A very important consideration for designing interactive PDF forms is ensuring that your forms and the data you gather is secure. The following functions and features in LiveCycle Designer ES provide security options for your forms:
PDF Security settings let you define the access capabilities users have to the PDF forms. In the Form Properties dialog box, you can specify a password that the users must enter to open and fill the form. You can also restrict various levels of access to the form. For example, you may want to allow users to fill fields and signatures but not add comments or pages to the form.
Digital signatures let you authenticate a signing party and ensure that a form is not altered after it is signed. To add a digital signature field to a form design, you can use a signature field or a data signature associated with a submit button. Use a signature field to protect the appearance of the form objects and the values they hold. Use a data signature to protect the integrity of the form data.
Password fields let you control access to a form. You can set character masking as an option to the field so that the data is not displayed on the screen. You can define whether the password is optional, recommended, or required, and you can set up messages to prompt users appropriately. All user input may be validated through scripting. You can also bind password fields to data sources.
Secure WSDL data connections let you use HTTP/HTTPS and message-level (SOAP) client authentication to access WSDL documents and to connect to secure web services by using a security token (embedded in the SOAP message header).
See also 

About secure forms