Re: Encrypting Elements and Transclusion

This is an interesting thought. Actually, I believe that XML
Encryption is more closely related to XInclude
(http// in the sense that the
encryption/decryption operation on XML substructure can be
seen as a InfoSet-to-InfoSet transformation. In XInclude,
the element (that is, element information item) to be expanded
by including an external InfoSet is clearly marked within
the source InfoSet. In other words, there is no separate
device (such as XPath) to specify which part of the source
document to be expanded.  This is good for modular parser
design as well as it allows on-the-fly encryption/decryption
during parsing.


Hiroshi Maruyama
Manager, Internet Technology, Tokyo Research Laboratory

From: "Joseph M. Reagle Jr." <> on 2000/10/13 00:58

To:   "Public XML Encryption List" <>
cc: (Henry S. Thompson),, (bcc: Hiroshi Maruyama/Japan/IBM)
Subject:  Encrypting Elements and Transclusion

I was speaking to Henry Thompson about some of the XML Encryption issues,
and he pointed out a similarity of element encryption (encrypting an element
and replacing it with a new "stub" element with the encrypted element as its
content) to transclusion (a linked resources is automatically fetch and
embedded in place of the link). In my nascent understanding of the problem I
hope encryption could borrow both the data model (Infoset, XPath, DOM, etc)
and the processing model (XSLT, DOM, XLink transclude) from elsewhere...

Consequently, I've been reading up on transclusion and thought I'd forward
on my references. If other folks have given any thought to this, or can shed
some light on the affects/requirements of  XLink on XML parsers and schema
validity, please do!

[1] Problems with Dynamically Assembled Document Portions, and Some
Solutions. Steven J. DeRose and Christopher R. Maden.

[2.1] XML XLink Requirements. Steven J. DeRose. W3C Note 24-Feb-1999
transclusion: A specific kind of linking in which access of
one end automatically causes another end(s) to be retrieved and embedded,
appearing much as if their data had occurred at the same place as the
initial end that triggered its inclusion. The original definition also
requires that systems provide direct access to the originating document as
a whole, in its original document context (including, for example, its
copyright notice).
[2.2] XML Link. Steve DeRose, Eve Maler, David Orchard, Ben Trafford. W3C
Candidate REC.
"embed": An application traversing to the ending resource should
load it in place of the starting resource.

[3]  "Prototyping an Updating Transclusion Tool based on XLink." By Richard
Tobin (University of Edinburgh), presented at XTech '99.  "We have
implemented prototype support for transclusion of changing material via
XLink. Our tool, which makes use of the XML and XSL support in Internet
Explorer Beta 2, will style and display XML documents which contain XLinks
with actuate='auto' and show='embed' as if the linked-to material was
actually contained within the linking element. Furthermore, we have written
an update server, so that if any of the URLs contained in the XLinks so
processed change, the page will be redisplayed. This update facility is
restricted to URLs which are being served from an HTTP server which is also
running our update server, but does NOT require polling from the
client.   Aside from providing a modest level of support for exploring the
benefits of XLink, standoff markup and just-in-time document composition, we
think the major contribution of this effort is in illustrating a relatively
novel distribution of effort for handling irregularly changing information
over the Web."

[4] auto/embed is not node transclusion. Paul Prescod.
(Interesting list of some of the questions regarding transclusion)

Joseph Reagle Jr.
W3C Policy Analyst      
IETF/W3C XML-Signature Co-Chair

Received on Monday, 16 October 2000 18:44:57 UTC