NuBits and NuShares on the same block chain

RobertLloyd 2014-09-20 16:27:12 UTC #1

As I understand it, there is only one Nu block chain, and this is for both NuBits and NuShares - is that right? If so, could someone explain a bit about it - how can one block chain be used for two things?

Ben 2014-09-20 18:03:26 UTC #2

The Nu blockchain carries transaction information for both units. Technically, I suppose you could say that it is the “NuShares” block chain, because it carries NSR transaction information, voting information (custodial, parking rates, motions), liquidity information, etc. Without the NSRs minting, the network could not be confirmed.

However, in addition to all of that information, the block chain also carries encoded information pertaining to NuBits transactions and parking-related transactions.

@sigmike can address things at a far deeper level than I can, but hopefully that overview helps address the basic questions.

cryptog 2014-09-25 08:02:34 UTC #3

so nubits double spending is prevented by proof of stake?

masterOfDisaster 2014-09-25 08:09:28 UTC #4

A developer needs to confirm that, but my understanding is that NuBits are secured by PoS and share a block chain with NuShares. And the PoS is done by the NuShares minting process.

cryptog 2014-09-25 08:19:43 UTC #5

I see. So it is a form of merge mining…

cryptog 2014-09-25 08:22:35 UTC #6

Now I am wondering about the rate of block minting per minute of the blockchain…
I sent and received my nubits within 10 seconds or so it seems.
It is very fast.
Would that imply that there is a block minted every 10s?

Ben 2014-09-25 12:02:07 UTC #7

No. Block timing is approximately one per minute. Like Peercoin (and other block chain-based cryptos) this process has variance. This means that it may be one minute between blocks, or, slightly more or slightly less. Sometimes it can be a lot more or a lot less. For instance, last week there was a ~40 minute time between two blocks on the Peercoin network – it happens, infrequently.

Transactions are broadcast to other nodes quickly in both systems. I could send you peercoins right now and depending on our proximity in the World, and the distance between our wallet nodes, you’d probably see the incoming transaction within 10 to 30 seconds, too. You would still need to wait for the six confirmations before you could spend the coins, however.

cryptog 2014-09-25 14:21:29 UTC #8

Tks for the clarification, Ben.
1mn…That is fast as Primecoin.
Not bad at all.
I suppose this is the standard block time of a normal Peershares implementation.
Would it be possible in the future to even shorten that 1mn?

Ben 2014-09-25 14:27:22 UTC #9

No, the “default” block spacing for Peershares is still 10 minutes. It can be modified by an offerer if they so chose to.

You can certainly run faster than 1 per minute (I’ve seen my local testnet run as fast as 15 seconds per block without a problem). The main concern with networks that run that fast is that you generate a lot more “orphaned” blocks because there’s a distance-based limitation to how fast transactions can be propogated around the network. What ends up happening is that your minting nodes “solve” a block, but by the time they can get that block broadcasted to the network, another node has solved the same block and beat the first node to propogating it.

cryptog 2014-09-26 06:43:15 UTC #10

Oh I see. So 1mn block seems like a good compromise.
By the way, my understanding is that the block time for NuShare’s PeerShares implementation is 1mn.

cryptog 2014-09-26 07:09:58 UTC #11

So my understanding is that 6mn (6 confirmation of 1mn each) is required to fully confirm a NuBit transaction. That is way longer than an usd cash transaction.
For online purchase I think it s totally acceptable but for a cup of coffee in the physical world, we would need merchants to tolerate 0 confirmation with some sort of insurance imho…

Cybnate 2014-09-26 07:53:00 UTC #12

6 confirmations are required for large transactions. Merchants would be fine when you buy a cuppa and they receive the transaction. If you double spend, the loss to the merchant is low. The risk of people double spending a couple of dollars or maybe even 100 dollars is very low in my opinion. And with all the CCTV everywhere they might recognise your face if you try to come back.

For larger transactions people are usually willing to wait a bit. And you will get a coffee for free usually

But let’s be clear the block chain isn’t really build for high volume microtransactions. That is where the side chains or open transactions (OT) come into play in the near future.

cryptog 2014-09-26 08:33:03 UTC #13

so NuBits cannot become the ultimate daily life crypto currency but at least it is a real crypto currency in the sense that there is no volatility…

masterOfDisaster 2014-09-26 09:31:36 UTC #14

The real risk would rather be others trying to pull off a big double spending coup and the merchant would be collateral damage suffering from seeing a transaction that would later be reversed by the “big coup”.
But as double spending attacks should be rare (if not then there’s something wrong), this might be no reason for the merchant to wait for a number fo confirmations.

masterOfDisaster 2014-09-26 09:46:21 UTC #15

NuBits can become the ultimate daily life crypto currency!
The main advantage over almost all other crypto concepts is that they can’t be considered currencies because of their high volatility.
There’s for sure a risk for merchants if the rely on zero confirmation transactions. But I consider this risk low. If it turns out that this risk is not low because of feasible attack vectors, the whole system has serious problems.
…but there are risks and possible costs when accepting other payment methods as well

cash
risk: counterfeit money
costs: none
credit cards
risk: reversed transactions
costs: transaction fees that need to be covered by the merchant
other crypto
risk: volatility when accepted directly
costs: when being handled by payment providers: transaction fees that need to be covered by the merchant

I see advantages over all of the payment methods mentioned above for NuBits. NuBits is close to cash without the chance to counterfeit it.

Cybnate 2014-09-27 01:32:27 UTC #16

Don’t forget the huge cost of credit cards due to fraud with them (https://en.wikipedia.org/wiki/Credit_card_fraud)
All creditcard holders are paying for that.

Although hard to substantiate I think the risk of double spends is lower than the cost in percentages of the use of creditcards. The transactions costs ( as in the profits of the creditcard companies) still come on top of that

miner 2014-09-27 09:59:57 UTC #17

Thanks Ben. This is Red.
This is kind of magic to me. As the Nushares dividends address are linked to PPC address, can we see it as a primary form of side chain for PPC?

cryptog 2014-09-27 10:50:50 UTC #18

@masterOfDisaster, @Cybnate .

Well NuBits cannot be as fast as cash unless we accept 0 confirmation.
And on the long run, NuBits would have to rely on a side chain to process all the micro transactions, which would imply some tx fees.

What would be the probability of double spending if we accept 0 confirmation?
What would be the tx fee if we rely on a side chain?

I think that if we can make sure than 1) is very low and than 2) is very low, then NuBits will replace cash…

masterOfDisaster 2014-09-27 14:31:21 UTC #19

ad 1)
If the system isn’t flawed it should be almost imposible to double spend.
The economical incentives for a double spending are bad in my opinion.
This is a quite high level view of the double spending attack, but it should help to start a discussion.

NBT (NuBits) and NSR (NuShares) transactions are on the same block chain.
The block chain is secure by PoS.
Minting is done solely with the NSR.
Assuming you want to double spend NBT, you need to buy them, spend them, bring a fork into play which becomes the new block chain, reverse the transactions in the former valid block chain and execute a transaction with the same NBT again.

Not having in-depth knowledge about the protocol I can only assume that the design is close to Peercoin’s PoS. An attack has either a low probability to be executed at a given point of time or needs a decent amount of NSR to be relatively projectable.
You might be able to try for an attack with a little amount of NSR and can even be successful with that. But how will you coordinate the surprising success with (double) spending the NBT?
If you have a sufficient amount of NSR and might be able to quite reliably pull off a double spending attack. But you shoot yourself in the foot undermining the trust in Nu which will likely crash the price level of NSR.
…it will be hard to achieve financial gain under these circumstances and based on these assumptions.

So I’d like to contend that the probability for double spending is close to zero.

For accepting zero confirmation transaction there might be other risks that need to be evaluated separately.

ad 2)
I’m sorry that I can’t contribute anything useful to answering that question

Cybnate 2014-09-28 01:23:09 UTC #20

I think there is also the risk that the merchant is not synchronised yet with the latest transactions in blockchain and that the attacker runs to that merchant to spend his coins again in the same block (likely creating an orphan block). That would require a lot of knowledge about the connections to the merchant’s wallet or deliberately trying to slow down their wallet in some way.

So again probably not worth the hassle and risks for a few hundred bucks.