#!/bin/bash
read -p "Puplic-Key1: " key
#read -p "Puplic-Key2: " a
cl=$(echo "$key"|wc -c)
clf=$(echo "$cl-1"|bc)
a=$(echo "$key"|cut -c$clf-)
n=$(echo "($key-$a)/10"|bc)
read -p "Geheimzahl: " x
y=$(echo "($x^$a)%$n"|bc)
echo "Geheimzahl lautet $y"