There seems to be renewed hype about Global Positioning Satellite tracking technologies in the run up to the Labour Party annual conference.
Not content with announcing vague plans for tracking the 24 million motor vehicles on the UK's roads for road toll gathering purposes, the politicians also seem to grasping at GPS as a magic wand technology for papering over the budget and resource cracks in their running of the Prison and Probation Services.
BBC Newsnight ran a story in February about Sky Guardian tags
Today's story in the Observer 500 paedophiles to be tracked by satellite tags:
"Sky Guardian will unveil the first electronic device made specifically to track paedophiles at this month's Labour party conference and is to test the technology on a volunteer MP this week"
Who exactly is this Labour MP ?
However, we have huge doubts about the security of the fundamental idea behind such technology. GPS receivers need a clear view of the sky in order to directly see at least 4 of the satellites in orbit.
However GPS simply does not work indoors, or even in many cases outside in the shadow of tall buildings (given our northern latitude, the buildings do not have to be skyscrapers in order to block a direct view to geostationary satellites along the equator) or even overhanging trees or bushes, exactly the places that are supposed to be "off limits".
There already exist GPS spoofing devices which replay the very weak signal from the satellites to the reciever, which has no possible means of authenticating that the signal it is getting is from a real GPS satellite or not.
GPS jamming devices are also relatively cheap and easy to make.
With one of these devices, a criminal could pretend to be under curfew, but could be anywhere else he chose to be, with the tag system providing him with an alibi.
The current electronic offender tags linking the tag to a base unit and a landline phone by short range radio are not perfect either, (have no criminals ever managed to pick the locks etc or otherwise physically remove the tags ?), but they seem to be less flawed than these proposed GPS tracking tags.
If this system is "far cheaper than the current tagging devices used to enforce curfews and probation orders which costs around ?500 per offender each month" then presumably its use will spread to other types of offender who are currently electronically tagged, thereby increasing the market and resources available to create and sell GPS spoofing devices.
If GPS tags are used for motor vehicle tolls across the whole of Europe, then the market for such GPS replay spoofers and area jammers to fool the tags as to their real location, will probably exceed that for "pirate" satellite and cable TV decoders i.e. they will be easily available for moderate cost.
CORRECTION: thanks to those people who have reminded us that GPS satellites are mostly not geostationary about the equator.
"GPS has poorer coverage the further you go from the equator, but the GPS satellites are NOT geostationary, they are in a 55 degree inclined orbit, which gives poorer coverage away from the equator.
There are 4 augmentation satellites (WAAS and EGNOS systems) that ARE
geostationary that can also be used for navigation, but the 24 GPS
satellites are NOT geostationary."