Dead man's Switch

I've been thinking in the past about how to ensure operational security when dealing with risk of loss of life, but after reading the creative story of Snowden’s dead man's switch solution I decided to put my ideas down for consideration.

The tactic is based on fact that the action to the author is more damaging than letting him be.
To create a dead man's switch protection, there are two main points to deal with:

Package

First thing to consider is if the package has sufficient importance to the threat actor, which would avert the action they might want to perform. If the data or asset has no importance to threat actor this tactic would not minimize the risk.
Next thing to consider is how to maintain the package value (if it is not deteriorating in time by itself) to the threat actor.
The data or asset, which is going to be exposed, damaged or deleted has to be either 

• very well hidden (preferably not even the author of the dead man's switch should know its location) or 
• it has to be copied and distributed, so any containment is not feasible.

In order to prevent premature exposure (in case of massive distribution), strong encryption might be a good idea.

The option to hide it is a bit more tricky, as that can’t be done by friends or anybody who can be related to the author, as that is easily traceable. Having several transfers from one person to another with different types of transfer (personal / delivery to PS box / fake address delivery / dead drop box) should make tracking the location sufficiently difficult, even though not impossible.

Trigger

The event, that should trigger the action to the package can either be 

• news about author or similar public event, or 
• it can be lack of “proof of life” signal (meaning author didn’t update his/her status on pre-defined website or has not sent such message in agreed interval)

There are also more complex possibilities, where the package action has to be performed by several people (e.g. decryption with several keys in correct order).

Another multi-person trigger mechanism might be to have extra role of observer, who will issue the signal to the package via indirect means (news/publication/website status/email/etc.)

With several layers of encryption, there is also a possibility of having multi-stage trigger, where some parts of the package get exposed, for example in case of arrest and later in case of disappearance or death.

Validation

No matter how complicated solution is chosen, trying it out is always a good idea, as flawed solution doesn’t provide the same effect as a feasible one.

Testing the distribution of the package is probably more important than the trigger, because if it can be tracked or contained before the trigger is executed, it would miss its purpose.

But in the end, what counts is the fact that the threat actor believes it is a feasible and can significantly affect him, thus minimizing the risk to the author of the dead man's switch.