void silc_mp_get_str(char *str, SilcMPInt *mp, int base);

    Converts integer `mp' into a string of base `base'. The `str'
    must already have space allocated. The function returns the same
    as `str' or NULL on error.

    For base 2 the returned string is in ASCII bit presentation, not
    in binary.  Use the silc_mp_mp2bin to encode integer into binary.