So you don't need a full blown authentication to allow access to your title, but you also don't want just anyone to gain access and read your confidential document. Single pass-phrase is the answer.
Using the REMOTE SECURITY API tab in the EDIT TITLE SETTINGS screen:
Remote script: http://www.e-digitaledition.com/clients/single_pass/xxxx (where xxxx is the case-sensitive pass-phrase of your choosing)
String returned on success: success
username field name: passphrase
password field name: check box for “not needed”
You can test the settings to make sure the passphrase works, then click the checkbox " I confirm that the above script has been tested to work. Please secure this title."
Update Title and your title should now be secured and only accessible by entering in the custom passphrase