•George Marsaglia produced a CD-ROM containing 600 megabytes of random numbers. These were produced using
the best pseudo-random
number generators, but were then combined bytes from a variety of random sources or semi-random
sources (such as rap music).
•Suppose X and Y are independent random bytes (integer
values 0 to 255), and at least
one of them is uniformly distributed over the values 0 to 255. Then both the bitwise exclusive-or of X
and Y, and X+Y mod 256, are
uniformly distributed over 0 to 255. In addition if both X and Y are approximately uniformly
distributed, then the
combination will be more closely uniformly distributed.
•In the Marsaglia CD-ROM the idea is to get the excellent
properties of the pseudo-random
number generator but to break up
any remaining patterns with the random or semi-random generators.