[Bitcoin-development] Bitcoin-development Digest, Vol 31, Issue 41

Ryan Carboni ryan.jc.pc at gmail.com
Wed Dec 25 06:53:54 UTC 2013


You just completely ignored my point. I'm not sure who's trying to insult
whom, or if you're attempting an argumentum ad hominem. My idea is
completely valid.

The only way to man in the middle to have such a large percentage of hash
power is to either a) attack a pool (which people would notice when their
withdrawals go nowhere), b) attack a large number of nodes, which must have
enough combined hash power to mine four blocks within three days for people
to notice (I think it is unlikely for Bitcoin point of sale nodes to have
significant hash power), or c) the attacker himself has 1% of the hash
power and is diverting it to conduct a man in the middle attack against one
single person (as opposed to a major retailer who has a round the clock IT
staff). In order for a large number of nodes to be attacked, it must be by
someone who either is a state actor or an ISP, at which point you've
already lost.

It's really simple math, it require on even the most optimistic estimates a
tenth of a percent of the total network hash power to mine 4 blocks within
three days with good luck. Or maybe this single person is on vacation, then
it would take a hundredth of a percent of the total hash power over two
weeks. I think very few people even have a hundredth of a percent of the
total hash power, which goes to show how secure the network is, and how
little my proposal would weaken network security. I'll concede that
difficulty could be reduced only by 80% if only four blocks were mined in 3
days, which would provide sufficient margin against these proposed man in
the middle attacks, because block-chain growth would be noticeably reduced.

But I repeat myself. Repeatedly. I wish you would understand my points. I'm
making a good faith effort to provide an original idea before it's possibly
too late. But fine. I have nothing more to add, and it's the holidays.


On Tue, Dec 24, 2013 at 2:47 AM, <
bitcoin-development-request at lists.sourceforge.net> wrote:

> An attacker with some small hashpower isolates you (as an individual)
> from the network by MITMing your network. You just switch the the
> attackers chain as if nothing happened because of the network rule
> that defines it as OK. Today, you will see that you're behind and warn
> the user.
>
> Was it really so hard to write a three-sentence paragraph to clarify
> the attack instead of insulting people? Still, posting ideas here
> without spending time to ensure you understand the Bitcoin network
> well is frowned upon.
>
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