Tomorrow, I’ll take part in a panel discussion at ETH Zürich, entitled “Internet and Trust”. From the flyer for the discussion: “The Internet relies on so many layers of trust that one is sometimes surprised that [it] actually works”. This is true, but I suppose that’s a property of any system of sufficient complexity, when viewed by someone who understands it well enough to know how much bubble gum and duct tape is used to hold it together.
Looking back on it, working to make the Internet more trustworthy has been a theme of my career, and I suspect, the careers of many who’ve worked on it. Internet measurement is largely concerned with bringing transparency to the opaque inner workings of a massively distributed, administratively disjoint system. And the Internet, after all, was born of a paradox of trust: in its earliest days, it was an academic project run by people who knew mostly each other and mostly liked each other and shared more or less the same values1. Everyone running a node connected to the Internet could be trusted to know what the right thing was, and to do it, in any particular situation. This level of trust was what made it possible to scale the Internet out in its early years - anyone could learn to play by the rules, and anyone who could play by the rules was welcomed to.
This trust was reflected in the protocols that drove the early Internet, and to a large extent drive them today. This is where the problems start. Authentication and confidentiality were added up and down the stack later2, when at all, and made optional. So many of the most basic problems we have with trust in the Internet, from routing operations and BGP hijacking to email and spam, derive precisely from this presumed trust among participants in the early experiment that became the predominant global communications network.
A fair amount of effort has gone recently into the judicious application of cryptography between the Internet’s transport and application layers, largely centered around increased deployment (and revision) of the TLS protocol. This effort has accelerated after Edward Snowden’s revelations made it clear how pervasive surveillance was on the Internet. This provides some assurance that you’re connected to the server you think you’re connected to, and that nobody can see or change the content of your communications with it3, which is exactly what you need when your threat model is an indiscriminately snooping nation-state.
It does nothing, though, about whether you can trust that server, or the infrastructure or the people behind it. Indeed, this cryptography can get too tightly locked down, for example allowing an app to communicate with its publisher without its user being able to see the contents of that exchange. In this case the user is left with to choice but to trust the app, or not to use it at all. This is where the question of “what does it mean to trust the Internet?” gets interesting, and is indeed where much of the current discussion about trust in the Internet leads, to what we in the protocol engineering community refer to as the Political and Economic layers of the stack.
Here there are no easy answers at all.
Confidentiality is the opposite of transparency. Confidentiality is necessary to protect Internet communications against unauthorized third parties. On the other hand, transparency is necessary to build trust between a first and a second party whose interests are not necessarily aligned, which is the case of most of the business models driving Internet content today. The questions need to be more nuanced here: transparency of what? Confidentiality from whom? Our protocols probably need knobs that are finer-grained than those we have in order to find the right balance.
All of which we may or may not get into during Tuesday’s talk. In any case, if you’re in Zürich, and this is at least a little interesting to you, please do drop by at 17:30 Tuesday 9 May, ETH Main Building, room HG G60.
1: See Richard Stallman’s writing on the birth of GNU at the MIT AI Lab, and early ARPANET node, for a counterpoint to this utopian oversimplification.
2: To some extent, this was born of technical inadequacy as much as it was of wide-eyed trust. Until the end of the 20th century, the simplest asymmetric cryptosystem remained patented, and ran slowly on computers of the time, which limited the deployment of cryptographic protocols. In addition, even uselessly rudimentary cryptographic technology was export-restricted by the United States until about this time.
3: It does this if you trust the Web PKI, which is another question entirely. Fortunately there’s a lot of work going on to make this work better as well, e.g Certificate Transparency. And it helps if you trust the routing infrastructure, too, which I won’t talk about here because it’s an incredible mess, held together only through the heroic efforts of the people who make it work.