This paper considers C2 random dynamical systems on a Banach space, and
proves that under some mild conditions, SRB measures are characterized by
invariant measures satisfying the Pesin's entropy formula, in which entropy is
equal to the sum of positive Lyapunov exponents of the system. This can be
regarded as a random version of the main result in Blumenthal and Young's paper
\cite{Young17}.Comment: 44pages, revised version with some corrected formulations and
argument