The Declining Half-Life of Secrets and the Future of Signals Intelligence

Today we’re going to look at a position paper from the New America think tank’s Cybersecurity Initiative. If you’re someone like me, that descriptor probably raises at least four red flags: regarding anything to do with Internet security, there’s a tremendous gulf in groupthink between people associated with the US government, and people associated with commercial or pro bono development of computer stuff. Which is precisely why it’s useful to read papers from the other side of the gulf, like this one. (This particular think tank appears to be more on the left as that term is used in US politics. I haven’t dug into their other position papers.)

Swire starts by pointing out that the government’s understanding of secrecy was developed during the Cold War, when it was, frankly, much easier to keep secrets. Paper documents in an archive, which readers must physically visit, and demonstrate their need-to-know to the man with a gun at the entrance, are inherently difficult to duplicate. But that entire archive probably fits on a $50 thumbdrive today. In a similar vein, regular readers will recall the standard military teletype with its data transfer rate of 75 bits per second, from Limitations of End-to-End Encryption (1978).

Also, once data has been exfiltrated, it’s much easier to broadcast it, because there are lots more news organizations who might take an interest—or you can just post it online yourself and rely on the tremendously accelerated speed of gossip. These things together are what Swire means by the declining half-life of secrets: secrets have always been expected to get out eventually, but the time scale is no longer decades. The metaphor of a reduced half-life seems spot on to me: leakage of secrets is inherently probabilistic, so exponential decay is the simplest model, and should give people the right first-order intuition.

Swire then moves on to discussing the effects of that groupthink gulf I mentioned. This bit is weaker, because it’s plain that he doesn’t understand why people might prefer the world-view of EFF. But it’s accurate as far as it goes. People associated with the government are starting from the premise that revealing a secret, regardless of its contents, is the worst possible thing anyone can do. (I confess to not understanding how one comes to think this, myself. It probably has to do with one’s default idea of a secret being something that really could get someone killed if it were revealed, never mind that only a tiny fraction of all classified information is that dangerous.) In contrast, the world-view of EFF begins with the premise that most information should be published, and that an organization doing something in secret from the general public probably means it knows, institutionally, that the general public would not approve. And, therefore, that it shouldn’t be doing it in the first place. Since most of the technology community takes this position, the government has an increasingly large problem trying to persuade that community to cooperate with its own attitude, and (Swire says) this will only get worse.

The paper concludes with some fairly weaksauce recommendations: plan for the possibility of disclosure; take the impact on public opinion (should the secret be revealed) into account when planning secret operations; put more effort into arguing for surveillance. Basically, business as usual but with more media savvy. This may be the best one can hope for in the short term, but I have some policy suggestions of my own:

  • Apply Kerckhoffs’ Principle to all surveillance programs. The overall design of the system, its budget, the nature of the data collected, all relevant policies and procedures, everything except the collected data should be public knowledge, subject to normal public oversight (e.g. any Congressional hearings on the topic should be conducted in public and on the record), and debated in public prior to implementation—just like any other government program. If that would render the surveillance useless, the logic of Kerckhoffs’ principle says it was already useless. (I’ve made this point before, on my main blog.)

  • Abandon the desire for exceptional access. The technology community has spent 20+ years explaining over and over and over again why exceptional access is impractical and makes security worse for everyone. Government agencies refusing to accept that message is probably the single strongest reason why the groupthink gulf is as wide as it is.

  • More generally, whenever there is a tradeoff between offense and defense in computer security, choose defense. Design cryptographic standards that are secure for everyone, even if they happen to be enemies of the USA right now (or might be at some time in the future). Disclose all security-critical bugs to the vendors, so they get fixed, even if this means not being able to pull off another Stuxnet. Think of this as the Internet analogue of the SALT and START treaties.

  • Split the NSA in half. Merge the offensive signals intelligence mission into the CIA, or scrap it, I don’t care. Merge the defensive cryptographic and cryptanalytic mission into NIST, declassify and publish everything, and do all future work in public (Kerckhoffs’ Principle again). Make it a bedrock policy that this organization only does offensive research in support of defensive programs (e.g. to demonstrate the (un)soundness of a cipher).

I’m willing to listen to reasons not to do these things, as long as they do not boil down to we’re scared of hypothetical enemy X.