Re: few days?
One of the best methods of optimising HPC tasks for decades has been to "buy next years computer instead".
This is a (slightly protracted) version of that.
The low interest (given that it only took a few hours on current hardware - it would only have taken a few days for the last few years) is what kept the secret for 40 years - the early leak, and the fact that it resisted (niche) efforts for even a small number of years is still impressive - but does also show that password entropy is really important.
Forward secrecy is really hard - how long you want something to remain secret depends on how disposable it is... If it's a login that you can revoke and set a new token then it only needs to be reasonable.
If it's protecting a file which you speculate might be released in it's encrypted form (i.e. you don't trust your cleaners, or it must be transmitted across non owned networks) then you might want it secret for a lot longer than 40 years... and that becomes very difficult indeed.
Biting the hand that feeds IT
