Topic: [ANN][YAC] YACoin ongoing development - page 97. (Read 380091 times)

Would there be ramifications to changing the code to reject a newly published chain if the lowest height block is 24 hours older than the highest published block?  I honestly don't understand chain trusts, etc, and have not found the explanation that clicks for me yet, so this may just invalidate a bunch of things - I don't know any better, but want to.  I brought up cementing earlier, and everyone was vehemently against the concept, but it strikes me as just another form of checkpoints, which is what NVC and PPC are using.

second question - regarding bitcoin knowing the difference between a diff1 and diff2 block but YAC does not - could you elaborate on this Balthazar?  What is YAC missing?

Ha - I was actually thinking about this a few days ago, and still haven't been able to find an obvious exploit. 

If I understand correctly function of PoW mining is coin distribution and PoS was ment to later with enough honest nodes takes over coin production and other functions (but not distribution at least not directly).

Now the two (PoS&PoW) obviously do not go along too well in this form.

Would it be possible to implement alterations of blockchain sequences according to timestamp like this: only POW blocks would be accepted by clients every day except on saturday when one hour would be allowed for only PoS blocks sequence.
That one hour would be extended by another hour or similar every week, so gradually PoS would replace PoW along with coin being distributed to increasing number of people.

If people would like to collect PoS revenue they would have to open their wallets all at once and "flood" the net.
As yacoin gets distributed to more people this flooding time would get extended until it happens all the time and takes it's proper function.

I said 1 hour on saturday - but it could be any day and duration determined upfront, for example 15 minutes every day or every third day or when N increments...

I think Nfactor change should get used for any incremental phasing out of functionality not needed anymore - be it dynamic active weight calculation or something else temporarily needed.

This sounds like one basic modification to do, changing PoW and PoS targets so there's rarely more than one PoW block PoS can orphan, and shouldn't interfere much with further future improvements.

Chain has worked without that much drama until now, if an interim targets fix can make do for a while, it may buy time while more complex improvements are evaluated. No need to risk introducing bigger loopholes trying to fix a smaller bug.

Good thing I copied it all and added to yacoin.org before it was deleted  I also setup a redirect to your explorer page (explorer.yacoin.org) as was done on yacointalk.

1. I need some time to recalculate a difficulty, but once difficulty is recalculated I can generate as many blocks as I need. 100, 1000 or even 10000 blocks could be generated without any problem. The only thing I need is a modified software.

2. Actually I don't need do it in shorter time. I can use my wallet for payments as usual while alternate chain is generated. A week/month/year later I'm publishing a fake chain which removes all of my transactions during this period from the main chain.

Such attack is impossible in Bitcoin or Novacoin, because those networks are able to see the difference between diff1 and diff2 blocks. But your version of YACoin makes no difference between such blocks.

The purpose of checkpoints is not a chain consistency control, chain should be able to control itself. Those checkpoints are able to prevent such type of attack, but it's not a solution. It's just another workaround.

It's just an additional measure to prevent (well, lower the risk) the live nodes from being fooled, so they can continue building on top of the valid chain.


Yeah, but exactly HOW can you make a valid chain that's LONGER than the previous valid chain in SHORTER time while spending considerably LESS energy to do it?

And now the same with hard checkpoints enabled.

Nope, this maxClockDrift condition is just a sanity checking threshold against the node with invalid time settings. It's not necessary to publish a chain immediately, real attacker will be able to publish his chain in any moment of the future. And clockdrift condition won't be able to prevent this.

I can generate chain and publish it a month or even year later... And it will overwrite the main chain if there are no checkpoints added. Just because there is no way to make a difference between valid or invalid timestamps if these timestamps are in the past.

Err, WTF?
https://en.wikipedia.org/wiki/Yacoin
(page deleted)

https://en.wikipedia.org/wiki/Wikipedia:Articles_for_deletion/Yacoin

I've added a small fix that preserves the old block trust model for blocks <400k (oops). https://github.com/saironiq/yacoin-cc/commit/2a394a39c2133aa600b81580f587733b2498a01d

I've also been thinking abount the issue Balthazar found (generating lower-difficulty fork from last checkpoint). The only way it can be achieved (the lower diff) is by faking the timestamps in the blocks (to keep diff low) and generating a longer chain than the current main chain. By faking the timestamps to be more distant from each other the difficulty is kept low. This, however, results in the attacker's fake longer chain to have a timestamp from the future - possibly more than the allowed clock-drift (depends on the length of the faked chain. If the timestamp is higher than "now + allowed drift", then such block is rejected by the client - thus fixing this issue.

The only open question is how long can the fake chain be to fit into the allowed clock-drift window.

One solution is reducing the nMaxClockDrift parameter in the code from the current 2 hours (!!!). I'd personally go for something like 15 minutes or so, as your system time needs to be faily accurate to even use HTTPS sites. Hell, even time-based one-time pads (TOTP) need clock accuracy to be within 1 minute (this is the thing you use for two-factor auth, eg. with Google's Authenticator)! And most operating systems keep the time updated for you automatically, anyway.

It's just a simple change, see:
https://github.com/saironiq/yacoin-cc/commit/ad5533d015ea910f4ebfb569f3065186b8923ae6

I've read all of the recent posts (twice actually) and gave this a lot of thought...


I think Sairon's fix is the best solution at the moment.  It seems to be easy to implement and it will solve the immediate issue.  While there may need to be other 'tweeks' down the road, we need to get YAC back up and running.  The inconstancy on Cryptsy and other market charts / exchanges aren't helping improve YAC's reputation and community.  Without either of these, I don't think we will have a chance to face some of these other issues...


I am (personally) not in favor of this.  Nothing against Novacoin but; YAC was branched from PPC/NVC and there has been a lot of development work to make it a unique (and useful) coin.  And by copying NVC's PoS modifications, we begin to lose some of our uniqueness.  And YAC isn't another 'clone' coin.  If it was; it would have been named CAC - Clone Another Coin....

If we do decide to move forward with Sarion's hard-fork, I am in favor of doing it by Feb 1st.  This gives 4 weeks for all pools and miners to update their software.  I believe this is more than enough time to properly communicate to everyone.  Also, a few thoughts / questions about how POS after this hard-fork.

Our block target for YAC is one minute.  This would imply that there would be a maximum of 720 POS blocks per day.  As YAC continues to grow, this may not offer many opportunities for people to mint their transactions.  Therefore, is it possible to....

1) Mint more than one transaction at once/per block? (i.e. Five transactions of 10 YAC w/ one coin-year each, in an unlocked wallet would mint in the same block, and be returned a single transaction (50.50 YAC)
2) Increase/remove the 'coin-age' cap? (I believe transactions stop gaining 'coin-age' after 90 days) 

IMO - These adjustments will allow people to continue to fairly PoS mine YAC, with out compromising any of the security or fundamental features of YAC.

There are serious reasons to doubt this.

It works as it was designed, and there is no crap except constant values which were chosen by hand of original developer. PoW blocks target spacing must be higher or at least equal to PoS blocks target spacing, because this system is originally designed for "slow" PoW blocks and "fast" PoS blocks. It doesn't work in the perverted version and there is nothing strange here. Orphans is just another part of self-regulation in this complex system. If developer tries to set PoW spacing lower than PoS spacing then network just forces him to get acceptable PoS/PoW ratio.

If you wish to have a "fast" PoW blocks then you need another system, because this system won't allow you so. You need cunicula's concept or something like that. I.e. no PoW and PoS blocks, but a homogenious chain with a new block type. It's even possible to reuse the current code by removing PoW blocks support and forcing PoS blocks to have a suitable header hash.

Such threshold looks like allowing the PoW generation only for miners with 8 or 10+ MH/s. I mean it's pretty senseless and won't change anything. This measure is only able to increase an extent of the problem by decreasing active inputs amount.

Recursion here, you can't define an argument of difficulty function as a function of difficulty.

Balthazar, thanks very much for your input!

So, what does everyone thing we should do?  I think if something isn't agreed upon soon, it may be a good idea to just rebase YAC to the latest NVC source. 

Maybe PoS minimum stake should depend on PoS difficulty, so small amounts are never staked if there's no need to.

I belive most of those PoW were unintentionally orphraned, but it could also be abused.

Sometimes your client wasn't able to get a freshly generated PoS into the blockchain. If you have other adresses that can PoS you are the only one that sees your longer chain and begins to PoS on top of your not acepted PoS block.

If you then resend your block(s) you orphran all other PoS-blocks if your chain has higher trust.
The more txt you have in your wallet it lags more and more and it becomes more likely that you block doesn't get transmitted on the first try and some people resend then manually.

Can somebody explain me why there's so many orphaned PoW-blocks in plain English please?
Why this wasn't happened before (in first 6 month)?
Why it happening now!?

Thank you in advance!!

PS: I've read all the posts above 

Oh, haven't seen that.

I agree that these changes wouldn't keepit safer for long. Problem with fixing PoS on it's own (Sairon's,NVC's and f.e. PPCs)has usually major negative sideeffects. NVC's solution gives huge inflation and I think this would hurt YAC significantly more that it hurts NVC so be shouldn't go there.


On the other hand am I not able to find any loopholes in my Decentralized Centralized Checkpointing-idea and it's simple.
It doesn't change anyting for 99% of the people owning YAC and only a few rich guys get higher rewards for their effords.

Decentralized Centralized Checkpointing idea:

I hope that not the reason why you think this way about my idea with decentralized centralized Checkpointing, but I think you don't dislike it just because of that. Anyways:


I know how PoS was "supposed" to work, but basically it's crap now without some mayor changes (even with your new rules additionally). PoS is allowed with wallets that have just 2YAC balance so just having such small PoS block doesn't add any security. On the other hand miners could do the following profitable:

Generate a bunch of small adresses and wait for them to be ready to POS. Once a pool found a PoS they keep it secret and mine a PoW on top of it. Most of the time they will fail to mine a block but they have more time to mine than the rest of the network since they can ophran 1 block. This gives them an advantage over mining without such and would result in loosing a lot of hashpower.

It also destroys the puropse of PoS adding any form of additional security. Where is the security benefit from having PoS-blocks with such little weight. PoS are sacre and unless they become meaningless for security (small PoS witout PoS-rewards). Mining pools wouldn't even have to own these small adresses, they could rent them or buy unpublished blocks. If they pay more than 5% per year even I'd consider splitting up but giving them a unpublished PoS-block is cost free.
A collaterall would prevent any fraud from the owners and would only be paid if miners actually lost some work.

This adjustment would also reduce the security benefits from having PoS at all so we could rather automatically increase every wallet with 5% per year and stop all that madness.

Fair enough. This will need to be changed, thanks.

You can freely choose another thresholds or function, but the reward shouldn't be fixed. Actually, you have a choice between red and blue pills right now... Logic vs. Emotions/Sanity vs. Morality/Practice vs. Worthless ideology. Worthless because the fixed RoI means no self-regulation, thats why it opens a security hole. Absense of self-regulation is just another type of centralization.

That's not true, it seems that you don't understand Bitcoin quite well.

1. Bitcoin is able to make a difference between diff1 or diff2 blocks, one diff2 block can't be beaten with one diff1 block.
2. Hardened checkpoints only purpose is to be a trigger for signature checking optimization and protection against compromised ISPs. And you can disable hardened checkpoints verification in bitcoin.