What is the progress on the MIT LCS35 Time Capsule Crypto-Puzzle? Ron Rivest posed a puzzle in 1999.  MIT LCS35 Time Capsule Crypto-Puzzle.


  The problem is to compute $2^{2^t} \pmod n$ for specified
  values of $t$ and $n$.  Here $n$ is the product of two large primes,
  and $t$ is chosen to set the desired level of difficulty of the puzzle.
  
  Note that the puzzle can be solved by performing $t$ successive
  squarings modulo $n$, beginning with the value $2$.  That is, set
  
  
  $W(0) = 2$,
  $W(i+1) = W(i)^2 \pmod n \quad$    for $i\ge0$,
  
  
  and compute $W(t)$.
  There is no known way to perform this computation more quickly
  without knowing the factorization of $n$.


In 1999 they predicted that we'd have 10 GHz processors by now.  I realise that raw GHz is a dumb way to measure speed, but how fast are computers for this kind of "intrinsically sequential" computing?

I guess my questions are:

1) What is the state of the art for computation which can not be parallelised?

2) Has anyone claimed to make any progress with this challenge?
2) Has anyone claimed to make any progress with this challenge?


Ah that question I can answer now...

I found the solution on the 15th of April 2019 and sent it to the MIT's CSAIL on the 16th of April. Another team shall have the answer by the 11th or 12th of May (they used a FPGA).

I noticed around the end of 2015 that if I used GMP I could find the answer on my Core i7-6700 CPU in about three years and a half. So I basically let my computer open 24/7 so that it'd solve the "puzzle". 

The secret message and the two primes shall be announced on the 15th of May during a ceremony where the "time capsule" shall be opened.

Link to the CSAIL's article about it:

Programmers solve MIT’s 20-year-old cryptographic puzzle