Re: [bitcoin-dev] Bitcoin-NG whitepaper.

From: Matt Corallo <lf-lists@mattcorallo•com>
To: Ittay <ittay.eyal@cornell•edu>,
	Ittay via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org>,
	Bryan Bishop <kanzure@gmail•com>
Cc: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>,
	Ittay Eyal <ittay.eyal@cornell•edu>
Subject: Re: [bitcoin-dev] Bitcoin-NG whitepaper.
Date: Wed, 14 Oct 2015 18:57:08 +0000	[thread overview]
Message-ID: <28CC699B-4DA8-4472-A795-9505418C688A@mattcorallo.com> (raw)
In-Reply-To: <CABT1wW=xqShMGU0+eDiNyNkr-77fQ_HnyKL87C6iGL-xq8BYVw@mail.gmail.com>

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That conversation missed a second issue. Namely that there is no way to punish people if there is a double spend in a micro block that happens in key block which reorg'd away the first transaction. eg one miner mines a transaction in a micro block, another miner (either by not having seen the first yet, or being malicious - potentially the same miner) mines a key block which reorgs away the first micro block and then, in their first micro block, mines a double spend. This can happen at any time, so you end up having to fall back to regular full blocks for confirmation times :(.

Also, Greg Slepak brought up a good point on twitter at https://twitter.com/taoeffect/status/654358023138209792. Noting that this model means users could no longer pick transactions in a mining pool which was set up in such a way (it could be tweaked to do so with separate rewards and pubkeys, but now the user can commit fraud at a much lower cost - their own pool reward, not the block's total reward).

On October 14, 2015 11:28:51 AM PDT, Ittay via bitcoin-dev <bitcoin-dev@lists•linuxfoundation.org> wrote:
>On Wed, Oct 14, 2015 at 2:12 PM, Bryan Bishop <kanzure@gmail•com>
>wrote:
>
>> On Wed, Oct 14, 2015 at 1:02 PM, Emin Gün Sirer
>> <bitcoin-dev@lists•linuxfoundation.org> wrote:
>> > while the whitepaper has all the nitty gritty details:
>> >      http://arxiv.org/abs/1510.02037
>>
>> Taking reward compensation back by fraud proofs is not enough to fix
>> the problems associated with double spending (such as, everyone has
>to
>> wait for the "real" confirmations instead of the "possibly
>> double-spend" confirmations). Some of this was discussed in -wizards
>> recently:
>> http://gnusha.org/bitcoin-wizards/2015-09-19.log
>
>
>Fraud proof removes all the attacker's revenue. It's like the attacker
>sacrifices an entire block for double spending in the current system. I
>think Luke-Jr got it right at that discussion.
>
>Best,
>Ittay
>
>
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