Quote from: smooth on October 06, 2014, 05:04:16 AM

Quote from: TheFascistMind on October 06, 2014, 04:13:14 AM

Isn't this what was happening to Auroracoin where it had declined from 16 ghps to 2.4 ghps

Not necessarily. What happens on many coins, especially lesser Scrypt coins, and what KGW was designed to partially address, is that hash rate comes and goes very quickly as large multipools move their hash rate around. This causes very rapid changes in hash rate and block times until the difficulty adjusts. Adjusting too slowly can be as bad or worse than adjusting too quickly, because you can be stuck with extremely dysfunctional block times for a long period.

If you adjust too quickly then even without any TW, the last few blocks of before the difficulty adjustment (to reduced difficulty) the attacker grabs with higher probability are a higher percentage of all the blocks.

As I described previously the attacker can ramp up the hashrate for one period, then pull his hash rate from the next.

So too quick is not an option. Period. BCX said this, so he shows he knows his shit.

As I wrote before, this cycling of the hashrate higher drives away miners, combined with stealing blocks on the lower hashrate cycle drives away miners.

BCX said this, so he shows he knows his shit.

You are apparently not thinking deep enough on this yet.

Quote from: smooth on October 06, 2014, 05:04:16 AM

I don't really know whether it is true or not, but I've heard from some people who are not complete idiots

TT who claimed that BBR's compression is insecure in some grand degree?

He was involved about Scrypt coins.

Quote from: smooth on October 06, 2014, 05:04:16 AM

that there was never a time warp exploit in KGW, and what as changed in AUR was window dressing serving as FUD repellant. And I'd add that ultimately didn't matter because all the "country coins" died anyway

As far as I know the only time wrap exploit that has ever been clearly identified and described is the original off-by-one bug identified by ArtForz in BTC and its clones.

I'm not ruling out that KGW might have an exploit or cryptonote difficulty adjustment might have an exploit, but big changes in hash rate or block times on AUR certainly don't demonstrate it at all.

KGW clearly has an exploit because it is thresholded at an exponentially declining well. So if you have enough hashrate, you can drive the hashrate adjustment at the time of your choosing. So you can ramp it up very high, then pull your hashrate slow enough to mine a secret fork while the hashrate doesn't adjust.

And the real huge flaw is KGW will stop at the most recent block, if you hit the threshold. So you can shorten the difficulty adjustment intervals and take over the chain per what I wrote above.

That is very obvious conceptually.