Sunday, February 13, 2011

Crypto Samples in java part four -Stream Cipher

SendStream.java

import java.io.FileOutputStream;
import java.io.ObjectOutputStream;

import javax.crypto.Cipher;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

public class SendStream {
 
 public static void main(String[] args) {
  
  String data = "This have I thought good to deliver thee rrrr";
  
  //---------------Encryption ---------------------------------

  SecretKey key = null;

  try {
   KeyGenerator keygen = KeyGenerator.getInstance("DES");
   key = keygen.generateKey();

   Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
   cipher.init(Cipher.ENCRYPT_MODE, key);
   
   FileOutputStream fos = new FileOutputStream("cipher.file"); 
   CipherOutputStream cos = new CipherOutputStream(fos, cipher);
   ObjectOutputStream oos = new ObjectOutputStream(cos);   
   
   
   oos.writeObject(data);
   oos.flush();
   oos.close();
   
   
   FileOutputStream fosKey = new FileOutputStream("key.file"); 
   ObjectOutputStream oosKey = new ObjectOutputStream(fosKey); 
   oosKey.writeObject(key);
   oosKey.writeObject(cipher.getIV());

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

 }

}



ReceiveStream.java

package ucsc.cipher;

import java.io.FileInputStream;
import java.io.ObjectInputStream;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;

public class RecieveStream {
 
 public static void main(String[] args) {
  SecretKey key = null;

  try {
   FileInputStream fisKey = new FileInputStream("key.file"); 
   ObjectInputStream oosKey = new ObjectInputStream(fisKey); 
   
   key =  (SecretKey)oosKey.readObject();
   
   byte[] iv = (byte[])oosKey.readObject();


   Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
   cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
   
   FileInputStream fis = new FileInputStream("cipher.file"); 
   CipherInputStream cis = new CipherInputStream(fis, cipher);
   ObjectInputStream ois = new ObjectInputStream(cis);   
   
   
            System.out.println((String)ois.readObject());   
   
  } catch (Exception e) {
   e.printStackTrace();
  } 

  
 }

}


5 comments :

  1. hai....

    its very grate article. please write more article in java security.

    ReplyDelete
  2. Hi Rama!

    Thank you very much for your comment :-)

    ReplyDelete
  3. IvParameterSpec(iv) ??
    what is that for

    ReplyDelete
  4. thats the initialization vector, you must use it if your mode is not ECB. In this example he uses CBC mode.

    ReplyDelete
  5. Amazing Article, thank you!. I am very glad to read your informative & practical blog. Kindly keep updating your blog.
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    ReplyDelete