int lcm = lcm(outlen, data.length);
        byte[] buf = new byte[outlen];
        int carry = 0;
        for ( int i = lcm - 1; i >= 0; i-- ) {
            carry = carry_add(data, buf, carry, i);
        }

        if ( carry != 0 ) {
            for ( int i = outlen - 1; i >= 0; i-- ) {
                carry += ( buf[ i ] & 0xff );
                buf[ i ] = (byte) ( carry & 0xff );