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To: "David A. Harding" <dave@dtrt.org>,
Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
References: <42cd5ffd-63e8-b738-c4ea-13d0699b1268@purse.io>
<20191004082031.ns3pgzwh2zz2mxyc@ganymede>
From: Braydon Fuller <braydon@purse.io>
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Subject: Re: [bitcoin-dev] Chain width expansion
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On 10/4/19 1:20 AM, David A. Harding wrote:
> On Thu, Oct 03, 2019 at 05:38:36PM -0700, Braydon Fuller via bitcoin-de=
v wrote:
>> This paper describes a solution [to DoS attacks] that does not
>> require enabling or maintaining checkpoints and provides improved secu=
rity.
>> [...]=20
>> The paper is available at:
>> https://bcoin.io/papers/bitcoin-chain-expansion.pdf
> [..] But I worry that the mechanisms could also be used to keep a node =
that
> synced to a long-but-lower-PoW chain on that false chain (or other fals=
e
> chain) indefinitely even if it had connections to honest peers that
> tried to tell it about the most-PoW chain.
Here is an example: An attacker eclipses a target node during the
initial block download; all of the target's outgoing peers are the
attacker. The attacker has a low work chain that is sent to the target.
The total chainwork for the low work chain is 0x09104210421039 at a
height of 593,975. The target is now in the state of a fully validated
low work dishonest chain. The target node then connects to an honest
peer and learns about the honest chain. The chainwork of the honest
chain is 0x085b67d9e07a751e53679d68 at a height of 593,975. The first
69,500 headers of the honest chain would have a delay, however the
remaining 52,4475 would not be delayed. Given a maximum of 5 seconds,
this would be a total delay of only 157 seconds.
|
