Re: [xml] Canonicalization (C14N) of an XML element

[Aleksey Sanin <aleksey aleksey com>]

> I am a newbie to libxml2, and I am not familiar with XPath, nor
> libxml2's NodeSet.
Hm... I am sorry but I have to ask if you really want to
write xmldsig implementation yourself. I did it once
(http://www.aleksey.com/xmlsec) and it is not an exercise
I can recommend for "a newbie to libxml2".


> These functions take the parameter 'xmlNodeSetPtr nodes', described as
> "The nodes set to be included in the canonized image, 
> or NULL if all document nodes should be included."
>
> So I built a node set, consisting of my single element node.
> Should I build a node set including all sub-nodes? 
Yes. You have to add all the nodes that you want to get
canonicalized. However, in this particular case there is
a better way. The xmlC14NExecute function allows one to
provide a callback that would be called to determine if
a given node is "visible" (i.e. included in c14n output)
or not. To canonicalize just a given node (with all the
attributes and children nodes) you can write a callback
function that would return "true" for your node, its attributes,
namespaces and children nodes and "false" for all other
nodes in the document.

Aleksey