Function silc_dh_generate_private
SYNOPSIS
int silc_dh_generate_private(SilcDH dh, SilcMPInt **x);
DESCRIPTION
Generates random private value `x' such that 0 < x < lpf at most of
length of lpf. Returns FALSE if the random number could not be generated.
Returns the generated value into `x' pointer sent as argument, unless
the `x' is NULL. The returned `x' must no be freed by the caller.