Can anyone please give me a working code of Encryption and Decryption

[d_ankoor]

Hi!
I am quite new to Java Security. I will be very grateful if anyone can send me the working code of Encryption and Decryption using Java. Thanks in advance. Ankur.....

[Monika]

function Encrypt(theText) {
output = new String;
Temp = new Array();
Temp2 = new Array();
TextSize = theText.length;
for (i = 0; i < TextSize; i++) {
rnd = Math.round(Math.random() * 122) + 68;
Temp[i] = theText.charCodeAt(i) + rnd;
Temp2[i] = rnd;
}
for (i = 0; i < TextSize; i++) {
output += String.fromCharCode(Temp[i], Temp2[i]);
}
return output;
}
function unEncrypt(theText) {
output = new String;
Temp = new Array();
Temp2 = new Array();
TextSize = theText.length;
for (i = 0; i < TextSize; i++) {
Temp[i] = theText.charCodeAt(i);
Temp2[i] = theText.charCodeAt(i + 1);
}
for (i = 0; i < TextSize; i = i+2) {
output += String.fromCharCode(Temp[i] - Temp2[i]);
}
return output;
}
// End -->
</script>
</HEAD>

[Monika]

The above one was from a discussion forum and the below one two.
/*Acme.Crypto.* is available for free download at www.acme.com*/

/* A small Applet to Encrypt and decrypt using Des3Cipher */

/* input - Type in some text in the textarea above Then enter an eight character key in the Key textfield and click the Encrypt button. */

/* Encrypted output in IE 3.02 and I.E 4.0

ȯ=0yân|A-s_`C_ÝK{BWÐÒ:_øÈ"`^Y¸`U_a EG¯0~5týóÎÆÀe$»7à ¿v_"|QB<)RëÇÜeQ/P__بšØsö)z+ô_;Rû¾ ?&»tÑ8"0M^Þ0ÐS__:~E;ÌaXÐðå¯ØÊߺ_éE

*/

/* Encrypted output in HotJava

ȯ=0yân|A-s_`C_ÝK{BWÐÒ:_øÈ??^Y¸`U_??EG¯?~5týóÎ?Àe$»7Ã?¿v_?|QB<)?ëÇ?eQ/P__بšØsö)z+ô_;?û¾?Ž&»tÑ8?0M^Þ?ÐS__?~E;Ì?XÐðå¯ØÊߺ_éE

*/

/* My observation is the encryption is not the same in both cases*/

/*This code works properly in Netscape navigator and Hot Java Browser */

/* My Code */

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.net.*;
import java.io.*;
import Acme.Crypto.*;

public class ClientApplet3 extends Applet implements ActionListener
{

String textToEncrypt;
byte[] textToDecrypt;
Font normal;
Font big;
Font bigMessage;

java.awt.Button encryptButton;
java.awt.Button decryptButton;
java.awt.Label encryptedLabel;
java.awt.TextArea encryptedTextArea;
java.awt.TextArea decryptedTextArea;
java.awt.Label decryptedLabel;
java.awt.Button resetButton;
byte[] desKey=null;

StringBuffer str1=new StringBuffer();

public void init()
{
super.init();

setLayout(new BorderLayout());
Panel topPanel = new Panel();
topPanel.setLayout(new FlowLayout(FlowLayout.CENTER,20,20));
resetButton = new java.awt.Button("Generate Key");
topPanel.add(resetButton);
encryptButton = new java.awt.Button("Encrypt");
topPanel.add(encryptButton);
decryptButton = new java.awt.Button("Decrypt");
topPanel.add(decryptButton);
add(topPanel,BorderLayout.NORTH);

Panel tempPanel = new Panel();
tempPanel.setLayout(new GridLayout(2,1));

Panel midPanel = new Panel();
midPanel.setLayout(new BorderLayout(20,0));
encryptedLabel = new java.awt.Label("Encrypted Text");
midPanel.add(encryptedLabel,BorderLayout.NORTH);
encryptedTextArea = new java.awt.TextArea();
midPanel.add(encryptedTextArea,BorderLayout.CENTER);
tempPanel.add(midPanel);

Panel bottomPanel = new Panel();
bottomPanel.setLayout(new BorderLayout(20,0));
decryptedLabel = new java.awt.Label("Decrypted Text");
bottomPanel.add(decryptedLabel,BorderLayout.NORTH);
decryptedTextArea = new java.awt.TextArea();
bottomPanel.add(decryptedTextArea,BorderLayout.CENTER);
tempPanel.add(bottomPanel);

add(tempPanel,BorderLayout.CENTER);

Color mint = new Color(128,175,175);

setBackground(mint);

normal = new Font(this.getFont().getName(), Font.BOLD, 12);
big = new Font(this.getFont().getName(), Font.BOLD, 14);
bigMessage = new Font(this.getFont().getName(), Font.BOLD, 16);
encryptedLabel.setText("Text To Encrypt");
decryptedLabel.setFont(normal);
decryptedLabel.setText("Message");
decryptedTextArea.setFont(big);
decryptedTextArea.setText("Type in some text in the textarea above\n");
decryptedTextArea.append("Then enter an eight character key in the Key textfield\n");
decryptedTextArea.append("and click the Encrypt button.");

encryptedTextArea.requestFocus();

// Code to add the Action Listener

encryptButton.addActionListener(this);
decryptButton.addActionListener(this);
resetButton.addActionListener(this);

}

public void actionPerformed(ActionEvent ae)
{

if (ae.getActionCommand() == "Encrypt")
{
showStatus("encryption Started");
encryptbutton_Clicked(desKey);

}
else if (ae.getActionCommand() == "Generate Key")
{

showStatus("Generate Key");

//Hard Coding the key for testing
desKey=fromString("d18a17ce851d99dfcb01d6c714e6446");
showStatus("Key Length :" + desKey.length + "Key in Hex Format:" + keyString(desKey) );
}
else if (ae.getActionCommand()== "Decrypt")
{
showStatus("Decrypting");
decrypt(desKey,str1.toString().getBytes());

}
}

void encryptbutton_Clicked(byte[] desKey)
{
String textToEncrypt = encryptedTextArea.getText();

if(textToEncrypt.length()==0)
{
decryptedTextArea.setText("Please enter some text to encrypt");
return ;
}

/// A simple Padding Scheme

// Pad the text if not a mutiple of 8
// the last charecter indicating the number of charecters padded
// for none

int Count = textToEncrypt.length() % 8;

if (Count != )
{
int PaddedChrs=1 ;

while(Count < 7)
{
textToEncrypt += 1;
Count += 1;
PaddedChrs += 1;
}

textToEncrypt+=PaddedChrs;

}

// Convert the clearText to bytes
byte[] clearText = new byte[8];
byte[] ciphertext = new byte[8];
int srcBegin =0;
int srcEnd =8;

Des3Cipher des;
String tempStr =null;

try
{
// Create the cipher

des = new Des3Cipher(desKey);

System.out.println("Text Length" + textToEncrypt.length());

for ( ;srcEnd<=textToEncrypt.length(); )
{
clearText=textToEncrypt.substring(srcBegin,srcEnd).getBytes();

// output to console to check the byte going for a six
System.out.println("To Encrypt " + new String(clearText));

srcBegin=srcEnd;
srcEnd = srcEnd+8;

des.encrypt(clearText,0, ciphertext,0);

textToDecrypt= ciphertext;
tempStr = new String(ciphertext);
str1.append(tempStr);
}

System.out.println("Encrypted String" + str1);
System.out.println("Encrypted String" + str1.length());

encryptedTextArea.setText("Cipher Text " + str1.toString());
encryptedLabel.setText("Encrypted Text");

encryptButton.setEnabled(false);
// decryptButton.setEnabled(true);
// decryptButton.setVisible(true);
encryptedTextArea.requestFocus();

}

catch (Exception e)
{
showStatus(e.toString());
}

}

private void decrypt(byte[] sessionKey,byte[] ciphertext)
{
try
{
Des3Cipher des;
String textToDecrypt = new String(ciphertext);
String tempStr ;
byte[] tempCipherText = new byte[8];
byte[] decrypted=new byte[8];
int srcBegin= ;
int srcEnd=8;
StringBuffer str = new StringBuffer();

des = new Des3Cipher(sessionKey);

for ( ; srcEnd<=textToDecrypt.length(); )
{
//textToDecrypt.getBytes(srcBegin,srcEnd,tempCipherText,0);
tempCipherText=textToDecrypt.substring(srcBegin,srcEnd).getBytes();
srcBegin=srcEnd;
srcEnd = srcEnd+8;

des.decrypt(tempCipherText,0,decrypted,0);

tempStr = new String(decrypted);
str.append(tempStr);
}

System.out.println("Decrypted Text " + str.toString());
encryptedTextArea.setText("Deciphered Text " + str.toString());
encryptedLabel.setText("Deciphered Text");

}

catch (Exception e)
{
e.printStackTrace();
}

}

public String keyString(byte[] key)
{
String returnVal = "";

for (int i=0; i < key.length; i++) {
returnVal += Integer.toHexString(key[i]&0xff);
}

return returnVal;
}

/**
* Returns a byte array from a string of hexadecimal digits.
*/
public byte[] fromString(String hex) {
int len = hex.length();
byte[] buf = new byte[((len + 1) / 2)];

int i = 0, j = 0;
if ((len % 2) == 1)
buf[j++] = (byte) fromDigit(hex.charAt(i++));

while (i < len) {
buf[j++] = (byte) ((fromDigit(hex.charAt(i++)) << 4) |
fromDigit(hex.charAt(i++)));
}
return buf;
}

/**
* Returns the number from to 15 corresponding to the hex digit <i>ch</i>.
*/
public int fromDigit(char ch) {
if (ch >= '0' && ch <= '9')
return ch - '0';
if (ch >= 'A' && ch <= 'F')
return ch - 'A' + 10;
if (ch >= 'a' && ch <= 'f')
return ch - 'a' + 10;

throw new IllegalArgumentException("invalid hex digit '" + ch + "'");
}

}
Kindly help at the earliest . Is it a problem with IE or the code ?

Thanx in advance

Kotesh Babu
kotesht@synectics.soft.net

sol :
1)____________
After evaluating your code, all seems to be well in your applet. The problem is that the IE VM uses Microsoft components that convert TextArea text
into a different form before it can be used. Since the Text is different in the TextArea in IE, your encryption or decryption will not work very well. Your
best bet is to use HotJava to run your applet or use Appletviewer which is included in the Sun JDK.

Although most applets will run fine in IE, anything that deals with Java cryptology should only run in a relatively PURE environment, like HotJava of a
JDK viewer.
**************************
Hi dude, well, if you want a basic cryptography method which is bidirectionnal (Read <->
Write) using a password, you can try this, it's not exhaustive, it's not like a try only like in
UNIX, neither PGP, but quite useful if you want to encrypt quickly with some safety:

u take each byte and u XOR it with another Byte.

i.e 'a' XOR 255 => encrypted 'a'
encrypted 'a' XOR 255 => 'a'

You can use a password with positionning byte inside it using modulus and maybe some
Random generic code add to it to make it harder a bit to encrypt it. For sure the Random
thing must be writted somewhere, but it makes it sometime less obvious.

the principle is the same the byte XOR the key

the key is going weird as you can program it using Password, Random Key, counter, etc.

I hope that this help you a bit,
for low security encryption !