For a long time, some people have worried about the government eavesdropping on their communications. But, it wasn't until Edward Snowden showed us how widespread and routinely this was being done that most people began to worry about eavesdropping. The latest global story about the San Bernardino iPhone was interesting because it showed how angry and agitated a government agency became because it could not easily read all of the messaging on one specific device used by one individual. All of the governmental surveillance agencies have expressed great concern over the idea that people can "go dark". Here's one example of an "official opinion" from the FBI in 2011, it is exemplary of all the other official positions (in fact, I think they must have a word document template when they write these positions).
DARPA Returns to the Dark Side?
Now it turns out that DARPA (Defense Advanced Research Projects Agency) wants you to develop a completely secure messaging app. The exact language they use to describe what they want is a "secure messaging and transaction platform"..."that can provide repudiation or deniability, perfect forward and backward secrecy, time to live/self-delete for messages, one time eyes only messages, a decentralized infrastructure to be resilient to cyber-attacks, and ease of use for individuals in less than ideal situations." This all sounds very "dark" to me. And, not only do they wanted to use the current encryption and security in existing communications apps, they also wanted to incorporate a decentralized backbone (rather than point-to-point) that would make eavesdropping even more difficult. The official technology request from DARPA is here.
They are looking for a completely public bulletin board that anyone can put a message on but that only the intended recipient can read. And their request for a decentralized, block-a-lot-of-work-to-chain backbone makes sense if you recall that DARPA instigated the development of the Internet. (It was called ARPANET back then which makes sense because DARPA was called ARPA back then.) One of the key design requirements for this progenitor of the Internet was that communication be decentralized so that it would be robust in the event that communication nodes were lost (presumably because communication centers could be destroyed during time of war).
Of course, with decentralized distribution of the messages, latency may be an issue if such a system is expected to be used in very time sensitive contexts. And, because of the egalitarian dispersal of messages in such an open, bulletin board like approach, scalability may be an issue. (You can't actively advertise who you are in your message in order for the recipient to find it without inadvertently exposing metadata that might be able to identify you. So, finding each other's secret messages may become a problem.)
DARPA Expects This to Progress in Three Phases
Modeling a platform suitable for experimentation with encryption
Prototyping versions of the promising platform designs
Commercialization, product rollouts
So it seems, at least on the surface, that DARPA wants everyone to have super secret, super-secure communications that no one can hack into. And, they're putting their money where their mouth is. It is an actual Small Business Technology Transfer (STTR) program that could earn participants up to $150,000 in the first phase. And phase 2 could pay as much as $2 million (that's the prototype phase). And for phase 3, you can commercialize it and reap any profits you might make.