Big, issue, you flip same coin 256 times, so you loose entropy
Care to explain that one?
If I flip heads 20 times in a row using a fair coin what is the odds that it will come up heads on the next flip?
50% < A true "fair coin" has no idea what you flipped in the past... so its 50%/50% ..period
In fact, I would argue, that as you approached 256 flips, you would get bored and would gradually change your enthusiasm and energy, thereby adding entropy.