From: Rusty Russell <rusty@rustcorp•com.au>
To: Peter Todd <pete@petertodd•org>,
Bitcoin Protocol Discussion
<bitcoin-dev@lists•linuxfoundation.org>,
"Christian Decker" <decker.christian@gmail•com>
Cc: Matt Corallo <matt@chaincode•com>
Subject: Re: [bitcoin-dev] Making OP_TRUE standard?
Date: Thu, 31 May 2018 12:17:58 +0930 [thread overview]
Message-ID: <87h8mov8v5.fsf@rustcorp.com.au> (raw)
In-Reply-To: <87muwhvozr.fsf@rustcorp.com.au>
Rusty Russell <rusty@rustcorp•com.au> writes:
> AFAICT the optimal DoS is where:
>
> 1. Attacker sends a 100,000 vbyte tx @1sat/vbyte.
> 2. Replaces it with a 108 vbyte tx @2sat/vbyte which spends one of
> those inputs.
> 3. Replaces that spent input in the 100k tx and does it again.
>
> It takes 3.5 seconds to propagate to 50% of network[1] (probably much worse
> given 100k txs), so they can only do this about 86 times per block.
>
> That means they send 86 * (100000 + 108) = 8609288 vbytes for a cost of
> 86 * 2 * 108 + 100000 / 2 = 68576 satoshi (assuming 50% chance 100k tx
> gets mined).
This 50% chance assumption is wrong; it's almost 0% for a low enough
fee. Thus the cost is only 18576, making the cost for the transactions
463x lower than just sending 1sat/vbyte txs under optimal conditions.
That's a bit ouch.[1]
I think a better solution is to address the DoS potential directly:
if a replacement doesn't meet #3 or #4, but *does* increase the feerate
by at least minrelayfee, processing should be delayed by 30-60 seconds.
That means that eventually you will RBF a larger tx, but it'll take
much longer. Should be easy to implement, too, since similar timers
will be needed for dandelion.
Cheers,
Rusty.
[1] Christian grabbed some more detailed propagation stats for me: larger
txs do propagate slower, but only by a factor of 2.5 or so.
next prev parent reply other threads:[~2018-06-01 1:20 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-08 23:57 Rusty Russell
2018-05-09 0:24 ` Olaoluwa Osuntokun
2018-05-09 3:02 ` ZmnSCPxj
2018-05-10 2:08 ` Rusty Russell
2018-05-09 17:56 ` Johnson Lau
2018-05-09 19:27 ` Peter Todd
2018-05-09 20:19 ` Johnson Lau
2018-05-09 20:59 ` Peter Todd
2018-05-09 22:06 ` Olaoluwa Osuntokun
2018-05-10 2:06 ` Rusty Russell
2018-05-10 2:27 ` Luke Dashjr
2018-05-10 3:07 ` ZmnSCPxj
2018-05-15 1:22 ` ZmnSCPxj
2018-05-17 2:44 ` Rusty Russell
2018-05-17 10:28 ` ZmnSCPxj
2018-05-17 17:35 ` Christian Decker
2018-05-17 20:06 ` Jim Posen
2018-05-21 3:44 ` Rusty Russell
2018-05-21 3:56 ` Peter Todd
2018-05-30 2:47 ` Rusty Russell
2018-05-31 2:47 ` Rusty Russell [this message]
2018-05-21 14:20 ` Russell O'Connor
2018-05-10 9:33 ` Jorge Timón
2018-05-10 9:33 ` Jorge Timón
2018-05-10 9:43 ` Luke Dashjr
2018-05-11 2:44 ` ZmnSCPxj
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