If you want to control access to a form through a password, add a password field to the form. When a user types in the password field, the characters are masked by a character that you select. If required, you can define a specific input pattern that the user must match to gain access to the form.
After you add a password field to the form design, you can edit the caption text and manipulate the object’s properties in the Field, Value, and Binding tabs of the Object palette. You can define these properties:
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Specify that LiveCycle Designer ES use the horizontal length of the text field to determine how many characters to allow in the password field.
A password field can be present without forcing users to supply a password. You can define whether the password is optional, recommended, or required, and you can set up messages to prompt users appropriately. All user input can be validated through scripting.
See also 

Overview of password fields