[Mailman-Developers] Encrypted lists predictable difficulties and implementation needs

[Rich Kulawiec]

On Sun, Mar 19, 2017 at 06:14:22PM +0100, Norbert Bollow wrote:
> That is true, if the attacker already knows whose communications they
> want to snoop on. However one of the main benefit of using encrypted
> communications is in the area of making it much more expensive and
> politically risky for the attacker to determine which targets have
> value.

The attacker (for many values of "attacker") is and will be particularly
interested in communications that are encrypted -- because they'll stand out.
Granted, this will diminish as more communications become encrypted, but
for the forseeable future, anyone using encryption or similar privacy
measures will be targeted:

	https://www.wired.com/2014/07/nsa-targets-users-of-privacy-services/

I agree with you that encryption makes it more expensive, and that's an
argument for deploying it, but I don't agree that it's politically risky:
there are no appreciable consequences for anyone engaging in this.  Even
at the commercial level (e.g., Verizon's insertion of unblockable cookies
in order to conduct surveillance) there are no appreciable consequences
for any violation of user privacy or security -- merely inconsequential
slap-on-the-wrist fines and then it's right back to business as usual.

> In the absence of encryption, that can be achieved by means of mass
> surveillance anywhere between the communications endpoints followed by
> (possibly AI-based) pattern analysis, at near-zero incremental cost and
> near-zero incremental risk per additional group that is subjected to
> such surveillance for reasons of its communications being possibly of
> interest to the attacker.

I almost entirely agree with you on this, but want to point out that
if an attacker has compromised an endpoint, they can stop there: there's
no need to worry about the rest.  And endpoints are already compromised
by the hundreds of millions, with more every day.  (And as more endpoints
become part of the IOT, the rate of compromise will increase drastically.)
I think it's quite reasonable to extrapolate a billion compromised
endpoints sometime in the next couple of years.  (I also think that
in a couple of years I'll shake my head at how much of an underestimate
that turned out to be.)

So if it becomes desirable or profitable for the new owners of those
systems to pay specific attention to encrypted mailing list traffic, they
will...and probably much quicker than anyone anticipates.  They won't
get it right the first or second time, just like they didn't get botnet
C&C organization right the first or second time -- but it won't take
them long to learn.


Thus the target end user population for encrypted mailing lists
looks something like this:

	Nobody using freemail providers -- these fall into two categories:
	those that are owned and those that are going to be owned.

	Nobody using webmail -- webmail implementations have a long
	and sad history of serious security issues.  And "browser
	security" is often an oxymoron.

	Nobody using Windows, MacOS, Android, or iOS.  There are already
	too many exploits on the table to keep track of, and there can be
	no doubt that these are only a fraction of the total: many more
	are held by security researchers, vulnerability brokers,
	intelligence agencies, etc.   And Linux probably should be
	added to that list in the near future, as its increasing
	deployment has clearly made it an attractive target.  (Nod to
	the past week's releases by the Shadow Brokers, which are surely
	the tip of the tip of the iceberg.)

	Nobody with poor email habits, e.g., top-posters, full-quoters,
	people who use HTML markup.  (Since these undercut encryption,
	sometimes rather badly.)

	Nobody using the IOT to send or receive email, e.g., their car,
	which was very likely pre-compromised at the factory.

That doesn't leave a lot of people.

I'm not saying "don't do it".  As an intellectual exercise and a
development challenge, it's interesting.  I'm saying "make sure --
if people are thinking about deploying this -- that they understand
that they have almost no chance of making this work as intended
in the real world."

---rsk