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Re: [xml-dev] XML Transformation


I am already using c14n canocalizer for transforming the xml. I am not sure if the other party is using it though. When i transform the xml though the namespace prefix "dsig" is removed from the inner <signture> tag and its child nodes as there is a defalut namespace (xmlns="http://www.w3.org/2000/09/xmldsig#") already defined for that nodeSo according to c14n is this correct way of transforming or
wrong. My partner says that no matter transformer you use you should not remove the "dsig" prefix. My argument is signature is always calculated after transforming using c14n.

The product i am is a federation product and even according to the SAML 2.0 specification for signing the c14n transformer has to be used.
The point of contention is that he says he has calculated the sig with the "dsig'" namespace(though he claims that he too has used c14n) and when i am doing the transformation it removes ???

I am not sure i will be able to post the exact xml here due to organizational policies here but let me find that out. As for XSLT i am not too familiar with that. As i had said earlier a SAXParser is used to read the socket input stream in axis/xmlsec(we are using these lib for xml related operations) to get the document node.

Additionally the xml is received over a SOAP channel managed by axis. I havent written any code for parsing or verifying signatures, we are using third party libs for xml operations.

Please let me know if you need some more data.


On Thu, Aug 7, 2008 at 5:45 PM, Richard Salz <rsalz@us.ibm.com> wrote:
You mean "I don't see why the inner... *cannot be* or *is not* removed"

It can.  Having it there, or not, does not change the semantics of the
XML.  It's just a side-effect of whatever implementation you are using.

If you really care about this -- for example, doing XML Digital Signatures
-- then you need something like xml c14n.  Otherwise I would not worry
about it.


STSM, DataPower Chief Programmer
WebSphere DataPower SOA Appliances

"Anishek Agarwal" <anishek@gmail.com>
08/07/2008 08:02 AM

Re: [xml-dev] XML Transformation

I still did not get the reply for this. Can someone please comment.


On Wed, Aug 6, 2008 at 2:50 PM, Anishek Agarwal <anishek@gmail.com> wrote:
According to the xml specification though
http://www.w3.org/TR/REC-xml-names/#scoping-defaulting the inner scope
definition overrides the parent one if the NSAttName is the same. In our
case of the xml above it is the same as its the default namespace. So i
dont see why the inner scope namespace declaration element be removed and
use the parent namespace.


On Wed, Aug 6, 2008 at 2:30 PM, Andrew Welch <andrew.j.welch@gmail.com>
> For better or worse, the digital signature mechanisms follow XML
> Canonicalization by deciding that namespace prefixes are significant:
> http://www.w3.org/TR/xml-c14n#NoNSPrefixRewriting
> for discussion.

!  That's good to know...

I guess it all comes down the fact that the prefix isn't expanded to
the URI.... which is the root cause of the problem of XPath requiring
the prefixes to be mapped elsewhere.

I guess there is an argument for dropping the URI altogether, and just
using the prefix.  Some things would get harder, but many more would
get a lot easier.

Andrew Welch
Kernow: http://kernowforsaxon.sf.net/

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