[ACTION-201] Make concrete proposal on whitespace removal c14n for XMLDSIG 1.1 (draft2)

6.5.2.1 Whitespace Removal in ds:SignedInfo

The element RemoveWhiteSpace is to provide a means to cause whitespace
removal irrespective of an XMLSchema on a SignedInfo level
[http://tinyurl.com/MT-Konrad-Lanz-OASIS-DSS#page=101].

xmlns:ds11="http://www.w3.org/2009/xmldsig11#"

<CanonicalizationMethod Algorithm="http://www.w3.org/2006/12/xml-c14n11">
  <ds11:RemoveWhiteSpace/>
</CanonicalizationMethod>

The paramer RemoveWhiteSpace in the
http://www.w3.org/2009/xmldsig11# namespace, causes whitespace nodes to
be removed from the pre-canonicalization node-set.

Note (non-normative): This is equal to executing an XPath filter
step as below in the square brackets.

(//. | //@* | namespace::*)
[not(self::text()) or not(normalize-space(self::text())="")]

See Section 4.3.3.4.1 to remove whitespace on the Reference level.

------

4.3.3.4.1 Whitespace Removal in data objects referred by Reference

This section provides a recommendation for removing whitespace if it is
insignificant (not to be confused with ignorable whitespace) to the
data objects. Pure whitespace nodes should be considered insignificant
by default on signature creation and reflected, by putting the following
Transform as the last transform before canonicalization
[http://tinyurl.com/MT-Konrad-Lanz-OASIS-DSS#nameddest=subsection.4.2.2].

xmlns:ds11="http://www.w3.org/2009/xmldsig11#"

<Transform Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
  <XPath>not(self::text()) or not(normalize-space(self::text())="" and
not(ancestor-or-self::*/@xml:space[1]="preserve"))</XPath>
</Transform>