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by adastra22 834 days ago
From the actual problem description:

Note that the puzzle can be solved by performing t successive squarings modulo n, beginning with the value 2. That is, set

W(0) = 2

W(i+1) = (W(i) ^ 2) (mod n) for i=1, 2, ...

and compute W(t).

There is no known way to perform this computation more quickly than to perform the t squarings sequentially, unless the factorization of n is known.

1 comments

Ah! Thanks. That immediately answers the second thing I was wondering about, since 2k RSA keys are still deemed safe (if barely / not for secrets that need to last a long time into the future)
In addition to what GP answered: note that I didn't crack anything. I just really did all the 79 trillion sequential computation needed to find the solution. That's the really need thing: you can encode the problem in a split second and yet decide how many sequential steps are needed to find the solution.
Yeah the cost of breaking the time lock is presumably less than breaking the order of the group.