Digital Signature Fields

In a PDF document, a digital signature is used to identify the person who signed a document. A digital signature will typically carry metadata information about the person signing the document. When a PDF document is signed, Acrobat stores an encrypted hash value of the entire document in the PDF document. Every time this PDF document is opened by an Acrobat application, it computes the document’s hash value and compares it against this encrypted hash value. If the values are equal, then it can confidently determine that the document has not been modified or changed.

Note: You must use Adobe Acrobat Professional to sign a PDF document. You cannot sign a PDF document using Adobe Reader.

The following table displays the required values for a digital signature field:

Keyword	Value	Default Value
action_item	Field	Required
action_name	A unique string to identify the digital signature field.	Required
action_type	DIGSIG_FIELD	Required
action_spec	The string you want displayed when you hover the mouse over the digital signature field in Acrobat.	Optional
action_range	Element_range \| cell_range	Element_range
action_instance	Single_instance	Single_instance

The following design script code creates a digital signature field.

Example:

! Create a Digital Signature Field
! The accumulated range box of the following elements
! define the Digital Signature field in the PDF document.
if ((level eq 1) and (color eq 9) and (type eq 3)) then
   action_item = field	
   action_name = "Chief Engineer" 	
   action_type = digsig_field
   action_spec = "John Doe, P.E."
endif

The design script above creates the following digital signature field. The text string (John Doe, P.E.) displays when you hover over the field.