OpenPGP key generation for GnuTLS

Create key pair. Write down the key number.
gpg --gen-key
Edit the key with the command below.
gpg --edit-key 1F8D4A4C
In gpg prompt enter passwd and specify empty password, type quit.
gpg --armor --export 1F8D4A4C> public.key
gpg --armor --export-secret-keys 1F8D4A4C> secret.key
Delete keys from keyrings if required.
gpg --delete-secret-keys 1F8D4A4C
gpg --delete-keys 1F8D4A4C