In our block of flats there is a communal bin store where we place our household rubbish for collection. Over the past year or two there has apparently been a problem with people who do not live in the flats dumping large amounts of rubbish there, leading to piles of rubbish bags on the floor and out through the door.
The flats management first attempted to prevent this was by setting up a security camera, but this seems to have been ineffective so, two weeks ago, they had a combination lock fitted to the door of the bin store. When I read about this my first thoughts were "This is not going to work" and "What waste of money". For a security measure to be effective it must not only achieve it's security aim, it must also fail in a way that is acceptable. Some of the people living in our flats seem to have enough difficulty with the idea that rubbish should go inside the bins. These people are not going to remember a door code. And what are they going to do when they get to the bin door and find they can't open it? Are they going to go all the way back up to their flat to get the letter with the door code? No. They are going to leave their rubbish on the floor outside the door, pretty much the result that the combination lock was intended to prevent.
Last week, just after the lock was installed I took my weekly rubbish bags down and successfully opened the door. Yesterday morning, however, the door refused to open, even though I was using the same door code. I brought my bin bags back up to my flat and then sent an email off to the flats management. This morning I went down to the bins again and the lock had been removed. There was, as I predicted, a pile of rubbish outside the door.
Yes, I know that if I have criticisms of the flats management then I should really get involved with it and go to meetings, but up until now I have been pretty happy with their actions. Security thinking is not easy. It is only through reading Bruce Schneier's blog that I became aware of the problems and trade-offs involved in trying to make things secure.