[xmlsec] XMLSEC Reference URI question

Aleksey Sanin aleksey at aleksey.com
Thu Jul 25 12:10:21 PDT 2002

According to C14N spec all whitespaces and eol symbols are preserved.
For example, take a look here:
To be precise, in XML whitespaces are treated as "text" nodes and all C14N
regular rules apply to these nodes (for example, you can exclude some 
using XPath expression before C14N, etc.)
I am doing my best to make XMLSec library complaint with the specs and
in this particular case XMLSec strictly follows the C14N spec by preserving
the whitespaces. About the reasons why does it fail, I can add more 
details for
possible options from my previous  email (whitespaces  were lost in 
Apache and
there are only two possible places :) ):
    1) Apache does not treate whitespaces as "text" nodes and by this when
    you run XPath expression these missed nodes are not included into output
    (and not processed by C14N)
    2) Apache does C14N in wrong way and removes white spaces


Moultrie, Ferrell (ISSAtlanta) wrote:

> Aleksey:
>   Ok .. I finally edited the document enough to get it to verify. 
> Here's what I had to change -- I haven't had a chance to re-read the 
> C14N spec in detail so maybe you can tell me if it's an xmlsec problem 
> or not. In order to get it to verify, I removed all the leading 
> whitespace (indenting with tabs) from the signed document, I also 
> removed all new-line sequences from between the elements in the signed 
> document. So -- the C14N transform (or something else in the web 
> world) is removing all the "formatting" (leading tabs and EOL 
> whitespace) from the XML in the Apache world. It's obviously 
> preserving that on the xmlsec side based on the buffer dump and the 
> fact that manually removing the whitespace works. I'd thought that the 
> C14N transform did that for me -- did I miss something or is there an 
> issue with the C14N transform in xmlsec. I'm going to go re-read the 
> C14N spec now -- but if you can tell me how you think it should behave 
> in xmlsec I'd appreciate it!
> Thanks!
>   Ferrell
> PS, I'm attaching the original document from the web folks (*06.xml, 
> fails) and my edited version (*06a.xml, works).
>     -----Original Message-----
>     From: Aleksey Sanin [mailto:aleksey at aleksey.com]
>     Sent: Thursday, July 25, 2002 11:43 AM
>     To: Moultrie, Ferrell (ISSAtlanta)
>     Cc: 'xmlsec at aleksey.com'; Dodd, Tim (ISS Atlanta)
>     Subject: Re: [xmlsec] XMLSEC Reference URI question
>     After quick look, the XMLSec output seems correct. XMLSec produced
>     exactly what
>     you've seleceted. However, the error says that digests do not
>     match and this means that
>     Apache generated another output. I do see few possible options:
>         1) Apache calculated wrong nodes set (from XPath expressions)
>         2) Apache did different C14N for the same nodes set
>         3) something else more stupid on Apache or XMLSec side
>     I would vote for option 1) since the C14N is very simple here (no
>     namespaces, etc.) and
>     we already have seen problems with XPath transform in Apache. But
>     only Apache output
>     "just before digesting" can actually help to identify the problem.
>     With best regards,
>     Aleksey

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