InfoPath Dev

I have created infopath forms and published them to Sharepoint Document Libraries and they work well.  In these forms I have used the 'full trust' option and signed the form specifying a trusted digital signature.  After a user enters data and the form is submitted to the document library, I can save the file as xml, modify it, and then upload it back to the library.  According to books I have read on infopath, one of the reasons for using a certificate is so the 'xml data will be secured'.  I don't get it - why can I modify any user's input and upload it back to the library?????   What am I missing?

Isn't that referring to when you use the digital signature feature within the form?  You have to put digital signatures in the form and in the configuration of the digital signature, then you tell it what section(s) to lock upon signing.  What you are doing is just putting a digital signature on the form template, which is the XSN file, not the XML data files that are created as a result.

<br>Makes sense.  Thanks! <\br>