Features

net.wars: Watching you watching me

A few months ago, a neighbour phoned me and asked if I'd be willing to position a camera on my windowsill. I live at the end of a small dead-end street (or cul-de-sac) that ends in a wall about shoulder height. The railway runs along the far side of the wall, and parallel to it and further away is a long street with a row of houses facing the railway. The owners of those houses get upset because graffiti keeps appearing alongside the railway where they can see it and covers flat surfaces such as the side wall of my house.

The theory is that kids jump over the wall at the end of my street, just below my office window, either to access the railway and spray paint or to escape after having done so. Therefore, the camera: point it at the wall and watch to see what happens.

The often-quoted number of times the average Londoner is caught on camera per day is scary: 200. (And that was a few years ago; it's probably gone up.) My street is actually one of those few that doesn't have cameras on it. I don't really care about the graffiti; I do, however, prefer to be on good terms with neighbours, even if they're all the way across the tracks. I also do see that it makes sense at least to try to establish whether the wall downstairs is being used as a hurdle in the getaway process. What is the right, privacy-conscious response to make?

I was reminded of this a few days ago when I was handed a copy of Privacy in Camera Networks: A Technical Perspective, a paper published at the end of July. (We at net.wars are nothing if not up-to-date.)

Given the amount of money being spent on CCTV systems, it's absurd how little research there is covering their efficacy, their social impact, or the privacy issues they raise. In this paper, the quartet of authors – Marci Lenore Meingast (UC Berkeley), Sameer Pai (Cornell), Stephen Wicker (Cornell), and Shankar Sastry (UC Berkeley) – are primarily concerned with privacy. They ask a question every democratic government deploying these things should have asked in the first place: how can the camera networks be designed to preserve privacy?

For the purposes of preventing crime or terrorism, you don't need to know the identity of the person in the picture. All you want to know is whether that person is pulling out a gun or planting a bomb. For solving crimes after the fact, of course, you want to be able to identify people – but most people would vastly prefer that crimes were prevented, not solved.

The paper cites model legislation (PDF) drawn up by the Constitution Project. Reading it is depressing: so many of the principles in it are such logical, even obvious, derivatives of the principles that democratic governments are supposed to espouse. And yet I can't remember any public discussion of the idea that, for example, all CCTV systems should be accompanied by identification of and contact information for the owner. "These premises are protected by CCTV" signs are everywhere; but they are all anonymous.

Even more depressing is the suggestion that the proposals for all public video surveillance systems should specify what legitimate law enforcement purpose they are intended to achieve and provide a privacy impact assessment. I can't ever remember seeing any of those either. In my own local area, installing CCTV is something politicians boast about when they're seeking (re)election. Look! More cameras! The assumption is that more cameras equals more safety, but evidence to support this presumption is never provided and no one, neither opposing politicians nor local journalists, ever mounts a challenge. I guess we're supposed to think that they care about us because they're spending the money.

The main intention of Meingast, Pai, et al, however, is to look at the technical ways such networks can be built to preserve privacy. They suggest, for example, collecting public input via the Internet (using codes to identify the respondents on whom the cameras will have the greatest impact). They propose an auditing system whereby these systems and their usage is reviewed. As the video streams become digital, they suggest using layers of abstraction of the resulting data to limit what can be identified in a given image. "Information not pertinent to the task in hand," they write hopefully, "can be abstracted out leaving only the necessary information in the image." They go on into more detail about this, along with a lengthy discussion of facial recognition.

The most depressing thing of all: none of this will ever happen, and for two reasons. First, no government seems to have the slightest qualm of conscience about installing surveillance systems. Second, the mass populace don't seem to care enough to demand these sorts of protections. If these protections are to be put in place at all, it must be done by technologists. They must design these systems so that it's easier to use them in privacy-protecting ways than to use them in privacy-invasive ways. What are the odds?

As for the camera on my windowsill, I told my neighbour after some thought that they could have it there for a maximum of a couple of weeks to establish whether the end of my street was actually being used as an escape route. She said something about getting back to me when something or other happened. Never heard any more about it. As far as I am aware, my street is still unsurveilled.