Digitally signing a form template authenticates you as the designer of the form template in the same way that a digital signature on a form authenticates the user who filled out the form. Adding a digital signature to a form template also enables the form template to operate at the Full Trust level. For example, a form template that contains managed code that uses the Full Trust level of security must either be installed on a user's computer or digitally signed by the form template designer so that it can be used.
Note: When Microsoft Office Outlook 2007 users send a copy of an InfoPath form as an e-mail message to other Office Outlook 2007 users, and that form is set to run at the Full Trust security level, the associated form template must be signed with a digital signature in order to work properly.
To add a digital signature to a form or a form template, a digital certificate is required. You can obtain a digital certificate through a commercial certification authority or from your internal security administrator. The decision to purchase a digital certificate depends on how widely your organization plans to deploy form templates.
If you digitally sign a form template that you are designing with a trusted root certificate, you help ensure the integrity and authenticity of the form template. You can also set the security level for the form template to Full Trust, which means that the form template can access files and settings on the user's computer or on a different domain, thereby enabling you to use a wider range of features in your form template. In addition, if you digitally sign your form template, you can deploy and update that form template by sending it and updated versions of it to others by using an e-mail program.
On the Tools menu, click Form Options.
Click Security and Trust, and then select the Sign this form template check box.
Click Select Certificate.
In the Select Certificate dialog box, click the certificate that you want to digitally sign the form template with.
Note: If a certificate is not trusted on a user's computer, InfoPath displays a security message and requires the user to enable trust for the certificate issuer before the user can open a form based on your form template.