Timewarp attack 600 second grace period

[AntoineP]

@sjors

Now if a malicious miners set their timestamp 2 hours in the future, relative to our node clock, and if our template is used by an ASIC that wants to roll nTime forward by up to 600 seconds, this is only safe if we assume all our peers have a matching clock.

Hmm i agree that we should seek to minimize the potential for creating an (even temporarily) invalid block. But that’s a lot of if’s to get there:

• A miner is malicious; and
• This miner finds the last block in a period; and
• Our ASIC rolls nTime, we find the first block of the new period; and
• Our ASIC finds a solution with nTime + n; and
• We find the block in less than s seconds; and
• A majority of the hashrate has a clock behind ours by more than n + s - 600 seconds.