From: Anthony Towns <aj@erisian.com.au>
To: bitcoin-dev@lists.linuxfoundation.org
Subject: Re: [bitcoin-dev] Let's deploy BIP65 CHECKLOCKTIMEVERIFY!
Date: Tue, 13 Oct 2015 03:06:37 +1000 [thread overview]
Message-ID: <20151012170637.GA21399@navy> (raw)
In-Reply-To: <1444633370859.8a298e9c@Nodemailer>
On Mon, Oct 12, 2015 at 12:02:51AM -0700, digitsu412 via bitcoin-dev wrote:
> First I think your unsaid assumption about the fragility of a soft
> fork showing incorrect confirmations is dependent on the percentage
> of hash power that didn't upgrade. If using your same numbers this
> was only 5% of the hash power, the attack is effectively not effective
> (u less the attacker knew an exact merchant that was unfortunately on
> the minority of the network.
Actually, just to take this scenario more explicitly...
Say you've got 5% of hashpower running on old software, along with,
say, 1500 nodes; and meanwhile you've got 95% of hashpower running new
software, along with 4000 nodes.
There's still about 750 nodes running 0.9 or 0.8 of 5400 total according
to bitnodes.21.co/nodes, so those numbers seems at least plausible to
me for the first week or two after a soft-fork is activated.
Eventually an old-rules block gets found by the 5% hashpower. The 4000
new nodes and 95% of hashpower ignore it, of course. With 8 random
connections, old nodes should have 92% chance of seeing an old node
as a peer, so I think around ~1300 of them should still be a connected
subgraph, and the old-rules block should get propogated amongst them
(until two new-rules blocks come along and orphan it).
An SPV client with 12 random connections here has 96% chance of having one
of the ~1300 old nodes as a peer, and if so, will see the old-rules block,
that will be orphaned, and may be at risk from double-spends as a result.
So I think even with just 5% hashpower and ~30% of nodes left running
the old version, a "damaging soft fork" still poses a fairly high risk to
someone receiving payments via an SPV client, and trusting transactions
with few confirmations.
Cheers,
aj
next prev parent reply other threads:[~2015-10-12 17:06 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-27 18:50 [bitcoin-dev] Let's deploy BIP65 CHECKLOCKTIMEVERIFY! Peter Todd
2015-09-27 20:26 ` jl2012
2015-09-27 20:27 ` Peter Todd
2015-09-27 20:27 ` Mark Friedenbach
2015-09-27 20:41 ` Btc Drak
2015-09-28 10:10 ` s7r
2015-09-28 10:48 ` Mike Hearn
2015-09-28 11:00 ` Adam Back
2015-09-28 11:40 ` Mike Hearn
2015-09-28 12:20 ` Eric Lombrozo
2015-09-28 12:26 ` Mike Hearn
2015-09-28 12:44 ` Eric Lombrozo
2015-09-28 12:54 ` Mike Hearn
2015-09-29 6:17 ` Eric Lombrozo
2015-09-29 12:02 ` Mike Hearn
2015-09-28 14:05 ` Btc Drak
2015-09-28 14:17 ` Mike Hearn
2015-09-28 21:12 ` odinn
2015-09-28 22:16 ` Dave Scotese
2015-09-28 11:04 ` Eric Lombrozo
2015-09-28 12:47 ` Tier Nolan
2015-09-28 13:01 ` Gavin Andresen
2015-09-28 13:28 ` Peter Todd
2015-09-28 13:43 ` Gavin Andresen
2015-09-28 14:14 ` Peter Todd
2015-09-28 13:21 ` Peter Todd
2015-09-28 13:41 ` Mike Hearn
2015-09-28 14:29 ` Peter Todd
2015-09-28 14:33 ` Mike Hearn
2015-09-28 14:43 ` Peter Todd
2015-09-28 14:51 ` Mike Hearn
2015-09-28 15:05 ` Peter Todd
2015-09-28 15:38 ` Mike Hearn
2015-09-28 16:52 ` jl2012
2015-09-28 17:14 ` Mike Hearn
2015-09-28 23:17 ` Jorge Timón
2015-09-29 12:07 ` Mike Hearn
2015-09-29 15:09 ` [bitcoin-dev] Why soft-forks? was: " Santino Napolitano
2015-09-29 13:30 ` [bitcoin-dev] " Jonathan Toomim (Toomim Bros)
2015-09-29 15:59 ` jl2012
2015-09-29 19:54 ` odinn
2015-09-29 18:31 ` Gregory Maxwell
2015-09-30 17:11 ` Mike Hearn
2015-09-30 17:58 ` Jorge Timón
2015-10-01 14:23 ` Tom Harding
2015-09-30 18:15 ` Adam Back
2015-09-30 19:26 ` Jeff Garzik
2015-09-30 19:56 ` Mike Hearn
2015-09-30 20:37 ` Jorge Timón
2015-09-30 21:06 ` Mike Hearn
2015-09-30 22:14 ` Jorge Timón
2015-10-01 0:11 ` Jorge Timón
2015-09-30 22:17 ` Jeff Garzik
2015-09-30 23:25 ` Gregory Maxwell
2015-09-30 20:15 ` Gregory Maxwell
2015-09-30 21:01 ` Mike Hearn
2015-09-30 22:59 ` Gregory Maxwell
2015-10-01 4:08 ` [bitcoin-dev] Crossing the line? [Was: Re: Let's deploy BIP65 CHECKLOCKTIMEVERIFY!] Tao Effect
2015-10-01 16:39 ` Jeff Garzik
2015-10-01 20:17 ` Milly Bitcoin
2015-10-02 12:23 ` Mike Hearn
2015-10-02 13:14 ` jl2012
2015-10-02 14:10 ` Marcel Jamin
2015-10-02 16:37 ` Gregory Maxwell
2015-10-07 15:00 ` [bitcoin-dev] Let's deploy BIP65 CHECKLOCKTIMEVERIFY! Anthony Towns
2015-10-07 15:46 ` Jonathan Toomim (Toomim Bros)
2015-10-07 16:02 ` Eric Lombrozo
2015-10-07 16:25 ` Eric Lombrozo
2015-10-07 16:26 ` Jonathan Toomim (Toomim Bros)
2015-10-07 16:38 ` Anthony Towns
2015-10-10 7:23 ` Anthony Towns
2015-10-12 7:02 ` digitsu
2015-10-12 16:33 ` Anthony Towns
2015-10-12 17:06 ` Anthony Towns [this message]
2015-10-13 0:08 ` digitsu
2015-09-29 20:03 ` Wladimir J. van der Laan
2015-09-30 4:05 ` Rusty Russell
2015-09-30 6:19 ` Adam Back
2015-09-30 12:30 ` Mike Hearn
2015-09-30 15:55 ` Jorge Timón
2015-09-30 19:17 ` John Winslow
2015-10-01 0:06 ` Rusty Russell
2015-09-30 17:14 ` Adam Back
2015-10-01 0:04 ` Rusty Russell
2015-10-02 1:57 NotMike Hearn
2015-10-02 2:12 ` GC
2015-10-05 10:59 ` Mike Hearn
2015-10-05 11:23 ` Jeff Garzik
2015-10-05 11:28 ` Mike Hearn
2015-10-05 12:04 ` Jorge Timón
2015-10-05 12:08 ` Clément Elbaz
2015-10-05 12:16 ` Jorge Timón
2015-10-05 12:29 ` Clément Elbaz
2015-10-05 15:42 ` Jorge Timón
2015-10-05 12:10 ` Mike Hearn
2015-10-05 15:33 ` Jorge Timón
2015-10-05 16:46 ` Mike Hearn
2015-10-06 6:20 ` Anthony Towns
2015-10-07 6:13 ` Micha Bailey
2015-10-05 13:29 ` Jorge Timón
2015-10-05 13:24 ` Jorge Timón
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