Zawy’s Alternating Timestamp Attack

[murch]

@sipa

If so, any solution will involve directly or indirectly requiring that the last timestamp within a window is at least 3.5 days (1/4 of 2 weeks) after the first timestamp (effectively outlawing the 4x limit from having an effect).

Both Zawy’s attack and my variant require the negative elapsed time to make up for the pushing blocks into the future. I have been pondering what you could do if the elapsed time were just underestimated, but non-negative, and so far I’m coming empty.