[Cado-nfs-discuss] DLP problem

Pierrick Gaudry pierrick.gaudry at loria.fr
Sat Dec 1 14:43:20 CET 2018


Dear David,

Could you have a look at the following thread on this mailing-list :
   https://lists.gforge.inria.fr/pipermail/cado-nfs-discuss/2018-November/000939.html

It seems that this answers your question.

Best regards,
Pierrick

On Sat, Dec 01, 2018 at 08:12:36AM +0800, ┃ Be Happy 、╯ wrote:
> I am not sure if I did this right, but I met a problem and I can't solve it.
> 
> I use the example you give in README.dlp:
> $ ./cado-nfs.py -dlp -ell 101538509534246169632617439 target=92800609832959449330691138186 191907783019725260605646959711
> and the answer is:
> p = 191907783019725260605646959711
> ell = 101538509534246169632617439
> log2 = 35338258800684599318721749
> log3 = 62614277196775799921779143
> The other logarithms of the factor base elements are in /tmp/cado.yliqctwz/p30.dlog
> target = 92800609832959449330691138186
> log(target) = 32359472153599817010011705
> 
> For the discrete logarithm of primitive root 2 (i.e. g=2), only log (target)/log2 mod ell, and the answer is
> 5995158352878681776097204.
> 
> But when I want to check out if the answer is right, so I compute
> 2^5995158352878681776097204 (mod 191907783019725260605646959711)
> I get 36195192389531979502867378706 and it's obviously not target.
> 
> 
> I and my classmate have the same problem and I don't know what is wrong.
> 
> 
> and I don't know how to build a file if I want to compute a 78-digit p, could you please help me?
> 
> 
> Cheers!
> 
> 
> David Wu


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