[bitcoin-dev] Progress on Miner Withholding - FPNC

Mike Brooks m at ib.tc
Fri Oct 9 00:16:40 UTC 2020


You are correct.

And also, I did prove what I set out to prove. The code provided privately
to the security team will in fact consume 99% of the CPU, which means it
does have an effect on the electorate.  It is true the node still
stubbornly passes messages, but I would argue that this is still very much
a problem that would concern operators, and perhaps the threshold for a
patch is much too high.  A layered security system like what is found in
bitcoin necessitates an attack chain.  The `getdata` message is an implicit
information disclosure that allows for the identification of dissenting
nodes.   As ZmnSCPxj pointed out, block mixing will give preemption at most
67% of the network, and the remaining dissenting nodes can be quelled by
maxing out their processing power.  All of this can be used together to
make sure that a withheld block becomes the prevailing solution.

FPNC rebalances incentives to serve the interests of the network, and
fundamentally resolves a class of abuses that reshape the electorate.  FPNC
will produce a more deceliterized and fair network than "first seen."


On Wed, Oct 7, 2020 at 5:12 PM Pieter Wuille <bitcoin-dev at wuille.net> wrote:

> On Wednesday, October 7, 2020 1:31 PM, Mike Brooks via bitcoin-dev <
> bitcoin-dev at lists.linuxfoundation.org> wrote:
> But first of all, I'd like to say that the idea for FPNC came out of a
> conversation with ZmnSCPxj's in regards to re-org stability.  When I had
> proposed blockchain pointers with the PubRef opcode, he took the time to
> explain to me concerns around re-orgs and why it is a bigger problem than I
> initially had thought — and I greatly appreciate this detail.   After
> touching base with ZmnSCPxj and Greg Maxwell there is an overwhelming view
> that the current problems that face the network outweigh any theoretical
> ones.
> Greg Maxwell isn't on this list, but assuming this is about the conversion
> you've had on Bitcoin Core's security disclosure list, I believe this is a
> misrepresentation. The discussion has been mostly around a DoS attack
> report which turned out to be a mistake.
> Cheers,
> --
> Pieter
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