/*
 * CryptHandler.java
 * Karl-Adam Karlsson
 * 06-10-15
 *
 * Crypthandler, laddar en nyckel från fil (om en path ges).
 * Sköter sedan kryptering och dekryptering av strängar.
 *
 * Där keyPath är path till filen innehållande nyckeln, eller null om man vill använda en default nyckel.
 */
import javax.crypto.*;
import java.security.*;
import java.io.*;


public class CryptHandler{
	Cipher enCipher, deCipher;
	SecretKey akey;
	/*
	* Konstruktor
	* 
	*/
	public CryptHandler(String keyPath){
		//LOADING KEY
		
		if(keyPath==null||keyPath.equals("")){
			System.out.println("Using DefaultKey for message text encryption.");
			keyPath = "DefaultKey";	
		}
			akey = loadKey(keyPath);

		// CREATING ENCRYPTCIPHER
		try{
			enCipher = Cipher.getInstance(akey.getAlgorithm() );
			enCipher.init(Cipher.ENCRYPT_MODE, akey);
		}catch(NoSuchAlgorithmException alEx){
			System.err.print(alEx);
			System.exit(1);	
		}catch(InvalidKeyException iKe){
			System.err.print(iKe);
			System.exit(1);
		}catch(NoSuchPaddingException  padEx){
			System.err.print("NO SUCH PADDING");
			System.exit(1);
		}
		// DONE CREATING CIPHER
		
		// CREATING DECRYPT CIPHER
		try{
			deCipher = Cipher.getInstance(akey.getAlgorithm() );
			deCipher.init(Cipher.DECRYPT_MODE, akey);
		}catch(NoSuchAlgorithmException alEx){
			System.err.print(alEx);
			System.exit(1);	
		}catch(InvalidKeyException iKe){
			System.err.print(iKe);
			System.exit(1);
		}catch(NoSuchPaddingException  padEx){
			System.err.print("NO SUCH PADDING");
			System.exit(1);
		}
		// DONE CREATING CIPHER
		
	}//end of constructor

	/*
	 * encrypt
	 * Takes a String and returns it encrypted
	 * @param String toEncrypt The String to Encrypt
	 * @return String A encrypted String.
	 */
	public String encrypt(String toEncrypt){
		try {
                // Gör om strängen till bytes
                byte[] myByte = toEncrypt.getBytes("UTF8");
                // kryptera datat
                byte[] enc = enCipher.doFinal(myByte);
    
                // Gör om till sträng från bytes och returnera
                return new sun.misc.BASE64Encoder().encode(enc);
            } catch (javax.crypto.BadPaddingException e) {
            	e.printStackTrace();
            } catch (IllegalBlockSizeException e) {
            	e.printStackTrace();
            } catch (UnsupportedEncodingException e) {
            	e.printStackTrace();
            } catch (java.io.IOException e) {
            	e.printStackTrace();
            }
            return "ENCRYPTION FAILED";

	}//end of encrypt

	/*
	 * decrypt, decrypts a String and returns it.
	 * @param Strin toDecrypt A encrypted String
	 * @return String The decrypted String
	 *
	 */
	public String decrypt(String toDecrypt){
		System.out.println("DECPYTING:  "+toDecrypt);
		try {
                // Gör från Sträng till bytes
                byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(toDecrypt);
                
    			
                // Decrypt
                byte[] myByte = deCipher.doFinal(dec);
    
                // Tillbaka till sträng och returnera.
                return new String(myByte, "UTF8");
            } catch (javax.crypto.BadPaddingException e) {
            	e.printStackTrace();
            } catch (IllegalBlockSizeException e) {
            	e.printStackTrace();
            } catch (UnsupportedEncodingException e) {
            	e.printStackTrace();
            } catch (java.io.IOException e) {
            	e.printStackTrace();
            }
            return "DECRYPTION FAILED";
        }//end of decrypt


	/*
	* loadKey
	* Loads a SecretKey Object from the file named <keyFileName>
	* @param keyFileName Name of file to load key from
	* @return SecretKey the loaded key.
	*/
	private SecretKey loadKey(String keyFileName){
		ObjectInputStream oInStr = null;
		SecretKey theKey = null;
		
		try{
			FileInputStream inFstream = new FileInputStream(keyFileName);
			oInStr = new ObjectInputStream(inFstream);
		}catch(FileNotFoundException fEx){
			System.err.print(fEx);
			System.exit(1);
		}catch(IOException ioe){
			System.err.print(ioe);
			System.exit(1);
		}
		
		try{
			theKey = (SecretKey)oInStr.readObject();
			oInStr.close();
		}catch(IOException io2){
			System.err.print(io2);
			System.exit(1);	
		}catch(ClassNotFoundException cNf){
			System.err.print(cNf);
			System.exit(1);
		}
	
	return theKey;
	}//end of loadKey

}//End of class