[sillysaurus3]

https://notehub.org/nz8d0

Basically, the longest chain is considered correct. And it has to work that way. It's why BTC is sybil-resistant.

So the attack is to get >51% of the hash power together, then mine in secret, creating a perfectly valid longer chain with a different tx history.

Publish it, and watch the world burn.

[mavdi]

I wonder what would be needed to gain 51% hash power? How many super computers would that be?

[gruez]

>How many super computers would that be?

you're asking the wrong question. mainly because bitcoin mining is done with ASICs and not general purpose computers. I would be surprised if the bitcoin network hashrate isn't higher than all the general purpose computing power in the world combined (converted to double SHA256 hash rate).