Can someone smarter than me clarify if this also means a single 4090 can crack it in about 160 hours? Or are there a lot of other efficiencies gained by adding multiple GPUs together?
> "With an RTX 4090, the Tinyhack found they could crack the encrypted ransomware'd files in seven days, and with 16 GPUs, the process would take just over ten hours."
(and 160h ≈ 7 days)
If you can have 10 Tesla cards, the number will be a bit shorter (around 14, I guess), since NVLink is much more efficient and creates a mesh between cards without hitting the PCIe.
Most bit-flips won't matter - either you get a false positive which is ruled out trivially, or the 1-in-$SearchSpace chance you get the false negative.
And agreed; coordination costs are negligible next to the cost of the calculation, so it should be effectively linear, and dominated by the luck of the draw on when the correct key is selected.