nsupdate, getting BADKEY error
Solution 1:
Are you sure you are using the right key, there is no other keys in your /etc/bind/ dir ? :-)
If so, check the permissions of your key file ?
chmod 400 /etc/bind/Kdyn.mydomain.com.+157+53489.private
Also, make sure that your secret match what dnssec-keygen have generated
(hint: the space in your secret line )