The Photographic Science of Detecting Fake Lottery Tickets
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The Photographic Science of Detecting Fake Lottery Tickets
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Re: The Photographic Science of Detecting Fake Lottery Tickets
#2What's funny about this to me is that the "04 02" reveals the fake without any kind of photographic analysis whatsoever. The numbers are supposed to be sorted smallest to largest. A valid ticket would read "02 04".
Re: The Photographic Science of Detecting Fake Lottery Tickets
#3Slightly related, I was wondering how the actual lottery tells if your ticket is real - do the machines record your ticket's serial number and number(s) chosen and then send the info to the lottery HQ? Or do the lottery machines compute an HMAC of some kind and encode it in the serial number on the ticket itself?
Re: The Photographic Science of Detecting Fake Lottery Tickets
#4not directly related, but this made me remember some reading I did awhile ago on EXIF analysis.
a really cool tool for EXIF http://www.sno.phy.queensu.ca/~phil/exiftool/
Re: The Photographic Science of Detecting Fake Lottery Tickets
#5Slightly related, I was wondering how the actual lottery tells if your ticket is real - do the machines record your ticket's serial number and number(s) chosen and then send the info to the lottery HQ? Or do the lottery machines compute an HMAC of some kind and encode it in the serial number on the ticket itself?
I don't know about this US lottery specifically but in most systems everything is recorded at HQ. Not just the numbers, but the place, the date and time, serial number etc
That way they can also check with CCTV.
It's an interesting topic in database design because the link to the store may fail at any time (remember lotteries started years ago on dialup) and you must not have an issued-unrecorded ticket at any point in the process
Re: The Photographic Science of Detecting Fake Lottery Tickets
#6Slightly related, I was wondering how the actual lottery tells if your ticket is real - do the machines record your ticket's serial number and number(s) chosen and then send the info to the lottery HQ? Or do the lottery machines compute an HMAC of some kind and encode it in the serial number on the ticket itself?
The lottery HQ has records of all tickets for a particular lottery, which gets checked against when you claim a prize.
I'm not sure whether the has-this-ticket-won-anything machines phone home to check it against those records, or whether they just assume the ticket is authentic and leave the proper verification for when a prize is claimed.
Re: The Photographic Science of Detecting Fake Lottery Tickets
#7Slightly related, I was wondering how the actual lottery tells if your ticket is real - do the machines record your ticket's serial number and number(s) chosen and then send the info to the lottery HQ? Or do the lottery machines compute an HMAC of some kind and encode it in the serial number on the ticket itself?
Considering they can tell which vendor sold a winning ticket, they must have a central database logging the numbers chosen for each ticket. Also, considering the amounts of money involved, I can't imagine them doing anything less secure.
Re: The Photographic Science of Detecting Fake Lottery Tickets
#8Can you use Photoshop filters to do this, or are there more professional programs to do so?
Re: The Photographic Science of Detecting Fake Lottery Tickets
#9What's funny about this to me is that the "04 02" reveals the fake without any kind of photographic analysis whatsoever. The numbers are supposed to be sorted smallest to largest. A valid ticket would read "02 04".
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Re: The Photographic Science of Detecting Fake Lottery Tickets
#10Is it possible to reverse engineer the image such that it passes all tests? Knowing the various algorithms that could be used, what would be involved in constructing the modification such that it doesn't reveal evidence of any modifications?
One thought would be to actually render an entire scene in something like POV-Ray. Imagine if something like this rendering http://www.povray.org/community/hof/chado.php contained a winning lottery ticket on the table. If you save the rendered image using the same compression algorithm and same EXIF heading information as a camera, how would one tell the difference?