Using Digital Signatures with Microsoft InfoPath E-forms
When designing an InfoPath e-form, there are two generic actions involved when creating e-forms enabled for digital signatures:
You can enable digital signatures for the entire form or for specific parts of the form. When users sign the form, the digital signature locks the data so that it cannot be changed, and stores the view with the digital signature.
You can optionally configure a prompt to the user to sign the form upon submittal if the user attempts to submit the form without a digital signature (this feature exists only for signatures that sign the entire form). If you do not enable this prompt, it is possible for a user to save the form without signing it.
During design time, when an InfoPath e-form enabled for digital signatures is imported as an IS document type, the signature field is set to "required." If an instance of this e-form is submitted at run time without a digital signature, a run-time exception will appear in the Integration Server error log, indicating that the form data "does not conform to the Publishable Document Type."
When an InfoPath template associated with signature-enabled form is imported as an IS document type, you are advised to examine the properties of the signature field in the document. The signature field is typically set to be a required field. If you want to accept e-forms that are enabled for digital signature but are not digitally signed, you must manually change the field type in the IS document type to "optional" to avoid errors at run time.