Encrypt And Decrypt Example in JAVA

Security is the first concern when you develope application what have sensitive data such as account number, passport number , etc .

Today i want to show example how to do simple encrypt and decrypt method in JAVA.

In this tutorial i will use 3rd party library, you can download the library by the following link :

•  Common-Codecs-1.8

The import library :

import org.apache.commons.codec.binary.Base64;
import java.io.*;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import javax.swing.JOptionPane;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

The SharedVector 

 private static byte[] sharedvector = {
    0x01, 0x02, 0x03, 0x05, 0x07, 0x0B, 0x0D, 0x11
    };

The Encrypt Method :

 public String EncryptText(String RawText)
    {
        String EncText = "";
        byte[] keyArray = new byte[24];
        byte[] temporaryKey;
        String key = "developersnotedotcom";
        byte[] toEncryptArray = null;
 
        try
        {

            toEncryptArray =  RawText.getBytes("UTF-8");        
            MessageDigest m = MessageDigest.getInstance("MD5");
            temporaryKey = m.digest(key.getBytes("UTF-8"));

            if(temporaryKey.length < 24) // DESede require 24 byte length key
            {
                int index = 0;
                for(int i=temporaryKey.length;i< 24;i++)
                {                   
                    keyArray[i] =  temporaryKey[index];
                }
            }        

            Cipher c = Cipher.getInstance("DESede/CBC/PKCS5Padding");            
            c.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(keyArray, "DESede"), new IvParameterSpec(sharedvector));            
            byte[] encrypted = c.doFinal(toEncryptArray);            
            EncText = Base64.encodeBase64String(encrypted);

        }
        catch(NoSuchAlgorithmException | UnsupportedEncodingException | NoSuchPaddingException | InvalidKeyException | InvalidAlgorithmParameterException | IllegalBlockSizeException | BadPaddingException NoEx)
        {
            JOptionPane.showMessageDialog(null, NoEx);
        }

        return EncText;        
    }

  

The Decrypt Method :

  public String DecryptText(String EncText)
    {

        String RawText = "";
        byte[] keyArray = new byte[24];
        byte[] temporaryKey;
        String key = "developersnotedotcom";
        byte[] toEncryptArray = null;

        try
        {
            MessageDigest m = MessageDigest.getInstance("MD5");
            temporaryKey = m.digest(key.getBytes("UTF-8"));           

            if(temporaryKey.length < 24) // DESede require 24 byte length key
            {
                int index = 0;
                for(int i=temporaryKey.length;i< 24;i++)
                {                  
                    keyArray[i] =  temporaryKey[index];
                }
            }
           
            Cipher c = Cipher.getInstance("DESede/CBC/PKCS5Padding");
            c.init(Cipher.DECRYPT_MODE, new SecretKeySpec(keyArray, "DESede"), new IvParameterSpec(sharedvector));
            byte[] decrypted = c.doFinal(Base64.decodeBase64(EncText));   

            RawText = new String(decrypted, "UTF-8");                    
        }
        catch(NoSuchAlgorithmException | UnsupportedEncodingException | NoSuchPaddingException | InvalidKeyException | InvalidAlgorithmParameterException | IllegalBlockSizeException | BadPaddingException NoEx)
        {
            JOptionPane.showMessageDialog(null, NoEx);
        }      

        return RawText; 

    }

   

}

By Mohd Zulkamal
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