All posts by Frank Stajano

Persec 2006 and Naccache on tapping mobile phones

Hardware & signals, Privacy technology

Over the past couple of months I attended about half a dozen events around the world (Brussels, Pisa (x3), Tokyo, Cambridge, York, Milan), often as invited speaker, but failed to mention them here. While I won’t promise that I will ever catch up with the reporting, let me at least start.

I was, with Ari Juels of RSA Labs, program chair of IEEE PerSec 2006, the security workshop of the larger PerCom conference, held in March 2006 in Pisa, Italy. I previously mentioned the rfid virus paper by Rieback et al when it got the (second) best paper award: that was the paper I found most enjoyable of the ones in the main track.

Ari and I invited David Naccache as the keynote speaker of our workshop. This was, if I may say so myself, an excellent move: for me, his talk was by far the most interesting part of the whole workshop and conference. Now a professor at the École Normale Supérieure in Paris, David was until recently a security expert at leading smartcard manufacturer Gemplus. Among other things, his talents allow him to help law enforcement agencies tap the bad guys’s cellphones, read the numbers in their phone books and find out where they have been.

His talk was very informative and entertaining, full of fascinating war stories such as the tricks used to steal covertly an expired session key from the phone of a suspect to decrypt a recorded phone call that had been intercepted earlier as cyphertext. The target was asleep in a hotel room, with his phone under recharge on his bed table, and the author and his agents were in the next room, doing their electronic warfare from across the wall. What do you do in a case like this? pretend to be the base station, reissue the old challenge so that the SIM generates the same session key, and then listen to the electromagnetic radiation from the pads of the SIM while the key is being transmitted to the handset via the SIM’s electric contacts. Brilliant. And just one in a rapid-fire sequence of other equally interesting real life stories.

David, like many of the other speakers at the workshop, has kindly allowed me to put up his paper and presentation slides on the workshop’s web site. It won’t be as good as his outstanding live talk, but you may still find it quite interesting.

On the same page you will also find two more papers by members of the Cambridge security group: one on multi-channel protocols by Ford-Long Wong and yours truly, and one attacking key distribution schemes in sensor networks by Tyler Moore.

Why so many CCTVs in UK? (again)

Privacy technology, Security economics

I previously blogged about Prof. Martin Gill’s brilliant talk on CCTV at the Institute of Criminology.

I invited him to give it again as a Computer Laboratory seminar. He will do so on Wed 2006-05-17, 14:15. If you are around, do come along—highly recommended, and open to all. Title and abstract follow.

CCTV in the UK: A failure of theory or a failure of practice?

Although CCTV was heralded as something of a silver bullet in the fight against crime (and by two Governments) scholarly research has questioned the extent to which it ‘works’. Martin Gill led the Home Office national evaluation on CCTV and has subsequently conducted more research with CCTV schemes across the country. In this talk he will outline the findings from the national evalaution and assess the views of the public, scheme workers and offenders’ perspectives (including showing film clips of offenders talking at crime scenes) to show just why CCTV has not worked out as many considered. Martin will relate these findings to the current development of a national strategy.

Cat with computer virus

News coverage

Live from IEEE PerCom in Pisa, Italy: “Is your cat infected by a computer virus?“, the paper about writing a virus for RFID tags, by Melanie Rieback, Bruno Crispo (Cambridge security group alumnus) and Andrew Tanenbaum, which got huge press coverage following its “press release” yesterday, has just been given a “best paper for high impact” award. The official Mark Weiser award went to a system paper, but they made up this ad-hoc award for this one… I’m glad it got an award. Somewhat lighthearted and in part debatable, but it was definitely the paper I enjoyed the most.

The authors have a web site for it at (following the perverse fashion of buying a new top level domain for every new thing you do) www.rfidvirus.org.

Why so many CCTVs in UK?

Security economics

I went to the Institute of Criminology yesterday afternoon. Prof Martin Gill of Leicester University gave a brilliant talk on their extensive study on assessing the effectiveness of CCTV in reducing crime.

This was a proper, scientifically-conducted study with plenty of field work and “user studies”—including fascinating simulations with cooperative shoplifters rigged up with hidden cameras and microphones, as well as interviews with convicted murderers.

The speaker had wonderful war stories on people protecting the wrong things, or the right things in the wrong ways, and generally failing to understand how criminals actually operate. He clearly speaks the same language as us and I told him I’d like to invite him to give a seminar here.

One gem among many was the shop that believed itself ultra-secure because it had a giant, scary-looking, 130-kg-of-muscle security guard at the exit; to which the expert shoplifter commented “I’ll have an easy time here! Their only protection is that enormous bloke over there that I can easily outrun!”. The chest size of the guard is only scary if you’re planning to pick a fight with him.

Another good point was that several of the murderers had acted on impulse (alcohol, jealousy, rage) and were not planning to kill anyone when they got up that morning. At the time of killing their victim they were not acting exactly rationally and even the presence of a machine-gun-armed guard wouldn’t have deterred them, let alone a camera.

Anyway, one of the interesting high level messages, and the reason why I file this under “Security economics”, is that the ubiquity of CCTV cameras in the UK is apparently a straightforward consequence of the plentiful availability of government money for CCTV. This created pressure to bid for CCTV installation grants regardless of their actual effectiveness, as an easy way to get at the allocated grant funds.

Obvious meta-questions would then be: why was CCTV so over-funded in the first place? who are the CCTV suppliers that made all the money? and is anyone in a position to reassure us that, as we’d like to believe, there were no links?