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Re: newbie Question about PKCS#7

From: Christian Geuer-Pollmann <geuer-pollmann@nue.et-inf.uni-siegen.de>
Date: Tue, 21 May 2002 13:54:13 +0200
To: Tom Gindin <tgindin@us.ibm.com>, reagle@w3.org
Cc: w3c-ietf-xmldsig@w3.org
Message-ID: <25317094.1021989253@pinkpanther>
Hi Tom,

in the example from the spec URI="http://example.com/bar.xml#chapter1", if 
you do not use any transforms which convert the octet stream into a node 
set (i.e. no transforms which return a node set), then the file contents 
are 'piped' into the digest method as is.

But if you (the developer) do something like XPath filtering, the octets 
from the file are treated as XML and are converted into a node set. But 
that's up to you. No transform - no node set.

Christian


--On Dienstag, 21. Mai 2002 07:39 -0400 Tom Gindin <tgindin@us.ibm.com> 
wrote:

>
>       Joseph:
>
>       If the syntax which has been suggested for transparent non-XML data
> could be interpreted as a node-set, then IMO we need a syntax which
> explicitly tells developers: "This reference accesses data transparently
> as a sequence of octets.  That data is part of the base on which the
> digest is calculated, but is not to be interpreted as XML."
>
>             Tom Gindin
>
>
> Joseph Reagle <reagle@w3.org> on 05/20/2002 05:40:02 PM
>
> Please respond to reagle@w3.org
>
> To:    Tom Gindin/Watson/IBM@IBMUS, "Ed Simon" <edsimon@xmlsec.com>
> cc:    "Roman Huditsch" <roman.huditsch@hico.com>,
>        <w3c-ietf-xmldsig@w3.org>
> Subject:    Re: newbie Question about PKCS#7
>
>
> On Thursday 16 May 2002 11:28, Tom Gindin wrote:
>>       Maybe I'm confused about the standard, but I don't see a "Type"
>> value for transparent binary data or a transform for it.  Does a
>> Reference with both Type and Transforms omitted mean binary?
>
> It is octets or a node-set.
>
> [[
> URI="http://example.com/bar.xml#chapter1"
>   Identifies the element with ID attribute value 'chapter1' of the
>   external XML resource 'http://example.com/bar.xml', provided as an
>   octet stream. Again, for the sake of interoperability, the element
>   identified as 'chapter1' should be obtained using an XPath transform
>   rather than a URI fragment (barename XPointer resolution in external
>   resources is not REQUIRED in this specification).
> ...
> The data-type of the result of URI dereferencing or subsequent Transforms
> is either an octet stream or an XPath node-set.
> ...
> If the data object is a node-set and the next transform requires octets,
> the signature application MUST attempt to convert the node-set to an octet
> stream using Canonical XML [XML-C14N].
> ]]
>
>
>
>
>
Received on Tuesday, 21 May 2002 07:49:12 GMT

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