Erm: the blowfish encryption was in reference to the old '-x' vi encryption option (using a now pretty insecure Unix 'crypt' function).

A better "configure GPG edit mode" .vimrc is here: http://vim.wikia.com/wiki/Edit_gpg_encrypted_files

I believe that's based on the one first posted by Wouter Hanegraaff <wouter@blub.net>.