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To: Mike Brooks <m@ib.tc>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Smaller Transactions with PubRef
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Good morning Mike,
The issue with SCRIPT re-evaluation is that reorgs cause more processing to=
be done by nodes.
Floating-point Nakamoto Consensus does not help here, since a node can rece=
ive the lower-scored block first, and *then* a higher-scored block, and thu=
s will ***still*** observe a reorg since the chain tip is replaced with a h=
igher-scored block later.
This still increases the processing load on validating fullnodes, and preve=
nts any kind of pruning from working for validating fullnodes.
A miner can also still mount a DoS on validating fullnodes, with `OP_PUBREF=
` and Floating-Point Nakamoto Consensus by re-mining the same block, and br=
oadcasting a block if it has higher score than the previous chain tip.
This locks the blockchain ***and*** increases the load on fullnodes, which =
have to re-validate uses of `OP_PUBREF` that might refer to the chain tip.
Regards,
ZmnSCPxj
> Hey=C2=A0 ZmnSCPxj,
>
> Re-orgs should be solved in a different=C2=A0way.=C2=A0
>
> Best Regards,
> Micahel
>
> On Sat, Aug 1, 2020 at 5:36 PM ZmnSCPxj <ZmnSCPxj@protonmail.com> wrote:
>
> > Good morning Mike,
> >
> > Hard NAK.
> >
> > The responses to the original posting already pointed out important pro=
blems with this:
> >
> > * Encourages address reuse, hurting fungibility and privacy.
> > * Prevents pruning, since access to previous blocks must always be avai=
lable in order to validate.
> > * Optimized implementation requires creating yet another index to previ=
ous block data, increasing requirements on fullnodes.
> > * Requires SCRIPT to be re-evaluated on transactions arriving in=C2=
=A0 newblocks, to protect against reorgs of the chaintip, and in particular=
`OP_PUBREF` references to near the chaintip.
> >
> > None of these issues have been addressed in your current proposal.
> > The proposal looks at clients only, without considering what validators=
have to implement in order to validate new blocks with this opcode.
> >
> > Regards,
> > ZmnSCPxj
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