[xmlsec] Setting base for evaluating Reference URIs when signing

[Jonathan Share]

Hi,

My background is that I'm writing a Pylons web application that will 
sign Widgets based on the current state of the w3c spec[1].

In order to do this I'm extracting the widget to a temporary directory 
and then using the PyXmlSec wrapper around the xmlsec library to create 
the Signature Template in memory creating Reference elements relative to 
the root of where I extracted the zip file, something like this.

<Reference URI="config.xml">
<DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
<DigestValue></DigestValue>
</Reference>