Subject: Re: [Bitcoin-development] Auto-generated miner backbone

From: Peter Todd <[email-masked]>
Date: Mon, 4 Nov 2013 07:20:39 -0500

On Mon, Nov 04, 2013 at 01:03:50PM +0100, Mike Hearn wrote:
> >
> > The suggested change is actually very simple (minutes of coding) and
> > elegant and addresses precisely the identified problem.
> >
> 
> Disagree. Unless I'm misunderstanding what they propose, their suggested
> change would mean anyone could broadcast a newly discovered block at any
> point and have a 50% chance of being the winner. That is a fundamental
> change to the dynamics of how Bitcoin works that would require careful
> thought and study.

It's worth pointing out that my previous post on this list for
"near-block broadcasts" - where blocks that almost but not quite met the
proof-of-work threshold are also broadcast so that propagation of
transactions can be proven - also naturally leads to their proposed
solution. Any miner who sees a near-block-broadcast extending a chain
fork that they aren't mining on would naturally see that as evidence
that the other side has more hashing power, and thus it's in their
interest to mine it rather than the side they are mining.

You know, the whole paper follows the same logic as the point I made
months ago in how if there is no explicit blocksize limit miners have
incentives to make their blocks large enough that they only propagate to
just over 50% of the hashing power, thus causing their competitors to
waste effort.  They analyze the situation in terms of a sybil attack,
where I proposed a more fundemental mechanism to achieve the same goal
based on simple physics.

-- 
'peter'[:-1]@petertodd.org
000000000000000719f061e0fa83343ddbe80d2b6a1fefc84691ffe8652385e0