Pasar esta fórmula matemática

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Me funciona así:

Código:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace ZyXEL
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button_Generar_Click(object sender, EventArgs e)
        {
            try
            {
                textBox_Password.Text = Calculo_Password(textBox_seedNumber.Text);
            }
            catch (Exception ex)
            {
                MessageBox.Show("Los números deben ser de 12 cifras hexadeximales [0-9, A-F, a-f]", "Error",
                    MessageBoxButtons.OK, MessageBoxIcon.Error);
            } 
        }

        private string Calculo_Password(string seedNumber)
        {
            int num = Convert.ToInt32(seedNumber.Substring(0, 6), 0x10);
            int num2 = num + 0x10f0a563;
            int num3 = Convert.ToInt32(seedNumber.Substring(10, 2), 0x10) & 7;
            int num4 = (num2 >> num3) | (num2 << (0x20 - num3));
            num4 ^= num;
            return num4.ToString("X");
        } 
    }
}

Gracias.