#!/bin/bash
# Niels Elgaard Larsen pincode encrypt/decrypt
# usage 
way=$1
kode=$2
pad=$3

if [[ x$way == "xe" ]]
then
    op="+"
elif [[ x$way == "xd" ]]
then
    op="-"
else
    echo \"e\" for encrypt, \"d\" for decrypt
    echo pincrypt e pin code   
    echo pincrypt d cryptpin code
    exit
fi	
echo kode=$1 pad=$2
ck=""
for pos in $(seq 0 3)
do
    ck=$ck$(expr "(" 10 + ${kode:$pos:1} $op ${pad:$pos:1} ")" % 10)
    echo $c
done
echo $ck