Fix the permissions of the enclosing directory ~/.gnupg because an attacker with enough rights on the folder could manipulate folder contents.
Make sure, the folder+contents belong to you:
chown -R $(whoami) ~/.gnupg/Correct access rights for .gnupg and subfolders:
find ~/.gnupg -type f -exec chmod 600 {} \;
find ~/.gnupg -type d -exec chmod 700 {} \;finally import your keys with your user (not sudo/root)
gpg --import key_sec.asc
