You can keep a file secure by making the file inaccessible to other users. For example, a file with permission 600 cannot be read except by its owner and the superuser. A directory with permissions 700 is similarly inaccessible. However, someone who guesses your password or who discovers the root password can access that file. Also, the otherwise inaccessible file is preserved on a backup tape every time that the machine files are backed up to tape.
Fortunately, an additional layer of security is available to all users of Solaris software in the United States, the Solaris Encryption Kit. The encryption kit includes the crypt command, which scrambles the data to disguise the text. For more information, see the crypt(1) man page.