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What’s the Difference between NovaCoin and PPCoin?

  • NovaCoin uses slightly different emission model.
  • NovaCoin uses scrypt hashing function for Proof-Of-Work.
  • NovaCoin implements BIP34, some other changes will be applied in the nearest future.
  • NovaCoin uses separated target limits for Proof-Of-Stake and Proof-Of-Work.
  • New blocks signing protocol allowed us to implement the full p2pool support.

What could you say about NovaCoin emission model?

It’s quite simple. There are two types of blocks, Proof-of-Work and Proof-of-Stake. Each makes contribution into existent coins volume.

  • Proof-of-Work block reward can be calculated using formula nBlockReward = 100 / (nMaxTarget / nCurrentTarget) ^ (1/6). It means, that reward cut a half every 64x multiply of difficulty.
  • Proof-of-Stake block reward based on CoinAge parameter and Proof-of-Stake difficulty. Interest can be calculated using formula nRewardCoinYear = 1 / (nMaxPoSTarget / nCurrentPoSTarget) ^ (1/6). It means, that interest starts from 100% per year and cut a half every 64x multiply of difficulty.

What’s Stake or Proof-of-Stake?

Stake/Proof-of-Stake is term referring to the use of currency itself (ownership) to achieve certain goals. In NovaCoin 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).

How is it energy-efficient when there is still mining?

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.

Why do you need central checkpointing?

As of PPCoin v0.2 centrally broadcasted checkpointing is no longer a critical part of the protocol. It’s main purpose now is to defend the network during the initial growth period and help ensure a smooth upgrade path if critical vulnerability is found. We are confident that central checkpointing can now be gradually weakened and eventually removed to achieve similar decentralization level of Bitcoin as the novacoin network matures.

Regular users could ignore broadcasted checkpointing by using -nosynccheckpoints option, if they wish.

When can I start generating proof-of-stake blocks?

After 30 days the network would start seeing proof-of-stake blocks. If you have balance novacoind would automatically try to generate stake for you. If you find a stake the reward is calculated using current proof-of-stake difficulty and coin-years amount consumed. 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 novacoin.conf and restart your novacoind. This way novacoind would try to keep your balance above 10000 coins when generating stakes.

Can I use encrypted wallet?

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.

Is there a cap on total money supply like Bitcoin’s 21 million?

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 1% annual inflation in the future (but it starts from higher values). 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.

How do I generate a vanity address containing some pattern like in a bitcoin vanity address?

(courtesy of dreamwatcher)
vanitygen -X 8 <pattern>
Once the key is generated you can use novacoind importprivkey <privkey> to import it into your wallet.

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