I got the following error message when I was trying to update my repositories.
apt-get update
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A03BE326C0EF29A4
Solution
gpg -q --output my-public.key --armor --export "A03BE326C0EF29A4" cat my-public.key | apt-key add - # Or you can import using gpg. cat my-public.key | gpg --no-default-keyring --keyring /etc/apt/trusted.gpg --import