Simple Encryption

This program displays a simple basic encryption using c#. This encryption is being used in a virus called VBSRedlof.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace RedOF
{
 class Program
 {
  public static string key;
  public static int[] KeyArr = { 4,8,7,8};//4037//4878//7835
  static void Main(string[] args)
  {

   Console.WriteLine("VCode  ");
   keygen();
   WRITEKey();
   string ans;
   ans = @"Love the way you lie";
   //ans= Console.ReadLine();
   //Console.WriteLine("\n \nREDOF{0}: {1}",key,Encode(ans).ToUpper());
   string qus = Encode(ans) + ":" + "RDF" + key;
   Console.WriteLine(qus);
   //Console.WriteLine("GOTKEY:{0}",GETKey(qus));
   Console.WriteLine("{0}", Decode(qus));
   
   //Encode("ggggg");
   Console.Read();
  }

  //prints anything
  static void prn(Object o)
  {
   Console.WriteLine(o);
  }
  
  //Gets the key from chipertext
  static string GETKey(string chiper)
  {
   char[] hh = { '1', '2', '3', ' ' };
   Console.WriteLine("Signature Index....{0}",chiper.IndexOf(":RDF", 1));
   chiper.CopyTo(chiper.IndexOf(":RDF",1)+4, hh, 0, 4);
   string res=null;
   //Console.WriteLine("{0}{1}{2}{3}", hh[0], hh[1], hh[2], hh[3]);
   foreach (char cc in hh)
    res = res + cc;
   return res;
  }

  //Writes the Key to the file
  static void WRITEKey()
  {
   Console.Write("KEY:");
   foreach (int t in KeyArr)
   {
    Console.Write(t);
    key = key + t;
   }
   Console.Write("\n");
  }

  //Generated Random Key
  static void keygen()
  {
   int rr;
   Random rnd = new Random();
   for (int i = 0; i < 3; i++)
   {
    rr = rnd.Next(1, 9);
    KeyArr[i] = rr;
   }
  }

  // Encodes the Plaintext
  static string Encode(string plaintxt)
  {
   int tempnum,asc,i=0;
   string tempchar=null;

   foreach(char ch in plaintxt)
   {
    i++;
    tempnum = Convert.ToInt32(ch);
    asc = Convert.ToInt32(KeyArr[i % 4]) + tempnum;
    tempchar = tempchar + Convert.ToChar(asc);
   }
   return tempchar;
  }

  //Decode.....
  static string Decode(string chipertext)
  {
   int tempnum, asc, i = 0;
   string tempchar = null;

   foreach (char ch in chipertext)
   {
    if (i >=chipertext.Length-8) 
    {
     i++;
    }
    else
    {
     i++;
     tempnum = Convert.ToInt32(ch);
     asc = tempnum - KeyArr[i % 4];
     tempchar = tempchar + Convert.ToChar(asc);
    }
   }
   return tempchar;
  }
 }
}