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Date: Wed, 9 Dec 2015 23:04:17 -0500
Message-ID: <CABCnA7VOknCC6j5HAazW31jx8kGqiM0t0+Qo8QydShzESV2HkQ@mail.gmail.com>
From: Akiva Lichtner <akiva.lichtner@gmail.com>
To: Loi Luu <loi.luuthe@gmail.com>
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Subject: Re: [bitcoin-dev] Scaling by Partitioning
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It's an interval (a,b) where a, b are between 0 and 21*10^6*10^8 .

Somebody pointed out that this is not easily accomplished using the current
code because there are no coin ids.


On Wed, Dec 9, 2015 at 4:16 PM, Loi Luu <loi.luuthe@gmail.com> wrote:

> I guess the most basic question is how do you define a coin here?
>
> Thanks,
> Loi Luu
> On 10 Dec 2015 2:26 a.m., "Akiva Lichtner" <akiva.lichtner@gmail.com>
> wrote:
>
>> Thanks for giving serious consideration to my post.
>>
>> With regard to your question "if a transaction spends a "coin" that
>> ends in "1" and creates a new coin that ends in "1", which partition
>> should process the transaction?", I would answer that only one
>> partition is involved. In other words, there are N independent block
>> chains that never cross paths.
>>
>> With regard to your question "what is the prior data needed to
>> validate that kind of TXs?" I do not understand what this means. If
>> you can dumb it down a bit that would be good because there could be
>> some interesting concern in this question.
>>
>> Since partitions are completely segregated, there is no need for a
>> node to work on multiple partitions simultaneously. For attacks to be
>> defeated a node needs to be able to work on multiple partitions in
>> turn, not at the same time. The reason is because if the computing
>> power of the good-faith nodes is unbalanced this gives attackers an
>> unfair advantage.
>>
>> On 12/9/15, Loi Luu via bitcoin-dev
>> <bitcoin-dev@lists.linuxfoundation.org> wrote:
>> > Dear Akiva,
>> >
>> > Its Loi Luu, one of the authors of the SCP protocol (
>> > http://eprint.iacr.org/2015/1168.pdf ).
>> >
>> > Before SCP, we had been thinking hard about how to do sharding
>> efficiently
>> > without degrading any security guarantee. A simple solution which splits
>> > the coins, or TXs in to several partitions will just not work. You have
>> to
>> > answer more questions to have a good solutions. For example, I wonder in
>> > your proposal, if a transaction spends a "coin" that ends in "1" and
>> > creates a new coin that ends in "1", which partition should process the
>> > transaction? What is the prior data needed to validate that kind of TXs?
>> >
>> > The problem with other proposals, and probably yours as well,  that we
>> see
>> > is that the amount of data that you need to broadcast immediately to the
>> > network increases linearly with the number of TXs that the network can
>> > process. Thus, sharding does not bring any advantage than simply using
>> > other techniques to publish more blocks in one epoch (like Bitcoin-NG,
>> > Ghost). The whole point of using sharding/ partition is to localize
>> > the bandwidth used, and only broadcast only a minimal data to the
>> network.
>> >
>> > Clearly we are able to localize the bandwidth used with our SCP
>> protocol.
>> > The cost is that now recipients need to  themselves verify whether a
>> > transaction is double spending. However, we think that it is a
>> reasonable
>> > tradeoff, given the potential scalability that SCP can provides.
>> >
>> > Thanks,
>> > Loi Luu.
>> >
>> > On Wed, Dec 9, 2015 at 12:27 AM, Akiva Lichtner via bitcoin-dev <
>> > bitcoin-dev@lists.linuxfoundation.org> wrote:
>> >
>> >> Hello,
>> >>
>> >> I am seeking some expert feedback on an idea for scaling Bitcoin. As a
>> >> brief introduction: I work in the payment industry and I have twenty
>> >> years'
>> >> experience in development. I have some experience with process groups
>> and
>> >> ordering protocols too. I think I understand Satoshi's paper but I
>> admit
>> >> I
>> >> have not read the source code.
>> >>
>> >> The idea is to run more than one simultaneous chain, each chain
>> defeating
>> >> double spending on only part of the coin. The coin would be partitioned
>> >> by
>> >> radix (or modulus, not sure what to call it.) For example in order to
>> >> multiply throughput by a factor of ten you could run ten parallel
>> chains,
>> >> one would work on coin that ends in "0", one on coin that ends in "1",
>> >> and
>> >> so on up to "9".
>> >>
>> >> The number of chains could increase automatically over time based on
>> the
>> >> moving average of transaction volume.
>> >>
>> >> Blocks would have to contain the number of the partition they belong
>> to,
>> >> and miners would have to round-robin through partitions so that an
>> >> attacker
>> >> would not have an unfair advantage working on just one partition.
>> >>
>> >> I don't think there is much impact to miners, but clients would have to
>> >> send more than one message in order to spend money. Client messages
>> will
>> >> need to enumerate coin using some sort of compression, to save space.
>> >> This
>> >> seems okay to me since often in computing client software does have to
>> >> break things up in equal parts (e.g. memory pages, file system blocks,)
>> >> and
>> >> the client software could hide the details.
>> >>
>> >> Best wishes for continued success to the project.
>> >>
>> >> Regards,
>> >> Akiva
>> >>
>> >> P.S. I found a funny anagram for SATOSHI NAKAMOTO: "NSA IS OOOK AT
>> MATH"
>> >>
>> >>
>> >> _______________________________________________
>> >> bitcoin-dev mailing list
>> >> bitcoin-dev@lists.linuxfoundation.org
>> >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>> >>
>> >>
>> >
>>
>

--001a113a986ef538bc0526834c44
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div>It&#39;s an interval (a,b) where a, b are between 0 a=
nd 21*10^6*10^8 .<br><br></div><div>Somebody pointed out that this is not e=
asily accomplished using the current code because there are no coin ids.<br=
><br></div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">=
On Wed, Dec 9, 2015 at 4:16 PM, Loi Luu <span dir=3D"ltr">&lt;<a href=3D"ma=
ilto:loi.luuthe@gmail.com" target=3D"_blank">loi.luuthe@gmail.com</a>&gt;</=
span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8e=
x;border-left:1px #ccc solid;padding-left:1ex"><p dir=3D"ltr">I guess the m=
ost basic question is how do you define a coin here?</p>
<p dir=3D"ltr">Thanks,<br>
Loi Luu</p>
<div class=3D"gmail_quote">On 10 Dec 2015 2:26 a.m., &quot;Akiva Lichtner&q=
uot; &lt;<a href=3D"mailto:akiva.lichtner@gmail.com" target=3D"_blank">akiv=
a.lichtner@gmail.com</a>&gt; wrote:<br type=3D"attribution"><blockquote cla=
ss=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;pa=
dding-left:1ex">Thanks for giving serious consideration to my post.<br>
<br>
With regard to your question &quot;if a transaction spends a &quot;coin&quo=
t; that<br>
ends in &quot;1&quot; and creates a new coin that ends in &quot;1&quot;, wh=
ich partition<br>
should process the transaction?&quot;, I would answer that only one<br>
partition is involved. In other words, there are N independent block<br>
chains that never cross paths.<br>
<br>
With regard to your question &quot;what is the prior data needed to<br>
validate that kind of TXs?&quot; I do not understand what this means. If<br=
>
you can dumb it down a bit that would be good because there could be<br>
some interesting concern in this question.<br>
<br>
Since partitions are completely segregated, there is no need for a<br>
node to work on multiple partitions simultaneously. For attacks to be<br>
defeated a node needs to be able to work on multiple partitions in<br>
turn, not at the same time. The reason is because if the computing<br>
power of the good-faith nodes is unbalanced this gives attackers an<br>
unfair advantage.<br>
<br>
On 12/9/15, Loi Luu via bitcoin-dev<br>
&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_bla=
nk">bitcoin-dev@lists.linuxfoundation.org</a>&gt; wrote:<br>
&gt; Dear Akiva,<br>
&gt;<br>
&gt; Its Loi Luu, one of the authors of the SCP protocol (<br>
&gt; <a href=3D"http://eprint.iacr.org/2015/1168.pdf" rel=3D"noreferrer" ta=
rget=3D"_blank">http://eprint.iacr.org/2015/1168.pdf</a> ).<br>
&gt;<br>
&gt; Before SCP, we had been thinking hard about how to do sharding efficie=
ntly<br>
&gt; without degrading any security guarantee. A simple solution which spli=
ts<br>
&gt; the coins, or TXs in to several partitions will just not work. You hav=
e to<br>
&gt; answer more questions to have a good solutions. For example, I wonder =
in<br>
&gt; your proposal, if a transaction spends a &quot;coin&quot; that ends in=
 &quot;1&quot; and<br>
&gt; creates a new coin that ends in &quot;1&quot;, which partition should =
process the<br>
&gt; transaction? What is the prior data needed to validate that kind of TX=
s?<br>
&gt;<br>
&gt; The problem with other proposals, and probably yours as well,=C2=A0 th=
at we see<br>
&gt; is that the amount of data that you need to broadcast immediately to t=
he<br>
&gt; network increases linearly with the number of TXs that the network can=
<br>
&gt; process. Thus, sharding does not bring any advantage than simply using=
<br>
&gt; other techniques to publish more blocks in one epoch (like Bitcoin-NG,=
<br>
&gt; Ghost). The whole point of using sharding/ partition is to localize<br=
>
&gt; the bandwidth used, and only broadcast only a minimal data to the netw=
ork.<br>
&gt;<br>
&gt; Clearly we are able to localize the bandwidth used with our SCP protoc=
ol.<br>
&gt; The cost is that now recipients need to=C2=A0 themselves verify whethe=
r a<br>
&gt; transaction is double spending. However, we think that it is a reasona=
ble<br>
&gt; tradeoff, given the potential scalability that SCP can provides.<br>
&gt;<br>
&gt; Thanks,<br>
&gt; Loi Luu.<br>
&gt;<br>
&gt; On Wed, Dec 9, 2015 at 12:27 AM, Akiva Lichtner via bitcoin-dev &lt;<b=
r>
&gt; <a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_bl=
ank">bitcoin-dev@lists.linuxfoundation.org</a>&gt; wrote:<br>
&gt;<br>
&gt;&gt; Hello,<br>
&gt;&gt;<br>
&gt;&gt; I am seeking some expert feedback on an idea for scaling Bitcoin. =
As a<br>
&gt;&gt; brief introduction: I work in the payment industry and I have twen=
ty<br>
&gt;&gt; years&#39;<br>
&gt;&gt; experience in development. I have some experience with process gro=
ups and<br>
&gt;&gt; ordering protocols too. I think I understand Satoshi&#39;s paper b=
ut I admit<br>
&gt;&gt; I<br>
&gt;&gt; have not read the source code.<br>
&gt;&gt;<br>
&gt;&gt; The idea is to run more than one simultaneous chain, each chain de=
feating<br>
&gt;&gt; double spending on only part of the coin. The coin would be partit=
ioned<br>
&gt;&gt; by<br>
&gt;&gt; radix (or modulus, not sure what to call it.) For example in order=
 to<br>
&gt;&gt; multiply throughput by a factor of ten you could run ten parallel =
chains,<br>
&gt;&gt; one would work on coin that ends in &quot;0&quot;, one on coin tha=
t ends in &quot;1&quot;,<br>
&gt;&gt; and<br>
&gt;&gt; so on up to &quot;9&quot;.<br>
&gt;&gt;<br>
&gt;&gt; The number of chains could increase automatically over time based =
on the<br>
&gt;&gt; moving average of transaction volume.<br>
&gt;&gt;<br>
&gt;&gt; Blocks would have to contain the number of the partition they belo=
ng to,<br>
&gt;&gt; and miners would have to round-robin through partitions so that an=
<br>
&gt;&gt; attacker<br>
&gt;&gt; would not have an unfair advantage working on just one partition.<=
br>
&gt;&gt;<br>
&gt;&gt; I don&#39;t think there is much impact to miners, but clients woul=
d have to<br>
&gt;&gt; send more than one message in order to spend money. Client message=
s will<br>
&gt;&gt; need to enumerate coin using some sort of compression, to save spa=
ce.<br>
&gt;&gt; This<br>
&gt;&gt; seems okay to me since often in computing client software does hav=
e to<br>
&gt;&gt; break things up in equal parts (e.g. memory pages, file system blo=
cks,)<br>
&gt;&gt; and<br>
&gt;&gt; the client software could hide the details.<br>
&gt;&gt;<br>
&gt;&gt; Best wishes for continued success to the project.<br>
&gt;&gt;<br>
&gt;&gt; Regards,<br>
&gt;&gt; Akiva<br>
&gt;&gt;<br>
&gt;&gt; P.S. I found a funny anagram for SATOSHI NAKAMOTO: &quot;NSA IS OO=
OK AT MATH&quot;<br>
&gt;&gt;<br>
&gt;&gt;<br>
&gt;&gt; _______________________________________________<br>
&gt;&gt; bitcoin-dev mailing list<br>
&gt;&gt; <a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D=
"_blank">bitcoin-dev@lists.linuxfoundation.org</a><br>
&gt;&gt; <a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitc=
oin-dev" rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation=
.org/mailman/listinfo/bitcoin-dev</a><br>
&gt;&gt;<br>
&gt;&gt;<br>
&gt;<br>
</blockquote></div>
</blockquote></div><br></div>

--001a113a986ef538bc0526834c44--