'Decrypts files.'

def perform_operation(self, indata, priv_key, cli_args):

    hash_method = cli_args[1]
    if (hash_method not in HASH_METHODS):
        raise SystemExit(('Invalid    hash    method,    choose    one    of    %s' % ',    '.join(HASH_METHODS)))
    return rsa.sign(indata, priv_key, hash_method)
