Quote from: goin2mars on March 13, 2014, 05:01:59 AM

Quote from: eduffield on March 13, 2014, 04:59:50 AM

Quote from: Cryddit on March 13, 2014, 04:31:10 AM

The kgw exploit is real.

The problem is that the software will accept blocks that are timestamped earlier than previous blocks, (for good reasons) up to the median timestamp of the previous 11.

Kgw counts these as very fast blocks and adjusts the difficulty up by its 20% maximum. Once. But you can use that once to roll the timestamp back after five blocks that are long enough to drive the difficulty 20%lower each.

So the exploit is to start mining your own block chain, time stamping several blocks into the future far enough to get the maximum downward adjustment of difficulty each time. Then jump backwards in time getting the maximum upward difficulty once. Rinse, repeat, and your chain gets ridiculous low difficulty and you mine a whole lot of blocks while advancing your timestamp not much further than the main chain.

When the time in the main block chain catches up, you release your own chain and force a reorganization, which allocates to you all the coins mined for the last umpty ump blocks.

I'm in the process of rewriting KGW for our purposes. I've spend a few hours thoroughly going through the code and I think I can come up with a better implementation that doesn't have these kind of problems. DarkGravity? Grin

Nice! On top as usual!

great dev!!