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Old 06-19-2012, 11:19 PM   #1
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Random Number Generator

Watching the channel destination America last night. The show was on Vegas cheats. They talked about the guy who hit 100,000 at Keno in Atlantic City. The guy worked for Nevada gaming commission. Apparently RNG is not random. Anybody know about this... I
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Old 06-20-2012, 12:38 AM   #2
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Re: Random Number Generator

What do you mean RNG is not random? RNG is not a single thing that people can touch or exists. Or are you saying that random number generation is not actually random?

There are differences between types of random number generators. For example, most computers use algorithms to generate random numbers. If you know the algorithm, you can predict the random number (making it not random). But there are more complicated random number generators out there. For example, the Stars RNG (http://www.pokerstars.com/poker/rng/) is perhaps one of the best I have ever heard of. The last time I checked, it generates random numbers from 3 sources: 1) A computer algorithm, 2) User inputs (i.e., mouseclicks from millions of stars users), 3) entropy (a truly unpredictable source of data).

It is possible that this casino used a weak RNG and this person knew the algorithm or that this person simply saw the results before they were posted.
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Old 06-20-2012, 01:15 AM   #3
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Re: Random Number Generator

Yeah basically what sherman said. Some RNGs create random numbers based on mathematical methods with a smaller set of beginning numbers. So if you know the algorithm you can guess the random numbers with a much greater probability because you will only need to guess the "seed number" or the initial number that creates the other random numbers by mathematical means. Once you know the seed and the algorithm, you'll know all the random numbers. And that old video keno machine used a crappy PRNG.

http://en.wikipedia.org/wiki/Pseudor...mber_generator

http://en.wikipedia.org/wiki/Random_seed
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Old 06-20-2012, 03:27 AM   #4
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Re: Random Number Generator

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Originally Posted by MrSKenny View Post
Watching the channel destination America last night. The show was on Vegas cheats. They talked about the guy who hit 100,000 at Keno in Atlantic City. The guy worked for Nevada gaming commission. Apparently RNG is not random. Anybody know about this...
Yes -- the club was using a PRNG, and using the time as a seed. The game was far too automated, including using the time to start the game. Once he knew the details of how the game was operated he followed a few games from his room until he could reproduce the results and then sent an agent to purchase a winning ticket. As I recall, it was proper ID that tripped up the operation and led to an investigation.
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Old 06-20-2012, 04:00 AM   #5
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Re: Random Number Generator

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Originally Posted by SheetWise View Post
Yes -- the club was using a PRNG, and using the time as a seed. The game was far too automated, including using the time to start the game. Once he knew the details of how the game was operated he followed a few games from his room until he could reproduce the results and then sent an agent to purchase a winning ticket. As I recall, it was proper ID that tripped up the operation and led to an investigation.
That's how Planet Poker was cracked in its early days. They used the time as a seed, but they didn't use enough bits to represent it, so the number of possible decks was limited enough that it was easy to search all the candidates and find the right one after examining a few hands. The guys that cracked it had a client program that could see everyone's hole cards, and they knew what the board would be.
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Old 06-20-2012, 03:09 PM   #6
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Re: Random Number Generator

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The guys that cracked it had a client program that could see everyone's hole cards, and they knew what the board would be.
The way you worded that could be misunderstood. They used the known hole cards of one player (them) plus the visible flop cards, and from that they could predict the last two board cards and could also determine what hole cards were dealt to all other players in the hand. But it sounded like you meant some kind of software hack, and it wasn't (I know you know this). Their "client" just scraped the visible cards from the game screen and from that could tell what other cards were dealt based on the algorithm. And the prediction required that the flop be dealt first.

Last edited by NewOldGuy; 06-20-2012 at 03:25 PM.
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Old 06-20-2012, 05:09 PM   #7
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Re: Random Number Generator

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The way you worded that could be misunderstood. They used the known hole cards of one player (them) plus the visible flop cards, and from that they could predict the last two board cards and could also determine what hole cards were dealt to all other players in the hand. But it sounded like you meant some kind of software hack, and it wasn't (I know you know this). Their "client" just scraped the visible cards from the game screen and from that could tell what other cards were dealt based on the algorithm. And the prediction required that the flop be dealt first.
It was a crack rather than a hack. The client program synchronized its clock with the system clock on the server to reduce the number of possible decks to around 200,000. Once it found the correct deck for one hand, it was even easier to determine the deck for all additional hands by making the synchronization even more accurate. The deck is determined by the seed which was stored as a 32-bit number. 32 bits can only represent about 4 billion decks rather than the 52! =~ 8 * 1067 possible decks, but since it was the number of milliseconds since midnight, it could really only represent 84.6 million decks, and then the synchronization brought it down to around 200,000, and perhaps only a few thousand after they did this the first time since the program would synchronize to within a few seconds. It only predicted the turn and river rather than the whole board since it needed the flop as you said. Here is the article by the security firm that did this, with a picture showing the GUI displaying the other player's hole cards.

Last edited by BruceZ; 06-20-2012 at 05:53 PM.
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Old 06-20-2012, 06:44 PM   #8
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Re: Random Number Generator

If they can synchronize to within a few seconds so that there are only a few thousand candidate decks, then they should be able to narrow down the possible flops to just a few based only on their hole cards. Only 1 in 1326 decks will give them their hole cards.
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Old 06-20-2012, 08:14 PM   #9
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Re: Random Number Generator

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Originally Posted by BruceZ View Post
If they can synchronize to within a few seconds so that there are only a few thousand candidate decks, then they should be able to narrow down the possible flops to just a few based only on their hole cards. Only 1 in 1326 decks will give them their hole cards.
Even if they can't nail it down to 1 deck, being able to know that the board will be 1 of, say, 10 possible boards would give a HUGE advantage.
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Old 06-20-2012, 09:03 PM   #10
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Re: Random Number Generator

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Originally Posted by BruceZ View Post
If they can synchronize to within a few seconds so that there are only a few thousand candidate decks, then they should be able to narrow down the possible flops to just a few based only on their hole cards. Only 1 in 1326 decks will give them their hole cards.
Actually it's 1 in 2652 decks if the site shows you which card you were dealt first and which you were dealt second. So if they can synchronize to within a 10.6 second window, that's 4*2652 decks, and then using just your hole cards, they can narrow down the possible boards to just 5 (not 4 because yours is always one of them, Monty Hall anyone? LOL).

Last edited by BruceZ; 06-20-2012 at 09:26 PM.
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