That's a very important point: I was thinking about several methods to give confidence to people, mainly this ones:
1. cryptographic proof before dealing cards: send an encrypted zip with the cards before the hand, and send the key to decrypt it after it.
2. code audits (allow methods to anyone could make an auditory on the code that gives the cards)
3. offer means to do an output audit (you can just register the cards you receive and then check if they are evenly distributed).
None of the methods seems to be enough to assure that the machine is not cheating by any means.
To choose the cards, the system is using the server's random generator (linux in this case), through a python script that calls it. The python code is SystemRandom() from the module random:
https://docs.python.org/2/library/random.html#random.SystemRandomIn other hand, I wouldn't need to cheat at all, becuase the nature of statistics says that house ever wins at the large scale. Players can take advantage of lucky strikes, if they manage their bets carefully, it's possible to take a profit.
I plan to offer other kinds of backings to help to create confidence in people. I will put my data so they can contatme directly too.