Q: What's the Difference between PPCoin and Bitcoin?
A: PPCoin is a crypto-currency project forked from Bitcoin and we aim to achieve energy-efficiency and keep as much as possible the original Bitcoin's preferable properties.
Q: What's Stake or Proof-of-Stake?
A: Stake/Proof-of-Stake is term referring to the use of currency itself (ownership) to achieve certain goals. In PPCoin proof-of-stake is used to provide minting and transaction processing in place of proof-of-work. Please refer to our design paper for details of this approach and our implementation.
The 'stake' field in the getinfo output shows the currency amount you currently staked to protect the network. This amount is subject to the holding period of 520-block maturity window before you can use it again (it would return to your balance once matured).
Q: How is it energy-efficient when there is still mining?
A: The energy efficiency we refer to is long-term energy efficiency, as in long term we do not require the use of energy to sustain the network.
Currently proof-of-work remains the most practical way of providing initial minting of a crypto-currency. So we decided to keep it as part of our hybrid design.
Q: Why do you need central checkpointing?
A: Decentralization is a hard problem. In our first release we still rely on a centrally broadcasted checkpointing mechanism to fully protect the network. We are actively considering/reviewing proposals to possibly substitute this part of the design and weaken/eliminate central checkpoint in the future to make ppcoin approach the level of decentralization of Bitcoin.
Q: When can I start generating proof-of-stake blocks?
A: After 30 days the network would start seeing proof-of-stake blocks. If you have balance ppcoind would automatically try to generate stake for you. If you find a stake the reward is 1 cent per coin-year consumed (can be roughly understood as 1% interest annually). The reward amount is added to your stake amount and is shown together in the 'stake' field of getinfo output.
Because stake is withheld from spending for 520 blocks, if you do need to keep your balance around to be spent soon we provided a configuration option 'reservebalance' to help you keep your balance from being used by stake. You can add a line 'reservebalance=10000' to ppcoin.conf and restart your ppcoind. This way ppcoind would try to keep your balance above 10000 coins when generating stakes.
Q: Can I use encrypted wallet?
A: Yes. Encrypted wallet is supported but there is some difference from Bitcoin. If you use an encrypted wallet you would have to unlock the wallet in order to mint blocks. For user security we added an option to the walletpassphrase RPC command to mint block only. In this unlocked wallet mode, one cannot send transaction through RPC command thus providing additional security to the wallet if hacker gains access via RPC.
Q: Is there a cap on total money supply like Bitcoin's 21 million?
A: There is no hard cap other than a 2 billion coin max put into the code for now. But that should not be interpreted as an approachable cap, as it might never get anywhere close to that. It should not be considered a hard cap either as it may get lifted but that's likely not needed in a very very long time. Due to the nature of the mint rate design it's not possible to predict a final limit as it depends heavily on market participation, as well as the influences between proof-of-stake minting and fee destruction (there may not even be a mathematical limit if minting continues to outpace fee destruction). What we do know is that the proof-of-work minting would slow down exponentially according to Moore's Law (we are aware that Moore's Law eventually would stop to apply), and proof-of-stake minting introduces at most 1% annual inflation. So generally speaking it is still a very low future-inflation design comparable to Bitcoin.
In 0.2 release a 'moneysupply' stat is included in the getinfo output so everyone can see how many coins are in the market.
Q: What us the math formula used to calculate how many PPCoins will be mined per day given the difficulty and a hasrate?
A: Mint per block is calculated as
9999 / (difficulty ** (1/4))
Then you can derive your expected daily earnings from there.
Q: What is the value of PPC?
A: http://www.proofofstake.com/ shows PPC to BTC trading price