Subject: [E2ee] Reducing Plaintext Metadata in E2EE Systems

From: Matthew Finkel <[email-masked]>
Date: Thu, 29 Jul 2021 14:12:30 +0000

Hi all,

This draft is very valuable, thanks to the authors for writing it. I'd
like to call more attention to the importance of reducing plaintext
metadata. The current draft contains:

   Existing protocols are vulnerable to meta-data analysis, even though
   meta-data is often much more sensitive than content.  Meta-data is
   plaintext information that travels across the wire and includes
   delivery-relevant details that central servers need such as the
   account identity of end-points, timestamps, message size.  Meta-data
   is difficult to obfuscate efficiently.

The phrasing of this paragraph leads me to wonder if obfuscation of
metadata should be included as a desirable feature. I don't mean to
imply it's possible to eliminate leaking all metadata in all E2EE
systems, but there is often some low-hanging fruit, like IP addresses or
non-routing metadata, that an E2EE system can try to protect or
obfuscate; e.g., MASQUE/OHTTP/Tor for IP addresses, and [0][1] for
protecting some extraneous message headers. I can open a PR if this is
helpful.

Thanks,
Matthew Finkel

[0] https://datatracker.ietf.org/doc/html/draft-autocrypt-lamps-protected-headers
[1] https://signal.org/blog/sealed-sender/

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From: Mallory Knodel <[email-masked]>
Date: Thu, 29 Jul 2021 10:27:34 -0400

Thanks a lot Matthew,

I agree that this should be a goal. Not all of the features should or 
could be part of every e2ee system, but the draft should demonstrate the 
"trajectory" of where the technology goes ideally.

Please do create a PR, I would be happy to review and merge.

-Mallory

-- 
Mallory Knodel
CTO, Center for Democracy and Technology
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