Shostack + Friends Blog Archive


OCR and License Plate Cameras

great-license-plate.jpgIn “The Vehicular Thomas Crowne Affair: how to creatively defeat photo radar,” Scrollin On Dubs points out that:

I just got my plate from AZ DMV and happily installed it this morning. It can still be read by the keen eye but from one of those crappy photo radar pictures it will be a non-trivial task to make out the characters.

He has other comments about how traffic cameras have made a stretch of road more dangerous–read the post.

Via Thurston at “Not Bad for a Cubicle.”

4 comments on "OCR and License Plate Cameras"

  • Brad says:

    Reminds me of the apocryphal tale of somebody taping a SQL injection string to their bumper and speeding by one of these traffic cameras. 🙂

  • Ian Goldberg says:

    I’m pretty sure this won’t work. They “canonicalize” plates before checking if they match already-issued plates. Two issued plates can’t differ only in that “O” is replaced with “0”, “I” with “1”, etc.
    Try it out for yourself:

  • eLKabong says:

    I dunno, I put in 0ODO0OD (zero oh dee oh zero oh dee), and it came up with no matches, so I say it works.

  • Mangoboy says:

    Back in the days when Ontario had photo radar, there was a guy my father knew (a Toronto cop, as it happened) who found a clever way to defeat it (probably). It was a non-technical solution. He noted two things:
    a) Photo-radar tickets are issued to the owner of the vehicle regardless who is driving, and
    b) Children under 12 years old are not liable for any offences committed against provincial or federal laws (the former includes the Ontario Highway Traffic Act).
    So he registered his car in his 2-year-old daughter’s name. The clerk tried to give him a hard time about it when he did so, but couldn’t find any rule that it violated. There’s no legal reason a 2-year-old can’t own a car.
    In theory, if he got nabbed by photo radar, a ticket would have been issued to her. But it would have been trivially thrown out in court because she can’t be charged under the law. AFAIK, he never had the chance to test this theory in court.
    This story made me realize how much overlap there is between the skillsets of good lawyers and hackers. They both study complex sets of rules, and try to find (and possibly exploit) overlooked circumstances.

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