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Re: Call for Adoption: Encrypted Content Encoding

From: Eliot Lear <lear@cisco.com>
Date: Tue, 8 Dec 2015 08:16:08 +0100
To: Martin Thomson <martin.thomson@gmail.com>
Cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-ID: <566683B8.1060406@cisco.com>
Hi Martin,

Thanks for your response.  Please see below.

On 12/7/15 10:51 PM, Martin Thomson wrote:

> I think that your proposal had some sort of implication that malware
> scanning was the responsibility of some sort of intermediary.  That's
> probably unintentional.  I think that all we need to do is acknowledge
> that this is a (value-neutral) choice.

Based on your explanation I now understand what you're saying.  You have
indeed surfaced unstated architectural claim here by both of us.  Mine
is this:

    The more opportunities there are for bad links, the more infections
    there will be.  And the converse holds true, of course. 
    Furthermore, not all systems will be inoculated from malware.

Let us assume that this statement is true, or Google and Yahoo! are
spending needlessly spending a whole lot of money scrubbing such links.

Yours, I think, is this:

    The end system is in the best position to protect itself against
    malware.

I largely agree.  Let's agree that these two architectural principles
are not mutually exclusive.

I will add one more assertion that I believe we also can agree on, which
is that some people can be fooled into clicking on links.  Phishing is
not the only threat vector.  A full scale automated system that uses
this encryption mechanism would also be at risk, and perhaps more
dangerous.  But that there is at least one threat that is well
understood by a lot of people is enough to recognize the problem.

The threat we must address is exacerbation of attacks (an example being
phishing) as relates to encrypted files where attackers have access to
recipients' public keys/certs.

Stating that "clients might need to use other means of protection..."
addresses  the latter architectural statement without acknowledging the
former.  We need to go just a bit further and simply state that "all
systems that receive the encrypted object are advised to take what
precautions they can to have some confidence that the object is free of
malware."   And then I would suggest several examples are in order, so
as not to be too opaque.

As an aside, part of the problem with this discussion is with the use of
the term "intermediary".  While perhaps correct in some sense, it is so
vague as to introduce an ambiguity that may further cause additional
confusion when having such discussions.  In one of the cases I
mentioned, we have a classic cache which neatly fits the term
"intermediary" as everyone understands it.  The term is expansive in its
use, and thus a tad misleading, regarding the case where the server is
The origin server for the object.  The above change covers both cases,
by the way.

Eliot



Received on Tuesday, 8 December 2015 07:16:39 UTC

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