Quote from: fairglu on January 19, 2015, 08:21:10 AM

Quote from: eagleflies on January 16, 2015, 09:49:29 PM

I think such attack could be mitigated with typical PoS if we used quite low Max Stake Age e.g. 1 week? And Min Stake Age of couple of hours? This way it does not matter if someone keeps staking for months since Weight will be capped.

Yep, tweaking can help, but it's all a matter of compromise and making it "harder" to attack.

For instance, even with stake age and other tweaks, you could envision someone stashing coins in thousandths of wallet addresses, distributing them in dozens of cloud VMs with a client modified for the purpose of the attack, and then starting them all at once, thus take over the chain.

If the attack is timed well enough, the above may not even be that costly: each address would need to hold the bare minimum for staking, and each VM would only need to run as long as necessary for the attack. Using digital ocean f.i., you could have 60 VMs (and daemons) up for 12 hour for just $5, which would be quite enough to overwhelm any low-volume PoS chain. You could even DDOS the few "friendly" top-staking nodes for good measure.

Preparation for such an attack would be very obvious if not planned well in advance (lots of transactions to distribute coins), and would be very obvious when it's running (lots of new nodes in the network), but would likely happen faster than anyone could react.

AFAIK the only protection against this would the be PoS difficulty retarget, but if that diff starts too low, it would not be able to move higher fast enough, as an attacker can throw a lot of cheap staking power.

If MinAge and MaxAge are low enough this should make such an attack much more costly.

Do you think Magi Coin's PoS should be resistant to such an attack? If yes, why?