Shuffling an array to create a random stream for encryption is well known. The weakness is in the security of the random number generator that performs the shuffling. But is it true or likely that the same array shuffled by two or more imperfect random number generators becomes more secure as it is shuffled by more numbers of known to the enemy random number generators.

The shuffling is a form of undersampling which increases security in my thoughts with the random array becoming more secure as it is shuffled more. Comments ?


It depends on the generators.

If your generators are independent, the worst-case result is no worse than shuffling with the best of the generators. However, if there's correlation between the generators, the result can be worse than using a single generator by itself (for example, I bet there's a way to shuffle repeatedly with RANDU that gets you the original array back).

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