[E2ee] Does the presence of overt, "Non-Ghost" surveillance actors/bots, inhibit E2E Security?

[Alec Muffett <[e-mail]>]

Hi All!

I'll be presenting this to the CFRG (Crypto Forum Research Group) at IETF
111, late on Friday evening (London time):

"A 'Duck Test' for End-to-End Secure Messaging"
https://alecmuffett.com/alecm/ietf-111/draft-muffett-e2esm-v1.18a.pdf

It's a reasonably short presentation-deck (albeit with a lot of slides)
offering a simple, robust, and easily understood metric for people to use
when judging assertions like:


*"The GCHQ 'Ghost' Proposal does not harm End-to-End Security"*
One interesting discussion that I *have* had, twice, regarding my draft is
regarding (Slide 25) whether "overt, blatant surveillance" inhibits a
system from being E2E-Secure - "because people will not be able to avoid
surveillance."

It's a great question, which I've answered with two different thought
experiments:


*Surveillance Scenario A:*
Imagine that the UK Government imposes a "Technical Capability Notice" on
WhatsApp and requires surveillance on everybody. Further imagine that
WhatsApp has the decency to tell everybody that surveillance is enabled.

Then Alice, in the UK, wants to talk to Bob with WhatsApp, but without
Surveillance. What does Alice do? Answer: there is nothing she can do
except "Fix the Government" or "Select a platform which does not implement
surveillance on behalf of the UK Government". Her intentions or desires are
incapable of changing anything about the situation, other than via
political means.


*Surveillance Scenario B:*
Say that you are using Signal to hold a group chat, and suddenly after a
month or so, it gets out that one of the people in the group chat ("Eve?")
is actually a member of the state security services.

Would that mean that Signal was suddenly no longer end-to-end encrypted?
No. If one did believe that, then E2E would have a "Schrodinger's
Cat"-quality - that it stops being E2E as soon as a spook looks at it.

But if the presence of unknown surveillance does not prevent something
being end-to-end encrypted, would the presence of *known* surveillance,
up-front, prevent something being considered end-to-end encrypted? Well,
when Eve was "outed", nothing has changed with the system other than user
choice to continue/not-continue to participate in the chat.

As 'user choice" was the only variable, user choice was also the
differentiator - including (big picture) the choice to use an individual
group chat *or* a messenger platform that was overtly enabled for state
surveillance. The choice to pull that surveilled chat or that surveilled
platform into one's own TCB/Trusted Compute Base/Zone of Trust, was a user
choice.


*Perspective*
In short: I think that "end-to-end secure messaging with state surveillance
overtly and transparently baked-in", is precisely *that*, and should be
highlighted as such, for exactly the reasons as explained in *RFC2804*.
Thus if people want to avoid surveillance, they should vote with their feet
and use a different platform, or obtain a different government; however the
surveillance should never be opaque, ghostly, or hidden.

What do others think, please?

- alec