The solution here, which the article fails to mention, and which every security expert will undoubtedly tell you, is to make sure you use super random numbers (that's the technical term, for the layperson) by adding two random numbers together.
When Random Isn't Random Enough: Lessons from an Online Poker Exploit
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Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#32The solution here, which the article fails to mention, and which every security expert will undoubtedly tell you, is to make sure you use super random numbers (that's the technical term, for the layperson) by adding two random numbers together.
Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#33I'm curious how actually random are current generators in online poker? I mean, some rather subtle patterns, situations would generate larger pots, therefore more rake. Or being on the new players side in 50/50 situations would 'help' to get him addicted. I am not talking about 100% of the time dealing someone pocket kings, and someone else pocket aces and king on the flop. Something subtle and very rare would be eno…
Even for bad poker sites they are using HW RNGs. I worked for a hybrid meat space/online casino and we were using IDQ cards. Except when we were not. Owner got squirrely and went for bottom dollar to implement a stand alone version of a carefully engineered system I had developed. The developers ended up using /dev/random instead of at least making a 1 gig rng lookup table. Also the ticketing system was unencrypted so you could print whatever you on a barcode and feed it to the redemption machine to clean it out. Also the games were not tested statistically. Literally a guy sat there and played games until it "felt" right.
I tried to help them out, but eventually I washed my hands of everything and walked away. Too many weird things going on. From talking to others in the industry it is not that different elsewhere.
TL;DR - If you do work for casinos be ready to walk away when things get weird.
Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#34The solution here, which the article fails to mention, and which every security expert will undoubtedly tell you, is to make sure you use super random numbers (that's the technical term, for the layperson) by adding two random numbers together.
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Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#35Earlier quoted context omitted.
The major sites don't do this. We know because many people out there collect literally millions of poker hands observed on these sites and mine the data for every kind of statistic you can think of. If anything significant was out of whack they would have picked it up. Look at the 'online poker' section of the twoplustwo forums for example. The random number generators used by these sites are hardware systems that us…
The random number generators used by these sites are hardware systems that use micro fluctuations in ambient temperature (for example) as a source of entropy and they are very careful to use enough bits of entropy for every card shuffled. It's amusing to realize that they could just read from dev/urandom with zero risk. They're probably not running Linux, but still. So, for anyone who's wondering if you need this, or…
FWIW, Windows has an equivalent of /dev/urandom. http://msdn.microsoft.com/en-us/library/windows/desktop/aa37...
Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#36I admit I am a total noob here, but couldn't you make something with a TV turned to a station with just static? I have often wondered about this but lack the 'propriate schoolin'.
http://www.random.org/ uses atmospheric radio noise to generate random numbers, similar to what you are proposing.
Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#37Earlier quoted context omitted.
The major sites don't do this. We know because many people out there collect literally millions of poker hands observed on these sites and mine the data for every kind of statistic you can think of. If anything significant was out of whack they would have picked it up. Look at the 'online poker' section of the twoplustwo forums for example. The random number generators used by these sites are hardware systems that us…
The random number generators used by these sites are hardware systems that use micro fluctuations in ambient temperature (for example) as a source of entropy and they are very careful to use enough bits of entropy for every card shuffled. It's amusing to realize that they could just read from dev/urandom with zero risk. They're probably not running Linux, but still. So, for anyone who's wondering if you need this, or…
But their devs can't charge as much if they say "I implemented the random number generator, is one line of bash code" rather than "I created a thermal system that is connected to our server where we will use its data as seeds to generate cryptographically random numbers".
Capitalism, we all play it ;)
Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#38It seems to me that the only major issue here is using a seed which can be trivially brute forced. Even if you don't look around the expected server time in order to guess the seed more quickly, 32 bits is really not hard at all to brute force these days.
I don't believe the number of bits the PRNG can generate is an issue here since we only need to uniformly get a number between 1 and 52, though what may be questionable is the cycle length of the PRNG if it weren't using an easily brute forced seed.
I'm not entirely convinced the off-by-1 is substantial, nor the fact that the shuffle produces duplicate shuffles (I can't intuit a significant bias, so I may well be wrong here).
So to summarize: never seed a PRNG with a small and easily brute forced value.
Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#39Earlier quoted context omitted.
The moral of the story is don't play poker for money where you suspect MITM to be in effect, because the connection is not secure.
It wasn't a MITM. Although I've done that too, ARP flood the router and redirect the traffic through myself. Only works on sites where they didn't peer validate the SSL cert. These were just packet dumps, wasn't associated with the WAP. It's hard to remember the exact details but I believe I was dumping the packets and decrypting them with the WEP key then piping them into a C program which just applied the decryptio…
Why would they even send that information to the client before it was needed anyway? Keep it on the server and push it when, and only when, the client needs to see it.
Re: When Random Isn't Random Enough: Lessons from an Online Poker Exploit
#40I understand that "swap with entire deck" can't possibly be uniform because it has 52^n input possibilities, which is not divisible by 52! (and that the correct Fisher-Yates having 52! input possibilities and being able to generate every possible outcome is one way to prove that it is uniform). However, I'm not sure I can come up with an intuition for why any particular bias should exist, or why there is a discontinu…
I'm not entirely sure, but I have been able to figure a few things out.
By running some simulations by shuffling the range from 1 to n (with n going from 3 to 7), I found that at least one of the most common permutations had always started with 2. I'm unable to come up with a reason to explain this, but I was able to figure out something else interesting.
Imagining that the deck is vertical and going through each card and swapping it with a random card in the deck, the random card that has been swapped will never move further up the deck while the other card can still possibly move further up the deck. This implies that cards at the top of the deck should stay near the top and the cards at the bottom should stay near the bottom. I tested this by taking the sum of the sums of the first half of all the permutations and the sum of the sums of the second half of all the permutations and found that the total sum of the first halves was slightly smaller than the total sum of the second halves.
n first halves | second halves
3 53 | 54
4 1265 | 1295
5 18322 | 18976
6 461683 | 498093
7 9638931 10051128
Note: for odd numbers I threw out the middle number.