Quote from: cypherblock on January 21, 2017, 02:09:07 PM

-snip-
Yeah that is the entire point, of the attack.

Anyway, my questions surrounding this attack are:

* Why does the paper call for making an even split between 2 groups of miners, as it's starting point? Wouldn't any division 10%/90% work just as well if you were able to isolate a merchant to the 10%?

Because a 50% split is enough. The idea is that you join the 50% side to make it stronger. Any bigger split would only improve your chances to pull this off.

Quote from: cypherblock on January 21, 2017, 02:09:07 PM

* Does this paper highlight anything new? (it seems obvious that comm disruption between groups will cause chain separation and removing disruption will cause one chain to get orphaned).

I have not read it, but it does not sound like anything new. To me this sounds like a sybil attack on miners.

Quote from: cypherblock on January 21, 2017, 02:09:07 PM

* For blockchains like Ethereum with short times between blocks I guess the term "delay" is appropriate, but really we are causing a complete comm disruption, for the time under which the attack takes place, between the groups, no?

No thats not needed and might cause the attack to get revealed. The delay must just be long enough for the victim to notice the confirmation(s), the attacker taking advantage of that fact and the block(s) getting orphaned.

Quote from: cypherblock on January 21, 2017, 02:16:44 PM

Quote from: piotr_n on January 21, 2017, 01:31:45 PM

I find it quite impossible in practice, to "split the miners into 2 equal groups by causing a communications delay between them".
It's probably even harder than splitting the internet in half.

If you look at this hashrate chart, you can see that by just targeting the 4 largest pools you could split the hashrate into 2 equal groups. So much easier than splitting internet in half. Now still there is the requirement of isolating a merchant node, so that it is only seeing blocks from one side. But problem seems halfway solved with 4 pool attack.

Still sounds like a difficult attack as you would need in depth knowledge how the miners are contected to the network and how those providing the actual hashing power are connected to the central node. There might also be fail saves in place.

Even if you just kick them of the relay network and there is no fail save (which I doubt considering the potential losses) you need to make sure no one gets a "something is wrong"-mail and notices the attack.