A psuedorandom generator G(x) can expand n random bits to n+1 psuedorandom bits that still &quot;look random&quot; to any efficient program that sees them. The existence of such a G that is efficiently computable is hard to prove (at least as hard as P!=NP) but there are many reasonable functions we theorize to have this property.<p>So with original entropy x, evaluate G(x) =&gt; x&#x27;, c. Output the random bits c and repeat with x = x&#x27;. The sequence of c is psuedorandom.<p>k=128 is the key length of the generator. We define an efficient program to be one that runs in some time polynomial in k. How big of a k you need is based on how powerful computers are at present.