#9205: Discrete logs to composite bases
-----------------------------+----------------------------------------------
Reporter: davidloeffler | Owner: was
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: number theory | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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At present, we have a discrete log function which claims to work for Z/NZ
when this group is cyclic, but it can be wrong when N is not prime, as in
this example:
{{{
sage: Mod(5,9).log(Mod(2, 9))
6
sage: sage: discrete_log(Mod(5, 9), Mod(2, 9))
5
}}}
The first answer is totally wrong, because Pari's znlog function is
intended to be used with a prime modulus and silently returns junk in the
non-prime case.
I need to be able to express elements of Z/NZ* in terms of generators in
the non-cyclic case anway, so I will fix this in the process.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9205>
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