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	<CAMZUoKn4noCEQR6eqf9hiZSMdk-3b8UHR1NrEFrKNoLSMzVjGQ@mail.gmail.com>
	<87zi5ehat5.fsf@rustcorp.com.au> <201801160415.55197.luke@dashjr.org>
From: "Russell O'Connor" <roconnor@blockstream.io>
Date: Tue, 16 Jan 2018 03:39:28 -0500
Message-ID: <CAMZUoKkb1zcw7N=_Gn3_0miuNVP_LKSYkbeA-U2Yt8+b2G+b7w@mail.gmail.com>
To: Luke Dashjr <luke@dashjr.org>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>,
	Russell O'Connor <roconnor@blockstream.com>,
	Kalle Alm <kalle.alm@gmail.com>
Subject: Re: [bitcoin-dev] BIP 117 Feedback
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On Mon, Jan 15, 2018 at 11:15 PM, Luke Dashjr <luke@dashjr.org> wrote:

> On Tuesday 16 January 2018 1:06:14 AM Rusty Russell via bitcoin-dev wrote:
> > The rule AFAICT is "standard transactions must still work".  This was
> > violated with low-S, but the transformation was arguably trivial.
> >
> > OTOH, use of altstack is completely standard, though in practice it's
> > unused and so only a theoretical concern.
>
> I'm not aware of a single standard/BIP that uses the altstack at all.
>

By "standard transaction" here, Rusty means that (P2SH or Segwit) scripts
that use the alt-stack pass the standardness checks and will be relayed by
recent Bitcoin Core software.

----

Regarding lowS:  I think the more severe standardness change was the added
requirement that (some of the) pubkeys in a multisig must be parsable.  I
have talked with people who cannot retrieve their funds now, when before
they could.  However, like lowS, this was only a change to the standardness
rules and not a consensus change, so these funds are not necessarily
permanently lost.  They can be retrieved with miner help.

I don't see how BIP 117, which is a change in consensus rules that could
cause permanent loss of otherwise well-secured funds (in addition to the
other issues raised about BIP 117), is even comparable to the previous
changes in only the standardness rules.

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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><div class=3D"gmail_quo=
te">On Mon, Jan 15, 2018 at 11:15 PM, Luke Dashjr <span dir=3D"ltr">&lt;<a =
href=3D"mailto:luke@dashjr.org" target=3D"_blank">luke@dashjr.org</a>&gt;</=
span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8e=
x;border-left:1px #ccc solid;padding-left:1ex"><span class=3D"">On Tuesday =
16 January 2018 1:06:14 AM Rusty Russell via bitcoin-dev wrote:<br></span><=
span class=3D"">&gt; The rule AFAICT is &quot;standard transactions must st=
ill work&quot;.=C2=A0 This was<br>
&gt; violated with low-S, but the transformation was arguably trivial.<br>
&gt;<br>
&gt; OTOH, use of altstack is completely standard, though in practice it=
9;s<br>
&gt; unused and so only a theoretical concern.<br>
<br>
</span>I&#39;m not aware of a single standard/BIP that uses the altstack at=
 all.<br></blockquote><div><br></div><div>By &quot;standard transaction&quo=
t; here, Rusty means that (P2SH or Segwit) scripts that use the alt-stack p=
ass the standardness checks and will be relayed by recent Bitcoin Core soft=
ware.</div><div><br></div><div>----</div><div><br></div><div>Regarding lowS=
:=C2=A0 I think the more severe standardness change was the added requireme=
nt that (some of the) pubkeys in a multisig must be parsable.=C2=A0 I have =
talked with people who cannot retrieve their funds now, when before they co=
uld.=C2=A0 However, like lowS, this was only a change to the standardness r=
ules and not a consensus change, so these funds are not necessarily permane=
ntly lost.=C2=A0 They can be retrieved with miner help.<br></div><div><br><=
/div><div>I don&#39;t see how BIP 117, which is a change in consensus rules=
 that could cause permanent loss of otherwise well-secured funds (in additi=
on to the other issues raised about BIP 117), is even comparable to the pre=
vious changes in only the standardness rules.<br></div></div></div></div>

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