Comment Re:what if the head is in sleep mode so no momentu (Score 1) 239
The key could be stored in static RAM, which does lose data instantly when power is lost (downside is that it's more expensive, but for a single encryption key that's not a problem). Alternately, you could just stick a capacitor on the board with enough power to erase the RAM. Or just bury the RAM cells inside the CPU, so it's impractical to access them (and make the CPU erase them on next power-on).