DCing algorithm

[YinYin]

Code:

/*Programmed by Silva
Stolen stuff from Blue Phoenix
Latest version: 14 Jan 2009
*/

   import java.io.*;

    public class ReadFile{
       public static void main(String[] args) throws IOException{
         File f;
         f=new File("template.dat");// file rawr
          
         if(!f.exists()&& f.length()<0)
            System.out.println("The specified file is not exist");
        
         else{
            FileInputStream finp=new FileInputStream(f);
            int counta = 0;
            int countTo123 = 0;
            byte b;
            byte d;
            do{
                countTo123++;
                b = (byte)finp.Read();
                if (countTo123 > 123)
                {

                    d = DecryptByte(counta, b);
                    counta++;
                    if (counta > 36)
                    {
                        counta = 0;
                    }
                    text += (char)d;
                }
            }
            while(b!=-1);
            finp.close();
         }
      }
      
       public static byte DecryptByte(int counta,byte b){
         String plainEncryptionKey = "odBearBecauseHeIsVeryGoodSiuHungIsAGo";
         b -= (byte)plainEncryptionKey.charAt(counta);
         return b;
      }
   }

My version :) (works faster because it uses streams ;) ).

C# version that only returns gibberish for me on both b+ and b-, any idea why?

Code:

public class ReadFile
    {
        public static string main(String FileName)
        {
            string text = "";
            StreamReader finp = new StreamReader(FileName);
            int counta = 0;
            int countTo123 = 0;
            byte b;
            byte d;
            while (finp.Peek() >= 0)
            {
                countTo123++;
                b = (byte)finp.Read();
                if (countTo123 > 123)
                {

                    d = DecryptByte(counta, b);
                    counta++;
                    if (counta > 36)
                    {
                        counta = 0;
                    }
                    text += (char)d;
                }
            }
            finp.Close();
            return text;
        }

        public static byte DecryptByte(int counta, byte b)
        {
            String plainEncryptionKey = "odBearBecauseHeIsVeryGoodSiuHungIsAGo";
            b -= (byte)plainEncryptionKey[counta];
            return b;
        }
    }