[bitcoin-dev] Significant losses by double-spending unconfirmed transactions
matthieu at blockcypher.com
Thu Jul 16 00:08:05 UTC 2015
On Wed, Jul 15, 2015 at 12:32 PM, Peter Todd <pete at petertodd.org> wrote:
> "In a Sybil attack the attacker subverts the reputation system of a
> peer-to-peer network by creating a large number of pseudonymous
> identities, using them to gain a disproportionately large influence."
Our "identities" aren't pseudonymous.
In the case of Bitcoin, there's something like 6,000 nodes, so if that
> 20% is achived via outgoing connections you'd have 600 to 1200 active
> outgoing connections using up network resources. Meanwhile, the default
> is 8 outgoing connections - you're using about two orders of magnitude
> more resources.
You're not talking about a Sybil attack anymore, just resource use. We do
know how to change default configurations to offer more connections.
If you are achieving that via incoming connections, you're placing a big
> part of the relay network under central control. As we've seen in the
> case of Chainalysis's sybil attack, even unintentional confirguation
> screwups can cause serious and widespread issues due to the large number
> of nodes that can fail in one go. (note how Chainalysis's actions were
> described(1) as a sybil attack by multiple Bitcoin devs, including
> Gregory Maxwell, Wladimir van der Laan, and myself)
We're not Chainanalysis and we do not run hundreds of distinct nodes. Just
a few well-tuned ones.
> What you are doing is inherently incompatible with decentralization.
That's a matter of opinion. One could argue your actions and control
attempts hurt decentralization. Either way, no one should play the
decentralization police or act as a gatekeeper.
Question: Do you have relationships with mining pools? For instance, are
> you looking at contracts to have transactions mined to guarantee
No, we do not. We do not know anyone else having such contracts. As you
know, Coinbase also denied having such contracts in place . But you seem
to have more relationships with mining pools than we do.
CTO and Founder, BlockCypher
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