  De, Trevisan and Tulsiani [CRYPTO 2010] show that every distribution over
$n$-bit strings which has constant statistical distance to uniform (e.g., the
output of a pseudorandom generator mapping $n-1$ to $n$ bit strings), can be
distinguished from the uniform distribution with advantage $\epsilon$ by a
circuit of size $O( 2^n\epsilon^2)$.
  We generalize this result, showing that a distribution which has less than
$k$ bits of min-entropy, can be distinguished from any distribution with $k$
bits of $\delta$-smooth min-entropy with advantage $\epsilon$ by a circuit of
size $O(2^k\epsilon^2/\delta^2)$. As a special case, this implies that any
distribution with support at most $2^k$ (e.g., the output of a pseudoentropy
generator mapping $k$ to $n$ bit strings) can be distinguished from any given
distribution with min-entropy $k+1$ with advantage $\epsilon$ by a circuit of
size $O(2^k\epsilon^2)$.
  Our result thus shows that pseudoentropy distributions face basically the
same non-uniform attacks as pseudorandom distributions.
