re: statue of limitations - if we are talking exponential levels of difficulty to crack vs. exponential increases in computing power (Moore's law) I wonder whether "we won't have the computing power to crack this for X years, so a statute of limitations of (X-1) years to solve this means that we are functionally unable to answer the question within the allotted time" becomes defensible as a reason to call something "impossible", i.e. it's improbable to solve during the statue of limitations