I'm still not following: With the user providing a random client seed (which is used for the final shuffle); how can your shufflepuff algorithm predict with precision that it will serve up the rigged deck?
I'm not discounting a site like Bitzino (or even ours) couldn't rig shuffles, as both sites produce the first shuffle and client seed - but if the user changes the client seed (which they are absolutely always encouraged to do, otherwise what's the point of even playing a provably fair game?), how can you predict the final shuffle (with the new, random, client seed) would in fact still be 'rigged'?
I think the original post is very well articulated, far better than I could, so I feel a bit bad trying to repeat it. But the point that some provably fair systems are kind of stupid and only allow 2^32 combinations -- which is small enough you can literally just try them all. If > 2^31 of the final outcomes are good for the house, then the house knows that it'll have an increased house edge by using that initial shuffle.
So really it's not a problem with provably fair, just bad ones. Provably fair systems like bustabit already prevent against precomputing a favorable initial seed. For a shuffling one, you just need to use logic that gives a shit load more possible final shuffles. (I recommend the pseudo code in my previous post, which shouldn't reduce the space at all)
OK, I follow that. Let's talk
practical --- are there really 2^31 outcomes that are good for the house (only) in Blackjack, Roulette, Video Poker?
Still would love seeing some real proof where I can change the client seed to anything I want, and still get one of those 'rigged' shuffles; otherwise this is just a thread with a ton of people (not you, or the OP) chiming in who have no understanding of how math or provably fair works.