/* 
	Encrypt.java

	Title:			Encryption Example
	Author:			Jon Voiculescu
	Description:	Simple method for encryption/decryption of a text
					Ascii codes of the key are added to the Ascii codes of the source text
					The result is shown in the text area.
					For decryption the addition is replaced by a substraction
*/

package Encrypt;
//
import java.awt.*;
import java.awt.event.*;
import java.applet.*;

public class Encrypt extends Applet 
{
// variables & constants
	String keyText = new String();						// Encription key
	String sourceText = new String();					// Text to be encrypted / decrypted
	String resultText = new String();					// The result of the encryption/decryption operation
	
// BEGIN GENERATED CODE
	// member declarations
	java.awt.TextField textKey = new java.awt.TextField();
	java.awt.Label labelKey = new java.awt.Label();
	java.awt.TextArea textAreaSource = new java.awt.TextArea();
	java.awt.Button bttnEncrypt = new java.awt.Button();
	java.awt.Button bttnDecrypt = new java.awt.Button();
// END GENERATED CODE

	boolean isStandalone = false;

	public Encrypt() 
	{
	}

	// Retrieve the value of an applet parameter
	public String getParameter(String key, String def) 
	{
		return isStandalone ? System.getProperty(key, def) :
			(getParameter(key) != null ? getParameter(key) : def);
	}

	// Get info on the applet parameters
	public String[][] getParameterInfo() 
	{
		return null;
	}

	// Get applet information
	public String getAppletInfo() 
	{
		return "Applet Information";
	}

	// Initialize the applet
	public void init() 
	{
		try {
			initComponents();
		}
		catch (Exception e) {
			e.printStackTrace();
		}
	}

	public void initComponents() throws Exception
	{
// BEGIN GENERATED CODE
		// the following code sets the frame's initial state
		textKey.setSize(new java.awt.Dimension(210, 20));
		textKey.setVisible(true);
		textKey.setText("Key");
		textKey.setLocation(new java.awt.Point(130, 10));

		labelKey.setSize(new java.awt.Dimension(90, 20));
		labelKey.setVisible(true);
		labelKey.setText("Encryption Key");
		labelKey.setLocation(new java.awt.Point(30, 10));
		labelKey.setFont(new java.awt.Font("dialog.bold", 1, 12));

		textAreaSource.setSize(new java.awt.Dimension(630, 440));
		textAreaSource.setVisible(true);
		textAreaSource.setText("Source Text");
		textAreaSource.setLocation(new java.awt.Point(30, 60));

		bttnEncrypt.setSize(new java.awt.Dimension(100, 20));
		bttnEncrypt.setVisible(true);
		bttnEncrypt.setLocation(new java.awt.Point(450, 10));
		bttnEncrypt.setLabel("Encrypt");
		bttnEncrypt.setFont(new java.awt.Font("dialog.bold", 1, 12));

		bttnDecrypt.setSize(new java.awt.Dimension(100, 20));
		bttnDecrypt.setVisible(true);
		bttnDecrypt.setLocation(new java.awt.Point(560, 10));
		bttnDecrypt.setLabel("Decrypt");
		bttnDecrypt.setFont(new java.awt.Font("dialog.bold", 1, 12));

		setSize(new java.awt.Dimension(697, 555));
		setLayout(null);
		setLocation(new java.awt.Point(0, 0));
		add(textKey);
		add(labelKey);
		add(textAreaSource);
		add(bttnEncrypt);
		add(bttnDecrypt);


		bttnEncrypt.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent e) {
				bttnEncryptActionPerformed(e);
			}
		});
		bttnDecrypt.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent e) {
				bttnDecryptActionPerformed(e);
			}
		});
// END GENERATED CODE
		setBackground(Color.white);
	}// end init
//------------------------------------------------Events------------------------------------------
//
//
//  										ENCRYPT
//
//------------------------------------------------------------------------------------------	
	public void bttnEncryptActionPerformed(java.awt.event.ActionEvent e)
	{
	int operation = 1;
	Action(operation);
	return;
	}// end encrypt
//											DECRYPT
//-------------------------------------------------------------------------------------------	
	public void bttnDecryptActionPerformed(java.awt.event.ActionEvent e)
	{
	int operation = -1;
	Action(operation);
	return;
	}// end decrypt
//-------------------------------------------------------------------------------------------
	void Action(int oper)
	{
	keyText = textKey.getText();								//read the text in the Key Field
	keyText = keyText.trim();									//remove leading or ending white spaces
	int keyLength = keyText.length();							//number of chars in Key
	sourceText = textAreaSource.getText();						//read the input text
	int sourceLength = sourceText.length();						//number of chars in the input text
	char[] result = new char[sourceLength];						//char array to store the result
	for (int i=0; i<sourceLength; i++)							//for every char in the input text
		{
		int keyPoz = i%keyLength;								//current position in the key string
		char currentSource = sourceText.charAt(i);				//current char in the input string
		char currentKey = keyText.charAt(keyPoz);				//read the correspond. char in key
		int source = (int)currentSource%128;					//get the ASCII code of the input char
		int key = (int)currentKey%128;							//get the ASCII code of the key char
		int newValue = (source + (oper*key))%128;				//add/substract them into a new ASCII code
		if (newValue<0) newValue = 128 + newValue;				//if the result is <0 make it pozitive
		result[i] = (char)newValue;								//store the coresponding char
		}//end for
	resultText = new String(result);							//convert the result array into string
	textAreaSource.setText(resultText);							//show the result
	return;
	}// end Action
//-----------------------------------------------------------------------------------------------

}// end Applet