back to article Oxfordshire reveals ANPR traffic camera sites

A council using automatic numberplate recognition to manage traffic has released the locations of the cameras, having previously refused to do so. Oxfordshire CC said it has spent £700,000 installing ANPR cameras to manage traffic within and around Oxford. In the last few weeks it has put up six electronic signs on roads …


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  1. smudge

    A pox on ALL their houses, er, cameras

    They're worried that if they disclosed the locations, we could work out which cameras belonged to the council and which ones were operated by the police.

    So what? We dislike and distrust ALL of them!!

  2. Grease Monkey Silver badge


    ANPR Cameras?

    Shirley the ANPR facitility is not a feature of the cameras but the computer system to which they are linked. As such any authority with CCTV over TCP/IP could implement ANPR on any or all of their cameras.

    ANPR is an emotive subject. Many people assume that it's being used to track them, however a traffic management system does not need to record registration details at all. A sensible developer would use one way encryption of the registration numbers. So as a car passes a camera it's registration details are hashed alonng with time and direction. As is passes the next camera the same is done again. With non-reversible encryption it doesn't matter where the data is stored or for how long there is no way for anybody to use the data for ant purpose other than it's orginal purpose. If you didn't use non-reversible encryption then data protection laws would make things complicated for any authority using such a system.

  3. Jelliphiish

    top gear

    had some positive, constructive thoughts on the solution, i particularly applaud Mr Leno and his opinion. Coffee cups and 'spandifoam.. the way forward.

  4. Anonymous Coward
    Anonymous Coward

    Possible scope creep?

    'Each route has between two and five ANPR cameras in the directions tracked, allowing journey times to be calculated'

    1) I thought ANPR was supposed to be used for tax/insurance checking. Is spying on people and recording thier journeys on a database justifiable simply for the purposes of traffic information?

    2) TrafficMaster is already collecting this information, but only uses the numberplate prefix (not that that is a lot better) then why is a council wasting public funds on this

    3) The statement above sounds not like an ANPR operation, but more like a SPECS operation to me

  5. Gordon Ross Silver badge

    @Grease Monkey

    If the reg is hashed with a date/time stamp, how can another camera match the reg ? The only way it could do it*, is to create the same hash based on the same information - which includes the date/time, which it won't know..

    *OK, I'll ignore trying to break the hash

  6. Anonymous Coward
    Big Brother

    @ Grease Monkey

    I agree with you, but they won't do that.

    It will be "We have them in our sights, now we can follow them."

    Sorry but the UK is capable and will to do this to its citizens.

  7. Ray0x6
    Big Brother

    @Grease Monkey

    Yeah, of course that is the way it *should* be done. But I can imagine the conversation:

    Dev: So, boss, how should I do this? I can write this system with a one-way hash to provide road users with the privacy or I can use a shared key encrypt.

    Boss: Which works best?

    Dev: Well, they will all work the same for our intents and purposes. But a one way hash provides the best protection for drivers and keeps us in line with the DPA. Also...

    Boss: Which is the fastest for us to implement?

    Dev: Ummm no difference, really.

    Boss: Best be on the safe side. Remember who's paying our wages: they might want that data.

    Dev: But the tax payer already knows what his number plate is.

    Boss: Who said anything about the tax payer? Hop!

  8. Anonymous Coward

    @Grease Monkey - encryption isn't possible

    > A sensible developer would use one way encryption of the registration numbers

    A sensible cryptanalyst would tell you there's no such thing.

    The second ANPR camera needs to ask the question "has <this registration number I just saw> passed the first camera, and if so then what time did it pass?". (This is needed to figure out speeds and/or journey times, which is the whole point of the camera system). So you have to have some way of easily answering that question. There are only about 33 million cars in the UK, so it would be easy to do a brute-force search for _every_ registration number.

    The right solution is to delete the data after 3 hours, which is what Oxford council currently claim to do. (The worry of course is that they may change their mind in future - and that's just a minor tweak to the data retention policy, it's far too easy to do. Also you could worry about the security of their systems - e.g. are they connected to the Internet?)

  9. Julian I-Do-Stuff
    Thumb Up

    @Grease Monkey

    Yep - hash the registration. Should be the first thing anybody thinks about when there is a genuine need to establish continuity of identity without actually identifying.

  10. Anonymous Coward

    @Grease Monkey

    ANPR cameras are better able to read the number plate - have you ever tried to read the number plate of an oncoming vehicle in the dark when it's got it's headlights on? Have you seen the effect on standard camera (lenses)... they flare so much that you're lucky if you can make out the car let, alone the number plate!

    As for "With non-reversible encryption it doesn't matter where the data is stored or for how long there is no way for anybody to use the data for ant purpose other than it's orginal purpose"

    Well, if they put it out there and someone knew the hashing algorithm (or it was applied in another place), they could deduce things like "you were in Oxford at 12:42 on the 27th October", or when the system is more widespread... they would be able to deduce a lot of your travelling info just from a number plate. Creep would set in when the police/whoever goes to the authorities with a hash of a reg-no and demands timestamps etc.

    As a previous poster stated, if you salt the hash with the date/time, the system becomes useless anyway.

    Basically, yes it does have to be both time-limited and deleted when no longer needed.

    We need a kermit the from icon, because some people really are muppets.

  11. MnM

    if they don't find a match, they what?

    they throw it away? So presumably they're only checking for matches against numberplates recorded by their own ringfenced system, to work out journey times, and not against DVLA records. For the moment.

    For a minute there I thought they were comparing against DVLA records, so failure to match would indicate fake plates. Throwing that away would be stupid irrespective of the politics.

  12. Steve Loughran

    Look for "Watchman"

    The likely kit for this is something called "watchman". Personally, I would love to get hold of this data, fascinating. I'd like it anonymised, but retaining some vehicle type info (make, model, colour), could be interesting to see if red cars are driven faster, white van behaviour, etc.

  13. AceRimmer

    @Possible scope creep

    ANPR = Automatic Number Place Recognition

    Nothing to do with tax or insurance its just mainly used for those purposes at the moment.

    Incidently the police cars also have it so that car registrations can also be quickly checked to see if the registration plate is on the alert/stolen list

    SPECS = SPEed Check Services

    All to do with speeding, nothing to do with vehicle tracking

  14. Fuzz

    @Grease Monkey

    As Gordon Ross has mentioned, if you hash the date and time with the reg then you aren't going to be able to get a match.

    If you just hash the reg it would be fairly trivial to create a lookup of every possible reg.

    I just did a quick test and it took around 10 minutes to create a sha1 for every possible combination of the A555 AAA format plates.

  15. Peter Simpson 1
    Big Brother

    And as long as we're calculating travel time...

    ...why not do one more calculation and make sure they're not exceeding the speed limit?

    And hey, since we have the plate number, we already know where to send the ticket!

    //we'll be able to pay for these cameras in no time!

    ///it's always about the money

  16. Anonymous Coward
    Anonymous Coward

    @AC at 11:11

    Ever been to Oxford? If you have, you will appreciate the reasons why Oxford CC uses its own ANPR system to do its traffic management rather than relying on a third party (Traffic Master) to give it information.

    Oxford has been very progressive with attempting to deal with the traffic issues in the city, and instead of having to wait for others, the city blazes its own trail that others end up following - perhaps.

    And yes, when it comes to traffic management, yes, please do record my license plate, as long as it is encrypted and dropped as the Oxford system does.

  17. Anonymous Coward

    @Grease Monkey

    Yep, sounds like a good idea. Create two hashes from two different RNGs that change alternately every 1.5 hours. If either camera detects a matching registration hash, and the travelling time minimum hasn't been met, flash the camera and store the picture. Job done, no registrations are stored in a retrievable state. No need to date/time salt.

  18. Anonymous Coward
    Anonymous Coward


    The statement from Oxford CC says that if the registration number is not matched again within 3 hours, it is deleted.

  19. Neiljohnuk

    encrypt or delete, never.

    The problem here is mission creep, its not going to stop, ever since that hitman was tracked from London to Scotland (for the hit) and back using the encrypted TrafficMaster data that they claimed couldn't be used that way. The Police couldn't beleive just how easy it might be, hence the grubby-mits own nation-wide ANPR system...

  20. Paul 4

    Peter Simpson 1

    Youll be lucky to exceed the speed limit down those roads.

  21. AlistairJ

    @AC at12:38 @ etc, no need for ANPR

    Speaking as former resident I can give them all the information they need. Basically all car journeys in and around Oxford, apart from the most wasteful trip down to the corner shop types of journey, have to use the ring road. This is because they have effectively closed the city centre to all through traffic, and the city has an old-style all-roads-are-radial layout.

    Thus on any journey around the town you will have entertain several large busy and intimidating roundabouts, endure long delays on the busy A34 and/or A40 (which incidentally, has been narrowed). So all car journeys take at least 30 minutes possibly much more.

    See, no need for that expensive ANPR.

  22. Anonymous Coward
    Anonymous Coward

    @AC 12:38

    Speaking as a resident of Reading, Oxford council cause more traffic in my town than you can imagine. It took Oxford council more than fifteen years (IIRC) to agree for a park and ride car park for Reading on their side of the town (for those who don't know, as soon as you are out of Reading, you're in Oxfordshire). Oxford are objecting to any plans to build a third Reading bridge, which is required to move congestion out of Reading town centre where it is intollorable, it will also supply Henley (in Oxford) with far better links to London/Heathrow and Reading. Oxford talk the talk about dealing with traffic problems, but they don't deliver anywhere except in the centre of Oxford, just ask some residents of Henley what they think about the new traffic lights that were installed last year...

  23. Anonymous Coward

    Typical Counciltards

    Increase the throughput through the town by decreasing speeds.....

    Let's not actually deal with the problem - caused by hundreds of empty buses and taxis. Deregulation of the public transport system is the worst thing this country has ever done to reduce productivity.

    It just goes to show - i

    Those who can, do

    Those who can't, teach

    and those who can't teach or do, get a job for life in the council.

  24. Anonymous Coward
    Anonymous Coward

    Oxford - "progressive"?

    > Ever been to Oxford? [...] Oxford has been very progressive with attempting to deal with the traffic issues in the city

    I live in Oxford, and it suffers some of the most regressive traffic policies I've seen anywhere in the country. Such policies routinely seem designed to cause congestion and frustrate the traveller regardless of their chosen means of transport. I can only hope the rest of the country views Oxford as an exercise in how not to manage traffic.

    Probably very profitable for the sign makers, though, the amount of "road litter" is astonishing.

  25. Anonymous Coward

    Oxfordshire's roads

    On top of that Oxfordshite County Council (that was a typo, but I thought it deserved to stay there) are planning to drop the speed limits on half of the county's A roads:

  26. JMB


    How long before the police get access to the data from the council ANPR cameras?

  27. Al fazed Bronze badge

    More of the old BLAH from OCC

    What this council do and what they say they are doing rarely match up.

    So they have no fuckin' chance with number plates !

    So, there must be an ulterior motive.


    Since this mob already wasted a few bob on that Iceland investment, a few more quid squeezed out of the local citizenry isn't going to be missed, is it ?


  28. Anonymous Coward
    Anonymous Coward

    LCD Plates, anyone?

    Just a thought. I know Ian Flemming thought of similar alternative a long time ago - ask 'Q'.

  29. Grease Monkey Silver badge

    @AC - encryption isn't possible (and all the other eejits)

    Of course it is you numpty. How do you think password encryption works? When you create your password it is fed through a one way algorithm to create the stored version of your password. Then each time you log on your input password is fed through the same algorithm and the result compared with the stored version. The same system would be used for numberplates.

  30. John Sturdy

    3 hours?

    If they expect you to take up to three hours to drive from one camera to the next... it's probably time to get out and start walking!

  31. Anonymous Coward
    Anonymous Coward

    @Grease Monkey

    Of course it's possible. But you can repeat the one-way hashing procedure for every car in Britain in seconds with a common laptop or, if you have the computing resources, milliseconds. That way, given the hashed data for any number place, and the hashing algorithm, you can trivially determine what number plate produced the hash.

    For one-way hashing of number plates to provide any kind of security you need to augment the input data. Random or essentially random data (like timestamps) wouldn't work as that would make the hashed data useless. The information added to the key has to meet a couple of requirements:

    A) It needs to be discernible to an ANPR camera, with very high precision.

    B) It needs to stay constant and relevant to the vehicle in question over the time the data is retained, otherwise you can't match data from one camera to data from another camera (e.g. including vehicle speed renders the key completely useless, including the number of passengers makes it unreliable.)

    C) The information mustn't be available anywhere but in the image captured by the camera (e.g. the colour of the vehicle is already linked to the number plate in other databases so doesn't represent added information.)

    Number plates are designed to identify cars, not to serve as encryption keys or passwords. Identifying cars is pretty much all they're useful for.

  32. Anonymous Coward
    Anonymous Coward


    "For a minute there I thought they were comparing against DVLA records, so failure to match would indicate fake plates. Throwing that away would be stupid irrespective of the politics."

    Where I live, we have one of the highest camera-per-mile ratios in the country, outside of a major metropolis - but I know someone who has been driving around for months with a personalised plate that is completely illegal but he's never been stopped. Of course, the fact that DVLA doesn't have it registered at all might explain why he hasn't been doorstopped, but there's nothing to stop the boys in blue pulling him over to the side of the road...

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