A method and apparatus are disclosed for generating random numbers using
the meta-stable behavior of flip-flops. A flip-flop is clocked with an
input that deliberately violates the setup or hold times (or both) of the
flip-flop to ensure meta-stable behavior. When a meta-stable event is
detected, an output bit is provided as a random bit. An even random
number distribution is obtained by "marking" half of the zeroes input to
the flip-flop as "ones" and the other half of the zeroes as "zeroes." In
addition, half of the ones are marked as "ones" and the other half of the
ones are marked as "zeroes." The marking signal is uncorrelated to any
noise to a high probability using a linear feedback shift register.