  We calculate the subgap density of states of a disordered single-channel
normal metal connected to a superconductor at one end (NS junction) or at both
ends (SNS junction). The probability distribution of the energy of a bound
state (Andreev level) is broadened by disorder. In the SNS case the two-fold
degeneracy of the Andreev levels is removed by disorder leading to a splitting
in addition to the broadening. The distribution of the splitting is given
precisely by Wigner's surmise from random-matrix theory. For strong disorder
the mean density of states is largely unaffected by the proximity to the
superconductor, because of localization, except in a narrow energy region near
the Fermi level, where the density of states is suppressed with a log-normal
tail.
