Quote from: Automatic Monkey on October 15, 2016, 04:48:10 AM

Quote from: poptartcat on October 15, 2016, 03:53:36 AM

Quote from: Automatic Monkey on October 15, 2016, 03:49:44 AM

Quote from: poptartcat on October 15, 2016, 12:54:01 AM

Besides the stake grinding mentioned above and other attacks that only PoS is vulnerable to, another issue is if there are only one or two exchanges controlling volume, and then an exchange gets hacked. If a hacker gets his hands on 10-50% of a PoW currency it sucks, and it's bad, but he can't attack the chain just by virtue of holding coins. This isn't the case with PoS currencies, where a hacker can basically control the blockchain if they get their hands on a large portion of the supply, either through an exchange or some other means. This led to the Vericoin/Mintpal rollback fiasco a while ago, and almost led to NXT rolling back their chain as well in one of the (many) Bter "hacks".

That's true, but if a person had control of that many PoS coins and corrupted the blockchain he would instantly make his own holdings worthless because nobody would want the coin anymore. Once a hack of that size was announced he wouldn't even have to attack the chain, people would be dumping like crazy until it's dead once they realized it was possible. if he were to buy enough coins to do this he would drive the price to the moon with his demand, very expensive for him and then what, turn it all into a shitcoin with forged blocks? Yes he could destroy the coin but he would destroy himself too, only someone very rich and insane could do it and everyone else who sold to him would profit from his loss before it happened. So I don't think that would ever happen.

Meanwhile you can get control of 50% of the BTC hash with 864165 TH. Miners are about $125/TH now, so for $108M you can control a network with a market cap of $10B. That's a 100:1 leverage, I like the odds of that happening a lot better.

Except you couldn't market buy that many miners. You'd have to like have your own chips fabbed, packaged, and setup your own warehouses to run them in, which may or may not cost more than 108M USD. But, your same logic applies, why would someone spend that much money to gain control over something that will then crash in value? Personally I think it's a helluva lot more likely to occur when some hacker can do it for (practically) free by hacking an exchange compared to someone spending hundreds of millions or more dollars creating the infrastructure to 51% Bitcoin, or in the case of other leading PoW coins like Litecoin or Monero or something maybe millions to tens of millions, still a lot more than what it costs to hack a website.

If you were Bitmain you could get that many miners, and they mine too. A PoW attacker has the advantage of not actually holding the coin, so if he destroys it he loses only his investment, which he can then use to mine something else or he can hold the blockchain hostage and make demands. A website hacker could attack PoS much more cheaply, but he would also make more money selling the coins than trashing the blockchain and ending up holding something he can't sell.

Also the community can do their part to prevent PoS attacks by staking their coins and not using the exchanges for storage. When the use of SDC exceeds the trading of SDC that will happen and there won't be enough coins in any one place to do what you are talking about.

I suspect there already aren't enough coins in one place to make this type of attack possible. The largest SDC wallet is less than 7% of the total.

https://chainz.cryptoid.info/sdc/#!rich

I can think of a few PoW wallets that are around 60%.