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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

#11

Post by bri3d »

Bud wrote: post #2

What'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".

The author mentions that anomaly in the article, but goes on to assume that the sorting is picked by the state printing the ticket (probably for the benefit of being able to continue the case study).

I also noted that the differing color of the "04 02" in that image can be spotted with the naked eye if zoomed in - no advanced analysis techniques necessary.

I think the techniques used were far more interesting than the particular case study - while the media and non-camera-original nature of the images made the author's most basic techniques somewhat ineffective, the fakes were overall very poorly executed.

Re: The Photographic Science of Detecting Fake Lottery Tickets

#12

Post by gergles »

FaceKicker wrote: post #3

Slightly 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?

For "online" games (like this one), your picks are transmitted to the lottery office which stores them and then transmits the serial number back to the terminal, which prints the ticket. This prevents a ticket from being issued that the lottery's central computer doesn't know about.

When it is time to verify the ticket, they simply send the serial number to the lottery central computer and that computer sends back the payout command (and invalidates that serial number from being paid by any other terminals.) The retailer is supposed to do some basic sanity checking for small prize amounts (is the ticket really on lottery paper, etc.) and obviously for larger prize amounts, there are several other methods to verify the authenticity of ticket stock that aren't public knowledge.

Re: The Photographic Science of Detecting Fake Lottery Tickets

#13

Post by 3pt14159 »

FaceKicker wrote: post #3

Slightly 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 machine creates a random number that is attached and encoded to your ticket and both the number, and the random bit are sent to HQ.

Re: The Photographic Science of Detecting Fake Lottery Tickets

#15

Post by simcop2387 »

excuse-me wrote: post #5
FaceKicker wrote: post #3

Slightly 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…

From my own experience with buying them, they solve that by saying "machine is down, i can't print any tickets". Not a very high tech solution but it certainly solves that problem completely.

Re: The Photographic Science of Detecting Fake Lottery Tickets

#16

Post by kijin »

excuse-me wrote: post #5
FaceKicker wrote: post #3

Slightly 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…

Then why did it take so long for them to announce how many winners there were? First they said "at least one", and then they said "three". If everything was stored in a central database, they could have found out the exact figures (and a lot more) as soon as the last winning number was announced.

Maybe it's due to lack of coordination between states? Or maybe they need to do fraud checking, etc. by watching CCTV footage from the point of sale?

Re: The Photographic Science of Detecting Fake Lottery Tickets

#17

Post by excuse-me »

kijin wrote: post #16
excuse-me wrote: post #5

Earlier quoted context omitted.

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…

Then why did it take so long for them to announce how many winners there were? First they said "at least one", and then they said "three". If everything was stored in a central database, they could have found out the exact figures (and a lot more) as soon as the last winning number was announced. Maybe it's due to lack of coordination between states? Or maybe they need to do fraud checking, etc. by watching CCTV foot…

Most of these lotteries date from the late 80s/early 90s and there isn't a lot of profit in updating them.

I went to some talks about the database design for the UK lottery where they admitted they didn't think it would be so popular and so hadn't really considered sharding.

They also were surprised that the number weren't uniformly distributed. They assumed numbers would be picked totally randomly while the first win was all numbers that could be birthdays and so there was an unusual number of winners and it took several days to work out how many.

Re: The Photographic Science of Detecting Fake Lottery Tickets

#18

Post by delinka »

To fake a lottery ticket for posting online, it'd be much easier just to print a fake ticket and then photograph it. I suppose, however, that the purpose of doing it digitally is to practice skills and "because I can."

To fake a lottery ticket for claiming a prize ... well, that'd be fraudulent and would result in loss of freedom for quite some time.

Re: The Photographic Science of Detecting Fake Lottery Tickets

#19

Post by scoot »

bri3d wrote: post #11
Bud wrote: post #2

What'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".

The author mentions that anomaly in the article, but goes on to assume that the sorting is picked by the state printing the ticket (probably for the benefit of being able to continue the case study). I also noted that the differing color of the "04 02" in that image can be spotted with the naked eye if zoomed in - no advanced analysis techniques necessary. I think the techniques used were far more interesting than th…

If it were the case that the numbers on this ticket were unsorted, you would expect all of the rows to be unsorted, whereas everything except 04 & 02 are in order, including the numbers that follow in the same row. Still interesting to see the "forensic" approach to this.

Re: The Photographic Science of Detecting Fake Lottery Tickets

#20

Post by greendestiny »

There is nothing scientific about any of these tests. What's a 'high' ELA or 'low'? The thing that triggers a 'positive' seems to be only the authors intuition. While some of the tests might show something, I'm pretty sure ELA is absolute garbage - you can't separate the number of needed resaves because of the content frequencies from number of times it has already been resaved.
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