DCing algorithm

[Boop]

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;
                  }
                  System.out.print((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 ).