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Date: Wed, 12 Feb 2014 19:39:11 -0500
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From: Alex Morcos <morcos@gmail.com>
To: Luke-Jr <luke@dashjr.org>
Content-Type: multipart/alternative; boundary=001a1135183c0ac14f04f23eebab
Cc: bitcoin-development@lists.sourceforge.net
Subject: Re: [Bitcoin-development] [RFC] [BIP proposal] Dealing with
	malleability
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I apologize if this has been discussed many times before.

As a long term solution to malleable transactions, wouldn't it be possible
to modify the signatures to be of the entire transaction.  Why do you have
to zero out the inputs?  I can see that this would be a hard fork, and
maybe it would be somewhat tricky to extract signatures first (since you
can sign everything except the signatures), but it would seem to me that
this is an important enough change to consider making.


On Wed, Feb 12, 2014 at 5:52 PM, Luke-Jr <luke@dashjr.org> wrote:

> On Wednesday, February 12, 2014 8:27:52 PM Mark Friedenbach wrote:
> > On 02/12/2014 08:44 AM, Alan Reiner wrote:
> > > Changing the protocol to use these static IDs is a pretty fundamental
> > > change that would never happen in Bitcoin.   But they can still be
> > > useful at the application level to mitigate these issues.
> >
> > Not to mention that it would be potentially very insecure to have
> > consensus depend on data (scriptSigs) which are not hashed in the Merkle
> > structure of a block.
> >
> > Not that anyone on this list has suggested such a change, but I've seen
> > it raised multiple times on the forum....
>
> This would be a problem if it was used in the merkle tree, but I'm pretty
> sure
> using it for input selection would be pretty safe. One could even avoid the
> index by simply using the hashScript as the sole input value; then even
> CoinJoins would be safe without breaking chains of transactions (although
> this
> would break address reuse entirely - but I don't see that as a problem in a
> theoretical world). One of those things that an altcoin could improve upon
> Bitcoin with... ;)
>
>
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<div dir=3D"ltr">I apologize if this has been discussed many times before.<=
div><div><br></div><div>As a long term solution to malleable transactions, =
wouldn&#39;t it be possible to modify the signatures to be of the entire tr=
ansaction. =A0Why do you have to zero out the inputs? =A0I can see that thi=
s would be a hard fork, and maybe it would be somewhat tricky to extract si=
gnatures first (since you can sign everything except the signatures), but i=
t would seem to me that this is an important enough change to consider maki=
ng.</div>

<div><br></div><div><br></div><div><br></div><div><br></div>
<div><br></div><div><br></div></div></div><div class=3D"gmail_extra"><br><b=
r><div class=3D"gmail_quote">On Wed, Feb 12, 2014 at 5:52 PM, Luke-Jr <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 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex"><div class=3D"">On Wednesday, February 12, 2=
014 8:27:52 PM Mark Friedenbach wrote:<br>
&gt; On 02/12/2014 08:44 AM, Alan Reiner wrote:<br>
&gt; &gt; Changing the protocol to use these static IDs is a pretty fundame=
ntal<br>
&gt; &gt; change that would never happen in Bitcoin. =A0 But they can still=
 be<br>
&gt; &gt; useful at the application level to mitigate these issues.<br>
&gt;<br>
&gt; Not to mention that it would be potentially very insecure to have<br>
&gt; consensus depend on data (scriptSigs) which are not hashed in the Merk=
le<br>
&gt; structure of a block.<br>
&gt;<br>
&gt; Not that anyone on this list has suggested such a change, but I&#39;ve=
 seen<br>
&gt; it raised multiple times on the forum....<br>
<br>
</div>This would be a problem if it was used in the merkle tree, but I&#39;=
m pretty sure<br>
using it for input selection would be pretty safe. One could even avoid the=
<br>
index by simply using the hashScript as the sole input value; then even<br>
CoinJoins would be safe without breaking chains of transactions (although t=
his<br>
would break address reuse entirely - but I don&#39;t see that as a problem =
in a<br>
theoretical world). One of those things that an altcoin could improve upon<=
br>
Bitcoin with... ;)<br>
<div class=3D"HOEnZb"><div class=3D"h5"><br>
---------------------------------------------------------------------------=
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Get your Android app in front of a whole new audience. =A0Start now.<br>
<a href=3D"http://pubads.g.doubleclick.net/gampad/clk?id=3D124407151&amp;iu=
=3D/4140/ostg.clktrk" target=3D"_blank">http://pubads.g.doubleclick.net/gam=
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pment@lists.sourceforge.net</a><br>
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velopment</a><br>
</div></div></blockquote></div><br></div>

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