#!/bin/bash

read -p 'Checking DKIM length for: ' DOMAIN
SELECTOR=default._domainkey

# Put the pubkey stuff from the DKIM record into a tmp file
dig txt $SELECTOR.$DOMAIN +short | awk -F'p=' '{print $2}' > /tmp/$DOMAIN.key.txt

# Strip out unnecessary characters
sed -i 's/[^a-zA-Z0-9+'/']//g' /tmp/$DOMAIN.key.txt

# Line wrap so openssl command will work
fold -w 78 /tmp/$DOMAIN.key.txt > /tmp/$DOMAIN.key
rm -f /tmp/$DOMAIN.key.txt

# Insert the pubkey blocks
sed -i '1 i\-----BEGIN PUBLIC KEY-----' /tmp/$DOMAIN.key
echo "-----END PUBLIC KEY-----" >> /tmp/$DOMAIN.key

echo " "
echo "DKIM TXT RECORD:"
echo "****************"
dig txt $SELECTOR.$DOMAIN +short
echo " "
echo "PUBKEY:"
echo "*******"
cat /tmp/$DOMAIN.key
echo " "
echo "STRENGTH:"
echo "*********"
openssl rsa -noout -text -pubin < /tmp/$DOMAIN.key

rm -f /tmp/$DOMAIN.key