Justin I believe that you are right so I will try to re-implement it. Thanks for your help. David, thank you as well. The answer I believe is somewhere close to both of you. Some sips of absinthe will help me get this through or at least provide the illusion that I did it ;)
On Monday, April 6, 2015 at 1:12:54 AM UTC+3, Justin C. Walker wrote: > > > On Apr 5, 2015, at 11:39 , absinthe wrote: > > > Dear all, thanks for your replies. In general I don't want others to do > the > > dirty work for me, so I ask the actual problem. Anyway, since I have to > > give more details to get the actual help... The case is that I want to > > implement NTRU (see here for details > > <http://en.wikipedia.org/wiki/NTRUEncrypt>) > > As you see, I have to construct polynomials, similar to the ones I was > > refering to and compute their inverse... So it is definite that I'm > going > > to have zero-divisors and the like... > > Thanks for your clarifications. I think the issue at the root of your > problem is that Sage's algorithm implementing "foo.inverse_mod(bar)" uses > the Euclidean algorithm (use the "?" or "??" operators as follows to see > details: > sage: foo.inverse_mod? or foo.inverse_mod??) > > I believe that the Euclidean algorithm assumes the underlying ring is > Euclidean (which in turns requires no zero divisors). In the Hoffstein-et > al article, they mention using an "easy modification" of said algorithm to > compute inverses, an exercise, I suppose, for the really-interested reader. > > HTH > > Justin > > -- > Justin C. Walker > Curmudgeon-at-large > Director > Institute for the Absorption of Federal Funds > ---- > 186,000 Miles per Second > Not just a good idea: > it's the law! > ---- > > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
