I like the innovation in the proof of stake concept in PPCcoin very much, but in the current PPCoin implementation, as far as I understand it, I see some drawbacks.
I’m also thinking about improving the proof of stake concept, therefore I have some questions:
Why using coinage for securing the network? Doesn't this make it more vulnerable to burning coin age double spending attacks?
Isn't it better to just sign with the coins itself?
(The reward of coins could be still 1% per coin age)
Isn't it better if you can secure the network at once with your coins? So why someone has to wait X days?
It's a good question. Main reasons are:
1) Using new coins to sign block could cause problem for the block chain to recover from a chain fork. This is why 30-day minimum is chosen with the assumption that any chain fork that extends that long has to be bugs, attacks, or major network partitioning incidents, and would have been resolved via developer and user intervention.
2) Stake kernel is verified before block acceptance/connection to prevent a type of DoS attack on block-chain storage. This also requires a hardening point consistent among all nodes. (As of v0.3 this hardening point is about 21 days due to the 9-day modifier generation window)
I have explained in the design paper that we chose not to redesign bitcoin's data structures so the above design choices were dictated by this decision.
Note the coin-age weighting is capped at 90-day age since v0.2. So beyond 90 days it's effectively generated by coins instead of coin-age.
