[Enigmail] Sender under duress

[Robert J. Hansen]

Derek L. VerLee wrote:
> A more interesting question is, can this be done without any
> prearranged signal?

This is not an interesting question.  For any message you receive, flip
a coin.  If it's "heads", then you assume it's coerced.  Over the long
run, sooner or later this (absurd!) coercion detection device will
correctly flag a coerced statement, indicating that it's possible.

The question should be "can it be done _reliably_," and the answer is
"unfortunately, no."  See below.

> An example would be referring to a fact (such as a previous event
> between the senders) that did not take place, and about which neither
> of you is likely to be mistaken, but which the adversary can not know
> did not take place.

Militaries know from long, bitter experience that people overwhelmingly
_do not think_ in a crisis situation.  It's almost as if people are
allergic to thinking.  They tend to run on autopilot.  This is why
military basic training drills things into you again and again and
again.  When you hear a gunshot, you dive for cover.  You don't ask
questions, you don't worry about whether you're in dress blues or tennis
shoes, you don't worry about whether you're tackling concrete or mud.
Gunshot?  DIVE.  Uniform, ours?  HOLD FIRE.  Not ours?  SHOOT.  When the
bullets start flying, soldiers spend a lot of time "on autopilot," just
going through these drills they've done thousands of times before.

The moral of the story: when someone has a gun to your head and is
telling you to have Alice meet you down at the pier in an hour, you will
react as you have trained to react.  If you've trained for this
situation, you will probably have codewords prearranged with Alice.  If
you haven't, you will probably do whatever the man with the gun says.

Also, even assuming that you're able to keep your head when someone has
a gun to it -- do you really want to gamble your life on you correctly
guessing what parts of your life the gunman does or doesn't know about?

If someone's got a gun to your head, it's a fair bet they're doing it
for a reason.  They want to succeed.  They're going to be motivated.
They will probably have done a surprising amount of homework.

This is a bet not worth taking.

(Incidentally, there is a fair bit of just plain good life lessons in
there.  If there's anything that worries you enough to keep you up at
night for fifteen minutes, spend an hour training for what to do if it
happens.  If your wife is pregnant and you're worried about what to do
if she goes into labor far from the hospital, take an EMT course.  If
you live in a bad neighborhood and you're afraid of home invasions,
practice loading your weapon in the dark and spend some time at a
shooting range.  If you've got a date coming up and you're concerned
it's not going to go well, spend some time perfecting your cooking
skills -- good cooks are always in demand.  Etcetera.  Worry is a wasted
emotion.  Training is never wasted.)