Security analysis of PoW/PoS hybrids with low PoW reward

[mgburks77]

What if everyone else IS NOT mining both?

As soon as someone doublespends successfully on the network using the current PoS protocol, any node that is even modestly intelligent is going to switch to a more belligerent protocol that better defends the value of their coins.  Then you run into this problem.

OK, but can they doublespend if some miners are already only doing PoW mining for a hybrid PoS coin?

No, so long as the PoW difficulty is high enough to actually secure the network.  This requires subsidy (block reward) to be high enough to justify lots of people mining the chain.  Hence why PeerCoin works.

Hi Tacotime, thanks for the information! I notice you have an ad in your signature that describes a PoS/PoW hybrid.

Have you been able to resolve the issue with that coin?

[tacotime]

Hi Tacotime, thanks for the information! I notice you have an ad in your signature that describes a PoS/PoW hybrid.

Have you been able to resolve the issue with that coin?

It's a very different system; basically PoS miners vote on every PoW block to verify the contents, and PoW blocks are validated one block at a time.  PoS miners are given complete control over the contents of PoW blocks and whether or not the PoW miner gets rewards.

This is a *really* experimental incentives system and it might do crazy things yet.  The Bitcoin core devs I've talked to are wary of it doing things I haven't predicted.  Additionally, it relies heavily on PoW (which I think is a good and reasonably fair distribution system).  But it does not have the "nothing at stake" forking issue.

It's more comparable to a blockchain with "two factor authentication" for every PoW block, to ensure that miners aren't putting weird transactions into the network or are simply not including transactions.

[omahapoker]

I've been a MINT investor from the start. go most on my MINT at 8

today i told them I sold half my stake and keeping it BTC. first thing i thought was just stick it in blackcoin.

but from what ive seen fromthe exchanges market has become the last 2 months i'm just sticking with BTC.


i wished they was a bigger response from MINT people.



people know i never bash MINT, but we have to address issues like this.

[mgburks77]

Hi Tacotime, thanks for the information! I notice you have an ad in your signature that describes a PoS/PoW hybrid.

Have you been able to resolve the issue with that coin?

It's a very different system; basically PoS miners vote on every PoW block to verify the contents, and PoW blocks are validated one block at a time.  PoS miners are given complete control over the contents of PoW blocks and whether or not the PoW miner gets rewards.

This is a *really* experimental incentives system and it might do crazy things yet.  The Bitcoin core devs I've talked to are wary of it doing things I haven't predicted.  Additionally, it relies heavily on PoW (which I think is a good and reasonably fair distribution system).  But it does not have the "nothing at stake" forking issue.

It's more comparable to a blockchain with "two factor authentication" for every PoW block, to ensure that miners aren't putting weird transactions into the network or are simply not including transactions.

Is there a projected release date or is it totally experimental? 

[tacotime]

Is there a projected release date or is it totally experimental? 

Hopefully testnet within 2-5 months or so, then mainchain launch after the testnet seems stable.

[mgburks77]

Is there a projected release date or is it totally experimental? 

Hopefully testnet within 2-5 months or so, then mainchain launch after the testnet seems stable.

Interesting. Thanks for the info!!!

[virtualfaqs]

Sheesh. Wish I saw this thread when it was first posted. For someone running around MINT & BC thread, I'm still missing info. 

[stormia]

Thank you for your help Blackcoin community, you know which people you are (rat4, Soepkip, etc). Perhaps now we can put our differences aside and work together or at the very least coexists as pure PoS coins.

Update on the potential security issues mentioned earlier.

As a cautionary measure and since MINT does not really need PoW, we have decided to get rid of the PoW. We don't want to take any security risk.
And since our ego is less important than your hard earned money, we won't have any problem to be thankful to another coin dev if it appears he has helped to increase MintCoin's security.

For now, a new wallet is available and this is a mandatory update!
https://mega.co.nz/#!YI4DETrC!0Cy_PFqWkLF52Ic_Hoo-5v_oyUGWa2R4dcIvlX1S2H0

[brokedummy]

Not really a big deal, if it is an issue just fork it to not accept any more POW blocks.

Looks like I called it on the first page. Thanks rat4 for exposing the flaw and not leaving anybody with a bag of unconfirmed mints. Good guy dev makes competing coin more secure.

[stormia]

Not really a big deal, if it is an issue just fork it to not accept any more POW blocks.

Looks like I called it on the first page. Thanks rat4 for exposing the flaw and not leaving anybody with a bag of unconfirmed mints. Good guy dev makes competing coin more secure.

+1. And sorry for being rude and assumptious with my initial post of this thread, it was uncalled for.

[damiano]

Hmm I know what I'm trying out tomorrow morning

 

[mchrist152]

Were not there other ways to fix this issue?

For example, if the problem is PoW difficulty gets too low, why not set a minimum difficulty for PoW mining?

Or, do not allow two PoW blocks in a row.  Enforce that a least one PoS block is between each PoW block?

I think those fixes might be better than to just eliminating PoW altogether.  Just trying to understand this better.

[noerc]

Were not there other ways to fix this issue?

For example, if the problem is PoW difficulty gets too low, why not set a minimum difficulty for PoW mining?

Or, do not allow two PoW blocks in a row.  Enforce that a least one PoS block is between each PoW block?

I think those fixes might be better than to just eliminating PoW altogether.  Just trying to understand this better.

If you set a lower bound to the difficulty that is much larger than the actual difficulty level then it is absolutely not profitable for any miner to generate PoW blocks anymore which basically leads to the same problem.

[mgburks77]

Or, do not allow two PoW blocks in a row.

What about this idea? Can it be implemented? And is it worth doing?

[sidhujag]

Were not there other ways to fix this issue?

For example, if the problem is PoW difficulty gets too low, why not set a minimum difficulty for PoW mining?

Or, do not allow two PoW blocks in a row.  Enforce that a least one PoS block is between each PoW block?

I think those fixes might be better than to just eliminating PoW altogether.  Just trying to understand this better.

If you set a lower bound to the difficulty that is much larger than the actual difficulty level then it is absolutely not profitable for any miner to generate PoW blocks anymore which basically leads to the same problem.

Most of the premined pos coins are not profitable to mine pow anyway.. 1 coin per block at 20 sats.

I figure the devs were either lazy or dont understand the code enough to fully remove pow thus they just set the reward to the minimum so its quick and dirty. In reality if the pow is not helping with block authentication it
should be removed... surely devs knew if a hybrid approach was beneficial or not to the security against attacks that are common sense with both pow and pos?

[noerc]

Or, do not allow two PoW blocks in a row.

What about this idea? Can it be implemented? And is it worth doing?

Wouldn't this be the same as raising the PoW difficulty to the level that only one PoW would be generated in the time one PoS block gets generated? I don't really see the difference.

[mgburks77]

Or, do not allow two PoW blocks in a row.

What about this idea? Can it be implemented? And is it worth doing?

Wouldn't this be the same as raising the PoW difficulty to the level that only one PoW would be generated in the time one PoS block gets generated? I don't really see the difference.

it wouldn't require that minors participate for a low block reward, yet you receive the same result

[omahapoker]

I'm a MINT investor and want to thank you guys for exposing the issue. and no destroying the coin


 i never bash people and dont know why MINT people did.


thanks again.

[danbi]

I am trying to qualify the claim made by the OP, that MintCoin had no PoS block in a hour.

What is the proof that this was because of the "attack", or there was just nothing to stake during that hour?

Also, how would an PoS block in a hybrid coin "invalidate many PoW blocks"? The PoW and PoS chains are pretty much independent, no?

[TotalPanda]

Hi

Is a classic standart non-POS sCrypt (end of POW) easily attackable ?