There is no need for a Linux implementation of this PRNG entropy source.

From Ulf:
ZkYarrow is used only to provide input to the Yarrow PRNG. This is not needed
on Linux because randomness is handled by the kernel.

[We are currently using /dev/urandom as the entropy source on Linux.
The difference is that /dev/random blocks, which would be the desired behavior
when Linux is first started and the PRNG has not collected enough entropy
yet. However that case is very unlikely and in normal operation we need
a constant stream of cryptographically secure randomness, not information-
theoretically secure randomness as provided be /dev/random.]
