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From: Timo Hanke <timo.hanke@web.de>
To: Luke Dashjr <luke@dashjr.org>,
Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
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Luke, do you mean to replace the first 4 bytes of the second chunk (bytes
64..67 in 0-based counting) by the XOR of those 4 bytes with the first 4
bytes of the midstate? (I assume you don't care about 12 bytes but rather
those 4 bytes.)
This does not work. All it does is adding another computational step before
you can check for a collision in those 4 bytes. It makes finding a
collision only marginally harder.
On Wed, May 11, 2016 at 7:28 AM, Luke Dashjr via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:
> On Wednesday, May 11, 2016 12:20:55 PM Sergio Demian Lerner via bitcoin-dev
> wrote:
> > On Tue, May 10, 2016 at 6:43 PM, Sergio Demian Lerner <
> > sergio.d.lerner@gmail.com> wrote:
> > > You can find it here:
> > >
> https://bitslog.wordpress.com/2014/03/18/the-re-design-of-the-bitcoin-blo
> > > ck-header/
> > >
> > > Basically, the idea is to put in the first 64 bytes a 4 byte hash of
> the
> > > second 64-byte chunk. That design also allows increased nonce space in
> > > the first 64 bytes.
> >
> > My mistake here. I didn't recalled correctly my own idea. The idea is to
> > include in the second 64-byte chunk a 4-byte hash of the first chunk, not
> > the opposite.
>
> What if we XOR bytes 64..76 with the first 12 bytes of the SHA2 midstate?
> Would that work?
>
> Luke
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
--001a1136069cecd65b053293783f
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<div dir=3D"ltr">Luke, do you mean to replace the first 4 bytes of the seco=
nd chunk (bytes 64..67 in 0-based counting) by the XOR of those 4 bytes wit=
h the first 4 bytes of the midstate? (I assume you don't care about 12 =
bytes but rather those 4 bytes.)<div><br></div><div>This does not work. All=
it does is adding another computational step before you can check for a co=
llision in those 4 bytes. It makes finding a collision only marginally hard=
er.</div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">On=
Wed, May 11, 2016 at 7:28 AM, Luke Dashjr via bitcoin-dev <span dir=3D"ltr=
"><<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_b=
lank">bitcoin-dev@lists.linuxfoundation.org</a>></span> wrote:<br><block=
quote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc=
solid;padding-left:1ex">On Wednesday, May 11, 2016 12:20:55 PM Sergio Demi=
an Lerner via bitcoin-dev<br>
wrote:<br>
<div><div class=3D"h5">> On Tue, May 10, 2016 at 6:43 PM, Sergio Demian =
Lerner <<br>
> <a href=3D"mailto:sergio.d.lerner@gmail.com">sergio.d.lerner@gmail.com=
</a>> wrote:<br>
> > You can find it here:<br>
> > <a href=3D"https://bitslog.wordpress.com/2014/03/18/the-re-design=
-of-the-bitcoin-blo" rel=3D"noreferrer" target=3D"_blank">https://bitslog.w=
ordpress.com/2014/03/18/the-re-design-of-the-bitcoin-blo</a><br>
> > ck-header/<br>
> ><br>
> > Basically, the idea is to put in the first 64 bytes a 4 byte hash=
of the<br>
> > second 64-byte chunk. That design also allows increased nonce spa=
ce in<br>
> > the first 64 bytes.<br>
><br>
> My mistake here. I didn't recalled correctly my own idea. The idea=
is to<br>
> include in the second 64-byte chunk a 4-byte hash of the first chunk, =
not<br>
> the opposite.<br>
<br>
</div></div>What if we XOR bytes 64..76 with the first 12 bytes of the SHA2=
midstate?<br>
Would that work?<br>
<br>
Luke<br>
<div class=3D"HOEnZb"><div class=3D"h5">___________________________________=
____________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.=
linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.org/mail=
man/listinfo/bitcoin-dev</a><br>
</div></div></blockquote></div><br></div>
--001a1136069cecd65b053293783f--
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