/*
 * KeyHandler.java
 * Karl-Adam Karlsson
 * 06-10-04
 *
 * KeyHandler, skapar en private key på 448bitar
 * som skall användas med Blowfish.
 * Sparar som fil med namn args[0]
 *
 */
import javax.crypto.*;
import java.security.*;
import java.io.*;


public class KeyHandler{

	/*
	* Konstruktor
	* Gör anrop för att skapa och spara nyckeln.
	* Som du ser är INTE keysize 448,
	* eftersom storleken uppenbarligen begränsas av policies
	*
	* se: http://java.sun.com/j2se/1.5.0/docs/api/javax/crypto/Cipher.html#init(int, java.security.Key)
	* En keysize på 448 och 256 genererade ett exception vid kryptering.
	* Medan 128 tycks fungera.
	*/
	public KeyHandler(String fileName){
		saveKey(fileName, genKey(128));
	}//end of constructor


	/*
	* genKey generates and returns a secret key
	* of desired Size.
 	*
	* @param int keysize the desired size of the key
	* @returns SecretKey of size keysize
	*
	*/
	private SecretKey genKey(int keysize){
		KeyGenerator aGenerator = null;
		String algorithm = "Blowfish";
		
		try{
			aGenerator = KeyGenerator.getInstance(algorithm);
			aGenerator.init(keysize);
		}catch(NoSuchAlgorithmException alEx){
			System.err.print(alEx);
			System.exit(1);
		}

	return aGenerator.generateKey();	
	}//end of genKey


	/*
	* SaveKey saves a SecretKey to file.
	* Both key to be saved and filename are parameters.
 	*
	* @param String fileName The file to save to.
	* @param SecretKey aKey The key to be saved.
	*
	*/
	private void saveKey(String fileName, SecretKey aKey){	
		File outFile  = new File(fileName);                    
		FileOutputStream outStream;            
		ObjectOutputStream oStream;
	

		try{
   			outStream = new FileOutputStream(outFile);
   			oStream = new ObjectOutputStream(outStream);
			oStream.writeObject(aKey);
			oStream.close();
			outStream.close();
   		
		} catch(IOException e) {
   			System.err.println("IO Exception");
   			e.printStackTrace();
   			System.exit(1);
		}
		
		
	}//endof saveKey


	/*
	* main
	* 
	*/
	public static void main (String[] args) {
		if(args==null || args.length < 1 ||args.length>1){
			System.out.print("Usage:\njava KeyHandler <secretKey>\n");
			System.out.println("Where <secretKey> is desired name of keyfile.");
		}
		else if(args.length==1&&args[0]!=null){
			new KeyHandler(args[0]);
		}
		else if(args[0]==null){
			System.out.println("Null is not a valid argument.");
			System.out.print("Usage:\njava KeyHandler <secretKey>\n");
			System.out.println("Where <secretKey> is desired name of keyfile.");
		}
  		
  	}//end of main
}//End of Class