Today’s paper is not primary research, but an expert opinion on a matter of public policy; three of its authors have posted their own summaries   , the general press has picked it up     , and it was mentioned during Congressional hearings on the topic . I will, therefore, only briefly summarize it, before moving on to some editorializing of my own. I encourage all of you to read the paper itself; it’s clearly written, for a general audience, and you can probably learn something about how to argue a position from it.
The paper is a direct response to FBI Director James Comey, who has for some time been arguing that
data storage and communications systems must be designed for exceptional access by law enforcement agencies (quote from paper); his recent Lawfare editorial can be taken as representative. British politicians have also been making similar noises (see the above general-press articles). The paper, in short, says that this would cause much worse technical problems than it solves, and that even if, by some magic, those problems could be avoided, it would still be a terrible idea for political reasons.
At slightly more length,
exceptional access means: law enforcement agencies (like the FBI) and espionage agencies (like the NSA) want to be able to wiretap all communications on the ’net, even if those communications are encrypted. This is a bad idea technically for the same reasons that master-key systems for doors can be more trouble than they’re worth. The locks are more complicated, and easier to pick than they would be otherwise. If the master key falls into the wrong hands you have to change all the locks. Whoever has access to the master keys can misuse them—which makes the keys, and the people who control them, a target. And it’s a bad idea politically because, if the USA gets this capability, every other sovereign nation gets it too, and a universal wiretapping capability is more useful to a totalitarian state that wants to suppress the political opposition, than it is to a detective who wants to arrest murderers. I went into this in more detail toward the end of my review of RFC 3514.
I am certain that James Comey knows all of this, in at least as much detail as it is explained in the paper. Moreover, he knows that the
robust democratic debate he calls for already happened, in the 1990s, and wiretapping lost.    Why, then, is he trying to relitigate it? Why does he keep insisting that it must somehow be both technically and politically feasible, against all evidence to the contrary? Perhaps most important of all, why does he keep insisting that it’s desperately important for his agency to be able to break encryption, when it was only an obstacle nine times in all of 2013? 
On one level, I think it’s a failure to understand the scale of the problems with the idea. On the technical side, if you don’t live your life down in the gears it’s hard to bellyfeel the extent to which everything is broken and therefore any sort of wiretap requirement cannot help but make the situation worse. And it doesn’t help, I’m sure, that Comey has heard (correctly) that what he wants is mathematically possible, so he thinks everyone saying
this is impossible is trying to put one over on him, rather than just communicate
this isn’t practically possible.
The geopolitical problems with the idea are perhaps even harder to convey, because the Director of the FBI wrestles with geopolitical problems every day, so he thinks he does know the scale there. For instance, the paper spends quite some time on a discussion of the jurisdictional conflict that would naturally come up in an investigation where the suspect is a citizen of country A, the crime was committed in B, and the computers involved are physically in C but communicate with the whole world—and it elaborates from there. But we already have treaties to cover that sort of investigation. Comey probably figures they can be bent to fit, or at worst, we’ll have to negotiate some new ones.
If so, what he’s missing is that he’s imagining too small a group of wiretappers: law enforcement and espionage agencies from countries that are on reasonably good terms with the USA. He probably thinks export control can keep the technology out of the hands of countries that aren’t on good terms with the USA (it can’t) and hasn’t even considered non-national actors: local law enforcement, corporations engaged in industrial espionage, narcotraficantes, mafiosi, bored teenagers, Anonymous, religious apocalypse-seekers, and corrupt insiders in all the above. People the USA can’t negotiate treaties with. People who would already have been thrown in jail if anyone could make charges stick. People who may not even share premises like what
good governance or
due process of law or
basic human decency mean. There are a bit more than seven billion people on the planet today, and this is the true horror of the Internet: roughly 40% of those people  could, if they wanted, ruin your life, right now. It’s not hard.  (The other 60% could too, if they could afford to buy a mobile, or at worst a satellite phone.)
But these points, too, have already been made, repeatedly. Why does none of it get through? I am only guessing, but my best guess is: the War On Some Drugs  and the aftermath of 9/11  (paywalled, sorry; please let me know if you have a better cite) have both saddled the American
homeland security complex with impossible, Sisyphean labors. In an environment where failure is politically unacceptable, yet inevitable, the loss of any tool—even if it’s only marginally helpful—must seem like an existential threat. To get past that, we would have to be prepared to back off on the
must never happen again /
must be stopped at all cost posturing; the good news is, that has an excellent chance of delivering better, cheaper law enforcement results overall.