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From: Johnson Lau <jl2012@xbt.hk>
In-Reply-To: <201704262001.10933.luke@dashjr.org>
Date: Thu, 27 Apr 2017 04:09:34 +0800
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Message-Id: <442502AC-CC00-481C-A864-5E5F6F648276@xbt.hk>
References: <201704202028.53113.luke@dashjr.org>
	<06E90C6D-8B4C-40A7-8807-8811A27AE401@xbt.hk>
	<201704262001.10933.luke@dashjr.org>
To: Luke Dashjr <luke@dashjr.org>
Cc: bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Segwit v2
Precedence: list


> On 27 Apr 2017, at 04:01, Luke Dashjr <luke@dashjr.org> wrote:
>=20
> On Wednesday 26 April 2017 7:31:38 PM Johnson Lau wrote:
>> I prefer not to do anything that requires pools software upgrade or =
wallet
>> upgrade. So I prefer to keep the dummy marker, and not change the
>> commitment structure as suggested by another post.
>=20
> Fair enough, I guess. Although I think the dummy marker could actually =
be non-
> consensus critical so long as the hashing replaces it with a 0.
>=20
>> For your second suggestion, I think we should keep scriptSig empty as =
that
>> should be obsoleted. If you want to put something in scriptSig, you =
should
>> put it in witness instead.
>=20
> There are things scriptSig can do that witness cannot today - =
specifically add=20
> additional conditions under the signature. We can always obsolete =
scriptSig=20
> later, after segwit has provided an alternative way to do this.

You can do this with witness too, which is also cheaper. Just need to =
make sure the signature covers a special part of the witness. I will =
make a proposal to Litecoin soon, which allows signing and executing =
extra scripts in witness. Useful for things like OP_PUSHBLOCKHASH

>=20
>> Maybe we could restrict witness to IsPushOnly() scriptPubKey, so =
miners
>> can=E2=80=99t put garbage to legacy txs.
>=20
> They already can malleate transactions and add garbage to the blocks. =
I don't=20
> see the benefit here.

Witness is cheaper and bigger

>=20
> Luke