If we presume that an attacker takes one day to crack a 64-bit key—which scrambles your data in one of 264 possible ways (18,446,744,073,709,551,616 unique permutations)—then it would take double that amount of time, two days, to break a 65-bit key, and four days to break a 66-bit key. Breaking a 128-bit key would take 264 times longer than a day, or fifty million billion years. By that time, I might even be pardoned.
