Re: CDN versus edge compute use case distinction (was: Requesting reviews of draft-vanrein-httpauth-sasl)

Eric Rescorla <> Fri, 15 May 2020 13:14 UTC

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From: Eric Rescorla <>
Date: Fri, 15 May 2020 06:11:10 -0700
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To: Michiel Leenaars <>
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Subject: Re: CDN versus edge compute use case distinction (was: Requesting reviews of draft-vanrein-httpauth-sasl)
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On Fri, May 15, 2020 at 1:17 AM Michiel Leenaars <>

> Fulfillment (like edge computing) is a different role from delivery, as
> the
> content or service delived by the edge node (like the postal piece) would
> just not exist. It is outsourcing core functionality. My reason to reply
> to
> the original thread was that the traditional CDN role can take place fully
> without authentication (even by pushing it to another subdomain),

I'm not going to get involved in a definitional argument here about what
a CDN is, but in the Web security model, the role of hosting static assets
generally cannot be done without authentication. The reason for this is
that those assets impact the semantics of the web page into which they
are loaded.

Specifically: When JS modules are loaded into a page using
a <script> tag they become part of the context of the page and have the
same privileges as if they were loaded from the origin server. If these
are not authenticated there are trivial attacks. There are other resource
types that are more "static" from the Web's perspective (images
for instance) but these also can be used for more subtle attacks.