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From: Bryan Bishop <kanzure@gmail.com>
Date: Thu, 27 Jul 2017 13:56:43 -0500
Message-ID: <CABaSBazdodBNWJ+q8AGhJ8xZ7F+BkWb=5yp9DCs4tHhVny28CA@mail.gmail.com>
To: Bitcoin Dev <bitcoin-dev@lists.linuxfoundation.org>,
	Bryan Bishop <kanzure@gmail.com>
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Subject: [bitcoin-dev] Fwd: [Mimblewimble] proofs of position and UTXO set
	commitments
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---------- Forwarded message ----------
From: Bram Cohen <bram@bittorrent.com>
Date: Thu, Jul 27, 2017 at 1:21 PM
Subject: Re: [Mimblewimble] Switch to Blake2
To: Ignotus Peverell <igno.peverell@protonmail.com>
Cc: Bryan Bishop <kanzure@gmail.com>


I have quite a few thoughts about proofs of position. I gave a talk about
it which hopefully gets the points across if you go through all the Q&A:

https://www.youtube.com/watch?v=52FVkHlCh7Y

On Mon, Jul 24, 2017 at 12:12 PM, Ignotus Peverell <
igno.peverell@protonmail.com> wrote:

> Interesting, thanks for the link. Seems we arrived at similar conclusions
> regarding the hash function, with similar frustrations with respect to
> blake2b/2s.
>
> Funny that it's also for the same merkle set application. We ended up with
> a Merkle Mountain Range [1] instead of a Patricia tree. The MMR is
> append-only and makes pruning easy, which works well for MimbleWimble. You
> can navigate down the MMR with just the position the element was inserted
> at, so we just keep a simple index for that. Memory layout is great as a
> lot of it is immutable and sit close together, although the current impl
> doesn't leverage that too well yet. Wonder if Bram looked at MMRs? Patricia
> trees may make more sense for Bitcoin though.
>
> Proof of positions are cool, might look at that some more in the near
> future, when we're less busy implementing everything else ;-)
>
>
> - Igno
>
> [1] https://github.com/ignopeverell/grin/blob/master/doc/merkle.md
>
> -------- Original Message --------
> Subject: Re: [Mimblewimble] Switch to Blake2
> Local Time: July 24, 2017 6:44 PM
> UTC Time: July 24, 2017 6:44 PM
> From: kanzure@gmail.com
> To: Ignotus Peverell <igno.peverell@protonmail.com>, Bram Cohen <
> bram@bittorrent.com>, Bryan Bishop <kanzure@gmail.com>
>
> On Fri, Jul 21, 2017 at 1:12 PM, Ignotus Peverell <
> igno.peverell@protonmail.com> wrote:
>
>> So I'm considering a switch to the Blake2 [3] hash function.
>>
>
> Bram recently made some comments about blake a few weeks ago:
> http://diyhpl.us/wiki/transcripts/sf-bitcoin-meetup/2017-07-
> 08-bram-cohen-merkle-sets/
>
> - Bryan
> http://heybryan.org/
> 1 512 203 0507 <(512)%20203-0507>
>
>
>



-- 
- Bryan
http://heybryan.org/
1 512 203 0507

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<div dir=3D"ltr"><br><div class=3D"gmail_quote">---------- Forwarded messag=
e ----------<br>From: <b class=3D"gmail_sendername">Bram Cohen</b> <span di=
r=3D"ltr">&lt;<a href=3D"mailto:bram@bittorrent.com">bram@bittorrent.com</a=
>&gt;</span><br>Date: Thu, Jul 27, 2017 at 1:21 PM<br>Subject: Re: [Mimblew=
imble] Switch to Blake2<br>To: Ignotus Peverell &lt;<a href=3D"mailto:igno.=
peverell@protonmail.com">igno.peverell@protonmail.com</a>&gt;<br>Cc: Bryan =
Bishop &lt;<a href=3D"mailto:kanzure@gmail.com">kanzure@gmail.com</a>&gt;<b=
r><br><br><div dir=3D"ltr">I have quite a few thoughts about proofs of posi=
tion. I gave a talk about it which hopefully gets the points across if you =
go through all the Q&amp;A:<div><br></div><div><a href=3D"https://www.youtu=
be.com/watch?v=3D52FVkHlCh7Y" target=3D"_blank">https://www.youtube.com/wat=
ch?<wbr>v=3D52FVkHlCh7Y</a><br></div></div><div class=3D"HOEnZb"><div class=
=3D"h5"><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">On Mon, J=
ul 24, 2017 at 12:12 PM, Ignotus Peverell <span dir=3D"ltr">&lt;<a href=3D"=
mailto:igno.peverell@protonmail.com" target=3D"_blank">igno.peverell@proton=
mail.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" style=
=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Int=
eresting, thanks for the link. Seems we arrived at similar conclusions rega=
rding the hash function, with similar frustrations with respect to blake2b/=
2s.<br></div><div><br></div><div>Funny that it&#39;s also for the same merk=
le set application. We ended up with a Merkle Mountain Range [1] instead of=
 a Patricia tree. The MMR is append-only and makes pruning easy, which work=
s well for MimbleWimble. You can navigate down the MMR with just the positi=
on the element was inserted at, so we just keep a simple index for that. Me=
mory layout is great as a lot of it is immutable and sit close together, al=
though the current impl doesn&#39;t leverage that too well yet. Wonder if B=
ram looked at MMRs? Patricia trees may make more sense for Bitcoin though.<=
br></div><div><br></div><div>Proof of positions are cool, might look at tha=
t some more in the near future, when we&#39;re less busy implementing every=
thing else ;-)<br></div><div><br></div><div class=3D"m_-8211544057623852129=
m_7438166164816387555protonmail_signature_block"><div class=3D"m_-821154405=
7623852129m_7438166164816387555protonmail_signature_block-user m_-821154405=
7623852129m_7438166164816387555protonmail_signature_block-empty"><br></div>=
<div class=3D"m_-8211544057623852129m_7438166164816387555protonmail_signatu=
re_block-proton">- Igno<br></div><div class=3D"m_-8211544057623852129m_7438=
166164816387555protonmail_signature_block-proton"><br></div><div class=3D"m=
_-8211544057623852129m_7438166164816387555protonmail_signature_block-proton=
">[1] <a href=3D"https://github.com/ignopeverell/grin/blob/master/doc/merkl=
e.md" target=3D"_blank">https://github.com/ignopeverel<wbr>l/grin/blob/mast=
er/doc/merkle.<wbr>md</a><br></div></div><div class=3D"m_-82115440576238521=
29HOEnZb"><div class=3D"m_-8211544057623852129h5"><div><br></div><blockquot=
e class=3D"m_-8211544057623852129m_7438166164816387555protonmail_quote" typ=
e=3D"cite"><div>-------- Original Message --------<br></div><div>Subject: R=
e: [Mimblewimble] Switch to Blake2<br></div><div>Local Time: July 24, 2017 =
6:44 PM<br></div><div>UTC Time: July 24, 2017 6:44 PM<br></div><div>From: <=
a href=3D"mailto:kanzure@gmail.com" target=3D"_blank">kanzure@gmail.com</a>=
<br></div><div>To: Ignotus Peverell &lt;<a href=3D"mailto:igno.peverell@pro=
tonmail.com" target=3D"_blank">igno.peverell@protonmail.com</a>&gt;<wbr>, B=
ram Cohen &lt;<a href=3D"mailto:bram@bittorrent.com" target=3D"_blank">bram=
@bittorrent.com</a>&gt;, Bryan Bishop &lt;<a href=3D"mailto:kanzure@gmail.c=
om" target=3D"_blank">kanzure@gmail.com</a>&gt;<br></div><div><br></div><di=
v dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><div>On=
 Fri, Jul 21, 2017 at 1:12 PM, Ignotus Peverell <span dir=3D"ltr">&lt;<a hr=
ef=3D"mailto:igno.peverell@protonmail.com" rel=3D"noreferrer nofollow noope=
ner" target=3D"_blank">igno.peverell@protonmail.com</a>&gt;</span> wrote:<b=
r></div><blockquote style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid=
 rgb(204,204,204);padding-left:1ex" class=3D"gmail_quote"><div>So I&#39;m c=
onsidering a switch to the Blake2 [3] hash function.<br></div></blockquote>=
</div><div><br></div><div>Bram recently made some comments about blake a fe=
w weeks ago:<br></div></div><div class=3D"gmail_extra"><div><a href=3D"http=
://diyhpl.us/wiki/transcripts/sf-bitcoin-meetup/2017-07-08-bram-cohen-merkl=
e-sets/" rel=3D"noreferrer nofollow noopener" target=3D"_blank">http://diyh=
pl.us/wiki/transcri<wbr>pts/sf-bitcoin-meetup/2017-07-<wbr>08-bram-cohen-me=
rkle-sets/</a><br></div><div><br></div><div class=3D"m_-8211544057623852129=
m_7438166164816387555gmail_signature"><div>- Bryan<br></div><div><a href=3D=
"http://heybryan.org/" rel=3D"noreferrer nofollow noopener" target=3D"_blan=
k">http://heybryan.org/</a><br></div><div><a href=3D"tel:(512)%20203-0507" =
value=3D"+15122030507" target=3D"_blank">1 512 203 0507</a><br></div></div>=
</div></div></blockquote><div><br></div></div></div></blockquote></div><br>=
</div>
</div></div></div><br><br clear=3D"all"><div><br></div>-- <br><div class=3D=
"gmail_signature" data-smartmail=3D"gmail_signature">- Bryan<br><a href=3D"=
http://heybryan.org/" target=3D"_blank">http://heybryan.org/</a><br>1 512 2=
03 0507</div>
</div>

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