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I'm considering two scenarios of hacking freshly installed bitcoin core node.
Does freshly installed bitcoin-core node have genesis block included in the installation?
This fresh node contacts some peer for downloading blockchain. Can malicious peer give node wrong chain? Is this attack possible and how is it mitigated in bitcoin?
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Does freshly installed bitcoin-core node have genesis block included in the installation?
Yes.
This fresh node contacts some peer for downloading blockchain. Can malicious peer give node wrong chain? Is this attack possible and how is it mitigated in bitcoin?
There is no way for the chain to be "wrong" that would not be detectable to the node. If it's invalid, the node will reject it. If there's a longer chain, the node will reject the shorter chain. If it's the longest, valid chain, it's not wrong.
So bitcoin relys on the fact that the node will eventually manage to get the main (longest) blockchain from honest peer? – croraf – 2017-11-02T21:53:53.533
@croraf That's unavoidable. There's simply no way to make the system work without at least one honest peer. No honest peers is equivalent to no network access at all. – David Schwartz – 2017-11-02T21:54:48.580
1by default the node will attempt to get connected to 30 peers, which usually contains enough honest peers to resolve any conflicts. – Jonathan Silverblood – 2017-11-03T07:07:35.727