DCing algorithm

[Silverthorn]

After Silva explained how the encryption of dat-files works (big thanks for that again), I tried to implement that into a programming language. As the only language I'm better at is Java, this code is written in Java (duh!).

Feel free to copy the code, or try to understand it. I seldomly write comments, and if I do, they're pretty useless :P

What it does: it reads the file template.dat (which has to be in the same folder as the class-object), decrypts it, and outputs the decrypted result into a txt-file.

On a side note: if you copy this code, I'd be pleased as punch if you leave the author notes in there. If you remove them, I'll stalk you until I chopped off your head after I cut out your heart, pulled out every single nail, sliced up your stomach and the usual stuff

Code:

/*
Programmed by Blue Phoenix
Explanations and help by Silva
Latest version: 14 Jan 2009
*/

import java.io.*;
import java.lang.*;

public class ReadIt {    

   public static void main(String args[]) throws IOException {
      int mod;
      char buffer;
      String finalCode = "";
      String plainEncryptionKey = "odBearBecauseHeIsVeryGoodSiuHungIsAGo";
      FileInputStream data = new FileInputStream("template.dat");
      int uselessCheck = 0;
            
      byte[] encr = new byte[plainEncryptionKey.length()];
      for (int i = 0; i < plainEncryptionKey.length(); i++)
         encr[i] = (byte)plainEncryptionKey.charAt(i);
            
      for (int i = data.read(); i != -1; i = data.read()) {
         byte encrSingle;
         if (uselessCheck >= 123) {
            buffer = (char)i;
            mod = (uselessCheck-123) % plainEncryptionKey.length();
            encrSingle = encr[mod];
            finalCode += decrypt(buffer,mod,(uselessCheck-123),encrSingle);
         }
         uselessCheck++;
      }
            
      // System.out.println(finalCode);
              
      try {
         FileOutputStream fout = new FileOutputStream ("Template.txt");
         new PrintStream(fout).println (finalCode);
         fout.close();
      }
      catch (IOException e) {
         System.err.println ("Unable to write to file");
         System.exit(-1);
      }
    
   }
    
   public static char decrypt(char buffer, int mod, int i, byte encrSingle) {
      byte datDecr;
      char decrChar;
      datDecr = (byte)buffer;
      decrChar = PatchData(i,mod,datDecr,encrSingle);
      return decrChar;
   }
        
   public static char PatchData (int i, int mod, byte datDecr, byte encrSingle){
      char result;      
      datDecr -= encrSingle;
      result = (char)datDecr;
      return result;
   }
      
}