4 ms·
Also, to break unknown/unseen PRNG, model a few popular classes of PRNG, a few common reductions (so for cards the naive val%52 and better rejection sampling),
by ChrisLomont 5y ago
Also, to break unknown/unseen PRNG, model a few popular classes of PRNG, a few common reductions (so for cards the naive val%52 and better rejection sampling), then solve across the states till you get one. Then watch a few more outputs, check that you guessed the source and reduction, and now you've cracked that too.
I doubt any poker site uses anything other than a crypto rand for deals because the technique I just explained would eat them alive. They can use fast and insecure PRNG for doing Monte Carlo hand evaluation, though, since that doesn't give you any advantage.
- downandout 5y agoSo building on this...many physical casinos use a manual shuffle, especially at higher limits, as bigger players tend to distrust shuffle machines. Even some online casinos with live dealers will shuffle the previous shoe on camera, manually. Since getting a truly random shuffle would take too long, this is a poor method of getting random results. Would it be possible to, at least to some degree, predict the order of the cards using one of these models, given the order of the cards prior to shuffling? I'm thinking something along the lines of being able to say that the odds of a given card being the next one are higher than they should be, not outright predicting the full order of the cards.
- ChrisLomont 5y agoIf I recall, something like 7 hand shuffles becomes indistinguishable from random. I'd guess a pro could get this level of mixing in a few shuffles
- downandout 5y agoYeah, but that's 7 shuffles of a single deck. Most casinos use 6 or 8 decks. They are certainly not shuffling 42+ times.
- ChrisLomont 5y agoShuffles don't multiply like that. Mixing is an exponential process. It's why mixing a little paint or a lot of paint isn't multiplicatively more work.