Entries Tagged "gambling"

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Rigged Poker Games

The Department of Justice has indicted thirty-one people over the high-tech rigging of high-stakes poker games.

In a typical legitimate poker game, a dealer uses a shuffling machine to shuffle the cards randomly before dealing them to all the players in a particular order. As set forth in the indictment, the rigged games used altered shuffling machines that contained hidden technology allowing the machines to read all the cards in the deck. Because the cards were always dealt in a particular order to the players at the table, the machines could determine which player would have the winning hand. This information was transmitted to an off-site member of the conspiracy, who then transmitted that information via cellphone back to a member of the conspiracy who was playing at the table, referred to as the “Quarterback” or “Driver.” The Quarterback then secretly signaled this information (usually by prearranged signals like touching certain chips or other items on the table) to other co-conspirators playing at the table, who were also participants in the scheme. Collectively, the Quarterback and other players in on the scheme (i.e., the cheating team) used this information to win poker games against unwitting victims, who sometimes lost tens or hundreds of thousands of dollars at a time. The defendants used other cheating technology as well, such as a chip tray analyzer (essentially, a poker chip tray that also secretly read all cards using hidden cameras), an x-ray table that could read cards face down on the table, and special contact lenses or eyeglasses that could read pre-marked cards.

News articles.

Posted on November 6, 2025 at 7:02 AM • View Comments

Coin Flips Are Biased

Experimental result:

Many people have flipped coins but few have stopped to ponder the statistical and physical intricacies of the process. In a preregistered study we collected 350,757 coin flips to test the counterintuitive prediction from a physics model of human coin tossing developed by Persi Diaconis. The model asserts that when people flip an ordinary coin, it tends to land on the same side it started—Diaconis estimated the probability of a same-side outcome to be about 51%.

And the final paragraph:

Could future coin tossers use the same-side bias to their advantage? The magnitude of the observed bias can be illustrated using a betting scenario. If you bet a dollar on the outcome of a coin toss (i.e., paying 1 dollar to enter, and winning either 0 or 2 dollars depending on the outcome) and repeat the bet 1,000 times, knowing the starting position of the coin toss would earn you 19 dollars on average. This is more than the casino advantage for 6 deck blackjack against an optimal-strategy player, where the casino would make 5 dollars on a comparable bet, but less than the casino advantage for single-zero roulette, where the casino would make 27 dollars on average. These considerations lead us to suggest that when coin flips are used for high-stakes decision-making, the starting position of the coin is best concealed.

Boing Boing post.

Posted on October 16, 2023 at 7:06 AM • View Comments

Gaining an Advantage in Roulette

You can beat the game without a computer:

On a perfect [roulette] wheel, the ball would always fall in a random way. But over time, wheels develop flaws, which turn into patterns. A wheel that’s even marginally tilted could develop what Barnett called a ‘drop zone.’ When the tilt forces the ball to climb a slope, the ball decelerates and falls from the outer rim at the same spot on almost every spin. A similar thing can happen on equipment worn from repeated use, or if a croupier’s hand lotion has left residue, or for a dizzying number of other reasons. A drop zone is the Achilles’ heel of roulette. That morsel of predictability is enough for software to overcome the random skidding and bouncing that happens after the drop.”

Posted on April 14, 2023 at 7:02 AM • View Comments

On the Randomness of Automatic Card Shufflers

Many years ago, Matt Blaze and I talked about getting our hands on a casino-grade automatic shuffler and looking for vulnerabilities. We never did it—I remember that we didn’t even try very hard—but this article shows that we probably would have found non-random properties:

…the executives had recently discovered that one of their machines had been hacked by a gang of hustlers. The gang used a hidden video camera to record the workings of the card shuffler through a glass window. The images, transmitted to an accomplice outside in the casino parking lot, were played back in slow motion to figure out the sequence of cards in the deck, which was then communicated back to the gamblers inside. The casino lost millions of dollars before the gang were finally caught.

Stanford mathematician Persi Diaconis found other flaws:

With his collaborator Susan Holmes, a statistician at Stanford, Diaconis travelled to the company’s Las Vegas showroom to examine a prototype of their new machine. The pair soon discovered a flaw. Although the mechanical shuffling action appeared random, the mathematicians noticed that the resulting deck still had rising and falling sequences, which meant that they could make predictions about the card order.

New Scientist article behind a paywall. Slashdot thread.

Posted on October 24, 2022 at 6:37 AM • View Comments

Cheating at Professional Poker

Interesting story about someone who is almost certainly cheating at professional poker.

But then I start to see things that seem so obvious, but I wonder whether they aren’t just paranoia after hours and hours of digging into the mystery. Like the fact that he starts wearing a hat that has a strange bulge around the brim—one that vanishes after the game when he’s doing an interview in the booth. Is it a bone-conducting headset, as some online have suggested, sending him messages directly to his inner ear by vibrating on his skull? Of course it is! How could it be anything else? It’s so obvious! Or the fact that he keeps his keys in the same place on the table all the time. Could they contain a secret camera that reads electronic sensors on the cards? I can’t see any other possibility! It is all starting to make sense.

In the end, though, none of this additional evidence is even necessary. The gaggle of online Jim Garrisons have simply picked up more momentum than is required and they can’t stop themselves. The fact is, the mystery was solved a long time ago. It’s just like De Niro’s Ace Rothstein says in Casino when the yokel slot attendant gets hit for three jackpots in a row and tells his boss there was no way for him to know he was being scammed. “Yes there is,” Ace replies. “An infallible way. They won.” According to one poster on TwoPlusTwo, in 69 sessions on Stones Live, Postle has won in 62 of them, for a profit of over $250,000 in 277 hours of play. Given that he plays such a large number of hands, and plays such an erratic and, by his own admission, high-variance style, one would expect to see more, well, variance. His results just aren’t possible even for the best players in the world, which, if he isn’t cheating, he definitely is among. Add to this the fact that it has been alleged that Postle doesn’t play in other nonstreamed live games at Stones, or anywhere else in the Sacramento area, and hasn’t been known to play in any sizable no-limit games anywhere in a long time, and that he always picks up his chips and leaves as soon as the livestream ends. I don’t really need any more evidence than that. If you know poker players, you know that this is the most damning evidence against him. Poker players like to play poker. If any of the poker players I know had the win rate that Mike Postle has, you’d have to pry them up from the table with a crowbar. The guy is making nearly a thousand dollars an hour! He should be wearing adult diapers so he doesn’t have to take a bathroom break and cost himself $250.

This isn’t the first time someone has been accused of cheating because they are simply playing significantly better than computer simulations predict that even the best player would play.

News article. Boing Boing post

Posted on October 9, 2019 at 12:26 PM • View Comments

Hacking Slot Machines by Reverse-Engineering the Random Number Generators

Interesting story:

The venture is built on Alex’s talent for reverse engineering the algorithms—known as pseudorandom number generators, or PRNGs—that govern how slot machine games behave. Armed with this knowledge, he can predict when certain games are likeliest to spit out money­insight that he shares with a legion of field agents who do the organization’s grunt work.

These agents roam casinos from Poland to Macau to Peru in search of slots whose PRNGs have been deciphered by Alex. They use phones to record video of a vulnerable machine in action, then transmit the footage to an office in St. Petersburg. There, Alex and his assistants analyze the video to determine when the games’ odds will briefly tilt against the house. They then send timing data to a custom app on an agent’s phone; this data causes the phones to vibrate a split second before the agent should press the “Spin” button. By using these cues to beat slots in multiple casinos, a four-person team can earn more than $250,000 a week.

It’s an interesting article; I have no idea how much of it is true.

The sad part is that the slot-machine vulnerability is so easy to fix. Although the article says that “writing such algorithms requires tremendous mathematical skill,” it’s really only true that designing the algorithms requires that skill. Using any secure encryption algorithm or hash function as a PRNG is trivially easy. And there’s no reason why the system can’t be designed with a real RNG. There is some randomness in the system somewhere, and it can be added into the mix as well. The programmers can use a well-designed algorithm, like my own Fortuna, but even something less well-thought-out is likely to foil this attack.

Posted on August 7, 2017 at 6:00 AM • View Comments

Predicting a Slot Machine's PRNG

Wired is reporting on a new slot machine hack. A Russian group has reverse-engineered a particular brand of slot machine—from Austrian company Novomatic—and can simulate and predict the pseudo-random number generator.

The cell phones from Pechanga, combined with intelligence from investigations in Missouri and Europe, revealed key details. According to Willy Allison, a Las Vegas­-based casino security consultant who has been tracking the Russian scam for years, the operatives use their phones to record about two dozen spins on a game they aim to cheat. They upload that footage to a technical staff in St. Petersburg, who analyze the video and calculate the machine’s pattern based on what they know about the model’s pseudorandom number generator. Finally, the St. Petersburg team transmits a list of timing markers to a custom app on the operative’s phone; those markers cause the handset to vibrate roughly 0.25 seconds before the operative should press the spin button.

“The normal reaction time for a human is about a quarter of a second, which is why they do that,” says Allison, who is also the founder of the annual World Game Protection Conference. The timed spins are not always successful, but they result in far more payouts than a machine normally awards: Individual scammers typically win more than $10,000 per day. (Allison notes that those operatives try to keep their winnings on each machine to less than $1,000, to avoid arousing suspicion.) A four-person team working multiple casinos can earn upwards of $250,000 in a single week.

The easy solution is to use a random-number generator that accepts local entropy, like Fortuna. But there’s probably no way to easily reprogram those old machines.

Posted on February 8, 2017 at 6:48 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.