OASIS ebXML Messaging Services TC

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  • 1.  Re: Signature Transforms

    Posted 08-24-2001 11:44
    David:
    
    The example starting on line 2045 is not consistent with the description
    on lines 2027 - 2036. I think there should be an enveloped-signature
    transform in the example to exclude the ds:Signature element.
    
    The enveloped signature transform is defined as follows in
    http://www.w3.org/TR/2001/PR-xmldsig-core-20010820/:
    
    6.6.4 Enveloped Signature Transform
    Identifier:
    http://www.w3.org/2000/09/xmldsig#enveloped-signature
    An enveloped signature transform T removes the whole Signature element
    containing T from the digest calculation of the Reference element containing
    T. The entire string of characters used by an XML processor to match the
    Signature with the XML production element is removed. The output of the
    transform is equivalent to the output that would result from replacing T
    with an XPath transform containing the following XPath parameter element:
    
       <XPath xmlns:dsig="&dsig;">
       count(ancestor-or-self::dsig:Signature |
       here()/ancestor::dsig:Signature[1]) >
       count(ancestor-or-self::dsig:Signature)</XPath>
    
    -Arvola
    
    -----Original Message-----
    From: David Fischer <david@drummondgroup.com>
    To: Ralph Berwanger <rberwanger@bTrade.com>
    Cc: ebXML Msg <ebxml-msg@lists.oasis-open.org>
    Date: Friday, August 24, 2001 8:27 AM
    Subject: Signature Transforms
    
    
    Hi Ralph,
    
    Remember in Vienna when we went back and forth on whether it is necessary to
    create a transform to exclude the Signature element?  I'm still not sure. .
    .
    
    http://www.w3.org/TR/2001/PR-xmldsig-core-20010820/
    
           <Reference URI="">
             <Transforms>
               <Transform
                 Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
                 <XPath xmlns:dsig="&dsig;">
    
    not(ancestor-or-self::dsig:Signature)
                 </XPath>
               </Transform>
             </Transforms>
             <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
             <DigestValue>. . .</DigestValue>
           </Reference>
    
    This seems to have a Transform excluding the Signature element.  However, in
    our
    example on page 54 we have:
    
           <ds:Reference URI="">
                <Transforms>
                    <Transform
    Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116">
                      <XPath xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">
                                  not(ancestor-or-self::eb:TraceHeaderList or
                          ancestor-or-self::eb:Via)
                     </XPath>
                     </Transform>
                 </Transforms>
             <ds:DigestMethod
    Algorithm="http://www.w3.org/2000/09/xmldsig#dsa-sha1"/>
             <ds:DigestValue>...</ds:DigestValue>
           </ds:Reference>
    
    We don't exclude the Signature in the Transform.  In Vienna, we decided that
    this happened automatically, can you confirm?
    
    Regards,
    
    David Fischer
    Drummond Group.
    
    
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