Even if the range is only 1,000 for each PRNG, things explode exponentially. What I'm actually trying to do is deal Bridge hands. There are 5.36E28 different hands that can be dealt, so even a 24 bit PRNG could cover only a tiny fraction, which may not be representative. My strategy is based loosely on the Enigma coding machine, but with a variation.

The idea is that the user will first select the sequence of PRNGs that will be used. The sequence will not be of fixed length (unlike Enigma, which had a set number of wheels) and PRNGs can be repeated within the sequence (again unlike Enigma, where a wheel could be used only once in any day's setting). Let's say that the attacker knows that a sequence of five PRNGs will be used without repeats, because he knows the Tournament Director. Even at a range of 1,000, that's 1.2E17 different series of deals that might come up. Since he won't see the first board before he starts playing, he won't have much time to work out what the other boards are likely to be. Getting access to the boards before play would be far easier, but that's beyond the scope of this lecture :-).

Thanks again for all the help,

John Davies

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