layoutinfo

Records location information for all visible signed items.

A hash is taken of each page containing a signed item, and this hash includes positioning information for all the signed items relative to each other in those pages.

Syntax

   <layoutinfo>
      <pagehashes>
         <pagehash>
            <pageref>page sid₁</pageref>
            <hash>pagehash₁</hash>
         </pagehash>
         ...
         <pagehash>
            <pageref>page sid_n</pageref>
            <hash>pagehash_n</hash>
         </pagehash>
      </pagehashes>
   </layoutinfo>

Table 1. layoutinfo parameters
Parameter	Type	Description
page sid	string	The scope ID of the page you are hashing.
pagehash	string	The hash of the page.

Available in

signature

Example

In the following example, the signature item includes hashes for the three pages on which items were signed:

   <signature sid="signature1">
      <layoutinfo>
         <pagehashes>
            <pagehash>
               <pageref>PAGE1</pageref>
               <hash encoding="base64">pJAdX7+zh9+zEe</hash>
            </pagehash>
            <pagehash>
               <pageref>PAGE2</pageref>
               <hash encoding="base64">s+tHT+SElktqw4sod5</hash>
            </pagehash>
            <pagehash>
               <pageref>PAGE3</pageref>
               <hash encoding="base64">Jo13Ds+eth3EsSGE</hash>
            </pagehash>
         </pagehashes>
      </layoutinfo>
   </signature>

Usage details

This option helps ensure the security of your forms when you have signed items that are positioned using relative positioning, and unsigned reference items. Reference items are items on which the relative positioning of other items is based. Without layoutinfo, it is possible to move signed items on the form - without breaking the signature - by moving their unsigned reference items. By using layoutinfo to record the position of the signed items relative to each other, you can detect this form of tampering.