it is... I don't think adding more address diversity at this time
wouldn't be good for the ecosystem.

What we might want to do is consider working on an address-next
proposal that has an explicit timeframe of N years out, and very loud
don't deploy this--- layered hashing is just one very minor slightly
nice to have... things like coded expiration times, abilities to have
amounts under checksum, etc. are probably more worth consideration.


On Thu, Jan 4, 2018 at 2:23 PM, Luke Dashjr via bitcoin-dev
<bitcoin-dev@lists.linuxfoundation.org> wrote:
> I know I'm super-late to bring this up, but was there a reason Bech32 omi=
tted
> the previously-discussed P2SH=C2=B2 improvements? Since deployment isn't =
too
> widespread yet, maybe it'd be worth a quick revision to add this?
>
> For those unfamiliar with the concept, the idea is to have the address in=
clude
> the *single* SHA256 hash of the public key or script, rather than
> RIPEMD160(SHA256(pubkey)) or SHA256(SHA256(script)). The sender would the=
n
> perform the second hash to produce the output. Doing this would in the fu=
ture
> enable relaying the "middle-hash" as a way to prove the final hash is in =
fact
> a hash itself, thereby proving it is not embedded data spam.
>
> Bech32 seems like a huge missed opportunity to add this, since everyone w=
ill
> probably be upgrading to it at some point.
>
> Luke
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