Subject: Re: [bitcoin-dev] BIP 117 Feedback

From: "Russell O'Connor" <[email-masked]>
Date: Tue, 16 Jan 2018 03:39:28 -0500

On Mon, Jan 15, 2018 at 11:15 PM, Luke Dashjr <[email-masked]> 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.