GMP used during 3 and a half years to solve MIT's LCS35

[Hans Åberg]

> On 30 Apr 2019, at 11:17, Laurent Desnogues <laurent.desnogues at gmail.com> wrote:
> 
> On Tue, Apr 30, 2019 at 11:00 AM Hans Åberg <haberg-1 at telia.com> wrote:
>> 
>>> On 29 Apr 2019, at 23:26, Bernard Fabrot <bfabrot at gmail.com> wrote:
>>> 
>>> Hi all,
>>> 
>>> that'd be me:
>>> 
>>> https://www.csail.mit.edu/news/programmers-solve-mits-20-year-old-cryptographic-puzzle
>>> 
>>> I wanted to thank you a lot for GMP and let you know that GMP did the 79
>>> 685 186 856 218 modulo/squarings without failing once.
>> 
>> It says in the description that it is designed to not be parallelizable, but cannot that be done for the individual iterations? Posit each each iteration is done in one cycle, then with a 4 GHz clock, it solved is 6.5 hours.
> 
> I doubt one can design hardware that could compute 2048-bit squaring
> mod 2048-bit in 1 cycle @4 GHz :-)  But I might be wrong. The team
> doing it with FPGA reached 70ns per squaring (cf.
> http://www.cryptophage.com/).

I mentioned it as a comparison: it seems they use an average of about 200 cycles per iteration.