W3C home > Mailing lists > Public > www-talk@w3.org > March to April 1995

Re: your mail

From: lilley <lilley@afs.mcc.ac.uk>
Date: Tue, 4 Apr 1995 14:52:49 +0100 (BST)
Message-Id: <17653.9504041352@afs.mcc.ac.uk>
To: www-talk@www10.w3.org
Cc: www-talk@www10.w3.org
Jon wrote:
>  Robert Robbins  <rrobbins@gdb.org> wrote:
> | On Mon, 3 Apr 1995, Dan Connolly wrote:
> |
> | > The right answer is digitally signed distributions. Then only can
> | > you be certain that the bits have not changed since they left
> | > the author's hands.

> | Doesn't this suggest some utility in extending the URN/URL concept to
> | include an optional computed checksum as part of the identifier? Verifying
> | perfect identity of what you are getting against what you thought you were
> | requesting has some value for materials other than programs, too.

Yes. In particular, it requires the MD attribute on all A and IMG tags, anything
thay takes a URI as an attrribute.

> | The checksum could be recomputed dynamically every time the file is
> | transferred (as checksums are now computed dynamically every time an IP
> | packet is placed on or taken from a communication medium).

> My initial reaction is it makes more sense for a new document type: 
> signed-html.
> The viewers for signed-html then worry about authentuicating the signature and
> displaying proper messages etc.

That is another level of security, where the document can be updated by 
the original author, signed again, and the link is still valid. MD checksums 
will not cope with that, as you say.

> I dont think a checksum is part of either a name (URN) or a location (URL).

But it is part of a link, in HTML 3.0; this does not require any changes 
to the URI syntax.

--
Chris Lilley
+----------------------------------------------------------------------+
|Technical Author, Manchester and North HPC Training & Education Centre|
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| Computer Graphics Unit,             |  Email: Chris.Lilley@mcc.ac.uk |
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|       "The first W in WWW will not wait."   Franois Yergeau         |
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Received on Tuesday, 4 April 1995 13:54:18 UTC

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