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lmnk

Random number generation predicton

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A few of my friends are heavily into online poker, and they have recently come across websites selling "Reverse RNGs", which claim that by collecting data from many previous hands, the software is able to predict an opponent's hand and some (if not all) of the community cards. The software is prohibitively expensive to test out, so they asked me if this is actually possible. I never thought that predicting the outcome of a random number generator would be possible. Is it possible to make predictions like this or should I just write these websites off a scam?

Here is one of the websites selling this software trying to explain how it works, it sounds like fluff to me.

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It can be done, it is really more dependent upon whatever algorithm the poker website is using for random number generation. As to whether it is a scam or not, keep in mind that they are selling something designed to help you cheat other people out of money... so they're not exactly in a highly ethical profession to begin with. :)

Also, I found this very telling and mildly amusing:

Our exact process cannot be explained

(I know that they mean "will not", but it just sounds funny to say it that way.)

Note, too, that casinos will not look very kindly on someone attempting to employ these methods. I read a story of a group of guys who reverse-engineered a video poker machine (or slot machine or something) and ended up getting in buttloads of legal trouble over it. (I forget the name of the book.)

EDIT: It was Kevin Mitnick's The Art of Intrusion, and it was an online slot machine... but the overall idea was the same.

Edited by mirrorshades
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Test it if you want, I know there used to be issues with the number generation in some of the online poker clients but they have all been fixed in any poker client of note.

http://www.pokerstars.com/poker/room/features/security/ <- I would say the software is a scam.

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Thanks for clearing this up, I figured that this software was just a scam and after doing some reading about random number generation I'm sure that it is. Not that I would actually use it to cheat (there are already better ways to do that if I wanted to), I was just wondering about how predicable it could be.

Edited by lmnk
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from a math point of view, you could so say reverse engineer their random number algorithm(s) with a low standard deviation assuming the collection of enough data, but I believe to be anywhere near accurate you would need to play hundreds if not thousands of games.

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from a math point of view, you could so say reverse engineer their random number algorithm(s) with a low standard deviation assuming the collection of enough data, but I believe to be anywhere near accurate you would need to play hundreds if not thousands of games.

Determining their exact algorithm wouldn't do you any good from a player perspective since the rng is reseeded constantly from multiple sources, and the only entropy you have any degree of control over (user input) has a set floor value regardless. I don't think you could affect enough input to reliably determine the effect, and it would seem there are too many variables to calculate without some insight to the undetermined seed.

The time and effort would likely be better spent creating a colluding botnet that gives a 2card per bot per table advantage, tracks player moves over time and connects to any number of the openly available backend win/loss player databases to change the play style depending on player history of who's in the hand and who's remaining (some people out there are down thousands and thousands of dollars, get your money in against them). ;)

'Oh look, CoolDad69 went in with his low pocket pair.. too bad he let me see the flop for so cheap and his pockets won't holdup'.. 'Looks like H0tSoccerMom is chasing another flush draw, lets just get our money in here.. with a nice all-in reraise with our nuts-high flush'.

Shuffle Highlights:

* A deck of 52 cards can be shuffled in 52! ways. 52! is about 2^225 (to be precise, 80,658,175,170,943,878,571,660,636,856,404,000,000,000,000,000 ways). We use 249 random bits from both entropy sources (user input and thermal noise) to achieve an even and unpredictable statistical distribution.

* Furthermore, we apply conservative rules to enforce the required degree of randomness; for instance, if user input does not generate required amount of entropy, we do not start the next hand until we obtain the required amount of entropy from Intel RNG.

* We use the SHA-1 cryptographic hash algorithm to mix the entropy gathered from both sources to provide an extra level of security

* We also maintain a SHA-1-based pseudo-random generator to provide even more security and protection from user data attacks

* To convert random bit stream to random numbers within a required range without bias, we use a simple and reliable algorithm. For example, if we need a random number in the range 0-25:

o we take 5 random bits and convert them to a random number 0-31

o if this number is greater than 25 we just discard all 5 bits and repeat the process

* This method is not affected by biases related to modulus operation for generation of random numbers that are not 2n, n = 1,2,..

* To perform an actual shuffle, we use another simple and reliable algorithm:

o first we draw a random card from the original deck (1 of 52) and place it in a new deck - now original deck contains 51 cards and the new deck contains 1 card

o then we draw another random card from the original deck (1 of 51) and place it on top of the new deck - now original deck contains 50 cards and the new deck contains 2 cards

o we repeat the process until all cards have moved from the original deck to the new deck

* This algorithm does not suffer from "Bad Distribution Of Shuffles" described in [2]

PokerStars shuffle verified by Cigital and BMM International

PokerStars submitted extensive information about the PokerStars random number generator (RNG) to two independent organizations. We asked these two trusted resources to perform an in-depth analysis of the randomness of the output of the RNG, and its implementation in the shuffling of the cards on PokerStars.

Both independent companies were given full access to the source code and confirmed the randomness and security of our shuffle. Visit Online Poker Random Number Generator for more details.

Edited by jabzor
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Wow, long posts to give a very simple answer:

Can RNGs be predicted?

Yes. The average computer will never see a true random number generator, just pseudo-random. Assuming the seed never changes, or changes predictably, the seed (or its source) can be guessed with a large enough sample size. The Blackjack game I wrote in High School CompSci can be easily broken and predicted with enough hands.

No. A True-Random generator will use real entropy sources to seed a pseudo-random system and reseed it often. Those cannot be predicted. You need both the algorithm and the seed to reproduce pseudo-random number chains, and since seeds in a True-Random system are generated by entropy, even if you determine one seed you are unlikely to determine the next. PokerStars RNG cannot be easily broken and predicted with any number of hands

Fin B)

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