[TRC] [DISCLOSURE] Terracoin Difficulty Collapse Exploit

[wmikrut]

Ok... I redirected my ~7Gh into TRC P2Pool:
http://www.wmikrut.com:9322/static/

That's all I have.

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[Remember remember the 5th of November]

I read the description of OP at least 50 times, but I dun' get it.

The way the attack works is that a miner collusion

I assume you mean that you need more than one node for this?

attempts to artificially inflates the time span of each retarget section

And this "group" of miners does this how? Inflation means to increase, increase means it will take longer than 2 minutes to create a block. Not sure how you'd do it. It's possible due to less nodes?

When the collusion gains momentum theoretically for terracoin I think the difficulty will collapse and block spacing drops close to 0

And again, how do you prevent people from finding blocks? Bear with me, I am thinking as I type, so basically miners will increase the difficulty, then stop till the retarget code decides it needs to go down? And when it goes down it gets exploited by the miners with the most hashpower again?

[Nolo]

I've moved 6GH/s to TRC.  We need an "Altcoin Rapid Response Team"  (ARRT) to fight off jackasses like this.   

[celkaris]

i personally moved my miners away from p2pool for now, it really looks broken, nearly every found block gets orphaned and stale rate is incredible, i gave a try to multipool.

I'd suggest you check your own p2pool stats (& graphs) page and maybe logs, it can still be coming from my setup.

i'll check my stats tomorrow and then decide if i try solomining or not.

[Nolo]

i personally moved my miners away from p2pool for now, it really looks broken, nearly every found block gets orphaned and stale rate is incredible, i gave a try to multipool.

I'd suggest you check your own p2pool stats (& graphs) page and maybe logs, it can still be coming from my setup.

i'll check my stats tomorrow and then decide if i try solomining or not.

I'm having a good bit of success solo mining.  Sure I'm getting some orphans, but that's to be expected. 

[wmikrut]

Yeah, things look a little messed up in P2Pool --- and tbh I don't know if I am contributing to a problem by using it.
I just wanted visibility that I was throwing what I had at it.

I'll switch out to straight solo mining.

[Syke]

Bear with me, I am thinking as I type, so basically miners will increase the difficulty, then stop till the retarget code decides it needs to go down? And when it goes down it gets exploited by the miners with the most hashpower again?

The main problem is the code allows the difficulty to drop by 90%. This is highly exploitable. This isn't the first time an alt-coin made the mistake of asymmetric difficulty adjustment problems.

[Nolo]

Bear with me, I am thinking as I type, so basically miners will increase the difficulty, then stop till the retarget code decides it needs to go down? And when it goes down it gets exploited by the miners with the most hashpower again?

The main problem is the code allows the difficulty to drop by 90%. This is highly exploitable. This isn't the first time an alt-coin made the mistake of asymmetric difficulty adjustment problems.

For now the temporary solution is for those of us who support this coin, to keep mining it regardless of difficulty or profitability.  Let the dev's work on a more permanent fix, but in the meantime we can protect it by consistently pushing high hash power onto it, to minimize ASIC jackassery. 

[pyra-proxy]

The way it seems, their solution is working very well given you don't have a stalled network like some other chains being borked with right now... with that said I only see a couple solutions to this kind of attack off the top of my head...

1) Implement merge mining and coordinate with a larger merge mine pool or two to pick you up right away to get a much higher base hash rate making this attack less profitable thus less desirable (but still not impossible and potentially not worth it given other attack vectors scummy players have taken by abusing the merge mining capability)

2) Change some mining parameter around so that ASICS are completely broken on this chain, I would think something even as simple as changing the hash algo to use SHA512 instead of 256 should do it no?  There are also the next gen hash algo's that could be looked at and there is a "fall back" to try scrypt or a scrypt merge mine.... asics are not very friendly to change given their nature so the change to break them would be easy.  Collude with any exchanges to halt trading and you could even 51% them back by breaking them and mining at a point before they started jacking with the chain and overwrite their blocks with newly fairly generated blocks.

[Nolo]

The way it seems, their solution is working very well given you don't have a stalled network like some other chains being borked with right now... with that said I only see a couple solutions to this kind of attack off the top of my head...

1) Implement merge mining and coordinate with a larger merge mine pool or two to pick you up right away to get a much higher base hash rate making this attack less profitable thus less desirable (but still not impossible and potentially not worth it given other attack vectors scummy players have taken by abusing the merge mining capability)

2) Change some mining parameter around so that ASICS are completely broken on this chain, I would think something even as simple as changing the hash algo to use SHA512 instead of 256 should do it no?  There are also the next gen hash algo's that could be looked at and there is a "fall back" to try scrypt or a scrypt merge mine.... asics are not very friendly to change given their nature so the change to break them would be easy.  Collude with any exchanges to halt trading and you could even 51% them back by breaking them and mining at a point before they started jacking with the chain and overwrite their blocks with newly fairly generated blocks.

Can the hash algorithm be changed without jacking up the current blockchain though?  Would that require a hard fork? 

[dreamwatcher]

The way it seems, their solution is working very well given you don't have a stalled network like some other chains being borked with right now... with that said I only see a couple solutions to this kind of attack off the top of my head...

1) Implement merge mining and coordinate with a larger merge mine pool or two to pick you up right away to get a much higher base hash rate making this attack less profitable thus less desirable (but still not impossible and potentially not worth it given other attack vectors scummy players have taken by abusing the merge mining capability)

2) Change some mining parameter around so that ASICS are completely broken on this chain, I would think something even as simple as changing the hash algo to use SHA512 instead of 256 should do it no?  There are also the next gen hash algo's that could be looked at and there is a "fall back" to try scrypt or a scrypt merge mine.... asics are not very friendly to change given their nature so the change to break them would be easy.  Collude with any exchanges to halt trading and you could even 51% them back by breaking them and mining at a point before they started jacking with the chain and overwrite their blocks with newly fairly generated blocks.

Can the hash algorithm be changed without jacking up the current blockchain though?  Would that require a hard fork?  

Any change that would be meaningful would most likely require a hard fork, that is a bit more difficult with TRC. TRC is now on a major exchange and if the TRC developers decide to hard fork, there will need to be some communication between the developers and the exchange, to lessen the chance of the exchange dropping TRC.

I have been thinking about this particular problem with ASIC manipulating Alt-coins. I have been trying to think of a tweak of some sort short of the complete scrypt parameter difficulty I have already proposed.

How about this:

Keep difficulty adjustment the same or relativity the same, and run the SHA-256 block hash through scrypt a limited number of times. LTC/NVC use a scrypt 1024:1:1 tuning, roughly this means that the data is run through the scrypt algo 1024x.

What if any of the SHA-256 coins, put a completed SHA 256 hash through a scrypt algo 2x, 10x, or 100x , whatever it takes to cripple the ASICs' efficiency. With the final result, of course, having to meet the difficulty requirement to solve the block. This is subject to the reality of how many times it would take before the coin becomes another LTC like coin. We still want the coin to be GPU friendly, just ASIC hostile.

Downside: mining software developers would have to get involved, or a community patch to a miner to run the SHA-256 hash through the scrypt algo.

Just throwing the idea out there...good or bad  

[pyra-proxy]

Basics are very very specialized so the change required to break them could be very simple.

[wmikrut]

Wouldn't that break FPGA's too?

[celkaris]

Wouldn't that break FPGA's too?

people holding ASICs probably still have GPU-based farms, maybe not reaching 60+Gh/s but currently, 20Gh/s may just be enough to disrupt the chain ; those type of rigs aren't that rare

This is probably what some of them decided to use their non-ASIC rigs for ; messing around with altcoins (benefiting from market?)

[pyra-proxy]

Wouldn't that break FPGA's too?

Yes but if the change is not too extensive and only dealing with things FPGA's can adjust for (as they are less specialized) then they may be fine, possibly just needing a firmware update.  And remember FPGA difference of power vs. GPU is considerably less of an impact than ASICs who are many fold more powerful.  So if this style of solution is used consider that....

[gambit]

I updated my terracoin wallet to 0.1.3 version. Is everything ok now? Can I trade my coins safely? 

[Milan77]

I do solo 16Ghash from last night, only orphans!
Yes, I have up-to-date wallet. This is bullshit. I will give up TRC and giveaway all of 10K TRC coins...

[wmikrut]

Wouldn't that break FPGA's too?

Yes but if the change is not too extensive and only dealing with things FPGA's can adjust for (as they are less specialized) then they may be fine, possibly just needing a firmware update.  And remember FPGA difference of power vs. GPU is considerably less of an impact than ASICs who are many fold more powerful.  So if this style of solution is used consider that....

I would hate to lose the use of my FPGAs on the chain... but if it would secure the coin, so be it.
I still have plenty of GPUs 

[Milan77]

Regular vs orphan ratio is 1:10 currently for me.

Please, if you think to keep ppl on TRC do something in Gods sake.

[aysyr]

I do solo 16Ghash from last night, only orphans!
Yes, I have up-to-date wallet. This is bullshit. I will give up TRC and giveaway all of 10K TRC coins...

I'll take some! Haha, I'm supporting TRC all the way so I would welcome it Now only if I could finally get my BFL ASIC I would keep that on the chain to increase our permanent network hashrate, but who knows if I'll even ever get it -.- But yea, even getting rid of ASIC miners would work for me since I have decent GPU power, and ASIC just lets those with more get more.

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