From: Luke Dashjr <luke@dashjr•org>
To: shaolinfry <shaolinfry@protonmail•ch>,
Bitcoin Protocol Discussion
<bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Moving towards user activated soft fork activation
Date: Tue, 28 Feb 2017 21:20:29 +0000 [thread overview]
Message-ID: <201702282120.29614.luke@dashjr.org> (raw)
In-Reply-To: <jo5-7HCZX7tgdMpIQgK85HCPP14FWxvOIbjV_oerIfc-HOP1GbK3SxFX82Ls23yU1L7y95QsFFggddMNdo5Sxy7YhTJhRFN1f8d6PaA8b7s=@protonmail.ch>
Without at least a majority hashrate validating blocks, it is possible just a
single invalid block could split the chain such that the majority continue
building a most-work on that invalid block.
This failure to validate a softfork is similar in some respects to a hardfork,
but with one critical difference: the default behaviour of old nodes will be
to follow the chain with the most-work that was valid under the pre-softfork
rules. This actually *inverts* the benefit of the softfork over a hardfork,
and makes a softfork deployed in such a manner de facto behave as if it had
been a hardfork, IF someone ever mines a single malicious block.
For this reason, I think a minority-hashrate softfork requires a much higher
degree of social support than merely the widespread agreement typical of
softforks. It might perhaps require less than the full ~100% consensus
hardforks require, but it likely comes somewhat close.
Once it gets over 50% hashrate enforcement, however, the situation improves a
lot more: a malicious block may split obsolete miners off the valid chain, but
it will eventually resolve on its own given enough time. Due to natural
fluctuations in block finding, however, automatic measurement may need to look
for >75%.
So I would suggest that instead of a simple flag day activation, this proposal
would be improved by changing the flag day to merely reduce the hashrate
requirement from 95% to 75%.
(In addition to the above concerns, if >50% of miners are hostile to the
network, we likely have other problems.)
Luke
next prev parent reply other threads:[~2017-02-28 21:20 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-25 23:55 shaolinfry
2017-02-26 17:34 ` Jameson Lopp
2017-02-27 16:02 ` shaolinfry
2017-02-27 16:50 ` Eric Voskuil
2017-02-28 21:20 ` Luke Dashjr [this message]
2017-03-12 15:47 ` shaolinfry
2017-03-05 14:33 Chris Belcher
2017-03-05 18:10 ` David Vorick
2017-03-05 18:48 ` Eric Voskuil
2017-03-05 21:31 ` Nick ODell
2017-03-06 9:18 ` David Vorick
2017-03-06 10:29 ` Edmund Edgar
2017-03-06 23:23 ` Gareth Williams
2017-03-07 1:07 ` Edmund Edgar
2017-03-07 17:37 ` Eric Voskuil
2017-03-07 9:17 ` Tom Zander
2017-03-07 18:13 ` Eric Voskuil
2017-03-07 19:13 ` Alphonse Pace
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