[bitcoin-dev] Scaling by Partitioning

Andrew onelineproof at gmail.com
Wed Dec 9 22:35:07 UTC 2015


Hi Akiva

I sketched out a similar proposal here:
https://bitcointalk.org/index.php?topic=1083345.0

It's good to see people talking about this :). I'm not quite convinced with
segregated witness, as it might mess up some things, but will take a closer
look.
On Dec 9, 2015 7:32 AM, "Loi Luu via bitcoin-dev" <
bitcoin-dev at 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 at 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"
>>
>>
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>>
>
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