#!/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