const char *silc_time_string(SilcInt64 time_val_sec);

    Returns time and date as string.  The caller must not free the string
    and next call to this function will delete the old string.  If the
    `time_val_sec' is zero (0) returns current time as string, otherwise the
    `time_val_sec' as string.  The `time_val_sec' is in seconds since Epoch.
    Returns NULL on error.