Since all users must have read access to the codice_2 file to do many common tasks (codice_5 will use codice_2 to map UIDs to login names for example), anyone could also read the password hashes of other users. To solve this problem, the file codice_7 was created to store the password hashes, with only root having read access. Under password shadowing, the 2nd field (password hash) is replaced by an 'x' which tells the system to retrieve the corresponding user's password via the codice_7 file.