You want to edit encrypted files in place with GNU Emacs, without decrypting them to disk.
Use the Emacs package crypt++.el:
~/.emacs: (if (load "crypt++" t) (progn (setq crypt-encryption-type 'gpg) (setq crypt-confirm-password t) (crypt-rebuild-tables)))
crypt++ provides a transparent editing mode for encrypted files. Once the package is installed and loaded, simply edit any GnuPG-encrypted file. You'll be prompted for the passphrase within Emacs, and the file will be decrypted and inserted into an Emacs buffer. When you save the file, it will be re-encrypted automatically.
Crypt++ is available from http://freshmeat.net/projects/crypt and http://www.cs.umb.edu/~karl/crypt++/crypt++.el.