Quote from: phillipsjk on September 26, 2014, 04:05:06 AM

Quote from: kokojie on September 25, 2014, 10:04:06 PM

Where's your rebuttal? I don't see anything disputing the fact that PoS is much more expensive to attack against. You just keep saying Bitcoin is expensive to attack, that's your opinion, I don't believe $500m is expensive for a well funded and determined attacker, such as nation government or big banks.

How many zero-day vulnerabilities and network nodes do you think you can find with $500 million?

With PoW nodes, they have no reason to be storing a "hot wallet". With PoS nodes, every node has a "hot wallet" in order to prove "stake".

The implication is that a determined attacker may be able to control more than 50% of the "stake" for a lot less than $500Million. As a bonus, they would be using less than 1MW of power while attacking the network (assuming thousands of machines to get good connectivity/node isolation).

Quote from: Odalv

Yes, I will only accept bitcoins with 12 * 6 = 72 confirmation (12 hour ... "old" money) so DOUBLE SPEND will NOT be possible with only 90% of hash power.

With >51% of the hash-power, an attacker can roll back transactions. With 90% of the hash-power, they can roll back 8 hours every hour (in secret until they release their fork).

Hot wallet requirement is depend on the actual implementation, Peercoin needs hot wallets, Bitshares and NxT do not. It's incorrect to say PoS needs to run hot wallets.

Also I can't understand the logic of spending money = successfully hacking thousands of machines (especially if they are PoS hot wallets, which the owner probably took measures to properly secure their private computer, if these private computers are so easily hacked, then all web servers are doomed). I can think of several ways to make my hot wallet on my private computer unhackable from the outside. Usually people lose their hot wallet because they got phished, their dropbox backup got hacked, or installed some malware/keylogger. A LOT more Bitcoin hot wallets has been hacked, compared to Peercoin PoS miner hot wallet, I think so far ZERO peercoin PoS miner hotwallet has been hacked, the reality doesn't agree with your theory.

Ok, let's assume in the unlikely event a hacker does obtain 51% of all currency available, then the chain can still just rollback the attacker address. If someone hacked 51% of all Bitcoin, you can be pretty sure Bitcoin is rolling back the attacker's address too, otherwise the eco-system will fail immediately. So the only way to attack a PoS network, is to buy the stake legitimately. Then as soon as you do start to attack the PoS network, the community will find out and act upon the aggression, your address will be getting blocked immediately, and lose all your stake that you spent an astronomical amount of money to buy. You can be pretty sure that any potential attacker would know this, therefore they won't even attempt this attack. This is the reason ZERO PoS network has been 51% attacked so far. It's basically a nuke in the PoS network's arsenal, it can be used, so the attacker in fear of the nuke, won't even attempt the attack, which end up making the nuke never used. But it's good to know it's there.

But if an attacker obtain 51% mining power in a PoW network, there's nearly nothing you could do, other than go out and out-spend the attacker by buying more hardware and spending more on electricity. I'm sure the hardware vendor and electricity companies would love to see this happen. If no one step up and out-spend the attacker, the attacker with their vast amount of hardware can PERMANENTLY disable the Bitcoin PoW network, there's nothing you could do to stop them, other than... converting Bitcoin to PoS

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