Actually, "#" and "*" to be removed to create Activation Code.
Code:
string pass_1 = "?????";
byte[] pass_1_b = Encoding.ASCII.GetBytes(pass_1);
string pass_2 = "??????";
byte[] pass_2_b = Encoding.ASCII.GetBytes(pass_2);
byte[] hexData = Convert.FromBase64String(Registratin_Code);
byte[] z1 = RC4.Decrypt(pass_1_b, hexData);
byte[] pass_3_b = new byte[16];
Buffer.BlockCopy(z1, 0, pass_3_b, 0, 16);
byte[] z5 = new byte[z1.Length - 16];
Buffer.BlockCopy(z1, 16, z5, 0, z1.Length - 16);
byte[] z3 = RC4.Decrypt(pass_3_b, z5);
string z3_str = BitConverter.ToString(z3).Replace("-", "");
string z4 = Encoding.ASCII.GetString(z3);
//************************************************************
string girdi = z4.Replace("#", "").Replace("*", "");
byte[] girdi_b = Encoding.ASCII.GetBytes(girdi);
byte[] x1 = RC4.Encrypt(pass_3_b, girdi_b);
byte[] x2 = new byte[x1.Length + 16];
Buffer.BlockCopy(pass_3_b, 0, x2, 0, 16);
Buffer.BlockCopy(x1, 0, x2, 16, x1.Length);
byte[] x3 = RC4.Encrypt(pass_2_b, x2);
//************************************************************
string Activation_Code = Convert.ToBase64String(x3);