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In-Reply-To: <201904040248.34162.luke@dashjr.org>
From: Ethan Scruples <ethan.scruples@gmail.com>
Date: Wed, 3 Apr 2019 23:04:58 -0400
Message-ID: <CACiOHGy9q_W+w1n6q2hxvbrD_SfvbQ3AsNe+W+UBgEV8QF2C3Q@mail.gmail.com>
To: Luke Dashjr <luke@dashjr.org>
Content-Type: multipart/alternative; boundary="00000000000019d1310585aba3ee"
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] assumeutxo and UTXO snapshots
Precedence: list

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> This is exactly the danger. UTXO snapshots are NOT an alternative to a
real IBD. There are HUGE security implications for this.

This is a perfect example of what I am talking about when I say that people
do not appear to notice that there is no important security implication to
be found here.

If there are huge security implications for this, then I am keen to hear
them. In the scenario I have described, what advantage does Bob have over
Alice? What actionable information has Bob gained, and what is the action
he can take with it in hand? What value does Bob receive in return for the
electricity he has spent validating the previous blocks? I cannot find any,
but I am open to hearing the answer, and I think others would benefit from
knowing it as well.

On Wed, Apr 3, 2019 at 10:49 PM Luke Dashjr <luke@dashjr.org> wrote:

> On Wednesday 03 April 2019 15:39:29 Ethan Scruples via bitcoin-dev wrote:
> > If we can get mandatory UTXO commitments soft forked into Bitcoin, we get
> > the advantage of a non-growing IBD,
>
> No, we don't. This is exactly the danger. UTXO snapshots are NOT an
> alternative to a real IBD. There are HUGE security implications for this.
> Frankly, the danger that someone would do such a thing is itself a good
> reason not to ever add UTXO commitments.
>
> Luke
>

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<div dir=3D"ltr">&gt; This is exactly the danger. UTXO snapshots are NOT an=
=C2=A0alternative to a real IBD. There are HUGE security implications for t=
his.=C2=A0<br><div><br></div><div>This is a perfect example of what I am ta=
lking about when I say that people do not appear to notice that there is no=
 important security implication to be found here.</div><div><br></div><div>=
If there are huge security implications for this, then I am keen to hear th=
em. In the scenario I have described, what advantage does Bob have over Ali=
ce? What actionable information has Bob gained, and what is the action he c=
an take with it in hand? What value does Bob receive in return for the elec=
tricity he has spent validating the previous blocks? I cannot find any, but=
 I am open to hearing the answer, and I think others would benefit from kno=
wing it as well.</div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr"=
 class=3D"gmail_attr">On Wed, Apr 3, 2019 at 10:49 PM Luke Dashjr &lt;<a hr=
ef=3D"mailto:luke@dashjr.org" target=3D"_blank">luke@dashjr.org</a>&gt; wro=
te:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px =
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On Wednesday=
 03 April 2019 15:39:29 Ethan Scruples via bitcoin-dev wrote:<br>
&gt; If we can get mandatory UTXO commitments soft forked into Bitcoin, we =
get<br>
&gt; the advantage of a non-growing IBD,<br>
<br>
No, we don&#39;t. This is exactly the danger. UTXO snapshots are NOT an <br=
>
alternative to a real IBD. There are HUGE security implications for this. <=
br>
Frankly, the danger that someone would do such a thing is itself a good <br=
>
reason not to ever add UTXO commitments.<br>
<br>
Luke<br>
</blockquote></div>

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