[Cryptography] Separating concerns

[Phillip Hallam-Baker]

On Thu, Aug 29, 2013 at 7:15 AM, Jerry Leichter <leichter at lrw.com> wrote:

> On Aug 28, 2013, at 2:04 PM, Faré wrote:
> >> My target audience, like Perry's is people who simply can't cope with
> anything more complex than an email address. For me secure mail has to look
> feel and smell exactly the same as current mail. The only difference being
> that sometime the secure mailer will say 'I can't contact that person
> securely right now because…'
> >>
> > I agree with Perry and Phill that email experience should be
> > essentially undisturbed in the normal case, though it's OK to add an
> > additional authorization step.
> >
> > One thing that irks me, though, is the problem of the robust, secure
> > terminal: if everything is encrypted, how does one survive the
> > loss/theft/destruction of a computer or harddrive? I'm no ignoramus,
> > yet I have, several times, lost data I cared about due to hardware
> > failure or theft combined with improper backup. How is a total newbie
> > to do?
> This is a broader problem, actually.  If you've ever had to take care of
> someone's estate, you'll know that one of the problems is contacting all
> the banks, other financial institutions, service providers, and other such
> parties they dealt with in life.  My experience dealing with my father's
> estate - a fairly simple one - was that having the *paper* statements was
> the essential starting point.  (Even so, finding his safe deposit box - I
> had the unlabeled keys - could have been a real pain if my sister didn't
> remember which bank it was at.)  Had he been getting email statements, just
> finding his mail accounts - and getting access to them - could have been a
> major undertaking.  Which is one reason I refuse to sign up for email
> statements ... just send me the paper, thank you.  (This is getting harder
> all the time.  I expect to start getting charged for paper statements any
> time now.)
>
> Today at least, my executor, in principle, work with the mail provider to
> get access.  But for truly secure mail, my keys presumably die with me, and
> it's all gone.
>
> You don't even have to consider the ultimate loss situation.  If I'm
> temporarily disabled and can't provide my keys - how can someone take care
> of my bills for me?
>
> We can't design a system that can handle every variation and eventuality,
> but if we're going to design one that we intend to be broadly used, we have
> to include a way to handle the perfectly predictable, if unpleasant to
> think about, aspects of day to day life.  Absolute security *creates* new
> problems as it solves old ones.  There may well be aspects to my life I
> *don't* want revealed after I'm gone.  But there are many things I *do*
> want to be easily revealed; my heirs will have enough to do to clean up
> after me and move on as it is.
>
> So, yes, we have to make sure we have backup mechanisms - as well as key
> escrow systems, much as the term "key escrow" was tainted by the Clipper
> experience.
>

Systems do need to be usable in practice and too much security can be a bad
thing. I am thinking about 'PRISM Proof' as a hierarchy of needs:

0 No confidentiality requirement
1 Content Confidentiality Passive intercept (met by STARTTLS)
2 Content Confidentiality Active Intercept (met by STARTTLS + validated
recipient server cert)
3 Content Confidentiality Coercion or compromise of Mail service provider
4 Content Confidentiality Coercion or compromise of Trusted Third Party
5 MetaData Confidentiality
6 Traffic Analysis Confidentiality

At present we only have a widely deployed solution for level 1.

The constituency that has a requirement for level 6 is probably very small.
Certainly none of us would benefit. Is is a hard goal or a stretch goal?

It is certainly a desirable goal for people like journalists but the cost
of meeting the requirement may not be acceptable.

At any rate, I think that starting by trying to build something to level 4
would be a good start and provide an essential basis for getting through to
levels 5 and 6.

It might be that to get from level 4 to level 6 the solution is as simple
as 'use a German ISP'.


Since we are talking about Snowden and Greenwald, folk might be amused to
learn that I was the other party who contacted Baghdad Boylen, General
Pertreaus's spokesperson who sent Greenwald a bizarre email which he then
lied about having sent (to me, Greenwald and Petreaus), apparently unaware
that while an email message can indeed be faked, it is improbable that
these particular message headers are faked.

Further, had any such attempted impersonation of Boylan taken place it
would have been a very serious matter requiring urgent investigation. Since
I was never contacted it is clear that no investigation took place which
can only mean that Boylen did send the emails and then lied about sending
them.

http://www.salon.com/2007/10/28/boylan/

If a UK military officer had sent a similar email he would be cashiered.
But then again, in the British army Colonels are not minted by the thousand
as in the US.


-- 
Website: http://hallambaker.com/
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