Explicit form for the discrete logarithm over the field ${\rm GF}(p,k)$
Gerasimos C. Meletiou · Czech digital mathematics library · 1993
summary:For $a$ generator of the multiplicative group of the field $GF(p,k)$, the discrete logarithm of an element $b$ of the field to the base $a$, $b e 0$ is that integer $z:1\le z \le p^k -1$, $b=a^z$. The $p$-ary digits which represent $z$ can be described with extremely simple polynomial forms.